Author Topic: Floating Habitat on Venus  (Read 55193 times)

Offline sanman

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Floating Habitat on Venus
« on: 11/27/2018 08:03 pm »
People have said the upper atmosphere of Venus at ~50km altitude is perhaps the most Earth-like environment that can be found in our solar system, outside of Earth itself. Some have speculated that it might be possible to have floating habitats in that upper atmospheric zone, based on the idea that under those conditions breathable atmosphere is a lifting gas. This could enable a large floating structure filled with oxygen-nitrogen atmosphere to also serve as a living space.

NASA even has a concept called HAVOC:

https://en.wikipedia.org/wiki/High_Altitude_Venus_Operational_Concept



How would such habitats be implemented in practice? Could they be built in space and then somehow dropped from orbit into place on Venus?

Would they be purely inflatable balloon-like structures, or could they be rigid dirigible-type structures, or some combination of both?

Could inflatable sections be inflated on the way down, with any rigid portions being cured/rigidified in-situ later on?

Could the habitats eventually somehow be fabricated on Venus itself?
« Last Edit: 12/02/2018 11:22 am by sanman »

Offline WellingtonEast

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Re: Floating Habitat on Venus
« Reply #1 on: 11/28/2018 11:14 pm »
If inflated objects can float in the upper reaches of Venus atmosphere, I am surprised that we haven't already tried to send small scientific packages there as atmosphere braking with Aeroshells is a developed technology.

I imagine they could be made quiet light and Venus sensing equipment being so close to the surface could provide a wealth of data especially as it would be drifting over the land and not stationary.

I did find this recent article on India's plan to do just this...

https://www.sciencemag.org/news/2018/11/india-seeks-collaborators-mission-venus-neglected-planet

Offline GWH

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Re: Floating Habitat on Venus
« Reply #2 on: 11/28/2018 11:55 pm »
Would they be purely inflatable balloon-like structures, or could they be rigid dirigible-type structures, or some combination of both?

Could inflatable sections be inflated on the way down, with any rigid portions being cured/rigidified in-situ later on?

This reminds me of JP Aerospace, who proposes an Airship to Orbit using a rigid airship accelerating with "hybrid electric chemical" propulsion to slowly accelerate. It's certainly an.... interesting... concept. I could imagine being a lot more successful operating in reverse.
http://www.jpaerospace.com/
https://www.tmro.tv/2016/11/30/low-earth-orbit-airships/

Also another application for air breathing electric thrusters after aerocapture.

Pretty off the wall concepts, but opens up some interesting possibilities when compared with the traditional heat shield + parachute concepts.

Offline speedevil

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Re: Floating Habitat on Venus
« Reply #3 on: 11/28/2018 11:59 pm »
It would be great if there was even a hair more hydrogen in the atmosphere.
It's really unfortunately dry.

Offline high road

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Re: Floating Habitat on Venus
« Reply #4 on: 11/29/2018 09:16 am »
How would such habitats be implemented in practice? Could they be built in space and then somehow dropped from orbit into place on Venus?


Why would you assemble them in space? Assemble them on Earth, launch them on a big enough launcher, inflate them over there. Afterwards install everything not needed for EDL/inflation/entry after inflation in a shirtsleeve environment.

Inflation on the way down seems to be the part that's the hardest to design for, if we're talking about large structures. Limiting the mass of the vehicle as much as possible until after that point looks very beneficial. On the other hand, structural integrity benefits the inflation process, and some parts may be too clumsy to install post inflation. Plenty of trade-offs to be made.

Quote
Could the habitats eventually somehow be fabricated on Venus itself?

For varying definitions of 'could'. Are you talking about building a sort of 'drydock' where larger structures can be assembled from individual parts shipped from Earth, in a shirtsleeve environment? I don't see any technical reason why not, but assembling the drydock in the first place is going to take some fancy construction work. You would need a very good reason to build larger structures than can be sent from Earth.

If you are talking about fabricating them from local materials: well, there's enough carbon, hydrogen and oxygen around to play around with. Protection from sulphuric acid and other sulphur compounds is going to be an issue that probably needs continual supplies from home, until you've done enough exploration of the planet to know what resources can be extracted from the surface. At this point, the heat at the surface is no longer a showstopping issue for mining operations. You can use the infrastructure at 50km altitude to produce all the coolant, fuel/power, lifting gas, remote operation etc you need.

Quote
Would they be purely inflatable balloon-like structures, or could they be rigid dirigible-type structures, or some combination of both?

Early on, you want dirigibles to make the days as long and the nights as short as possible. (about four earth days for a full day, depending on where you put the habitat). You also want to avoid drifting to the poles. Afterwards, if the structures become much bigger and not quite manoeuverable anyway, designs will probably become more spherical, or somewhat tear-shaped for stability. But even then, there will be rigid internal structures. Unlike inflatables on Earth, the living area provides (some of) the lift.

Quote
Could inflatable sections be inflated on the way down, with any rigid portions being cured/rigidified in-situ later on?

That is the idea. You could also inflate before coming down. Do a search for 'hamsterball' to find the explanation in the previous Venus-related thread. Inflation on the way down becomes harder for larger, heavier structures.

If inflated objects can float in the upper reaches of Venus atmosphere, I am surprised that we haven't already tried to send small scientific packages there as atmosphere braking with Aeroshells is a developed technology.

I imagine they could be made quiet light and Venus sensing equipment being so close to the surface could provide a wealth of data especially as it would be drifting over the land and not stationary.

I did find this recent article on India's plan to do just this...

https://www.sciencemag.org/news/2018/11/india-seeks-collaborators-mission-venus-neglected-planet

Some of the Vega and Venera missions had atmospheric probes on them. Since then, getting missions funded has been an issue. Atmospheric probes without propulsion will eventually drift to the poles in a month or so, IIRC. Probably to be destroyed in the storms there. There's a lot of research left to do on Venus, but most of that research has different optimal altitudes. There's a learning curve to design spacecraft fit for Venus' upper atmosphere, and not too many scientists currently have a Venus-related career which would have them actively supporting Venus-probes. That sums up most of the reasons.

It would be great if there was even a hair more hydrogen in the atmosphere.
It's really unfortunately dry.

As far as we can tell, the SO2 over there is converted to SO3 which reacts with water. Adding more H2 would just increase the amount of sulphuric acid in the clouds for quite some time. A good measurement of exactly how much sulphuric acid there is to work with, would go a long way in determining how viable ISRU is. Probably a lot easier than digging it out of the ground on Mars, considering it's all liquids and gas. There might be plenty hydrogen left to support quite a high level of human activity.

Offline edzieba

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Re: Floating Habitat on Venus
« Reply #5 on: 11/29/2018 12:57 pm »
Is there any reason not to fully inflate and kit out any habitat in Earth orbit before boosting it to Venus? All that mass needs to be boosted anyway regardless of configuration, and for atmospheric entry lower density is an advantage.

Offline RonM

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Re: Floating Habitat on Venus
« Reply #6 on: 11/29/2018 03:54 pm »
Is there any reason not to fully inflate and kit out any habitat in Earth orbit before boosting it to Venus? All that mass needs to be boosted anyway regardless of configuration, and for atmospheric entry lower density is an advantage.

The inflated envelope would be exposed to orbital debris. Best to keep it packed and protected on the trip to Venus.

Offline sanman

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Re: Floating Habitat on Venus
« Reply #7 on: 11/30/2018 05:05 pm »
I've read that divers and submariners have used helium-oxygen mixtures instead of nitrogen-oxygen to breathe with, and have done just fine (other than the cartoon-voice side-effect).

Could helium-oxygen provide enough advantage as a lifting gas compared to nitrogen-oxygen, to make it worth using instead?

Offline speedevil

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Re: Floating Habitat on Venus
« Reply #8 on: 11/30/2018 07:07 pm »
Is there any reason not to fully inflate and kit out any habitat in Earth orbit before boosting it to Venus? All that mass needs to be boosted anyway regardless of configuration, and for atmospheric entry lower density is an advantage.

You do not in the stowed configuration need to transport in air.
If you are considering a large base of say a hundred tons solid mass, lifted by air, that would need around a hundred tons of air to lift it. (approximately).

Inflate with half the nominal pressure of hydrogen, would be one option, to save considerably on the launch mass. Then inflate with nitrogen, and carefully react the hydrogen with incoming oxygen for free water.

Note that the entry in the deflated case is not a very low areal density one - for the hundred ton mass class base, it's 150kg/m^2 or so.

I am assuming a large base, as you'd want it to be able to do ISRU of CO2 to make CO/O propellant, and a robust structure large enough to carry a fuelled rocket capable of lifting people.

A hundred tons may be too small.

I see no particular reason from a debris POV to not launch inflated - this is a nearly zero pressure balloon, which will pretty much require flying robots anyway. Sticking a square of tape over a pinhole isn't a real issue.


Offline sanman

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Re: Floating Habitat on Venus
« Reply #9 on: 12/01/2018 01:21 am »
Some of these high-altitude balloons over the Earth use solar heating to assist their buoyancy. Even a simple black plastic garbage bag can be used to demonstrate this on a hot day. Would such solar thermal heating/absorption be useful for a floating Venus habitat?
« Last Edit: 12/01/2018 01:46 am by sanman »

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #10 on: 12/01/2018 12:38 pm »
I've read that divers and submariners have used helium-oxygen mixtures instead of nitrogen-oxygen to breathe with, and have done just fine (other than the cartoon-voice side-effect).

Could helium-oxygen provide enough advantage as a lifting gas compared to nitrogen-oxygen, to make it worth using instead?

An interesting idea. It might be of use in the initial stages depending on how big the habitat was and the mass of the equipment needed. A considerable amount of lift would be provided by simple 21% Oxygen 79% Nitrogen air. By my calculation around 0.67 kg of lift per cubic metre, but Helium would provide almost 3 times as much which would be very useful assuming that initially whatever gas is used would be imported from earth.

But longer term Helium has two big draw backs – it amounts to only 12ppm of the atmosphere of Venus compared to 3500ppm for Nitrogen, so Nitrogen can be much more easily sourced locally which is important as a lot will be required. And Helium has a much greater tendency to leak compared to Nitrogen and this problem will only be exacerbated as the volume and surface area of the habitat increases.

Another option would be to increase the pressure of the atmosphere in the habitat whilst maintaining the same partial pressure of oxygen so that it floated deeper down in the atmosphere. This would provide the added advantage of increased radiation protection, but at the cost of additional heat loading.

It’s hard to say exactly what pressure / temperature / altitude would be most suitable at the moment, in fact it might be beneficial to allow the habitat to rise and descend (within bounds) depending on circumstances deeper = higher pressure and temperature, higher = lower pressure and temperature.
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #11 on: 12/01/2018 12:46 pm »
Some of these high-altitude balloons over the Earth use solar heating to assist their buoyancy. Even a simple black plastic garbage bag can be used to demonstrate this on a hot day. Would such solar thermal heating/absorption be useful for a floating Venus habitat?
Changing the heat absorption properties of the envelope or its covering might be useful, although bear in mind that if people are living in the envelope it will make their environment hotter as well. This would be counteracted to some extent by reduced atmospheric temperature at higher altitudes.
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Offline TripleSeven

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Re: Floating Habitat on Venus
« Reply #12 on: 12/01/2018 12:48 pm »
I've read that divers and submariners have used helium-oxygen mixtures instead of nitrogen-oxygen to breathe with, and have done just fine (other than the cartoon-voice side-effect).

Could helium-oxygen provide enough advantage as a lifting gas compared to nitrogen-oxygen, to make it worth using instead?

An interesting idea. It might be of use in the initial stages depending on how big the habitat was and the mass of the equipment needed. A considerable amount of lift would be provided by simple 21% Oxygen 79% Nitrogen air. By my calculation around 0.67 kg of lift per cubic metre, but Helium would provide almost 3 times as much which would be very useful assuming that initially whatever gas is used would be imported from earth.

But longer term Helium has two big draw backs – it amounts to only 12ppm of the atmosphere of Venus compared to 3500ppm for Nitrogen, so Nitrogen can be much more easily sourced locally which is important as a lot will be required. And Helium has a much greater tendency to leak compared to Nitrogen and this problem will only be exacerbated as the volume and surface area of the habitat increases.

Another option would be to increase the pressure of the atmosphere in the habitat whilst maintaining the same partial pressure of oxygen so that it floated deeper down in the atmosphere. This would provide the added advantage of increased radiation protection, but at the cost of additional heat loading.

It’s hard to say exactly what pressure / temperature / altitude would be most suitable at the moment, in fact it might be beneficial to allow the habitat to rise and descend (within bounds) depending on circumstances deeper = higher pressure and temperature, higher = lower pressure and temperature.

you seem quite knowledeable...and I am fascinated by your post

what would be the pressure of the "balloons" ie the PSID?

if the habitats could "float" at the 1 bar or close to that line  that would be an enormous advantage in terms of "life" because just to "go outside" and work on things would not require a pressure suit...

Offline daedalus1

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Re: Floating Habitat on Venus
« Reply #13 on: 12/01/2018 01:54 pm »
Getting into and out of Venus's gravity well is almost as difficult as Earth's. It would be far easier just to have an orbital outpost. Obviously tou wouldn't have 1G unless it spun.

Offline KelvinZero

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Re: Floating Habitat on Venus
« Reply #14 on: 12/01/2018 02:21 pm »
Getting into and out of Venus's gravity well is almost as difficult as Earth's. It would be far easier just to have an orbital outpost. Obviously tou wouldn't have 1G unless it spun.
What would you do with the orbital outpost though? What ISRU? There are various ideas to scoop atmosphere and also use it for station keeping. That gives you carbon and oxygen, and a bit of nitrogen, a tiny bit of sulphur and not much else (hydrogen down in the ppm it seems)

Maybe you could build space solar power and orbiting lasers to eventually power reusable SSTO craft. It would be easier to develop that around earth of course, though people might be nervous of those sorts of lasers in orbit.

Although there are limited elements you can build some miracle materials with pretty much just carbon. This technology mix seems pretty specialised to Venus though.

Offline daedalus1

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Re: Floating Habitat on Venus
« Reply #15 on: 12/01/2018 02:31 pm »
'What would you do with an orbital outpost?'
Nothing, about the same as a floating outpost. It is cheaper and easier to bring carbon and oxygen from earth to Venus orbit than from the atmosphere.

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #16 on: 12/01/2018 05:51 pm »
I've read that divers and submariners have used helium-oxygen mixtures instead of nitrogen-oxygen to breathe with, and have done just fine (other than the cartoon-voice side-effect).

Could helium-oxygen provide enough advantage as a lifting gas compared to nitrogen-oxygen, to make it worth using instead?

An interesting idea. It might be of use in the initial stages depending on how big the habitat was and the mass of the equipment needed. A considerable amount of lift would be provided by simple 21% Oxygen 79% Nitrogen air. By my calculation around 0.67 kg of lift per cubic metre, but Helium would provide almost 3 times as much which would be very useful assuming that initially whatever gas is used would be imported from earth.

But longer term Helium has two big draw backs – it amounts to only 12ppm of the atmosphere of Venus compared to 3500ppm for Nitrogen, so Nitrogen can be much more easily sourced locally which is important as a lot will be required. And Helium has a much greater tendency to leak compared to Nitrogen and this problem will only be exacerbated as the volume and surface area of the habitat increases.

Another option would be to increase the pressure of the atmosphere in the habitat whilst maintaining the same partial pressure of oxygen so that it floated deeper down in the atmosphere. This would provide the added advantage of increased radiation protection, but at the cost of additional heat loading.

It’s hard to say exactly what pressure / temperature / altitude would be most suitable at the moment, in fact it might be beneficial to allow the habitat to rise and descend (within bounds) depending on circumstances deeper = higher pressure and temperature, higher = lower pressure and temperature.

you seem quite knowledeable...and I am fascinated by your post

what would be the pressure of the "balloons" ie the PSID?

if the habitats could "float" at the 1 bar or close to that line  that would be an enormous advantage in terms of "life" because just to "go outside" and work on things would not require a pressure suit...
Thanks  :) There are a range of possibilities depending on the setup.
The situation is analogous to a Helium balloon in Earth’s atmosphere with terrestrial air replacing Helium as the lifting gas and Venusian atmosphere replacing Earth’s atmosphere as the medium.

Such a balloon is less dense than the atmosphere surrounding it, so it will rise. Higher up, as the atmospheric density reduces, the balloon will expand until either it pops, or the balloon fabric provides sufficient resistance to prevent further expansion and no further volume increase is possible. The fixed volume balloon will continue to rise steadily losing buoyancy until the density of the balloon matches that of the surrounding atmosphere at which point it will float at that altitude with a slightly higher pressure than the surrounding air.

The change in pressure and temperature in the Venusian atmosphere can be seen here:
https://en.wikipedia.org/wiki/Atmosphere_of_Venus#/media/File:Venusatmosphere.svg

At just under 50 km altitude the temperature is around 20 degrees C and the atmospheric pressure is between 1 and 2 bar. This is the ideal location to float the balloon. If it floats too high add weight or restrict the volume if it’s too low remove weight or increase the volume.

Bizarrely a person could probably climb onto the outside of the vehicle in shirtsleeves with just a face mask to provide oxygen and protect the mucus membranes from sulphur dioxide (Avatar style). No pressure suit required, although it wouldn’t be advisable and no doubt the safety wonks would have a conniption! The atmosphere of Venus contains around 150ppm SO2 but 500ppm exposure is probably OK for short periods especially with a face mask. 
https://www.ncbi.nlm.nih.gov/books/NBK208295/
« Last Edit: 12/01/2018 05:52 pm by Slarty1080 »
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Online Bob Shaw

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Re: Floating Habitat on Venus
« Reply #17 on: 12/01/2018 05:57 pm »
There have already been balloons in the atmosphere of Venus, deposited by the Soviet Union in 1986.

Offline TripleSeven

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Re: Floating Habitat on Venus
« Reply #18 on: 12/01/2018 06:03 pm »
I've read that divers and submariners have used helium-oxygen mixtures instead of nitrogen-oxygen to breathe with, and have done just fine (other than the cartoon-voice side-effect).

Could helium-oxygen provide enough advantage as a lifting gas compared to nitrogen-oxygen, to make it worth using instead?

An interesting idea. It might be of use in the initial stages depending on how big the habitat was and the mass of the equipment needed. A considerable amount of lift would be provided by simple 21% Oxygen 79% Nitrogen air. By my calculation around 0.67 kg of lift per cubic metre, but Helium would provide almost 3 times as much which would be very useful assuming that initially whatever gas is used would be imported from earth.

But longer term Helium has two big draw backs – it amounts to only 12ppm of the atmosphere of Venus compared to 3500ppm for Nitrogen, so Nitrogen can be much more easily sourced locally which is important as a lot will be required. And Helium has a much greater tendency to leak compared to Nitrogen and this problem will only be exacerbated as the volume and surface area of the habitat increases.

Another option would be to increase the pressure of the atmosphere in the habitat whilst maintaining the same partial pressure of oxygen so that it floated deeper down in the atmosphere. This would provide the added advantage of increased radiation protection, but at the cost of additional heat loading.

It’s hard to say exactly what pressure / temperature / altitude would be most suitable at the moment, in fact it might be beneficial to allow the habitat to rise and descend (within bounds) depending on circumstances deeper = higher pressure and temperature, higher = lower pressure and temperature.

you seem quite knowledeable...and I am fascinated by your post

what would be the pressure of the "balloons" ie the PSID?

if the habitats could "float" at the 1 bar or close to that line  that would be an enormous advantage in terms of "life" because just to "go outside" and work on things would not require a pressure suit...
Thanks  :) There are a range of possibilities depending on the setup.
The situation is analogous to a Helium balloon in Earth’s atmosphere with terrestrial air replacing Helium as the lifting gas and Venusian atmosphere replacing Earth’s atmosphere as the medium.

Such a balloon is less dense than the atmosphere surrounding it, so it will rise. Higher up, as the atmospheric density reduces, the balloon will expand until either it pops, or the balloon fabric provides sufficient resistance to prevent further expansion and no further volume increase is possible. The fixed volume balloon will continue to rise steadily losing buoyancy until the density of the balloon matches that of the surrounding atmosphere at which point it will float at that altitude with a slightly higher pressure than the surrounding air.

The change in pressure and temperature in the Venusian atmosphere can be seen here:
https://en.wikipedia.org/wiki/Atmosphere_of_Venus#/media/File:Venusatmosphere.svg

At just under 50 km altitude the temperature is around 20 degrees C and the atmospheric pressure is between 1 and 2 bar. This is the ideal location to float the balloon. If it floats too high add weight or restrict the volume if it’s too low remove weight or increase the volume.

Bizarrely a person could probably climb onto the outside of the vehicle in shirtsleeves with just a face mask to provide oxygen and protect the mucus membranes from sulphur dioxide (Avatar style). No pressure suit required, although it wouldn’t be advisable and no doubt the safety wonks would have a conniption! The atmosphere of Venus contains around 150ppm SO2 but 500ppm exposure is probably OK for short periods especially with a face mask. 
https://www.ncbi.nlm.nih.gov/books/NBK208295/

thanks that jibes with what I have heard.  I am intrigued by this for several reasons...first I think such a "balloon" uncrewed would be an ideal platform for a wide variety of scientfic instruments, including some very detailed radar mapping, surface probes and even maybe some surface return programs.  Second it is possible that there is life in the atmosphere...and third it would be an interesting technology effort

for crewed "stations" (maybe 5=10 people) it is the same as the above plus it simplifies enormously the on orbit issues of solar radiation and provides a "more shirtsleeve" environment where you dont have to wear a full pressure suit (with the issues you have noted)

thanks again

Offline sanman

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Re: Floating Habitat on Venus
« Reply #19 on: 12/02/2018 04:17 am »
An interesting idea. It might be of use in the initial stages depending on how big the habitat was and the mass of the equipment needed. A considerable amount of lift would be provided by simple 21% Oxygen 79% Nitrogen air. By my calculation around 0.67 kg of lift per cubic metre, but Helium would provide almost 3 times as much which would be very useful assuming that initially whatever gas is used would be imported from earth.

But longer term Helium has two big draw backs – it amounts to only 12ppm of the atmosphere of Venus compared to 3500ppm for Nitrogen, so Nitrogen can be much more easily sourced locally which is important as a lot will be required. And Helium has a much greater tendency to leak compared to Nitrogen and this problem will only be exacerbated as the volume and surface area of the habitat increases.

Graphene is one of those much-hyped materials that's attracted a lot of investigation for various promised benefits.
I remember reading way back about research into using Graphene as a barrier to trap Helium, which it's supposed to be impermeable to:

http://news.cornell.edu/stories/2008/09/cu-physicists-create-worlds-thinnest-balloon

https://www.nature.com/articles/ncomms5843

http://science.sciencemag.org/content/335/6067/442

Apparently, the only Helium loss that cannot be avoided is through Quantum Tunneling(!)  :o


Quote
Another option would be to increase the pressure of the atmosphere in the habitat whilst maintaining the same partial pressure of oxygen so that it floated deeper down in the atmosphere. This would provide the added advantage of increased radiation protection, but at the cost of additional heat loading.

It’s hard to say exactly what pressure / temperature / altitude would be most suitable at the moment, in fact it might be beneficial to allow the habitat to rise and descend (within bounds) depending on circumstances deeper = higher pressure and temperature, higher = lower pressure and temperature.

The whole reason why divers and submariners have used the helium-oxygen breathing gas mixtures in the past, was to reduce their risk of suffering "the bends", which occurs when pressure is reduced suddenly after prolonged exposure to higher pressures. This is because at higher pressures the inhaled nitrogen gas dissolves and enters the bloodstream, so that if pressure suddenly reduces then the dissolved nitrogen quickly returns to gaseous state forming bubbles in the bloodstream, which is dangerous to human health.

What's the risk that a human crew in a floating Venus hab could somehow encounter this kind of problem?

If there's a significant risk, then maybe helium-oxgyen could be useful to mitigate it.

I've read that the balloons on the Vega missions encountered winds up to 700 km/h, causing them to be swept across large distances around Venus within mere hours.

What minimum altitude is required to avoid wind/weather/turbulence?

I'm imagining it wouldn't be safe to do a manned mission without first mapping out known atmospheric weather patterns, including particular updrafts, downdrafts, and related currents. Are these things already adequately known, or are they yet to be determined, or are they generally impossible to reliably predict?
« Last Edit: 12/02/2018 04:22 am by sanman »

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #20 on: 12/03/2018 12:56 am »
An interesting idea. It might be of use in the initial stages depending on how big the habitat was and the mass of the equipment needed. A considerable amount of lift would be provided by simple 21% Oxygen 79% Nitrogen air. By my calculation around 0.67 kg of lift per cubic metre, but Helium would provide almost 3 times as much which would be very useful assuming that initially whatever gas is used would be imported from earth.

But longer term Helium has two big draw backs – it amounts to only 12ppm of the atmosphere of Venus compared to 3500ppm for Nitrogen, so Nitrogen can be much more easily sourced locally which is important as a lot will be required. And Helium has a much greater tendency to leak compared to Nitrogen and this problem will only be exacerbated as the volume and surface area of the habitat increases.

Graphene is one of those much-hyped materials that's attracted a lot of investigation for various promised benefits.
I remember reading way back about research into using Graphene as a barrier to trap Helium, which it's supposed to be impermeable to:

http://news.cornell.edu/stories/2008/09/cu-physicists-create-worlds-thinnest-balloon

https://www.nature.com/articles/ncomms5843

http://science.sciencemag.org/content/335/6067/442

Apparently, the only Helium loss that cannot be avoided is through Quantum Tunneling(!)  :o


Quote
Another option would be to increase the pressure of the atmosphere in the habitat whilst maintaining the same partial pressure of oxygen so that it floated deeper down in the atmosphere. This would provide the added advantage of increased radiation protection, but at the cost of additional heat loading.

It’s hard to say exactly what pressure / temperature / altitude would be most suitable at the moment, in fact it might be beneficial to allow the habitat to rise and descend (within bounds) depending on circumstances deeper = higher pressure and temperature, higher = lower pressure and temperature.

The whole reason why divers and submariners have used the helium-oxygen breathing gas mixtures in the past, was to reduce their risk of suffering "the bends", which occurs when pressure is reduced suddenly after prolonged exposure to higher pressures. This is because at higher pressures the inhaled nitrogen gas dissolves and enters the bloodstream, so that if pressure suddenly reduces then the dissolved nitrogen quickly returns to gaseous state forming bubbles in the bloodstream, which is dangerous to human health.

What's the risk that a human crew in a floating Venus hab could somehow encounter this kind of problem?

If there's a significant risk, then maybe helium-oxgyen could be useful to mitigate it.

I've read that the balloons on the Vega missions encountered winds up to 700 km/h, causing them to be swept across large distances around Venus within mere hours.

What minimum altitude is required to avoid wind/weather/turbulence?

I'm imagining it wouldn't be safe to do a manned mission without first mapping out known atmospheric weather patterns, including particular updrafts, downdrafts, and related currents. Are these things already adequately known, or are they yet to be determined, or are they generally impossible to reliably predict?
I believe it would be unlikely that an atmospheric pressure of more than 2 bars would be required. At this pressure and altitude the temperature would already be on the high side. I don’t think there is any likelihood of a sudden depressurisation as the atmospheric pressure inside and out would be the same. There is no problem with breathing air at 2 bars provided the partial pressure of oxygen is reduced. Higher pressures do have adverse effects.

Being a balloon it would be carried by the wind so although it would move rapidly with respect to the ground, the atmosphere around it should be relatively still compared to the balloon. I don’t think it would be possible to avoid the winds on Venus - 700 km/hr high up but at the surface the CO2 is almost supercritical and the wind speeds are just a few km/hour so it’s more like an ocean current.

It would certainly be wise to research the wind patterns in detail before attempting any such mission, but wind speed should not be a show stopper. Not sure if this is remotely likely, but in extremes a vehicle caught in a "down draft" could always inflate an emergency additional balloon to increase its buoyancy and drag it against the flow.


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Offline sanman

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Re: Floating Habitat on Venus
« Reply #21 on: 12/03/2018 09:35 am »
I believe it would be unlikely that an atmospheric pressure of more than 2 bars would be required. At this pressure and altitude the temperature would already be on the high side. I don’t think there is any likelihood of a sudden depressurisation as the atmospheric pressure inside and out would be the same. There is no problem with breathing air at 2 bars provided the partial pressure of oxygen is reduced. Higher pressures do have adverse effects.

Being a balloon it would be carried by the wind so although it would move rapidly with respect to the ground, the atmosphere around it should be relatively still compared to the balloon. I don’t think it would be possible to avoid the winds on Venus - 700 km/hr high up but at the surface the CO2 is almost supercritical and the wind speeds are just a few km/hour so it’s more like an ocean current.

It would certainly be wise to research the wind patterns in detail before attempting any such mission, but wind speed should not be a show stopper. Not sure if this is remotely likely, but in extremes a vehicle caught in a "down draft" could always inflate an emergency additional balloon to increase its buoyancy and drag it against the flow.

I was thinking sudden up-or-down movement could then have associated sudden changes in pressure, so that's why I was asking about suffering the bends.

For winds up to 700km/h it sounds like a large balloon/dirigible might not be able to survive that, including any turbulence forces. Up to what altitudes do these winds extend? Here on Earth atmospheric weather/movement are only supposed extend up to 10km altitude, and above that it's quite calm. But I guess Venus with its more extreme solar heating and tidal locking has much more atmospheric convection going on.

How is a floating habitat supposed to survive high wind velocities on Venus?

Offline high road

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Re: Floating Habitat on Venus
« Reply #22 on: 12/03/2018 09:48 am »
'What would you do with an orbital outpost?'
Nothing, about the same as a floating outpost. It is cheaper and easier to bring carbon and oxygen from earth to Venus orbit than from the atmosphere.

An orbital outpost would be equally fine for teleoperating surface or low-atmosphere equipment, but a floating outpost would have the added benefit of providing a shirtsleeve environment for maintenance and refitting of surface equipment, researching samples, and possibly even allow short trips to the surface to look at things with human eyes if there would ever be a need to do that. IMO, that's about exactly the same as what a human crew on Mars would eventually be filling their days with.

The whole reason why divers and submariners have used the helium-oxygen breathing gas mixtures in the past, was to reduce their risk of suffering "the bends", which occurs when pressure is reduced suddenly after prolonged exposure to higher pressures. This is because at higher pressures the inhaled nitrogen gas dissolves and enters the bloodstream, so that if pressure suddenly reduces then the dissolved nitrogen quickly returns to gaseous state forming bubbles in the bloodstream, which is dangerous to human health.

What's the risk that a human crew in a floating Venus hab could somehow encounter this kind of problem?

For the people inside the hab, not really a problem. Unless it al goes horrible wrong, that is. For the people working outside (assuming there will always be things that nimble humans are better at than clunky robots), it's conceivable that accidents could happen that would have them fall through the atmosphere for a few km's. There are methods to prevent this from being lethal, but all have their downsides. Making those humans less nimble, for one.

Quote

I've read that the balloons on the Vega missions encountered winds up to 700 km/h, causing them to be swept across large distances around Venus within mere hours.

What minimum altitude is required to avoid wind/weather/turbulence?

I'm imagining it wouldn't be safe to do a manned mission without first mapping out known atmospheric weather patterns, including particular updrafts, downdrafts, and related currents. Are these things already adequately known, or are they yet to be determined, or are they generally impossible to reliably predict?

The weather balloons survived that though. Turbulence at the terminator could be a likely concern. Especially if you can't avoid passing through it every other day. Way, waaay more mapping is needed to be able to say anything useful can be said about this, though.

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #23 on: 12/03/2018 11:22 am »
I believe it would be unlikely that an atmospheric pressure of more than 2 bars would be required. At this pressure and altitude the temperature would already be on the high side. I don’t think there is any likelihood of a sudden depressurisation as the atmospheric pressure inside and out would be the same. There is no problem with breathing air at 2 bars provided the partial pressure of oxygen is reduced. Higher pressures do have adverse effects.

Being a balloon it would be carried by the wind so although it would move rapidly with respect to the ground, the atmosphere around it should be relatively still compared to the balloon. I don’t think it would be possible to avoid the winds on Venus - 700 km/hr high up but at the surface the CO2 is almost supercritical and the wind speeds are just a few km/hour so it’s more like an ocean current.

It would certainly be wise to research the wind patterns in detail before attempting any such mission, but wind speed should not be a show stopper. Not sure if this is remotely likely, but in extremes a vehicle caught in a "down draft" could always inflate an emergency additional balloon to increase its buoyancy and drag it against the flow.

I was thinking sudden up-or-down movement could then have associated sudden changes in pressure, so that's why I was asking about suffering the bends.

For winds up to 700km/h it sounds like a large balloon/dirigible might not be able to survive that, including any turbulence forces. Up to what altitudes do these winds extend? Here on Earth atmospheric weather/movement are only supposed extend up to 10km altitude, and above that it's quite calm. But I guess Venus with its more extreme solar heating and tidal locking has much more atmospheric convection going on.

How is a floating habitat supposed to survive high wind velocities on Venus?
Turbulent forces might will be an issue - I don't know further reseach is needed, but if wind speeds between the habitat and the atmosphere are even remotely close to 700km/hour the whole idea is impossible. I suspect that the winds will be more like the Earths jet streams and it would be possible to fly in them but I'm not arguing from a possition of strength on that point.
This may be of interest - there will be no escaping the wind and probably no station keeping - the habitat would have to go with the flow so to speak.
https://www.researchgate.net/figure/Average-wind-speed-versus-altitude-within-the-Venus-atmosphere_fig3_24381363
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Offline edzieba

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Re: Floating Habitat on Venus
« Reply #24 on: 12/03/2018 11:35 am »
The whole reason why divers and submariners have used the helium-oxygen breathing gas mixtures in the past, was to reduce their risk of suffering "the bends", which occurs when pressure is reduced suddenly after prolonged exposure to higher pressures. This is because at higher pressures the inhaled nitrogen gas dissolves and enters the bloodstream, so that if pressure suddenly reduces then the dissolved nitrogen quickly returns to gaseous state forming bubbles in the bloodstream, which is dangerous to human health.
Noooot quite. Heliox and Trimix (O2 + Nitrogen + Helium, kind of a cheaper Heliox variant when full Heliox is not necessary) are used when air is not sufficient for the pressures required. For why, we need a brief primer on gas mixes:
Once you get beyond around 1.3 bar partial pressure of O2, you start to encounter Oxygen Toxicity. With air (21% O2) that means a limit of around 6.2 Bar, or ~50m. So to dive deeper (without an atmospheric diving hardsuit) you need a breathing gas mix with a reduced O2 percentage. You could decrease the O2 percentage and add more nitrogen (this is called Nitrox, which can be in various mixes with different N2/O2 proportions) but below ~30m (above our O2 limit) you start to encounter Nitrogen Narcosis. For this reason, you need to look at gas mixes that combine a small portion of O2 with another gas (the 'diluent' gas). Helium is the one used most commonly, as it has the fewest deleterious effects on the body when used at high pressure.

tl;dr Unless you're pressurising your habitat beyond 4 Bar, any messing about with alternate diluent gasses is not really for health reasons, but for some other reasons (e.g. ISRU). Pressurising at 1 Bar with air (or Nitrox 20, for simplicity of handling and ECLSS) would be desirable for a shirtsleve environment. Any other gas mixes and pressures would need a good reason.

Offline Crispy

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Re: Floating Habitat on Venus
« Reply #25 on: 12/03/2018 12:30 pm »
How would visiting vehicles work?

You'd either need very good station keeping to offer up a "landing pad" to a spacecraft under powered descent, or "landers" would have their own balloons, which then fly over to the station for docking. Both are tricky in high winds.

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #26 on: 12/03/2018 01:00 pm »
The whole reason why divers and submariners have used the helium-oxygen breathing gas mixtures in the past, was to reduce their risk of suffering "the bends", which occurs when pressure is reduced suddenly after prolonged exposure to higher pressures. This is because at higher pressures the inhaled nitrogen gas dissolves and enters the bloodstream, so that if pressure suddenly reduces then the dissolved nitrogen quickly returns to gaseous state forming bubbles in the bloodstream, which is dangerous to human health.
Noooot quite. Heliox and Trimix (O2 + Nitrogen + Helium, kind of a cheaper Heliox variant when full Heliox is not necessary) are used when air is not sufficient for the pressures required. For why, we need a brief primer on gas mixes:
Once you get beyond around 1.3 bar partial pressure of O2, you start to encounter Oxygen Toxicity. With air (21% O2) that means a limit of around 6.2 Bar, or ~50m. So to dive deeper (without an atmospheric diving hardsuit) you need a breathing gas mix with a reduced O2 percentage. You could decrease the O2 percentage and add more nitrogen (this is called Nitrox, which can be in various mixes with different N2/O2 proportions) but below ~30m (above our O2 limit) you start to encounter Nitrogen Narcosis. For this reason, you need to look at gas mixes that combine a small portion of O2 with another gas (the 'diluent' gas). Helium is the one used most commonly, as it has the fewest deleterious effects on the body when used at high pressure.

tl;dr Unless you're pressurising your habitat beyond 4 Bar, any messing about with alternate diluent gasses is not really for health reasons, but for some other reasons (e.g. ISRU). Pressurising at 1 Bar with air (or Nitrox 20, for simplicity of handling and ECLSS) would be desirable for a shirtsleve environment. Any other gas mixes and pressures would need a good reason.

I doubt the habitat pressurisation would ever be allowed to rise above 2 bar as at that pressure the flaoting altitude would be a bit low and the temperature a bit high more likely to be 0.8-1.5bar which as you confirm should not need anything other than Nitrox.
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Offline edzieba

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Re: Floating Habitat on Venus
« Reply #27 on: 12/03/2018 01:03 pm »
How would visiting vehicles work?

You'd either need very good station keeping to offer up a "landing pad" to a spacecraft under powered descent, or "landers" would have their own balloons, which then fly over to the station for docking. Both are tricky in high winds.
Aerial capture a'la Corona/Hexagon/SMART would work (if you can float with a dirigible, then you can fly aerodynamically), as would an enormous dirigible doughnut with a net strung across the hole.
Either would require pinpoint EDL and offer a single 'land'ing attempt, but that's likely to be unavoidable on Venus unless all descent stages were designed to touchdown on the surface and survive long enough to relaunch to the floating hab (which seems rather impractical).

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #28 on: 12/03/2018 01:05 pm »
How would visiting vehicles work?

You'd either need very good station keeping to offer up a "landing pad" to a spacecraft under powered descent, or "landers" would have their own balloons, which then fly over to the station for docking. Both are tricky in high winds.
It might be a problem depending on levels of wind turbulence. If high then the whole concept becomes very difficult if not impossible. Docking would be a problem as the incoming craft would probably need its own balloon / airship arrangement. Might still be doable...
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Offline high road

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Re: Floating Habitat on Venus
« Reply #29 on: 12/04/2018 09:38 am »
How would visiting vehicles work?

You'd either need very good station keeping to offer up a "landing pad" to a spacecraft under powered descent, or "landers" would have their own balloons, which then fly over to the station for docking. Both are tricky in high winds.

As on Earth, you don't need powered descent on Venus. It's a massive complication with few benefits.

Don't think aircraft, think ships. Capsules can descend using parachutes and/or balloons (which only need to slow them down, not lift them), and can descend to lower altitudes, as long as they don't stay there too long. There, or while descending, they could be picked up by tugs, which would probably be large drones working per three or four. These tugs would probably do all transportation between habs and other infrastructure, and even move the habs themselves if necessary, much like tugboats bring in massive ships in harbours. The tugs would hang from a hab or a dedicated support infrastructure to recharge when not in use.

High winds are not a problem, as long as they're constant for long enough to allow docking procedures. Which we don't know yet.

Offline KelvinZero

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Re: Floating Habitat on Venus
« Reply #30 on: 12/04/2018 10:07 am »
How would visiting vehicles work?

You'd either need very good station keeping to offer up a "landing pad" to a spacecraft under powered descent, or "landers" would have their own balloons, which then fly over to the station for docking. Both are tricky in high winds.
Heres an idea. Instead of a landing pad you have a very high altitude torus shaped balloon. My guess is that the size and high altitude allow it to have fairly predictable motion. The vehicle lands similar to F9R except that it is hooked as it passes through the center of the torus. The weight of the vehicle drags the torus down from very high altitude to the base altitude where we have earth pressure. This might also save some fuel compared to the F9R on earth because it could probably be hooked with greater residual velocity than landing on a concrete pad on earth.
Relaunching could happen from the center of the torus, or if more clearance is required perhaps it is dropped from the torus before ignition.

Similarly, instead of a torus you pass through, perhaps it is easier to have a more conventional balloon with a cable hanging down, and you hook somehow to that, a hundred meters or so beneath the balloon.

Additionally you could go with my orbital laser idea and possibly have the ability to hover, heating the atmosphere for thrust.

Offline Lampyridae

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Re: Floating Habitat on Venus
« Reply #31 on: 12/04/2018 01:59 pm »
How would visiting vehicles work?

You'd either need very good station keeping to offer up a "landing pad" to a spacecraft under powered descent, or "landers" would have their own balloons, which then fly over to the station for docking. Both are tricky in high winds.

As on Earth, you don't need powered descent on Venus. It's a massive complication with few benefits.

Don't think aircraft, think ships. Capsules can descend using parachutes and/or balloons (which only need to slow them down, not lift them), and can descend to lower altitudes, as long as they don't stay there too long. There, or while descending, they could be picked up by tugs, which would probably be large drones working per three or four. These tugs would probably do all transportation between habs and other infrastructure, and even move the habs themselves if necessary, much like tugboats bring in massive ships in harbours. The tugs would hang from a hab or a dedicated support infrastructure to recharge when not in use.

High winds are not a problem, as long as they're constant for long enough to allow docking procedures. Which we don't know yet.

Absolutely. It's also worth noting that at low enough altitudes an empty BFR/Starship is basically a rigid balloon and willl bob around in the (very hot and dense) lower atmosphere.

Offline sanman

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Re: Floating Habitat on Venus
« Reply #32 on: 12/04/2018 02:38 pm »
It's one thing to send an inflatable to be inflated above Venus just before descent. But what about dirigibles - how would they be done?

I'm picturing that you'd maybe launch a fairing packed with smaller segments up to LEO, which would then be assembled up there into scaffolding and turned into the structure of a dirigible. Then perhaps a booster would be attached that assembly, to spiral it out higher and higher, until at some safe distance the skin could be fitted on. Then finally the booster would send everything into a Trans-Venus Injection. Aerobraking would then be used upon arrival at Venus.

Otherwise, if orbital construction isn't possible, then bring all the pieces to Venus and somehow assemble it all there while using an existing inflatable to stay afloat in the upper atmosphere.


The tallest mountain on Venus is Maxwell Montes with a height of 11km above mean ground level.
https://phys.org/news/2016-12-weather-venus.html
Quote
The highest point on Venus, Maxwell Montes, is therefore the coolest point on the planet, with a temperature of about 655 K (380 °C; 716 °F) and an atmospheric pressure of about 4.5 MPa (45 bar)

Maybe the top could be a site for various robotic activities such as manufacturing.

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #33 on: 12/05/2018 02:39 pm »
How would visiting vehicles work?

You'd either need very good station keeping to offer up a "landing pad" to a spacecraft under powered descent, or "landers" would have their own balloons, which then fly over to the station for docking. Both are tricky in high winds.

As on Earth, you don't need powered descent on Venus. It's a massive complication with few benefits.

Don't think aircraft, think ships. Capsules can descend using parachutes and/or balloons (which only need to slow them down, not lift them), and can descend to lower altitudes, as long as they don't stay there too long. There, or while descending, they could be picked up by tugs, which would probably be large drones working per three or four. These tugs would probably do all transportation between habs and other infrastructure, and even move the habs themselves if necessary, much like tugboats bring in massive ships in harbours. The tugs would hang from a hab or a dedicated support infrastructure to recharge when not in use.

High winds are not a problem, as long as they're constant for long enough to allow docking procedures. Which we don't know yet.

Absolutely. It's also worth noting that at low enough altitudes an empty BFR/Starship is basically a rigid balloon and willl bob around in the (very hot and dense) lower atmosphere.
True, unless the Starship weighs more than about 20,0000kg (density around 65kg/cubic m) in which case it will land. The lighter it is the higher up it will float, although given the steep decline in pressure with altitude I doubt it would float that high up. And it would also roast at somewhere between 300-500 degrees C
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Offline indaco1

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Re: Floating Habitat on Venus
« Reply #34 on: 12/15/2018 02:34 pm »
How do you refuel it without sinking?

Non-native English speaker and non-expert, be patient.

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #35 on: 12/15/2018 03:18 pm »
How do you refuel it without sinking?

You would need to inflate the envelope further to increase the volume of the habitat or its bouyancy aids.
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Offline high road

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Re: Floating Habitat on Venus
« Reply #36 on: 12/18/2018 09:43 pm »
How do you refuel it without sinking?

You would need to inflate the envelope further to increase the volume of the habitat or its bouyancy aids.

The launch infrastructure would not be a habitat, but a dedicated structure. The launch/release of the rocket will cause a violent upward motion of the structure that would be very detrimental to anyone or anything not absolutely required for the launch.

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Re: Floating Habitat on Venus
« Reply #37 on: 02/01/2019 12:55 pm »
Had what I think is a different idea for geo-engineering after reading this paper.

Suppose you seeded Venus with a large number of floating platforms in the 50-55km altitude region, each of which was producing semi-transparent "bubbles" of this reduced graphene oxide (RGO) or other CO2-derived membrane of choice.  The bubbles aren't airtight, but instead have holes at their weighted undersides, in a manner similar to hot air balloons.  The weight would need to include some form of passive catalyst for extracting water from the atmosphere and keeping the inside of the bubble relatively humid.

You populate the insides those bubbles with SO2-tolerant lichens and other epiphytes - some genetic engineering likely required - and as they go about their CO2 breathing life-cycles they release O2 into the bubble, keeping it neutrally buoyant. 

You also want these bubbles to stick together when they come into contact with each other, so maybe there's an electrostatic or mechanical (e.g. velcro) type effect one can exploit when manufacturing the RGO.  Eventually, you start building up floating islands of (very) many bubbles, such that one would get the impression of travelling through an ocean filled with buoys.

In this scenario, when it comes to launching rockets, your launch platform just needs to corral up as many or as few of these bubbles as necessary to maintain neutral buoyancy, and release them all when you launch.

Offline sghill

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Re: Floating Habitat on Venus
« Reply #38 on: 02/01/2019 01:40 pm »
Had what I think is a different idea for geo-engineering after reading this paper.

Suppose you seeded Venus with a large number of floating platforms in the 50-55km altitude region, each of which was producing semi-transparent "bubbles" of this reduced graphene oxide (RGO) or other CO2-derived membrane of choice.  The bubbles aren't airtight, but instead have holes at their weighted undersides, in a manner similar to hot air balloons.  The weight would need to include some form of passive catalyst for extracting water from the atmosphere and keeping the inside of the bubble relatively humid.

You populate the insides those bubbles with SO2-tolerant lichens and other epiphytes - some genetic engineering likely required - and as they go about their CO2 breathing life-cycles they release O2 into the bubble, keeping it neutrally buoyant. 

You also want these bubbles to stick together when they come into contact with each other, so maybe there's an electrostatic or mechanical (e.g. velcro) type effect one can exploit when manufacturing the RGO.  Eventually, you start building up floating islands of (very) many bubbles, such that one would get the impression of travelling through an ocean filled with buoys.

In this scenario, when it comes to launching rockets, your launch platform just needs to corral up as many or as few of these bubbles as necessary to maintain neutral buoyancy, and release them all when you launch.

Cool idea, but there is near zero water in the Venusian atmosphere because the solar wind has stripped way most of the water vapor and hydrogen. Oxygen could be stripped (at great cost) from CO2, and Nitrogen cryogenically separated, with both acting as a lifting gas, but water would have to be imported.
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Offline mikelepage

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Re: Floating Habitat on Venus
« Reply #39 on: 02/01/2019 03:44 pm »
Had what I think is a different idea for geo-engineering after reading this paper.

Suppose you seeded Venus with a large number of floating platforms in the 50-55km altitude region, each of which was producing semi-transparent "bubbles" of this reduced graphene oxide (RGO) or other CO2-derived membrane of choice.  The bubbles aren't airtight, but instead have holes at their weighted undersides, in a manner similar to hot air balloons.  The weight would need to include some form of passive catalyst for extracting water from the atmosphere and keeping the inside of the bubble relatively humid.

You populate the insides those bubbles with SO2-tolerant lichens and other epiphytes - some genetic engineering likely required - and as they go about their CO2 breathing life-cycles they release O2 into the bubble, keeping it neutrally buoyant. 

You also want these bubbles to stick together when they come into contact with each other, so maybe there's an electrostatic or mechanical (e.g. velcro) type effect one can exploit when manufacturing the RGO.  Eventually, you start building up floating islands of (very) many bubbles, such that one would get the impression of travelling through an ocean filled with buoys.

In this scenario, when it comes to launching rockets, your launch platform just needs to corral up as many or as few of these bubbles as necessary to maintain neutral buoyancy, and release them all when you launch.

Cool idea, but there is near zero water in the Venusian atmosphere because the solar wind has stripped way most of the water vapor and hydrogen. Oxygen could be stripped (at great cost) from CO2, and Nitrogen cryogenically separated, with both acting as a lifting gas, but water would have to be imported.

Not disputing the general point, but Neon is a gas commercially extracted from Earth's atmosphere, which is somewhat rarer (18ppm) than water vapour is (20ppm) in the Venusian atmosphere.  There also happens to be about 20ppm Lithium in Earth's crust.  Which is to say there is not a lot of these elements, but considerably more than zero when you consider it's a whole Earth-sized planet.  Also fairly sure water vapour would be easier to extract from the Venusian atmosphere than (chemically inert) Neon, or (chemically bound) Lithium. 

Cheaper to import water at first, but I think in the long term it will be cheaper to ISRU the water on Venus, especially once we have top notch catalysts, some cleverly genetically modified algae or perhaps both.  Also, craft that can survive for long enough, and have enough autonomy/power to stay at the right altitude/latitude, to do the extraction.

Offline Lemurion

Re: Floating Habitat on Venus
« Reply #40 on: 02/05/2019 07:30 pm »
The big issue for me is getting back. The floating habitats seem a lot easier than the air-launched orbital vehicle the return requires. SSTO doesn’t seem any more practical on Venus than Earth so at least the early versions will have to drop a multi-stage vehicle into the Venusian atmosphere and hope it keeps its return capabilities.

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Re: Floating Habitat on Venus
« Reply #41 on: 02/06/2019 03:31 am »
The big issue for me is getting back. The floating habitats seem a lot easier than the air-launched orbital vehicle the return requires. SSTO doesn’t seem any more practical on Venus than Earth so at least the early versions will have to drop a multi-stage vehicle into the Venusian atmosphere and hope it keeps its return capabilities.

Maybe all you need is one stage with drop tanks. Something like a tri-core configuration with expendable outboard cores having prop tanks only.

Offline mikelepage

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Re: Floating Habitat on Venus
« Reply #42 on: 02/06/2019 04:19 am »
The big issue for me is getting back. The floating habitats seem a lot easier than the air-launched orbital vehicle the return requires. SSTO doesn’t seem any more practical on Venus than Earth so at least the early versions will have to drop a multi-stage vehicle into the Venusian atmosphere and hope it keeps its return capabilities.

Yeah, you might be able to get away with a single stage vehicle if you have a skyhook type setup - you'd want something that orbits at roughly the same speed as the winds blow - but otherwise I think you're left with having to build/grow a platform many times the size of the expected launch vehicles.

Offline high road

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Re: Floating Habitat on Venus
« Reply #43 on: 02/06/2019 07:57 am »
Had what I think is a different idea for geo-engineering after reading this paper.

Suppose you seeded Venus with a large number of floating platforms in the 50-55km altitude region, each of which was producing semi-transparent "bubbles" of this reduced graphene oxide (RGO) or other CO2-derived membrane of choice.  The bubbles aren't airtight, but instead have holes at their weighted undersides, in a manner similar to hot air balloons.  The weight would need to include some form of passive catalyst for extracting water from the atmosphere and keeping the inside of the bubble relatively humid.

You populate the insides those bubbles with SO2-tolerant lichens and other epiphytes - some genetic engineering likely required - and as they go about their CO2 breathing life-cycles they release O2 into the bubble, keeping it neutrally buoyant. 

You also want these bubbles to stick together when they come into contact with each other, so maybe there's an electrostatic or mechanical (e.g. velcro) type effect one can exploit when manufacturing the RGO.  Eventually, you start building up floating islands of (very) many bubbles, such that one would get the impression of travelling through an ocean filled with buoys.

In this scenario, when it comes to launching rockets, your launch platform just needs to corral up as many or as few of these bubbles as necessary to maintain neutral buoyancy, and release them all when you launch.

Cool idea, but there is near zero water in the Venusian atmosphere because the solar wind has stripped way most of the water vapor and hydrogen. Oxygen could be stripped (at great cost) from CO2, and Nitrogen cryogenically separated, with both acting as a lifting gas, but water would have to be imported.

This again. There's quite a lot of sulfuric acid up there in those clouds (exactly how much still needs more research). Sulfuric acid breaks down into water and SO3, which is a normal part of the weather cycle on Venus (which might have contributed to the hydrogen escaping the planet in the first place). It might actually be easier to ISRU water on Venus than extract it from the soil on Mars

The big issue for me is getting back. The floating habitats seem a lot easier than the air-launched orbital vehicle the return requires. SSTO doesn’t seem any more practical on Venus than Earth so at least the early versions will have to drop a multi-stage vehicle into the Venusian atmosphere and hope it keeps its return capabilities.

Getting back is definitely the biggest issue. It requires the most infrastructure. However, a launch vehicle that's at small as possible and is brought to Venus in individual stages (of which the suborbital parts are equipped with an expendable heat shield), should be quite doable. Launch operations are the more difficult part.

The big issue for me is getting back. The floating habitats seem a lot easier than the air-launched orbital vehicle the return requires. SSTO doesn’t seem any more practical on Venus than Earth so at least the early versions will have to drop a multi-stage vehicle into the Venusian atmosphere and hope it keeps its return capabilities.

Yeah, you might be able to get away with a single stage vehicle if you have a skyhook type setup - you'd want something that orbits at roughly the same speed as the winds blow - but otherwise I think you're left with having to build/grow a platform many times the size of the expected launch vehicles.


Isn't a skyhook much more massive and complex than such a platform? All you need to do on location is inflate the structure and assemble it (with the assembly approach depending on how the modules EDL).
« Last Edit: 02/06/2019 11:39 am by high road »

Offline mikelepage

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Re: Floating Habitat on Venus
« Reply #44 on: 02/07/2019 08:40 am »
The big issue for me is getting back. The floating habitats seem a lot easier than the air-launched orbital vehicle the return requires. SSTO doesn’t seem any more practical on Venus than Earth so at least the early versions will have to drop a multi-stage vehicle into the Venusian atmosphere and hope it keeps its return capabilities.

Yeah, you might be able to get away with a single stage vehicle if you have a skyhook type setup - you'd want something that orbits at roughly the same speed as the winds blow - but otherwise I think you're left with having to build/grow a platform many times the size of the expected launch vehicles.


Isn't a skyhook much more massive and complex than such a platform? All you need to do on location is inflate the structure and assemble it (with the assembly approach depending on how the modules EDL).

Still not sure if the cost-benefit would work out, but I do think a skyhook makes more sense at Venus than it does at Earth because wind speeds on Venus mean there's no need to keep the skyhook in a geostationary orbit.  Floating platforms will be moving at the speed of the jet-stream - circling the planet in 4-5 days or roughly 400km/h - and it's from these that suborbital craft would launch.  This means the CoM of the skyhook can be in an ~18 hour orbit and the cable itself can be about half the length as it would be at Earth.

The way I think of it is that when it comes to a floating platform in the Venusian atmosphere, you effectively have to count the mass of any rocket propellent twice.  First when considering the buoyancy requirements of your platform, and then again when you actually launch the rocket.

The floating launch platform has to be big enough such that the mass change over that time period prior to launch - while you use ISRU to fuel your rocket - should make a manageably small difference to the altitude where the platform is at neutral buoyancy.  Note that many delta-v maps have 27km/s to orbit for Venus - which is presumably an estimate to get to orbit from the surface.  I'm assuming that launching from a 50km altitude floating platform - where air pressure is similar to Earth surface - the delta-v to orbit is roughly similar to the 9.4km/s required on Earth.  The deeper you go, that delta-V to orbit figure would dramatically increase towards 27km/s, so you really want your launch platform to be so huge/buoyant relative to your launch vehicle, that it makes little to no difference and you can still launch from that ~50km altitude.

Every mole of 80%N2-20%O2 atmosphere in your airship/launch platform that displaces a mole of CO2 in Venus' atmosphere gives you 15.2 grams of buoyancy.  So as a BoE calculation, I estimate that at ~50km, 1 bar, and ~75 degrees C, a fully fuelled SpaceX Starship (1400 ton) requires ~2,600,000 m3 of atmosphere to remain buoyant, while the full SSH stack (4400 ton) would require ~8,300,000 m3 of that same atmosphere to remain buoyant.  That's 13x and 41.5x respectively the volume of Hindenburg, the largest airship ever built.  Even a Falcon 9 (550 ton) would require something over 5x Hindenburg .

On the other hand, a small suborbital vehicle like New Shepard has a liftoff mass (I've read) of about 75 ton, but I'm not sure if that includes the capsule.  So if you imagine a 100 ton single stage craft w/ capsule, that would require 188,000 m3 of buoyant force, which means an airship approximately the size of the Hindenburg as a launch platform in the Venusian clouds.  Much more manageable, especially once you consider the liveable area of the base would be much larger than the hanging cabin of Hindenburg.

Having a substantial infrastructure like a skyhook in orbit means you can dramatically reduce the size of your launch platform's displacement volume, as well as the amount of propellent you need to generate using ISRU for the return journey.  At least at first, sending small capsules back and forth between a skyhook in orbit and floating cloud bases seems a much more likely scenario to me.

Offline high road

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Re: Floating Habitat on Venus
« Reply #45 on: 02/07/2019 12:55 pm »
The big issue for me is getting back. The floating habitats seem a lot easier than the air-launched orbital vehicle the return requires. SSTO doesn’t seem any more practical on Venus than Earth so at least the early versions will have to drop a multi-stage vehicle into the Venusian atmosphere and hope it keeps its return capabilities.

Yeah, you might be able to get away with a single stage vehicle if you have a skyhook type setup - you'd want something that orbits at roughly the same speed as the winds blow - but otherwise I think you're left with having to build/grow a platform many times the size of the expected launch vehicles.


Isn't a skyhook much more massive and complex than such a platform? All you need to do on location is inflate the structure and assemble it (with the assembly approach depending on how the modules EDL).

Still not sure if the cost-benefit would work out, but I do think a skyhook makes more sense at Venus than it does at Earth because wind speeds on Venus mean there's no need to keep the skyhook in a geostationary orbit.  Floating platforms will be moving at the speed of the jet-stream - circling the planet in 4-5 days or roughly 400km/h - and it's from these that suborbital craft would launch.  This means the CoM of the skyhook can be in an ~18 hour orbit and the cable itself can be about half the length as it would be at Earth.

I always confuse the Skyhook and Rotovator concepts. How much would that be made easier by the superrotating atmosphere?


Quote
The floating launch platform has to be big enough such that the mass change over that time period prior to launch - while you use ISRU to fuel your rocket - should make a manageably small difference to the altitude where the platform is at neutral buoyancy.  Note that many delta-v maps have 27km/s to orbit for Venus - which is presumably an estimate to get to orbit from the surface.  I'm assuming that launching from a 50km altitude floating platform - where air pressure is similar to Earth surface - the delta-v to orbit is roughly similar to the 9.4km/s required on Earth.  The deeper you go, that delta-V to orbit figure would dramatically increase towards 27km/s, so you really want your launch platform to be so huge/buoyant relative to your launch vehicle, that it makes little to no difference and you can still launch from that ~50km altitude.

Wouldn't you ISRU lift gas as you ISRU fuel? That way, the station remains at the same altitude troughout fuel production process and launch operations. And methane can be used both as fuel and as a much better lifting gas than nitrogen/oxygen.

Quote
Every mole of 80%N2-20%O2 atmosphere in your airship/launch platform that displaces a mole of CO2 in Venus' atmosphere gives you 15.2 grams of buoyancy.  So as a BoE calculation, I estimate that at ~50km, 1 bar, and ~75 degrees C, a fully fuelled SpaceX Starship (1400 ton) requires ~2,600,000 m3 of atmosphere to remain buoyant, while the full SSH stack (4400 ton) would require ~8,300,000 m3 of that same atmosphere to remain buoyant.  That's 13x and 41.5x respectively the volume of Hindenburg, the largest airship ever built.  Even a Falcon 9 (550 ton) would require something over 5x Hindenburg .

Well, for starters: there's no point in using air as a lifting gas for the launch infrastructure. It's not like you're going to live in it. For the same reason as rockets don't usually launch from Times Square. You don't put your launch infrastructure anywhere near anything that isn't absolutely required for launch operations. Using CH4 gives you almost double the lift power than air. Using H2 gives you almost triple the lift. That's down to a few Hindenburgs. And you might even want to design an even smaller rocket that still meets all your needs, if launch infrastructure is truly the limiting factor.

Quote
On the other hand, a small suborbital vehicle like New Shepard has a liftoff mass (I've read) of about 75 ton, but I'm not sure if that includes the capsule.  So if you imagine a 100 ton single stage craft w/ capsule, that would require 188,000 m3 of buoyant force, which means an airship approximately the size of the Hindenburg as a launch platform in the Venusian clouds.  Much more manageable, especially once you consider the liveable area of the base would be much larger than the hanging cabin of Hindenburg.

Wait, why would you need a rocket to meet up with a skyhook/rotovator? The entire point is to meet up with it without needing to go quite as fast or as high. So a plane or inflatable that can reach that specific altitutude is a lot better. Not requiring a (suborbital) rocket is one of the pros of using a skyhook.

And even on a small rocket platform, or even the inflatable where the airplane rests under between flights, you don't want to have people. The moment the rocket/plane releases, the increased buoyancy is going to be painfully uncomfortable. And you don't want a launch mishap to destroy your habitat.

Quote
Having a substantial infrastructure like a skyhook in orbit means you can dramatically reduce the size of your launch platform's displacement volume, as well as the amount of propellent you need to generate using ISRU for the return journey.  At least at first, sending small capsules back and forth between a skyhook in orbit and floating cloud bases seems a much more likely scenario to me.

Well, landing Starhip-style vehicles is out of the question indeed. Small capsules are the way to go until there's a need to send bigger things, regardless is you get them to orbit using a skyhook. What that means for refueling for the interplanetary trip is indeed an important design consideration.

Offline jongoff

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Re: Floating Habitat on Venus
« Reply #46 on: 02/08/2019 04:17 am »
Another potential option is a hypersonic skyhook, ie one where the tip is above the atmosphere, and traveling at some intermediate speed between that of a Low Venus Orbit and the speed at the cloud-tops. My guess is that a skyhook that is traveling at cloud-top speeds is still going to be impractical with realistic near-term materials. But the question is what is possible? If you could knock the dV to orbit down from the probably 8.5ish km/s you'd need normally down into the 4-6km/s range, then an SSTO option becomes a lot more feasible. Alas, my tether's math-fu is not strong, and Kirk Sorensen is heads down with his FLiBe fission power startup these days.

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Offline mikelepage

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Re: Floating Habitat on Venus
« Reply #47 on: 02/08/2019 06:31 am »
I always confuse the Skyhook and Rotovator concepts. How much would that be made easier by the superrotating atmosphere?

Quote
Wait, why would you need a rocket to meet up with a skyhook/rotovator? The entire point is to meet up with it without needing to go quite as fast or as high. So a plane or inflatable that can reach that specific altitutude is a lot better. Not requiring a (suborbital) rocket is one of the pros of using a skyhook.

And even on a small rocket platform, or even the inflatable where the airplane rests under between flights, you don't want to have people. The moment the rocket/plane releases, the increased buoyancy is going to be painfully uncomfortable. And you don't want a launch mishap to destroy your habitat.

Ack, I always forget that people also use the term "skyhook" to refer to "rotovator" shenanigans.  The skyhook wikipedia page distinguishes between rotating and non-rotating skyhooks, and in the rotating section it talks about about the HASTOL study, where they propose trying to get a scramjet to rendezvous with with a tip of a rotating skyhook moving at Mach 15-17, intercept altitude 150km ;D  Having two moving parts like something out of Mission Impossible and that's not what I mean at all.

What I mean is effectively a space elevator without the bottom 100km.  A non-rotating, gravity stabilised skyhook, the bottom tip of which is basically stationary relative to the approaching rocket/capsule, and remains in the general vicinity of the floating habitat such that the launch window for a suborbital rocket might be minutes or hours long.  The super rotation of the Venusian atmosphere means that suborbital craft will have significant horizontal velocity, and therefore the CoM of the skyhook can be substantially less than GEO in altitude. To be fair, I'm still talking about a cable well over 10,000 km long, but I believe this gets us down into the range where other materials besides carbon nanotubes can be considered.

What I'm trying to get to is a platform that is same order of magnitude as Hindenburg, and a launch vehicle small enough that you don't have to have a dedicated launch platform separate from habitats.  True, you will eventually want this, but not at first when you're mass constrained. 

I guess the way I can see it is a structure with two blimps connected catamaran-style.  The rocket launch/landing platform is part of the "cross strut" between the two blimps, but probably as close as feasible to one end so that launch vehicle thrust would always point below/away from the habitat proper.

Good point that you want CH4 as a lifting gas, but I still think you want blimps with breathable atmosphere as the majority of its lifting gas so that the process of filling and launching a rocket doesn't affect buoyancy unduly.  I can imagine a separate gas CH4 balloon might be used specifically to offset the weight of CH4 in cryo storage, and likewise a separate gas O2 balloon used to offset the weight of cryo O2.  But you don't ever want a situation where converting gas prop to liquid cryo pro results in the whole platform losing buoyancy.  Instead you want something like this:

1) Rocket prop tanks empty, platform cryo tanks full, platform gas prop balloons full.
2) Rocket prop tanks full, platform cryo tanks empty, platform gas prop balloons full.
3) Rocket launches, platform cryo tanks filled from gas condensed from prop balloons asap to regain neutral buoyancy.
4) ISRU on platform fills cryo tanks and gas balloons proportionately to build up stores while maintaining neutral buoyancy.
5) Next rocket lands. Repeat.



Offline ThinkerX

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Re: Floating Habitat on Venus
« Reply #48 on: 02/08/2019 09:44 pm »
Wild and possibly misplaced thought here:

Venus has a number of tall mountains and plateaus.  Perhaps conditions atop these peaks and plateaus might be significantly less hostile than 'lower down?'  Perhaps enough so where ground installations could be placed without worrying about the components getting melted by extreme heat or crushed by insane pressures?

Offline Robotbeat

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Re: Floating Habitat on Venus
« Reply #49 on: 02/09/2019 04:24 am »
Indeed. Temperature on Maxwell Montes, the highest mountain on Venus, is thought to be about 380C, significantly lower temperature than the datum. That's low enough that there are even a few polymers that can function at least for a time, like Kapton and some forms of silicone.
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Offline WIgorN

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Re: Floating Habitat on Venus
« Reply #50 on: 09/07/2019 07:35 pm »
Inhabited floating islands will be after an increase in the albedo of Venus.
Manned missions are incomparably more expensive

The main thing is why ???
Many airship drones

Many mini-balloons with high / adjustable reflectivity.
Carriers in a protected environment are colonies of unicellular algae.
Delivery for example from the moon. It is significantly cheaper and faster.
« Last Edit: 09/07/2019 07:36 pm by WIgorN »

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #51 on: 09/09/2019 11:59 am »
Inhabited floating islands will be after an increase in the albedo of Venus.
Manned missions are incomparably more expensive

The main thing is why ???
Many airship drones

Many mini-balloons with high / adjustable reflectivity.
Carriers in a protected environment are colonies of unicellular algae.
Delivery for example from the moon. It is significantly cheaper and faster.

Why is a good questiom that could be applied to any crewed space flight. But for those who believe in human space flight as something that should be encouraged to help expand mankinds horizons then the atmosphere of Venus offers probably the most benign environment beyond Earth, with 1g gravity, an atmosphere that is roughly at room temperature, provides a high degree of radiation protection and a manageable pressure for human habitation. A plentiful supply of solar power is also readily available.
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Offline ThePonjaX

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Re: Floating Habitat on Venus
« Reply #52 on: 09/10/2019 12:41 am »
This is for Starship but I think belongs here too:

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Offline WIgorN

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Re: Floating Habitat on Venus
« Reply #53 on: 09/13/2019 07:36 pm »
Inhabited floating islands will be after an increase in the albedo of Venus.
Manned missions are incomparably more expensive

The main thing is why ???
Many airship drones

Many mini-balloons with high / adjustable reflectivity.
Carriers in a protected environment are colonies of unicellular algae.
Delivery for example from the moon. It is significantly cheaper and faster.

Why is a good questiom that could be applied to any crewed space flight. But for those who believe in human space flight as something that should be encouraged to help expand mankinds horizons then the atmosphere of Venus offers probably the most benign environment beyond Earth, with 1g gravity, an atmosphere that is roughly at room temperature, provides a high degree of radiation protection and a manageable pressure for human habitation. A plentiful supply of solar power is also readily available.
Without an outpost on the moon, production base, electromagnetic accelerator of cargo and passenger capsules.
All these floating islands are more theory, with the actual cost of shipping 1 kg per moon about $ 1M
It is not yet clear what is there with atmospheric static electricity and acid aerosols in the atmosphere

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Re: Floating Habitat on Venus
« Reply #54 on: 11/15/2019 04:43 am »
The big issue for me is getting back. The floating habitats seem a lot easier than the air-launched orbital vehicle the return requires. SSTO doesn’t seem any more practical on Venus than Earth so at least the early versions will have to drop a multi-stage vehicle into the Venusian atmosphere and hope it keeps its return capabilities.

Getting back is definitely the biggest issue. It requires the most infrastructure. However, a launch vehicle that's at small as possible and is brought to Venus in individual stages (of which the suborbital parts are equipped with an expendable heat shield), should be quite doable. Launch operations are the more difficult part.

Alternatively - the great difficulty of getting back to orbit could be an opportunity.  I thought of this recently as a joke and then started wondering if it could actually work...

Use the Venus cloud base(s) as a prison.

Not for Earth offenders, but for anyone who commits a significant crime whilst beyond cis-lunar space*.  Rationale: anyone who is in space is presumably a highly trained individual, yet if someone commits such a crime that no-one else in their colony can trust them any more, then the whole colony faces a dilemma.  Using the death penalty might sound like an easy solution in an environment where so much can kill you - but arguably it is even more problematic in space, because people tend to do irrational things if they think their life (or the life of someone they love) is in danger from other people, and the damage a single individual can do to a whole colony in space is significantly greater.  You don't ever want smart, desperate people holding a whole space ship/space station/colony to ransom.

What could be useful is a form of exile which gives those highly skilled individuals an out.  (To use a Game of Thrones analogy, they would be "taking the black").  They'd be going somewhere - Venus - where they would have purpose - building a penal colony as they did in early Australia.  It's just somewhere they couldn't return from.  Arguably, because of the spacious warm environment, it would eventually become somewhere people would want to go - by which time the problem of launching to orbit from the cloud base will be closer to a solution.

*I say beyond cis-lunar space, because whether it's Mars or other asteroids, those colonies will have regular ships moving to and from Earth on interplanetary trajectories.  We likely don't want to be wasting the propellent for trans-Venusian burns on these offenders. The way it could work is that there would be a cargo starship en route back to Earth from the colony where the offence occurred.  The offender is put in a Dragon-sized capsule within that ship, with a n-month supply of food/supplies.  The starship - out of their control - sets that capsule on a trajectory that gets an Earth gravity assist to Venus before correcting its own trajectory for Earth landing.  The offender then has literally one chance to succeed landing their capsule on the Venus cloud base and making a life there.

Would make a good story if nothing else  ;D

Offline Shevek23

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Re: Floating Habitat on Venus
« Reply #55 on: 11/15/2019 07:20 am »
I like the idea of Venus exploration and possible colonization in cloud settlements. I am thinking in terms of the Starship architecture, and so on a pretty large scale, but a level of effort comparable to that required for Mars settlement using Starship and SuperHeavy should enable sustainable Venus cloud colonies. SuperHeavy would be required, and the scale of a minimal platform for sustainable use would be quite large, that of a fair sized orbital space station in mass, and huge in volume of course.

My target is 55 km altitude above datum, where the atmospheric temperature is about 300 K. At that height, the ambient pressure is about 53 percent that at Earth sea level--descending to full Earth SL pressure involves going down about 5 more km, where the temperature would be quite hot by human standards, so any station there should wait for more advanced platforms.

I want to stress, we should not think in terms of using breathable air as our lift gas. That is just bad engineering, and it seems to me it is a concept not seriously thought out. There is some advantage in using nitrogen for lift gas, since there is actually a fair amount of nitrogen available to be sequestered by quite simple means, but it is quite a poor lift gas, and since a Starship approach requires us to obtain hydrogen to make methane anyway, we should just use hydrogen. There is no advantage to using breathable air as a lift gas and quite a few disadvantages, so I assume the lift gas and breathable atmosphere inside habitations are quite separate--therefore the low pressure at 55 km is no hardship, we just have humans and any plants or animals living in pressurized volumes, lifted by separate hydrogen balloon cells. The lift of hydrogen is pretty fantastic in a carbon dioxide atmosphere, and the area of a hydrogen gas cell versus a nitrogen one would be half as great, meaning its weight is half as much too. (There is an application where nitrogen is the right substance to use for lift, but not as the major workhorse lift gas for fixed platforms!)

There are drawbacks to setting up aerostatic platforms in Venus's atmosphere versus say colonizing Mars, but let me list the advantages:

1) Gravity is nearly Earth normal. One of the gravest barriers we can anticipate to long term human space colonization is the unknown degree to which lower gravity may have harmful effects in various contexts. But Venus's surface gravity, not appreciably reduced at 55 km altitude being wafted along in the atmosphere there, is 90 percent Earth's. We don't know for sure if even that ten percent reduction might have harmful consequences, but it seems far less likely than say Mars's much lower gravity, or Luna's or Titan's still lower. A big platform in Venus's atmosphere will be practically a Terran setting as far as this goes, or it seems reasonable to hope so, and if Venus's gravity is not sufficient, we probably can't hope to settle any other planet at all.

3) Very effective radiation shielding. Venus has only quite a weak magnetic field, though there are electromagnetic interactions of the solar wind with its upper atmosphere that give some magnetic protection, but at 55 km altitude, quite a lot of mass of carbon dioxide atmosphere is interposed between the platform and space radiation. It would be comparable to that provided by Earth's own atmosphere at the same pressure, and that is deemed a fair benchmark for what artificial centrifugal space habitats would need. Being nearer the Sun, solar events are more powerful, by roughly a factor of two, Venus orbiting close to 0.7 AU, but solar particles are with rare exceptions numerous but of relatively low, subrelativisitic energy, and the atmosphere will stop those dead before they reach down to 55 km. Cosmic rays will be cut down to close to Terran sea level intensities.

3) Abundant sunlight, half the time, in quite convenient form. The upper atmosphere filters out ultraviolet (but humans and any habitat flora or fauna would be under domes anyway, which can add UV filtering as needed). About half the sunlight is reflected away by the upper cloud layers above 55 km, but the target altitude is between the upper thin layers and the lowest, densest band, and the half of sunlight that gets down bounces around between these layers, producing bright diffuse light comparable in intensity to full sunlight without clouds in the tropics on Earth at high noon. Thus, solar panels can generate power steadily without needing to be mounted so as track the Sun; just firmly mount them anywhere facing outward, and power will flow from them at near full Terran peak levels. The planet surface turns very slowly but at 55 km, the superrotating middle atmosphere circulates around the planet in 4 Earth days. Therefore a drifting cloud platform would be in full daylight for 48 hours or so, followed by a 48 hour night. Half the time, we have bright, useful sunlight, much more than on Mars.

4) I am very glad to see someone has noticed Venus has hydrogen, in the form of sulfuric acid. Wikipedia describes the density at maximum cloud density as about the same as water in Earth storm clouds. We need to obtain this hydrogen to make methane to launch rockets to return to Earth in any case, and I think it is going to prove quite practical to do so with reasonable efforts. We might be able to get as much as we need just filtering it out of the 55 km level atmosphere, and if not, various means of "dipping" down 7 km where the major cloud density is are easy to envision--tethered "buckets," or free flying aircraft that dive down, scoop up large quantities of sulfuric acid filtered much the way helicopters operating in the deserts filter out dust and sand from their engine intakes, and return to height with full tanks.

Given hydrogen, all the essential 4 atoms of Terran biology are ready to hand--carbon, oxygen, nitrogen and hydrogen. We need other stuff; a little bit of sulfur for instance--behold we have sulfur.

I have a scheme in mind for obtaining material from the regolith below, sending down uncrewed drones to grab samples of surface material and return them to altitude using aerostatic lift. This is where nitrogen comes in handy by the way--if the thing dives down ballasted by the nitrogen condensed to liquid form, the cold LN2 is a heat sink enabling the probe structure to endure the intense heat temporarily, then when it has grabbed some hundreds of kg or tonnes of material, we can then inflate a balloon with the nitrogen. It is less efficient as a lift gas, but easily obtained-we can afford to vent some as part of the cooling process--and the very fact large quantities are needed make it more effective as ballast for going down.

Thus, the more common elements found in the regolith can be obtained steadily as well. We should be able to retrieve iron, silicon and other common elements Terran biology needs pretty extensively this way, and acquire building material.

Venus is thus a planet we can colonize, without terraforming it first. (The subject of terraforming Venus is an advanced one, I will just say I am against it; not only is the effort required a project for the far future, it seems ill advised to me. I am talking about colonizing Venus as it is, not changing it).

5) As another planet, Venus is the closest. it might not actually be as easy to get to as Mars in delta-V terms, though I think the Hohmann transfer is less energetic than Mars Hohmann transfer, but if we seek a faster transfer, we can get crewed ships there in under two months, within the limits of planned Starship operations. This is based on Musk tweeting an upper atmospheric entry speed of 13 km/sec, which probably will involve multiple passes, first braking off high interplanetary speed while looping back up to low orbit, then entering from orbital speed after cooling off. That is actually good, as it allows the ship to separate the problems of encountering Venus as a whole from phasing with the somewhat unpredictable position of a drifting sky platform!

Acknowledging certain drawbacks, first let me note that the high gravity, which means Starship cannot reach orbit all by itself, is still lower than Earth's. For Starships to return to orbit, we must deliver some SuperHeavies to the platform and operate them, meaning we need to generate not 1200 tonnes of propellant, but that plus 3300 more, or 4500 all up. I do have a scheme in mind for getting the SHs to Venus. But as noted, we have a source of hydrogen, a bit difficult to get but available wherever the platform drifts; we have carbon and oxygen in rather ridiculously insistent abundance, and we have ample solar power available. Manufacturing many thousands of tonnes of meth-lox is a matter of importing the equipment and solar panels to power it, and obtaining the hydrogen.

Given we do have some SuperHeavies, and the means to fuel them along with Starships, the lower gravity and smaller radius of Venus add considerably to the payload to LVO, doubling it in fact; 300 tonnes to LVO is quite reasonable. We only need half as many launches to fuel up a Starship for return to Earth, and the TEI even for a fast 2 month passage back to Earth is fairly modest from LVO. Such operations involve half an order of magnitude more propellant than launching from Mars, but the SuperHeavies can return to the platform for reuse.

There is no prospect of humans visiting the surface personally until quite extensive infrastructure is developed--such as an array of solar power satellites that can beam microwave power down to any surface installations. Given power, it should be quite possible to set up bases on the surface, but we do need a lot of it, and to make heavy and heavily insulated habitats, able to resist some serious crush pressure by a substance that is both quite hot and conductive. But heat pumps can bail out the heat that seeps in through insulation. The catch is that most methods of generating power in situ are no good on Venus's surface; even an advanced high temperature fission power plant is scarcely hotter than the surface and so the Carnot efficiency of such an installation would be low, hence my notion we'd want to beam the power in from space. That won't be happening for quite some time. Hence my suggestion of quick smash and grab surface probes. The tonnage of regolith they grab will be scientific samples as well as raw material for the expanding colonies.

I do have a plan for landing a first Starship in the atmosphere, involving a lift ballute using methane initially as the lift gas. This is inefficient, though still vastly superior to nitrogen--you just can't use nitrogen for this purpose at all. If we can however "land" with enough methane to bear the remaining Starship structure and any equipment payload left over, if that includes a means of either splitting the methane into hydrogen and carbon, or obtaining sufficient flows of new hydrogen via obtaining sulfuric acid, we can improve the lift--we would need another extra gas cell to take advantage of this to be sure. But if we split a methane molecule, and sequester the carbon, we obtain two ultralight hydrogen molecules where we had one methane molecule, thus we wind up displacing twice the atmosphere for 1/4 the lift gas mass. We would also need to produce come kind of ballast to make use of this improved lift. I believe it would be possible to compress the carbon dioxide atmosphere to form "Dry ice" if we can chill it, and with insulated storage, possibly kept cool by flows of cold nitrogen gas, this serves as ballast we can readily drop. It should then be possible to acquire enough lift to enable landing a fully loaded Starship bringing in more equipment and solar panels and hydrogen cells, and so we should be able to bootstrap one ballute-landed Starship into a platform of as many as we need to prepare to receive and maintain some SuperHeavy boosters, and thus enable some Starships to return to LVO and from there back to Earth.

Offline high road

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Re: Floating Habitat on Venus
« Reply #56 on: 11/18/2019 06:27 pm »
Alternatively - the great difficulty of getting back to orbit could be an opportunity.  I thought of this recently as a joke and then started wondering if it could actually work...

Use the Venus cloud base(s) as a prison.

Not for Earth offenders, but for anyone who commits a significant crime whilst beyond cis-lunar space*.  Rationale: anyone who is in space is presumably a highly trained individual, yet if someone commits such a crime that no-one else in their colony can trust them any more, then the whole colony faces a dilemma.  Using the death penalty might sound like an easy solution in an environment where so much can kill you - but arguably it is even more problematic in space, because people tend to do irrational things if they think their life (or the life of someone they love) is in danger from other people, and the damage a single individual can do to a whole colony in space is significantly greater.  You don't ever want smart, desperate people holding a whole space ship/space station/colony to ransom.

What could be useful is a form of exile which gives those highly skilled individuals an out.  (To use a Game of Thrones analogy, they would be "taking the black").  They'd be going somewhere - Venus - where they would have purpose - building a penal colony as they did in early Australia.  It's just somewhere they couldn't return from.  Arguably, because of the spacious warm environment, it would eventually become somewhere people would want to go - by which time the problem of launching to orbit from the cloud base will be closer to a solution.

*I say beyond cis-lunar space, because whether it's Mars or other asteroids, those colonies will have regular ships moving to and from Earth on interplanetary trajectories.  We likely don't want to be wasting the propellent for trans-Venusian burns on these offenders. The way it could work is that there would be a cargo starship en route back to Earth from the colony where the offence occurred.  The offender is put in a Dragon-sized capsule within that ship, with a n-month supply of food/supplies.  The starship - out of their control - sets that capsule on a trajectory that gets an Earth gravity assist to Venus before correcting its own trajectory for Earth landing.  The offender then has literally one chance to succeed landing their capsule on the Venus cloud base and making a life there.

Would make a good story if nothing else  ;D

Actually, you would want such a prison colony anywhere where it actually benefits you. Venus is probably too much of a niche. But having a way to force people to endure the hardships of living on an NEO maintaining that pesky space mining machinery, that would seriously improve the reliability of your production chain. Coming back from an NEO without the right ship/supplies/people noticing is kinda hard too. Still, I love the visual you've put into my head.

Quote
Good point that you want CH4 as a lifting gas, but I still think you want blimps with breathable atmosphere as the majority of its lifting gas so that the process of filling and launching a rocket doesn't affect buoyancy unduly.  I can imagine a separate gas CH4 balloon might be used specifically to offset the weight of CH4 in cryo storage, and likewise a separate gas O2 balloon used to offset the weight of cryo O2.  But you don't ever want a situation where converting gas prop to liquid cryo pro results in the whole platform losing buoyancy.  Instead you want something like this:

1) Rocket prop tanks empty, platform cryo tanks full, platform gas prop balloons full.
2) Rocket prop tanks full, platform cryo tanks empty, platform gas prop balloons full.
3) Rocket launches, platform cryo tanks filled from gas condensed from prop balloons asap to regain neutral buoyancy.
4) ISRU on platform fills cryo tanks and gas balloons proportionately to build up stores while maintaining neutral buoyancy.
5) Next rocket lands. Repeat.

How does using air instead of CH4 help with the change if buoyancy when the total mass suddenly changes by a fully fueled rocket worth?

as for step 3: getting stuff to liquid requires time, while your launch infrastructure is zooming up fast, expanding all the way. A release valve seems a simpler, if more wasteful approach. Or detachable balloons that detach moments after the rocket does, allowing the complex launch infrastructure to remain stable while the far simpler balloons can focus on condensing the lift gas.

For step 5, this isn't a problem. Just burn some of that fuel to quickly evaporate the rest of it to produce enough lift gas for the empty rocket.
« Last Edit: 11/18/2019 06:36 pm by high road »

Offline Shevek23

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Re: Floating Habitat on Venus
« Reply #57 on: 11/19/2019 11:56 pm »
....

How does using air instead of CH4 help with the change if buoyancy when the total mass suddenly changes by a fully fueled rocket worth?...

Well, it can help sort of.

I want to be very clear--for the general purpose of lifting static weights in a Venus cloud platform of any scale, breathable air is a quite poor choice of lift gas.

Using pure nitrogen will offer small but entirely preferable improvement, but if we assume as I do that any large, long term projects there will surely involve ISR, and that the best options by far involve hydrogen containing compounds for fuel, and therefore hydrogen extraction, mainly from sulfuric acid, will be a priority, hydrogen itself is therefore available. Nor is the economy of using hydrogen in any way improved by forming other light gases with it, for purposes of aerostatic lift.

(On the other hand, using pure hydrogen for rocket fuel, versus methane, involves using overall more hydrogen than using methane despite its somewhat inferior performance, so meth-lox is in fact going to be pretty much the ideal approach to take I believe, even if we don't need it for the interplanetary part of the mission--but of course Starship uses just that, and it works fine).

BUT, nitrogen does have this single advantage--it is going to be easier to obtain overall. This probably does not justify using it for the primary lift gas for static lift; for instances where we have fixed weights to lift, and intend to keep them indefinitely, even if hydrogen is relatively costly, it is well worth using instead for that. If hydrogen is so hard to get or crack from sulfuric acid that we cannot rely on it for routine lift, we probably can't afford hydrogen containing fuels for liftoff and fueling interplanetary ships, and thus Venus would be quite difficult to visit or live on. I can't see why we should not use hydrogen, then.

Nitrogen however will be available fairly "cheaply," and so one quick and dirty way to enable an aerostatic launch platform for a rocket on any scale is to simply use an extra large (nearly triple the volume, and double the area hence dead weight of cell surface, and about 20-25 percent larger in linear dimensions, than a corresponding lift hydrogen cell) set of nitrogen balloons, sufficient to lift the entire dead weight of the rocket.

We don't have to specify the exact size or characteristics of the rocket, though for disclosure I am thinking of a complete SuperHeavy/Starship stack, loaded with an extra 150-200 tonnes of LVO payload to boot, so notably over 5000 tonnes all up. Venus's lower gravity and radius mean a Starship type of launch vehicle can get double payload versus Earth, you see. But imagine it on any scale. The other relevant thing to know is the initial thrust to weight ratio of the rocket, for reasons to become apparent shortly.

Nitrogen, in a carbon dioxide atmosphere, at the same ambient pressure and temperature, will displace 44 kg of "air" for every 28 kg of nitrogen mass. (Note that breathable air of standard Earth composition would cost nearly 2 kg of net lift in available weight, and is hardly desirable for that reason alone).

Thus for every 28 kg of nitrogen we refine from the ambient atmosphere, by a relatively simple compression/cooling process removing the CO2, we can lift 16 kg of dead weight, including of course the cell material.

 (However, this lift cell being part of a larger fixed platform, the dead weight of the cell material and suspension for it can in fact be offset by hydrogen lift in other cells, freeing up the full lift of the nitrogen for our variable weight load, the rocket).

Thus, every tonne the rocket masses (not weighs; aerostatic forces are in proportion to the gravity field, the same setup would work on Earth, albeit with higher suspension loads by 10 percent, but the same gas masses--except for Earth's air being of 2/3 the molar mass of course, which worsens things) requires 7/4 of a tonne of nitrogen to lift--if it were a 5000 tonne BFR stack, we'd need 8750 tonnes of nitrogen therefore.

If it were hydrogen, we would need only 240 tonnes of it! But of course I grant, the hydrogen is relatively hard to come by, not by any means impossible, but pricey, so we expend hydrogen only where we must, and aim to conserve it where we don't require it as rocket fuel. Note that the ratio in sheer mass is nearly a factor of 37, so that is how much more "expensive" hydrogen would have to be than nitrogen before we would want to give serious thought to using nitrogen routinely for all loads.

So we fire the rocket. As the engines spin up and the thrust surges from zero to full near-and-somewhat-better-than Earth SL thrust, the thrust presumably exceeds the weight (here it is weight, not mass) of the stack and the thing starts rising. Long before that, of course the partial relief of even some weight means our formerly balanced aerostatic system is now enjoying super-lift, and starts to rise.

This is where it is important to know how much the thrust of full throttle lift-off of the rocket exceeds the dead weight, because that governs how fast it lifts off the pad, and relieved of its full weight, the platform will rise up after it--we want the rocket to briskly pull up and away from the platform, and it will not do to have the platform bounding up right behind it. Presumably the blast of force from the engine exhaust will push down on it a bit, but I am envisioning a grid work, or even an open hole under the engines, to minimize "splashing" the platform structure with the flame. However, the net excess of unchecked buoyant lift versus the remaining dead weight of the platform does not tell us the whole story as it would in vacuum; here the platform is of course immersed in Cytherian atmosphere, and unlike denser objects we are more used to, the sheer inertia of setting enough "air" in motion for the platform volume to flow up into is a substantial multiplication of its total inertia (this is the kind of thing one learns about studying aerostatics!) Aerodynamic drag of course also applies, on a very large cross section area--the platform, even if we don't vent any lift gas at all, will surge up briskly under the acceleration of the 5000 tonne (or whatever size) excess lift, but will be checked at a terminal upward velocity and the damn rocket can finally pull ahead and escape already.

But of course, having at some cost obtained and stored nearly 9000 tonnes of nitrogen, we can, because that is probably cheaper than obtaining 300 tonnes of hydrogen gas, simply open up rip panels on our nitrogen cells and let the nitrogen pour back into the Cytherian atmosphere it came from.

When we do that, the excess lift is dropped, and the platform coasts to a stop. If we release the gas the second the rocket lifts off the pad, well, that will have taken some time to reach from zero thrust, and we will be rising, but probably not very fast. If we have some decent expansion room in our primary lift cells, filled but not entirely filled with hydrogen, there is no problem at all.

Now I think we can do a bit better than this, and conserve our lift gases and not have to vent any of them, but I need to investigate the method I have in mind here a bit more. For a quick preview, it involves using steam, hot water vapor, as the temporary lift gas, and rapidly chilling that down using a spray of liquid nitrogen or LOX.

I wrote more about the aerostatics of sulfuric acid products and related wizardry, but anyway the topic of how to manage rocket launches and other sudden releases of weight while maintaining aerostatic is well addressed I think.

Offline mikelepage

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Re: Floating Habitat on Venus
« Reply #58 on: 11/20/2019 04:01 am »
Actually, you would want such a prison colony anywhere where it actually benefits you. Venus is probably too much of a niche. But having a way to force people to endure the hardships of living on an NEO maintaining that pesky space mining machinery, that would seriously improve the reliability of your production chain. Coming back from an NEO without the right ship/supplies/people noticing is kinda hard too. Still, I love the visual you've put into my head.

Coming back from a NEO about as hard as putting people there in the first place ;) Sure, you still have all the difficulties of living in space, and supplies can be rationed by a controlling authority to make it difficult to escape, but the problem with any prison that produces something of value to the outside world, is if the barrier is human-created, it's corruptible: if you know/can bribe the right people, or you organise a jailbreak, you can get out.  You would literally be setting up the pre-conditions for space piracy - which is also a cool story ;D   

What I like about a Venus cloud base as a prison is that the difference in difficulty between going there and coming back is a far more effective barrier that makes going there a one-way trip.  I nearly called it a "maximum security prison" in my first post.

***

On another note: I only just realised that H2S is a lifting gas in Venus atmosphere - somewhat less so than breathable air, but still not too bad.  H2S also just happens to be the output of sulfate-reducing microorganisms.  It would be interesting to see if a craft hosting such organisms could provide self-sustaining lift, but would likely cause objections from the planetary protection folks as these organisms would be prime candidates for pre-existing life in the Venusian clouds, if it exists.

Offline Shevek23

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Re: Floating Habitat on Venus
« Reply #59 on: 11/20/2019 06:15 am »
Seriously, what is it with people wanting any lifting gas that is just barely able to marginally lift a fraction of its own mass, versus one that lifts twenty times its own mass, just because it is barely possible?

What is the attraction?

Hydrogen sulfide, as I noted, was once and might still be used as a refrigerant, meaning it is relatively easy to shift between gas and liquid state and therefore useful for heat pumping--which is definitely a thing to want in Venus cloud colonies that descend below 55 km. As it happens, I'd like aerostatic platforms to go below 55 km mainly to increase the radiation shielding provided by the atmosphere. That's one of Venus's top attractions, right behind 90 percent of Earth gravity. At 55 km, the temperature is 300 K, which is comfortably warm for most people; Europeans might find it a bit too warm, people from the tropics could go a bit lower. To go a lot lower, it gets sweltering fast! But at 55 km, as noted pressure only a bit above half Earth SL pressure. Now with the lower gravity, to get that pressure, there needs to be more mass above than at the same pressure above Earth SL. So it is close to 60 percent the mass of atmosphere above Earth SL, thus about that much of the cosmic ray protection--some populations on Earth live that high up. I'd like a bit more honestly.

To go down lower though, say to 50 km within close range of the highest sulfuric acid concentrations, we'd have to actively cool the habitable zone.

And that pretty much puts paid to the idea of using breathable nitrogen-oxygen mix--now the pressure is closer to Terran SL, or even a bit higher, but chilling the air one breathes relative to the ambient temperature detracts from buoyant lift quite as much as the higher pressure we'd want to maintain at ambient temperature at 55 km kills it higher up. At least at 55 km, we could contemplate a lower pressure, with higher oxygen content (increasing fire risk)--some space station studies worked with half an atmosphere or less, and of course if you go over to pure oxygen, the pressure can get way down. But it would screw up cooking, and as mentioned, there is fire risk, and other possible consequences. And raising the percentage of oxygen raises the average molar mass of the air, thus hurting lift a bit that way.

If there were lots of settlements in Venus's atmosphere, with tens of thousands of people, a risky operation farther down, where if the cooling system fails people roast, is more something to consider since it will take a while for the temperature to get really high, buying time to fix the air conditioning, and if all else fails, people can abandon the platform--or simply drop some ballast or release more lift gas to rise up to cooler levels. If they have someplace else to run to, it is worth doing if there is some gain for it. As noted, the sulfuric acid is mostly down there at around 48 km up, where it is about as dense as water in rain clouds on Earth. So that's a reason to have at least something automated.

Going down also cuts down on the ambient sunlight levels, which was point 3 in favor of Venus. And it raises exposure to damage by the sulfuric acid. On the whole I'd rather stay up at 55 km if possible, not have to worry about my life depending on air conditioning, have plenty of power and live in a somewhat higher than ambient pressurized setting, at say 70 percent Earth surface pressure, with my breathing air decoupled from the ambient pressure outside. (70 percent is about where the FAA requires commercial aircraft to provide passengers either a pressurized cabin, or supplemental oxygen, about equivalent to 3 km or 10,000 feet on Earth).

But yeah, if we went down, we might prefer heat pumps operating with H2S rather than ammonia.

But...either ammonia or H2S require hydrogen to synthesize!

Neither is a superior lift gas to hydrogen. Nothing is superior to hydrogen for buoyant lift unless one could contrive to make something with such strong walls it could maintain perfect vacuum inside, and such walls of course tend to be quite hefty themselves.

So--to have ammonia, or H2S, or methane, we need hydrogen anyway. To have drinking water and water for crops, we need hydrogen. We can, with some effort, get hydrogen, and crack the sulfuric acid it is in.

Why not then just use the hydrogen?

Let's survey the lift gas candidates a bit. Carbon dioxide has molar mass 44, so displacing one mole displaces 44 kg.

H2S masses 34. In addition to the uses for heat pumping, the fact that it is suitable for that suggests it might be easier than most gases to liquefy by means of pressure and cooling, and thus to shift back and forth between gas and liquid state; more on this below with ammonia. It has other uses too, in moderate quantities, and it gives us something useful to do with sulfur we liberate from sulfuric acid. But as a lift gas it is pretty terrible, even worse than Terran style air mix, in that 34 kg of it are needed to lift a measly 10 kg.

We also can't realistically acquire it without harvesting sulfuric acid--it is found in the atmosphere loose I believe, but in tiny traces.

O2, which we need for lots of reasons, masses 32 and thus a mole of it will lift 12 kg, so we need 8/3 the mass of anything we want to lift.

N2 as noted masses 28 and thus lifts 16 kg, so we need 7/4 the mass of what we want to lift.

Ammonia masses 17, and requires 3 hydrogen atoms to make, along with pretty easily available nitrogen--but we still need to harvest sulfuric acid to make it.

See how it has dropped down to not a lot over half the molar mass of nitrogen, and therefore we are more ahead of the game on lift--now, 17 kg of this stuff will lift 27 kg, at long last we have something that masses less than what it can lift! That's nice. But it's real virtue in the aerostatic biz is that we might find we can compress it with moderate power expenditure, and cool off the adiabatic heating, and see it condense nicely into liquid ammonia. At 300 K, ammonia can be liquid at moderate pressure, and at standard pressure (not that that is particularly relevant in a cloud colony at 55 km up, where the breathable air is going to be at higher pressure but we don't want to store ammonia within that volume, and the ambient pressure is substantially lower) it can be stored liquid with moderate chilling. I'd do both--make a pressure vessel that can take the ambient-temperature vapor pressure, and then chill the ammonia down to ambient temperature, insulating the tank; the chill buys us time in case active cooling fails before the pressure rises to make it a bit of a bomb. H2S might or might not be superior in these respects, I don't know.

Here's the great advantage of being able to liquefy a lift gas--whenever we vacate a cubic meter formerly occupied by any gas, of any molar mass whatsoever, which we condense into a much smaller volume, the full weight of the ambient air density flows in. Another way to look at it, in gas form, part of the total displacement lift goes to lift the payload, but the rest goes to lift the molecule itself. Condensing it means we nullify both lifts, or rather they are parts of the same lift.

So, at 55 km I figure the atmosphere is about 1 kg per cubic meter exactly, and being able to condense either fluid or evaporate it lowers or raises lift by the full difference. Note that sulfur dioxide, which is heavier than CO2, would give us the same variation (if it made sense to use that, it doesn't of course--but perhaps it might be worthwhile to ship some chlorofluorocarbon refrigerant fluids, if they are dramatically easier than ammonia or hydrogen sulfide to shift between states--and those big molecules I believe are all quite a bit heavier than carbon dioxide per mole. The difference between using a light two-state fluid and a heavy one is that we need a constant amount of some other lift gas to lift the part heavier than the atmospheric molecules with the heavy ones, overall lift volume must then be more. But it might be worthwhile if we can shift lots of mass back and forth very rapidly!

Ammonia might bear some consideration as a primary lift gas, but it is not as good as:

H2O--in steam form, because it needs to be hotter than the ambient temperature to be a gas at all, steam is lighter than the 18 molecular weight would suggest, and like H2S and NH3, can be shifted between states, and we need lots of it for various reasons. But of course having to maintain a hotter temperature means lift depends on constant power--on Venus we have plenty of solar power when we are on the day side, but not so much on the night side! Nothing in fact. So again, steam lift is a good idea for variable lift situations perhaps, but once again we need hydrogen to make it. We don't need to crack CO2 to get it--we can get all the oxygen we need to make water from the same sulfuric acid molecule we get the hydrogen from.

Moving along, we come to methane. Methane masses only 16, and thus displaces 28 additional kg, so it is the opposite of nitrogen in that respect, needing only 4/7 the mass to lift a given mass. This is good, also we need it for ISR with something like Starship. And as the simplest hydrocarbon it is the base of a lot of molecules we might want to synthesize.

But note it takes the equivalent of 2 hydrogen molecules to make.

Now, what is there lighter than methane, that exists as a gas? I always forget what the first noble gas after helium is; there is that, but where are we going to get it? It's in the atmosphere, but in tiny trace amounts. On Earth, helium is actually easier to get, and I think that is true of Venus's atmosphere too--forget argon or neon, I forget which is which, helium is actually more common! With helium we are doing pretty good, we displace 44 kg with just 4, and thus a kg of helium can lift 10 kg of other stuff. Nice! But of course helium is infamously hard to contain, and while more common than other noble gases, it is still quite rare.

So that brings us to hydrogen, and if helium, lifting ten times its own mass, is impressive, hydrogen then is twice as impressive, lifting 21 kg.

Now this business of saying X kg of a gas lifts Y kg payload is a bit of a misdirect; what matters is how much lift you can get out of a cubic meter of volume. In that respect, hydrogen is just fractionally more effective than helium. Its real virtue with respect to helium, on Earth or Venus, is that it is far easier to obtain! Harder on Venus, but still easier than isolating helium. On Earth, hydrogen has the drawback of being flammable, but this does not apply on Venus.

A cubic meter of hydrogen will lift 954.5 grams at 55 km above Venus.
The same volume of helium, will lift 909 grams.
Steam, if hot enough, will lift 660 grams.
Methane will lift 636 grams.
Ammonia will lift 614 grams.
Nitrogen, or carbon monoxide, will lift 367 grams
Breathable air will lift 346 grams.
Oxygen will lift 273 grams.
Hydrogen sulfide will lift 227 grams.

So why in the name of jeezely Pete should anyone get excited about H2S being technically a lifting gas, when the same volume of pure hydrogen, the same 2 hydrogen atoms one needs to make the hydrogen sulfide, lifts 4.2 times as much!?!

The hydrogen lifts 2.76 times the mass the breathable air volume can lift, and we still have to crack carbon dioxide to get the oxygen in the breathable air. The large volume difference corresponds to the air that lifts a given mass beyond itself requiring 1.97 times the surface area to contain it, and while gas cell material can be remarkably light, still what exactly is the point of doubling the mass of it?

What benefit do we gain from the vain privilege of boasting the air we breathe is also lifting us?

It is nice that we don't need to actually lift the air, and it gives a little extra lift. Quite little however, and all the above assumed the air is the same ambient pressure as the atmosphere outside. Not a problem at all for some unbreathable lifting gas, of which hydrogen is far and away the best; it can just expand and contract, changing pressure and temperature with altitude, and why should anyone lifted by it care a lot?

But at 55 km, to breathe, we will want our air to be say 0.7 atmospheres, or more like 0.75 but let's go with the slightly lower value. That is higher than 0.53 and means that at a given temperature, it is denser in proportion, so the actual lift value of air at 0.7 atm at 300 K in carbon dioxide at that temperature and 0.53 atm pressure will be not 346 grams but less than half that--just about 160 grams in fact! That's much worse than triple the volume for the same lift, that is six times the volume, and the area to enclose it in a cell--which by the way now has to be much much stronger than typical balloon material has to be, and thus far heavier!--is close to 3.3 times as much!

We don't want the pressure and temperature of the air we breathe to vary either, and it won't if we keep to the same altitude, but actually we might find the platform having to rise or fall a bit, or in an emergency, quite a lot. Why compound the emergency by subjecting all people, plants and animals with the varying pressure and temperature too? During a sudden and precipitous descent, a lightweight structure had better be able to compress to avoid being broken, and thus there will be pressurization and heating--but we can combat the latter at least by dumping in reserves of cold oxygen and nitrogen, and thus maintain the volume. This is unfortunate, as rising back to target altitude must happen slowly lest people suffer from "the bends," since they will have taken in more dissolved nitrogen. But if breathable air were the lift gas, if we were little bitty bugs on the bottom of a gigantic spherical bubble of nitrogen and oxygen being collapsed collectively, that dump of chilling air to keep people from being air-roasted would fatally lower the lift and cause us to plummet further to certain death. If the lift is separate, we only cool a marginal share of the total volume and it makes little difference to the lift. Going up, as in the rocket launch scenario, it is not that difficult to make fabric walls that can contain a full atmosphere pressure, still better 0.7, so if were possible for the platform to reach open space, the habitation portion is still fine. Coupled to expanding lift gas, everyone freezes and dies of anoxia.

How many of the "hey you can float the sky city in its own breathing air!" enthusiasts have ever made any attempt to do the math of figuring out what the volume of air needed to do that would be, and how gigantic a sphere it would be, dwarfing the mass of the actual material structure people live on?

Of course I think it makes more sense to have the habitation separate from the lift cell cluster!

Please for the love of heaven, would someone explain to me why the quaint and quirky fact that breathable air is indeed a lift gas on Venus has somehow obscured the fact that it is a mediocre to poor one, and that we'd be much better off using hydrogen? What is this fascination with anything else as though hydrogen had something wrong with it?

Offline high road

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Re: Floating Habitat on Venus
« Reply #60 on: 11/20/2019 07:40 am »
....

How does using air instead of CH4 help with the change if buoyancy when the total mass suddenly changes by a fully fueled rocket worth?...

Well, it can help sort of.

BUT, nitrogen does have this single advantage--it is going to be easier to obtain overall. This probably does not justify using it for the primary lift gas for static lift; for instances where we have fixed weights to lift, and intend to keep them indefinitely, even if hydrogen is relatively costly, it is well worth using instead for that. If hydrogen is so hard to get or crack from sulfuric acid that we cannot rely on it for routine lift, we probably can't afford hydrogen containing fuels for liftoff and fueling interplanetary ships, and thus Venus would be quite difficult to visit or live on. I can't see why we should not use hydrogen, then.

Nitrogen however will be available fairly "cheaply," and so one quick and dirty way to enable an aerostatic launch platform for a rocket on any scale is to simply use an extra large (nearly triple the volume, and double the area hence dead weight of cell surface, and about 20-25 percent larger in linear dimensions, than a corresponding lift hydrogen cell) set of nitrogen balloons, sufficient to lift the entire dead weight of the rocket.

Now I think we can do a bit better than this, and conserve our lift gases and not have to vent any of them, but I need to investigate the method I have in mind here a bit more. For a quick preview, it involves using steam, hot water vapor, as the temporary lift gas, and rapidly chilling that down using a spray of liquid nitrogen or LOX.

I wrote more about the aerostatics of sulfuric acid products and related wizardry, but anyway the topic of how to manage rocket launches and other sudden releases of weight while maintaining aerostatic is well addressed I think.

So the short version of this: Nitrogen is much easier to come by on Venus than hydrogen (pure or as part of a more complex molecule). We'd probably be throwing it out anyway as byproduct of harvesting other compounds out of the atmosphere. So why not use it as a cheap lift gas and release it simultaneously through pressure vents on the moment of launch. Great point.

You could split the lift gas envelopes between a primary envelope that contains a light gas carrying the dry mass of the launch platform, and secondary envelopes with nitrogen that compensate for the mass of the rocket and fuel (production).

Good idea to use spare cryogenic fuel as coolant for rapidly cooling phase changing lift gasses as well. So many options!

I always thought it would be better to have the launch vehicle as small as possible, especially because protecting them against sulfuric acid exposure means they need costly adaptations anyway. But using an existing architecture that can get to Venus in the first place without needing specific reentry technology probably offsets this extra cost.

Actually, you would want such a prison colony anywhere where it actually benefits you. Venus is probably too much of a niche. But having a way to force people to endure the hardships of living on an NEO maintaining that pesky space mining machinery, that would seriously improve the reliability of your production chain. Coming back from an NEO without the right ship/supplies/people noticing is kinda hard too. Still, I love the visual you've put into my head.

Coming back from a NEO about as hard as putting people there in the first place ;) Sure, you still have all the difficulties of living in space, and supplies can be rationed by a controlling authority to make it difficult to escape, but the problem with any prison that produces something of value to the outside world, is if the barrier is human-created, it's corruptible: if you know/can bribe the right people, or you organise a jailbreak, you can get out.  You would literally be setting up the pre-conditions for space piracy - which is also a cool story ;D   

What I like about a Venus cloud base as a prison is that the difference in difficulty between going there and coming back is a far more effective barrier that makes going there a one-way trip.  I nearly called it a "maximum security prison" in my first post.

***

Ah yes, you specifically said exile. My mind must filter out punishment without chances for redemption. So supplying the station and sending back samples uses small launchers, I assume, as any human sized infrastructure makes it as easy to escape from Venus as it would be to escape from an asteroid. (as in: most attempts resulting in death as life support doesn't take the extra passenger into account).

Another reason to hope RL succeeds in reusing their rocket. Options!

Quote

On another note: I only just realised that H2S is a lifting gas in Venus atmosphere - somewhat less so than breathable air, but still not too bad.  H2S also just happens to be the output of sulfate-reducing microorganisms.  It would be interesting to see if a craft hosting such organisms could provide self-sustaining lift, but would likely cause objections from the planetary protection folks as these organisms would be prime candidates for pre-existing life in the Venusian clouds, if it exists.

However, that would allow us to create habitats specifically to allow such local life to flourish and study. Or even (unlikely), that there are already some life forms that use this technique as a 'floating bladder' like certain sea creatures use swimming bladders. Add a UV absorption mechanism to their metabolism, and you've got some more material for that story. ;-)
« Last Edit: 11/20/2019 07:56 am by high road »

Offline high road

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Re: Floating Habitat on Venus
« Reply #61 on: 11/20/2019 08:14 am »
Seriously, what is it with people wanting any lifting gas that is just barely able to marginally lift a fraction of its own mass, versus one that lifts twenty times its own mass, just because it is barely possible?

What is the attraction?

1) storage: H2 escapes through the envelope. So you'd need a much more impermiable envolope material to reduce this, adding mass and required lift gas. And you'd need to continuously produce H2 to make up for the escaping gas.
2) triple usage: phase changing materials can be used as a lifting gas, coolant and ballast. Which means you solve a lot of problems with one single substance, and nothing is lost when you 'drop' ballast in a pinch because it's getting too hot.
3) easier to come by. Getting H2 from sulfuric acid is going to be pretty energy intensive. N2 is likely going to be much easier to come by, while certain biological or chemical processes that are happening anyway or easy to add to the mix of processes needed to keep people alive and rockets to orbit, might result in other easily obtainable gases.
4) availability. Once the settlement hits a certain habitable volume, you're no longer going to need lifting gas, but rather ballast, as the air in the habitable volume itself exceeds the required lift. At which point I assume you would use water as ballast in aesthetically pleasing ways. (because by then, there would be enough infrastructure to help out in a pinch so emergency systems become less and less critical).
« Last Edit: 11/20/2019 08:16 am by high road »

Offline Shevek23

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Re: Floating Habitat on Venus
« Reply #62 on: 11/20/2019 08:18 am »
Here is how I think a platform for eventual human habitation can be bootstrapped with Starships.

TransVenus Injection from LEO to a Hohmann transfer orbit to Venus is 3570 meters per second; that puts the ship in a hyperbolic escape from Earth that at a great distance from Earth slows to the 2755 m/sec which is the orbital speed difference between Earth's orbit and that elliptical transfer down to 0.7 AU. The transfer takes a bit under 5 months, but note that a more energetic, costly orbit can do it in under two--that's what the eventual crewed ships will use. For uncrewed payload missions, we don't need them to hurry. The encounter speed of the Starship with Venus's atmosphere, taking into account Venus's potential, is about 11 km/sec, similar to Apollo reentry from the Moon, and supposedly within Starship capability (or returning from Mars, or even the Moon as in Dear Moon, would be impossible). It might take a two pass skip to Low Venus Orbit. For later shipments, that is good, it allows the orbiting Starship to phase its final entry to match a platform being blown around Venus fast enough to circle it in four days; being blown by winds its location is a bit unpredictable so it is good not to do a direct entry. For the first ship it doesn't matter, there is no there there until it "lands!"

Now how can it "land?" The goal is to reach 55 km above datum, not actually the surface, which is much too hot to visit. (Yet. I have a scheme in mind for diving probes that can scoop up regolith, OreDivers, and bounce back up to 55 km on buoyant lift before it cooks. These would want to use nitrogen for lift, because it is expendable, and because the poor lift of nitrogen means it is effective mass ballast while it is condensed in liquid form as heat sink. For staying on the surface we require a lot of infrastructure, but we can in fact acquire material from the surface I believe. But that's for a bit later!)

Well, there are such things as parachutes, and if we design a parachute that can be inflated with lift gas--a ballute--we might be in business. Unfortunately we cannot easily acquire useful lift gas on the fly, so whatever lifts the ship had better be stored in the ship when it enters the atmosphere.

The Starship, on its second entry pass, enters the atmosphere much as a Starship landing on Earth from LEO would only from a somewhat slower orbit.

By the way, for later depot ships accumulating propellant to send crew ships home, I figure "Low Venus Orbit" to be about 250-300 km above the surface--note that density of the atmosphere matches Earth's more than 50 km up, and that the lapse rate is lower due to the lower gravity; against this orbital speed hence drag at any given level of exo-atmospheric density is lower therefore. But also, it takes less deceleration to decay a slower orbit, so it does not pay to go too low.

Having shed its hypersonic speed much as it would at Earth or Mars, it is now descending "skydiver" style, but there is no place to propulsively land on. instead, at some point when subsonic terminal velocity is reached, well under 100 m/sec descent rate, we deploy the ballute, or a set of them.

Now the question is, which lift gas have we hauled all the way from Earth?

We realistically have just several choices. Nitrogen, still less oxygen, are just too poor to consider. The mass requirements just simply cannot close for them, it is not a question of agreeing to have less useful payload for the kewlness of it, it just won't work.

We can use ammonia, methane or pure hydrogen. There is no reason to use ammonia when methane is both better and what the Starship is designed to store on interplanetary missions anyway. I cannot quite decide if hydrogen might be a candidate or not--it all depends on whether a sufficient mass and volume can be kept from boiling off on the 5 month coast to Venus. I actually believe Starships ought to invest in active reconstitution of boiled off liquid methane and oxygen, but it is one thing to do that with substances that keep liquid at 100 K, and quite another with one that must be chilled down to 30 K. If hydrogen is possible, we should use it, but I don't assume it is. That leaves methane.

As noted, 4 tonnes of methane lift 7 other tonnes, when evaporated to ambient temperature and pressure. I calculated the capacity of a Starship almost topped off with propellant--not quite, because there is no point in loading in oxygen that would go to combust the methane we need for lift gas, and no place to store extra methane as cargo but the main tanks, so we just have to forego loading in some oxygen. With that in mind, I found that a Starship that must achieve TVI as stipulated can retain 146 tonnes of methane, and carry 136 tonnes of cargo.

So it becomes a question of how to boil 146 tonnes of methane fast enough, and warm it up to ambient, soon enough to prevent the ship from falling down to really dangerously hot levels. Well, actually, that rising pressure and temperature sort of come in handy! If our ballute operating as a parachute does not slow us down a lot, the ship keeps sinking. If we pump the residual methane into the ballute, the deeper we sink, the lower the fully expanded volume of the methane will be, the more heat flows into the ballute and boils the methane and heats the gas. If we actually trim back the payload a bit, we will have an excess of methane lift and so when only partially warmed up, the methane lift will check descent, and the ship will rise.

Note that @mikelepage's notions about a standard Starship design with Shuttle-like cargo doors might come in awfully handy here; in skydiving mode we can open the doors and deploy the ballute set, and the built in crane can be useful at future stages.

With extra lift, the Starship rises up to target altitude, and we can then vent the surplus methane and stabilize right there.

Now we have something like 100 tonnes worth of stuff in the cargo hold, which can be deployed. This would include solar panels for instance--having some mounted on the cargo bay door insides would be quite nice.

Should operations to harvest sulfuric acid and produce hydrogen begin immediately? There is an alternative!

Note that a methane molecule contains 4 hydrogen atoms, and thus, if we have a process instead to split off the carbon, we produce not one but two hydrogen molecules. Thus the same hydrogen we ship in the form of methane can over time be liberated (if we have a practical way to split methane like that) to double in volume, and displace not the total 400 tonnes (counting the methane mass itself along with the payload and dry mass of the ship) but 800 tonnes, and so the net lift beyond the 40 tonnes or so this hydrogen itself masses can rise to 760 tonnes. Of course the carbon is still there, massing over 100 tonnes, we want to keep it as ballast for the moment. In fact with the rest of the ship massing only 250 tonnes, we shall need to acquire some 410 tonnes of ballast!

I think this can be done by means of compressing carbon dioxide and chilling it into solid form, which we can accumulate in insulated, chilled bags.

Now it is possible you see to "land" a second Starship massing 410 tonnes without this one having to do the same rope trick with the ballute and stored methane.

If we can do all this with hydrogen instead of methane, just 34 tonnes of it will suffice to enable 585 tonnes of cargo! One of many possible hitches with that is that storing that much LH2 would take up nearly half the entire cargo volume, whereas squeezing nearly 600 tonnes of payload into a mere 500 cubic meters is quite a feat of packing too! Not to mention what 600 tonnes of downmass will do to the mass balance during hypersonic reentry.

Anyway, we don't have that kind of lift capacity at the first unit core station--yet. Sending a second ship after the first has had time to accumulate the hydrogen enables just 400 or so tonnes to land. That is of course 280 tonnes downmass cargo, minus any propellant used; the mass balance will be off, the total mass will be high, these things are only somewhat offset by Venus's lower gravity. I believe though the design can be finessed, especially since these Starships are one shot each, none of them will return to orbit, they are in fact Venus station modules. So they can have extra large canards I suppose.

It skydives down the way Starships normally land, only intercepting the platform, doing a kind of J hook past it so as not to torch it, coming down off to the side, and then a special hook arrangement catches it to suspend it--as its loaded weight settles on the structure, it drops the 440 or so tonnes of frozen carbon dioxide accumulated. There's plenty more where that came from! Now the ships are in equilibrium and safe.

The multiple hundred tonnes of second ship payload can include more solar panels, must include more deflated lift cells, and had better get started on the hydrogen collection. If at all possible, we must also get started on Sabatier processing to create methane and LOX--note we have now two Starship tank sets to store 2400 tonnes of propellant in, so we need gas cells permitting hydrogen to lift 3000 tonnes already.

We need to keep going then, on similar lines, only now hydrogen is coming from sulfuric acid that is somehow harvested and split. Given that, every 2 kg of hydrogen we accumulate is accompanied by 32 of sulfur and 64 of oxygen. If we can just drop the sulfur (though actually we want to keep some for various purposes, and any we can afford to keep beyond that is ballast we can drop if we need to) the oxygen in gaseous form as noted can lift an additional 24 kg, and added to the gaseous hydrogen's 42 that comes to 66 kg we can lift. So actually if we take about half the hydrogen and run it into the Sabatier process, we can by various means keep lift and weight in balance, by shifting various gases into partially liquid form, and we can pull ahead with fueling up the various Starship hulls to store many thousands of tonnes of propellant.

Eventually, we have to send a SuperHeavy to Venus. In fact for safety we should send several. Fortunately, a SuperHeavy should be well able to launch itself into LEO, and if it si refueled there, easily make TVI. The problem is the things are not designed to reenter! But I believe they could be outfitted with a frame holding ablative tiles, designed for the one-time entry (Actually again a skip reentry, though with ablative that is not as necessary, but again it has to phase to come down near the platform). Perhaps it can land with the frame bearing the remnants of the ablative and these items stored for possible future use.

Now we are closing in on the goal. With propellant production, aerostatic balance management, and a SuperHeavy or three based there, it becomes possible at last to send a crewed ship which can hook on like all the others.

Eventually, it will be desired to send this crewed vessel home to Earth again.

The bad news about Venus's high gravity is that we need a two-stage launch system. Thw good news about it being lower than Earth's is, payloads with Starship type systems double! it becomes possible to place some 300 tonnes of propellant into LVO per tanker launch, and possible indeed for the Crew Starship to have retained considerable of the propellant they launched with, so between the rapid refueling a depot Starship, in four or with a suitable specialized Tanker design even just three launches, and the fact that a launched crew ship would be light on payload and retain some propellant itself, it becomes possible for these crew ships to start returning to Earth remarkably soon, and to achieve rapid 2-month return trajectories. We pay a price in low payload, and also in high speed entries at both ends; I calculated the 2-month trajectories aiming for the top speed Musk has tweeted, of 13 km/sec entries. Actually on returning to Earth, these might go into LEO instead of landing, to transfer crew to another Starship for landing; or they could land on Earth of course.

This initial platform would be quite gigantic, but I envision it as stage one. The next stage might be to use it as a construction base for a kilometer or more long airship, pretty much on traditional airship design lines but gigantic of course even by airship standards. Such a ship could lift some tens of thousands of tonnes.

Note that we might contemplate putting a "well" for Starship landings and launches, having to accommodate SuperHeavies of course, right in the middle of this super-airship. If the airship can make significant airspeed, say 50-60 knots, then we have another way of dealing with the sudden superbuoyancy caused by launching a 5000 tonne stack--if the "spaceport" well is located aft of the center of mass, suddenly having a tail-up pitch will automatically cause such a ship to drive itself down by dynamic lift. This buys time for lift that was achieved less efficiently than hydrogen in the form of steam, or ammonia, or perhaps hydrogen sulfide if that is easier to condense than ammonia, to be converted to liquid form. Note the SuperHeavy will RTLS, and contribute its dead weight to the project of stabilizing the giant colony ship. Now the notion of having a well in the tail conflicts with my basic notion of an airship in the form of a gigantic version of the Zeppelin NT, with three "keels" that form a symmetrical semirigid frame, a moderately pressurized hull stiffening three gores of fabric, the hull then covered with solar paneling to power the whole thing--the people and other habitat stuff, plants and so forth, would live inside the keels, a bit like the three keels of the American Naval rigids USS Akron and Macon. But another approach is to have two such hulls fused together as Siamese twins, making a form that is flatter than traditional airship design, twice as wide as it is tall, which improves the dynamic lift performance, and widening it makes more room in the region aft the center of mass, halfway or more toward the tail structure, for the landing/launch well.

Alternatively, we could have a traditional airship shape towing a toroidal launch/landing assembly, relying on the buoyancy management strategies I described, if all else fails, just on lifting the SH/SS stack with nitrogen that is sacrificed.

This is the actual first fully operational "cloud city" then, actually a huge airship. Propulsion of the thing enables it to choose its winds and thus manage its course around Venus over 4 days, to escape possible turbulent vortices.

It is possible, if my notion of an OreDiver that plunges down to the surface quickly, grabs many tonnes of pretty much random regolith, and returns to 55 km altitude with this payload via inflating a big nitrogen balloon, that much of the material to construct such an airship-city could be in situ Venus material.

If OreDiver is not possible, then I suppose Venus will remain a sideshow of low interest, but if it can be made to work, and the sort of material that can be brought up is diverse enough, the colonization of Venus can proceed.

Offline Shevek23

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Re: Floating Habitat on Venus
« Reply #63 on: 11/20/2019 08:48 am »
...Nitrogen is much easier to come by on Venus than hydrogen (pure or as part of a more complex molecule).

Yes. It is possible to get it by compression and cooling, no actual chemical processing required
We'd probably be throwing it out anyway as byproduct of harvesting other compounds out of the atmosphere.
Relatively cheaper than hydrogen. I don't think it will be actually practically free like that. There is more nitrogen in Venus's atmosphere than Earth's, but there is a whole hell of a lot more carbon dioxide. So it is more like extracting argon or neon from Earth's atmosphere than the quite easy process of getting either oxygen or nitrogen from our air. Probably not as hard as getting noble gases from air, but much harder than getting nitrogen is on Earth. But it is available right there, as much so as carbon dioxide is.

It ain't free though.
So why not use it as a cheap lift gas and release it simultaneously through pressure vents on the moment of launch. Great point.
I've spent a long time in previous years thinking about airships and aerostatics generally.
Again it is not so much that it is cheap, as that it is cheaper than hydrogen. It is more expendable, that doesn't mean I'm comfortable with the idea of throwing it away freely. That's just the fallback.

You could split the lift gas envelopes between a primary envelope that contains a light gas carrying the dry mass of the launch platform, and secondary envelopes with nitrogen that compensate for the mass of the rocket and fuel (production).
I said that. Believe it or not, I edited that post to shorten it, so maybe I edited that out?

I'm actually thinking of many many gas cells, in a rather ad hoc crowd of them.

People often don't realize how gigantic airships could be. I had the privilege in real life to see a "small" Goodyear blimp moored at the airport I lived next to, and sought to approach it. I didn't even get very close, but I could see how tremendous this 7-10 tonne job was. The Goodyear blimps of the postwar years up to when they switched over to Zeppelin NTs were pretty much WWII era "L" ships, smaller than the near-standard "K" ships of the war, the training version essentially. That's what this thing was. I can only vaguely imagine the majesty of something like the USS Macon or of course Graf Zeppelin or Hindenburg; the smallest WWI Zeppelins were bigger than this Goodyear blimp.

So part of my rant against using breathing air for lift gas is that people don't seem to realize that if we have something like a 1000 tonne or so platform and it is embedded like a snow globe in breathing air, it won't look like a snow globe, with the castle or whatever reaching most of the way to the top. Nope, all the stuff that globe can lift will be rattling around on the bottom of an otherwise empty sphere. I think people would find it downright oppressive, actually. Not cool at all.

Good idea to use spare cryogenic fuel as coolant for rapidly cooling phase changing lift gasses as well. So many options!
As I said, though, not actually sure that will really work. There was this DARPA project in the early to mid 2000s called "Walrus" which many people in the LTA boards I was on were excited about, and I was catching the steam balloon bug, and realizing the great utility of switching a gas to liquid and back again--I didn't like the idea of ammonia much at that time, and it is certainly more appropriate on Venus than Earth.

So I was hoping to come up with some scheme to quite rapidly condense the water instead of just venting it. Someone else suggested spraying liquid nitrogen into the steam. I think when I did the math I discovered, not too surprisingly really, that due to conservation of energy, the lift you lose by collapsing the water into liquid goes via the heat of vaporization being released from the water to whatever cooled it into warming that stuff into gas, and then that expands the coolant gas into lift gas itself. Perhaps if we used something that also had a high heat capacity and was a heavy molecule? It might or might not work.

Though as I also said here, on Venus it is valuable to recover the water as water, and we can still release the warm nitrogen if it really amounts to nearly the same lift.

I always thought it would be better to have the launch vehicle as small as possible, especially because protecting them against sulfuric acid exposure means they need costly adaptations anyway. But using an existing architecture that can get to Venus in the first place without needing specific reentry technology probably offsets this extra cost.
Well, the whole genius of Starship, if that is how it works out to really demonstrate, is that you design one ship and don't make lots of variations each of which has to be retested and recertified.

As you see, I am not talking about an Apollo type effort here--throw 3 guys at Venus with some sort of LVO return vehicle parked there, let them descend and fly around in a small blimp with a Titan rocket strapped to the belly for some months, then climb into the ultralight capsule and blast back into orbit, get on their ship and go home. Heck you can't even plant a flag on Venus! Or you could drop one but even made of Kevlar it would just melt.

Nope, I'm talking about an effort comparable to Musk's Mars colonization. Using the same hardware he came up with for Mars.

I figure we should be going full on Heinlein here; Musk is determined to make part of the "future history" real; I always liked Between Planets better than Red Planet.

"Venus and Freedom!"

Offline Shevek23

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Re: Floating Habitat on Venus
« Reply #64 on: 11/20/2019 09:42 am »
Seriously, what is it with people wanting any lifting gas that is just barely able to marginally lift a fraction of its own mass, versus one that lifts twenty times its own mass, just because it is barely possible?

What is the attraction?

1) storage: H2 escapes through the envelope. So you'd need a much more impermiable envolope material to reduce this, adding mass and required lift gas. And you'd need to continuously produce H2 to make up for the escaping gas.
Hydrogen is slippery, but not nearly as bad as helium, which is a monotomic noble gas. Yet the containment of helium for blimps has been much improved.

An ironic outcome of Venus colonization might be a sort of retro-plantation-punk, whereby materials on Venus tend to be from plants grown in the habitats, so we might revert back to the days of cotton envelopes--but probably not goldbeater's skin, that is just too labor intensive! No, the big rigids of the 1930s were already switching to new gas cell materials synthesized for better durability and leak resistance. Indeed some hydrogen will seep out, but slowly, and the bigger the cell, the slower the relative loss rate will be.  Meanwhile we had better be obtaining hydrogen in truckload amounts, or might as well stay home. So the slow leak rate is easily compensated.
2) triple usage: phase changing materials can be used as a lifting gas, coolant and ballast. Which means you solve a lot of problems with one single substance, and nothing is lost when you 'drop' ballast in a pinch because it's getting too hot.
I discussed that, but you only want that for variable weights, not for steady fixed ones.

Neither ammonia nor hydrogen sulfide can be made without hydrogen. Breathing air can be, but it is not useful in this category at all.

3) easier to come by. Getting H2 from sulfuric acid is going to be pretty energy intensive. N2 is likely going to be much easier to come by,
You get what you pay for, nor will nitrogen be free either. Whereas, if we are going to be accumulating fuel for returning people back to orbit and fueling their ships to go back to Earth, we had better be obtaining hydrogen anyway.

There are technically alternatives. I would seriously look into carbon monoxide fuel with LOX for oxidant. But...I doubt very much it would work out to enable even two stage to orbit, even on Venus, and can it do so allowing RTLS reuse of the booster stage? Anyway it is a whole new design, there are just loads of issues I would foresee.

Similarly, on paper there are alternatives to the chemically propelled Starship to go Between Planets. But take solar electric. I've looked into it. To beat a 2 month transfer, or even a Hohmann orbit 5 month mosey, a solar powered ship would require really large masses of solar cells, and a pretty heavy installation of Hall thrusters, never mind how we store the xeon! Actually "primitive" impulsive burn chemical rockets, even foregoing the ultra high Isp of hydrogen for the more mediocre Isp of methane, are pretty hard to beat to go someplace as "close" as Venus.

So ISR is probably the key, and that means methane. And that means hydrogen to literally burn. It is a costly operation, but that's space travel for you.

Fortunately, Venus has quite a lot of relatively easily available solar power, in between the cloud layers. Half the intense sunlight bounces off into space, but half of it gets through the top clouds and bounces around between the cloud layers for quite bright diffuse sunlight; no need to point your panels anywhere, just mount them fixed and you have power for 48 hours--then deep darkness for 48 hours.

So you "mine" sulfuric acid and crack it all day, and use the Sabatier process to make methane... but nothing stops us from upping the sulfuric acid mining and processing to make more hydrogen than we need for ISR, and is why I think hydrogen must be widely available.

Meanwhile if we don't harvest hydrogen at all, we can hardly have a habitable colony, can we. What, we are going to ship all the drinking and crop water from Earth? I don't think so.

As for non-ISR strategies like the "Apollo" style "three guys in a blimp until the return launch window is about to open, then up they go on a Titan II, hasta la vista Venus, we're never coming back!" if you do the math, I think you find it is flat impossible for them to land enough already processed nitrogen to buoy themselves. If NASA is going to land one blimp on Venus, that blimp will at least have to have something as good as ammonia or methane. Why not hydrogen then? (Maybe because it is too hard to ship the distance because of boiloff? Or volume storage issues? If we can't ship hydrogen by the way, we sure can't ship helium either, and if we can ship helium we can ship hydrogen).
while certain biological or chemical processes that are happening anyway or easy to add to the mix of processes needed to keep people alive and rockets to orbit, might result in other easily obtainable gases.
This seems to relate to the other thing you say below that downright mystifies me.
How?
How can biology or chemistry conjure up substances unless either they are concentrating something present in situ but in small amounts, or something brings the substances in?
Who talks about these amazing result processes in any detail that I might learn from them?

But we are talking about lift gases here. Those have to be simple--complex molecules are heavy molecules; the name of the game of a buoyant lift gas is to have a light molecule. Simple, few atoms, half the game is to have the atoms present at all, then we turn to how to split them to organize them the way we want.

In Venus's middle atmosphere, where we humans can live, what "Certain" processes are actually happening? In a first landed minimal platform module, what processes can we make happen, that don't involve rolling up our sleeves and dipping into the sulfuric acid clouds and using energy and equipment to crack the acid into somehting else? Some kind of bacterial action or what?

Besides sulfuric acid there is hydrogen sulfide, but I think my research showed that the latter is a tiny fraction of the former. But maybe if there is some process that attracts the molecule somehow. I think you must be alluding to something biological.
4) availability. Once the settlement hits a certain habitable volume, you're no longer going to need lifting gas, but rather ballast, as the air in the habitable volume itself exceeds the required lift. At which point I assume you would use water as ballast in aesthetically pleasing ways. (because by then, there would be enough infrastructure to help out in a pinch so emergency systems become less and less critical).

It does not work that way. Where is the mindless process that keeps on producing a mix of nitrogen and oxygen whether wanted or not, like the brooms in the Disney version of the Sorcerer's Apprentice. It seems that people making claims like this have invoked some kind of magic they believe in that gives them nitro-oxygen for free. But no, the ground state of things in Venus's atmosphere at the levels where temperatures are bearable is not to produce nitrogen sorted out from the carbon dioxide, nor is it to produce free oxygen in any form whatsoever. Are you thinking, "plants turn CO2 into oxygen?" They do, but they require water to do so, that's part of the chemistry involved. We must go and fetch some water, or anyway hydrogen. Having fetched hydrogen, we should bloody well use hydrogen!  Both types of gas require work to get. I've granted the hydrogen will cost more energy and more work, but it is worth a hell of a lot more too.

The last guy who tried to insist that Venus colonies should use air and not hydrogen said "I didn't get it" and then proceeded to talk about the colony getting large and just growing itself seamlessly somehow, like he thought it was one big organism or something.

Even so, if we had Lexx type technology like that, it would remain more rational for the giant bugs to use hydrogen than nitrogen to buoy themselves.

The hardest thing about getting hydrogen by the way is that the cloud layers where it is most abundant are down another 7 km or so, and it is literally boiling hot down there. But there is some at 55 km, less than in the densest layer by a factor of 30. It is not clear to me whether we'd need to put down buckets as it were, either lower collectors on tethers, or send down aircraft to ramscoop it in, or whether a slow steady filtering of the ambient air up high to catch the thin gruel of sulfuric acid there will be adequate.

Either way, it takes energy to gather the acid, and then energy to crack it, but we pretty much have to try, or how the heck can we do anything without hydrogen? We'd have no water, no food, and hence-no air.

I've spoken about nitrogen advisedly many times. It is nitrogen that is easier to extract, not air. Without water we cannot convert CO2 into oxygen and carbon.

Meanwhile a factor of two in gas cell area is nothing to shrug off on the gigantic scale of aerostatics! Air is thin stuff, and trying to support serious masses of condensed materials such as our life forms are used to dealing in requires marshaling really huge volumes of it. Anything we can do to cut down the mass of material needed to shepherd gases, we should.

Broadly speaking, I think the rather magical seeming processes you are talking about come under the rubric of "growth and expansion." But it seems someone has done a sleight of hand, making it seem reasonable that nitrogen and oxygen will just come along naturally, but hydrogen is unnatural or something.

Without hydrogen, nothing is going to Venus but some probes and nothing is going to be launched at all. There is hydrogen, it is locked up in sulfuric acid, so that is where to go for it.

Offline Lampyridae

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Re: Floating Habitat on Venus
« Reply #65 on: 02/24/2020 04:16 pm »
The advantage of breathing-gas-as-lifting-gas comes from Landis-style floating cities. To take his example, a 1km diameter spherical aerostat will lift 700k tonnes - two Empire State buildings or seven Gerald R Ford class aircraft carriers. A 2km diameter aerostat will lift 16 million tonnes, which at 50% available mass allows you to have a 3.14km^2 plate in the middle* of it covered with soil to a depth of 2m for flowerbeds and lawn. For an exploration habitat, hydrogen or helium is fine.

With large sizes come additional challenges but also interesting opportunities.

As for temperature, the average temperature at the 1 bar level as measured by the VeRa experiments is 77 degrees C at the equator but drops to 42 degrees at the poles. At the 0.5 bar level, it's -7 degrees at the poles. Near the poles, an aerostat at the 0.8 bar level would experience that balmy 27 degrees, although the temperature would fluctuate. Midnight is actually hottest near the poles.

*subject to sensible design, probably lower in the aerostat for CoG

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #66 on: 06/10/2020 09:52 pm »
Hmmm, how did I not see this Venus habitat thread? Odd... I didn't see the NTR or the air-breathing stage thread either.. Is the "Someone said something on the Internet" signal not working? Hmmm, plugged in, yes, power's on... I wonder if the switch is... GAHHHHH! MY EYES!!!! (Yep, right there on the warning label once my eyes clear of enough spots "Do not look directly into signal light" Thanks Acme...grumble-grumble, stupid coyote... :)

Anyway: Shevek 23;
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Seriously, what is it with people wanting any lifting gas that is just barely able to marginally lift a fraction of its own mass, versus one that lifts twenty times its own mass, just because it is barely possible?

What is the attraction?

Simply put you're going to be using it anyway so why not 'use' it? Note there's nothing that assumes or says you have to use it ONLY though and that's not usually outright stated but is inferred.

Your also asked:
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How many of the "hey you can float the sky city in its own breathing air!" enthusiasts have ever made any attempt to do the math of figuring out what the volume of air needed to do that would be, and how gigantic a sphere it would be, dwarfing the mass of the actual material structure people live on?

Everyone from Buckminster Fuller to Geoffrey Landis has done the calculations as have many more as well. Yes the sphere is gigantic but that's also the point since it has so much volume available for use. And with it BEING 'breathing-air' you can in fact use the entire volume for habitat space. The thing is you don't normally START with a single huge sphere and you of course have to work your way up and that will include using other lifting gasses as the need arises. I suspect you're also not taking into account how light the internal and 'living' structure can and probably will be.

And:
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People often don't realize how gigantic airships could be. I had the privilege in real life to see a "small" Goodyear blimp moored at the airport I lived next to, and sought to approach it. I didn't even get very close, but I could see how tremendous this 7-10 tonne job was. The Goodyear blimps of the postwar years up to when they switched over to Zeppelin NTs were pretty much WWII era "L" ships, smaller than the near-standard "K" ships of the war, the training version essentially. That's what this thing was. I can only vaguely imagine the majesty of something like the USS Macon or of course Graf Zeppelin or Hindenburg; the smallest WWI Zeppelins were bigger than this Goodyear blimp.

This assumption lacks a bit in that most of us are VERY aware how 'big' airships are and quite cognizant of the issues they present as many of us ARE in fact LTA enthusiasts as well :)

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So part of my rant against using breathing air for lift gas is that people don't seem to realize that if we have something like a 1000 tonne or so platform and it is embedded like a snow globe in breathing air, it won't look like a snow globe, with the castle or whatever reaching most of the way to the top. Nope, all the stuff that globe can lift will be rattling around on the bottom of an otherwise empty sphere. I think people would find it downright oppressive, actually. Not cool at all.

And again this shows you're not familiar with the suggested designs rather than those designs are flawed :) Somewhat more like "Cloud Nine" or "City Sky" than a 'snowglobe' design (https://www.citylab.com/design/2011/11/ctiy-sky/527/, https://worldbuilding.stackexchange.com/questions/36667/can-cloud-nine-be-built) and it would have multiple floors and possibly inner structures. (I wish I could find a good illustration outside of "The Millennial Project" of an "apostle cluster" bubble design but that's essentially how you'd probably 'build-up' such a large design) As Lampyridae said above you could use up to 50% of the 'sphere' for habitat with no real issues. Sure you'd have to be careful of you CoG area but you can in fact build some structures right up to the top if you're light enough and tensegrity structure can be very light weight after all. A 1000 tonne 'internal structure' is a LOT of structure yes, but it would take about a half-kilometre sphere to support using 'air' alone.

Sure airships were/are big but they had to be since they had the lift gas separated from the 'habitat' sections and you'd have that early on in Venus colonization as well. But in such designs as the size of your habitable and lifting gas area increases so does your diffusion across any given interface so at some point you'll need to physically separate the "air" from the direct lifting gas (as opposed to your indirect lifting gas of the air you breath) since any of the 'decent' lifting gasses are going to have issues when mixed with oxygen.

I really like your Starship example, (and I like that as it follows along nicely from a BotE I did using Mars Direct as a basis) I rechecked the Selenian Boondocks article "Venusian Rocket Floaties" as I'd hoped he'd done a "Starship" update but apparently not. (https://selenianboondocks.com/2013/11/venusian-rocket-floaties/)

While I understand the desire to not make major modifications to the Starship I'd point out that you'd be doing something similar for Martian colonization for "one-way" Starships as well so you might as well make some changes to a "one-way" Venus Starship. Moreso as the Starship may require some heavy modification to handle Venus anyway. (https://www.rolledalloys.com/shared/library/technical-papers/corrosive/The-Performance-of-Stainless-Steels-in-Concentrated-Sulfuric-Acid.pdf)

You'd want to have more than one area along the dorsal surface to deploy the 'ballutes' of methane since you have to deploy them pretty fast and evenly so it would be more than one 'bay' that would need to be installed. I'd suggest an alternative configuration though as I can see a good number of reasons not to 'clutter' the colonies dorsal and ventral surfaces if you can avoid it.

Instead I'd suggest installing canard-to-fin side 'blisters' that would house an inflatable balloon structure in a configuration similar to the FIRST re-entry glider concept:
http://www.astronautix.com/f/firstre-entryglider.html#:~:text=FIRST%20(Fabrication%20of%20Inflatable%20Re,of%20space%20crew%20from%20orbit.&text=The%20crew%20member%20would%20use,correct%20attitude%20for%20re%2Dentry.

The main reason is so that, like the concept, your entry is far less rough by spreading the loading and heating into a much larger area. Secondary is that you can then deploy flexible solar cell sheets both above the space and below to increase your initial power influx. (@about 50km altitude the sunlight reflected from most of the cloud base equals about half that of the direct sun)

You're also going to need to put a dedicated propulsion system on the Starship deploy-able once you're 'down' to help keep the now-habitat near the equator areas. (Probably replace the landing gear on a standard Starship with deploying ducted props?)

Using 'surplus' methane to produce hydrogen make (and then gradually replacing the lift-methane with lift hydrogen) would make sense and you'll eventually have to deploy more lift balloons as the standard mass of the colony increases. The idea of 'catching' an incoming Starship is neat but I'm not sure it would make sense considering they are already going to be 'one-way' Starships so why not make them all similar in that respect?
Wouldn't it make more sense to make each one a 'core' colony module and then provide a way for them to link-up 'in-flight' once at Venus? Linking four of them nose-to-nose would give you a circular 'colony' base to grow from and using differential thrust on the propulsion should give you pretty good control of your colony.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Floating Habitat on Venus
« Reply #67 on: 06/11/2020 10:36 am »
I wondered why you weren't responding to this thread a while back  :)

For Starship, I assume a coating would be enough? It adds mass, but Venus does have a little less gravity, so I was hoping that would cancel out.

I haven't bothered doing the math for a Starship based architecture so far, because I usualy like my habitat ideas as light as possible. The size of a floating launch facility for a full starship and superheavy stack is kinda over the top for my early-settlement-tastes. But using one as a hab, especially if you could disassemble it into multiple parts (take out tanks, plumbing, engines, what have you, float and use them all independently and use the use the entire volume of the Starship as a habitat), that's a nice idea. A few-sizes-fit-all Starship is bound to become cheaper than a custom built module anyway.

Edit: So essentially this means going full on Tatooine Shipyard, with a jumble of reused parts, while floating in the air. Great visual.
« Last Edit: 06/11/2020 10:39 am by high road »

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #68 on: 06/11/2020 04:52 pm »
I wondered why you weren't responding to this thread a while back  :)

Someone on the internet was wrong and I had to deal with that first! (Ya, right... THAT would be a lifetime job right there :) )
Seriously life has been a bit more wild than usual and and I've fallen behind on most things and trying to catch up.

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For Starship, I assume a coating would be enough? It adds mass, but Venus does have a little less gravity, so I was hoping that would cancel out.

Coating, Teflon alloy or some of the stainless types mentioned in the article above if they can be used to make a Starship with. I'd prefer the alloy or the compatible type if possible as the coating can get damaged and therefore you have to assume and plan maintenance on it. A lot of things you can do but they each have trade offs and advantages and disadvantages.

Part of the reason I suggested the design I did was to limit possible ingress points for SA and other contaminants.

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I haven't bothered doing the math for a Starship based architecture so far, because I usual like my habitat ideas as light as possible.

True but you have to start somewhere and I'll grant Starship is a good option. (I worry about the engine bay/bells actually as that's going to be be a problem area but you're going to need it for weight and balance for a good while) HAVOC in some ways makes sense too but you're going to be much more limited on initial space to 'grow' into. That's one reason I like the FIRST shape for such a mission as you have a much larger initial space and you can compensate for growth by adding lift-cells into the spaces between the booms and the main body.

Being honest I'm still more partial to the MD Habitat structure as an initial 'seed' since you're main lift comes from a hydrogen balloon but you then inflate a large Tefzel "pillow" sphere around the Hab to expand your space. Join several of those to form a seed colony and move the lift balloons to an outer structural 'ring' assembly as you grow. Still you'd obviously have more internal room to grow with a Starship as a basis.


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The size of a floating launch facility for a full starship and superheavy stack is kinda over the top for my early-settlement-tastes.

A lot of the discussions I've seen on a Venus floating spaceport DO point out that it makes thing REALLY simple if your "spaceport" masses so much that it essentially doesn't notice any launch or landing happening :) I'll be upfront that I don't in fact like the concept of Starship/Super-Heavy as basis for an interplanetary transportation system for the specific reason that like Mars Direct on which it is based it goes out of its way to avoid and discourage any build up of off-planet infrastructure. While it can be argued that it would benefit from such it is at it's core avoiding it and generally suggesting it has no purpose and therefore should be ignored. Space Stations, fuel depots and other orbital 'assets' are side-tracks and distractions, dedicated cargo and passenger interplanetary vehicle are discouraged and disparaged since Starship does it all in one vehicle despite the obvious compromises and costs added. Despite Musk's (and many fan's) claims Starship is really only designed to go to and colonize Mars and it has to be heavily modified to be used anywhere else. Really a tether and lighter aerodynamic 'shuttle' for travel to and from Venus would be vastly better and cheaper than trying to use a Starship/Super-Heavy launch system, but in the case of the Starship/Super-Heavy "hammer" all problems look like nails :)

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But using one as a hab, especially if you could disassemble it into multiple parts (take out tanks, plumbing, engines, what have you, float and use them all independently and use the use the entire volume of the Starship as a habitat), that's a nice idea. A few-sizes-fit-all Starship is bound to become cheaper than a custom built module anyway.

That's one thing I didn't bring up but as a point to 'use' a Starship properly it really should be suspended from the a balloon deployed from the nose as it's a 'vertical' interior design and the tanks of propellant in the suggestion are going to require extra lifting bags to put it into a horizontal position. My suggestion is going to have space and the ability to put the expanded lift cells further aft where needed in this scenario. You'd have to have more lift cells to deploy fitted aft towards the propulsion bay if I'm visualizing the original Starship concept correctly? (Shevek 23?)

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Edit: So essentially this means going full on Tatooine Shipyard, with a jumble of reused parts, while floating in the air. Great visual.

Nice visual yes, but inaccurate I'm afraid :) You won't have many (if any) parts floating around as you want to keep the number of things you have to track and control to a minimum so you won't break anything up into parts but find a way to use the parts in place or 'store' them for raw materials or later use.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #69 on: 06/11/2020 07:02 pm »
Edit: I apologize for the tone of this post but I truly am having trouble finding most of this anything but deliberate misunderstandings and condescending straw-man attacks and that bothers me greatly. If it IS actual misunderstanding and cross-purpose discussion errors then please tell me so but as it stands I shot from the hip and regret nothing... Well till I do :)

Hydrogen is slippery, but not nearly as bad as helium, which is a monotomic noble gas. Yet the containment of helium for blimps has been much improved.

Actually in some ways it's slipperier due to the way it defuses through materials :) Part of the reason you don't want a hydrogen filled space next to an oxygen filled space on Venus is the hydrogen will tend towards the oxygen filled space rather than the CO2 atmosphere. The larger your interface the more chance of diffusion.

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An ironic outcome of Venus colonization might be a sort of retro-plantation-punk, whereby materials on Venus tend to be from plants grown in the habitats, so we might revert back to the days of cotton envelopes--but probably not goldbeater's skin, that is just too labor intensive! No, the big rigids of the 1930s were already switching to new gas cell materials synthesized for better durability and leak resistance.

While plant and other 'grown' materials will be used extensively inside the habitats a cotton envelope would require too much maintenance and upkeep on Venus. Teflon-plastics will likely have to be produced locally as outer envelopes, they are also pretty good at retaining lifting gases :)

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Meanwhile we had better be obtaining hydrogen in truckload amounts, or might as well stay home. So the slow leak rate is easily compensated.

Yes but it's not JUST the 'leakage' rate you have to worry about which is the point of not using it in a space in contact with an oxygen atmosphere. It does not 'just' defuse out of the 'top' of the gas cell but ALL the surface area of the gas cell.

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Whereas, if we are going to be accumulating fuel for returning people back to orbit and fueling their ships to go back to Earth, we had better be obtaining hydrogen anyway.

An assumption of any long-term stay on Venus is that you will be rapidly building up the capacity to 'mine' all sorts of resources from Venus itself. Yes 'hydrogen' will be one but part of the reason for NOT using it as a lifting gas if you don't have to is so that you have more to use for more important process.

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There are technically alternatives. I would seriously look into carbon monoxide fuel with LOX for oxidant. But...I doubt very much it would work out to enable even two stage to orbit, even on Venus, and can it do so allowing RTLS reuse of the booster stage? Anyway it is a whole new design, there are just loads of issues I would foresee.

Actually RTLS is vastly easier on planets like Venus and Earth than anywhere else and I'll note that limiting yourself to what 'works' on Earth, (Starship/SH) is going to cause more problems than a more efficient solution using local materials. For example while I don't see using LOX/CO2 it's a viable option for Venus since you have so much of it and can use passive and active lift to assist. You will likely still use Methalox propellant but not in a VTVL system as that would be wasteful and inefficient under the circumstances.

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Similarly, on paper there are alternatives to the chemically propelled Starship to go Between Planets. But take solar electric. I've looked into it. To beat a 2 month transfer, or even a Hohmann orbit 5 month mosey, a solar powered ship would require really large masses of solar cells, and a pretty heavy installation of Hall thrusters, never mind how we store the xeon! Actually "primitive" impulsive burn chemical rockets, even foregoing the ultra high Isp of hydrogen for the more mediocre Isp of methane, are pretty hard to beat to go someplace as "close" as Venus.

Why would you need to 'beat' a 60 day transfer? That's an odd assumption if it's not people. Cargo is generally insensitive to time and for interplanetary travel "time" is not "money" either so there's no real argument for spending any more than you have to. Would you need large arrays? Yes but about half the size you'd need for Mars and they are getting cheaper all the time so it's not really a valid argument. (Unless of course you are trying to avoid any orbital or space based infrastructure which is what Mars Direct and Elon Musk would prefer. As I said there's a good reason I don't like either assumption) You said yourself earlier that 5 months is more probable for cargo flights and that's a little more than a powered transfer for SEP cargo craft.

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So ISR is probably the key, and that means methane. And that means hydrogen to literally burn. It is a costly operation, but that's space travel for you.

Methane yes but that's because it's vastly easier to store and transfer than hydrogen and hydrogen is going to be important but likely we'll mostly use it in the form of methane for most uses.

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As for non-ISR strategies like the "Apollo" style "three guys in a blimp until the return launch window is about to open, then up they go on a Titan II, hasta la vista Venus, we're never coming back!" if you do the math, I think you find it is flat impossible for them to land enough already processed nitrogen to buoy themselves. If NASA is going to land one blimp on Venus, that blimp will at least have to have something as good as ammonia or methane. Why not hydrogen then? (Maybe because it is too hard to ship the distance because of boiloff? Or volume storage issues? If we can't ship hydrogen by the way, we sure can't ship helium either, and if we can ship helium we can ship hydrogen).

The concept material clearly states they will use helium. They won't use hydrogen as a lifting gas because of the diffusion issues, (oxygen will diffuse as well so that's something to keep in mind) it's vastly safer to use helium for such a mission. Now if it was a different design rather than a single envelope airship/gondola they yes you'd probably use hydrogen over helium. That's what I suggested for the Green Dragon probe since it can be synthesized on site in experimental batches and is something we want to study anyway. But that has a separate gas-bag than what HAVOC would use.

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This seems to relate to the other thing you say below that downright mystifies me.
How?
How can biology or chemistry conjure up substances unless either they are concentrating something present in situ but in small amounts, or something brings the substances in?
Who talks about these amazing result processes in any detail that I might learn from them?

You talk about some of the process directly in this very post? Why are you confused?

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But we are talking about lift gases here.

No and specifically you 'only' talk about "lifting gases" when it suits you while ignoring your own discussion of other aspects and uses of said gasses. In context it does not MATTER why you're 'talking' about a gas or a product it matters only when that material is applied in a certain way. In this case we're going to be producing a LOT of hydrogen, oxygen, carbon and other resources so HOW they are used is dependent on the needs at the time.

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Those have to be simple--complex molecules are heavy molecules; the name of the game of a buoyant lift gas is to have a light molecule. Simple, few atoms, half the game is to have the atoms present at all, then we turn to how to split them to organize them the way we want.

Here's another fallacy in the idea that you or even should have only "one" lifting gas. In fact lets look at the list shall we?
Helium
Hydrogen
Methane
Ammonia
Oxygen
Nitrogen
Carbon Monoxide.. The list goes on. (In fact Silane has similar lift to oxygen but I don't recommend it for a lifting gas : ) )

Mix and match and use as needed but ensure you are very unlikely to have 'combinations' that could end up detrimental to your colony. (Hint: mixed methane/hydrogen/ammonia and say oxygen?)
 
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In Venus's middle atmosphere, where we humans can live, what "Certain" processes are actually happening? In a first landed minimal platform module, what processes can we make happen, that don't involve rolling up our sleeves and dipping into the sulfuric acid clouds and using energy and equipment to crack the acid into something else? Some kind of bacterial action or what?

Uhm you're whole point in getting there is "rolling up your sleeves" and getting to work. You're being rather obtuse and I suspect on purpose to fit the narrative but to be clear YOU (as a Venus colonist) are aiding, abetting and likely maintaining those process to extract the needed resources to live on Venus. You already acknowledge that this must be so yet when it's pointed out that there are going to be many byproducts of such activity you act as if it's by some unknown and unknowable process.. Unless it fits your point...

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It does not work that way. Where is the mindless process that keeps on producing a mix of nitrogen and oxygen whether wanted or not, like the brooms in the Disney version of the Sorcerer's Apprentice. It seems that people making claims like this have invoked some kind of magic they believe in that gives them nitro-oxygen for free. But no, the ground state of things in Venus's atmosphere at the levels where temperatures are bearable is not to produce nitrogen sorted out from the carbon dioxide, nor is it to produce free oxygen in any form whatsoever. Are you thinking, "plants turn CO2 into oxygen?" They do, but they require water to do so, that's part of the chemistry involved. We must go and fetch some water, or anyway hydrogen. Having fetched hydrogen, we should bloody well use hydrogen!  Both types of gas require work to get. I've granted the hydrogen will cost more energy and more work, but it is worth a hell of a lot more too.

Case in point in fact. Following your 'logic' you have a Starship arriving filled with methane and 'cargo' which then uses the methane to inflate lift cells to float. Good so far but they need to hurry and have another Starship arrive before they starve or run out of air to breathe because they can't MAKE any on Venus. "It doesn't work that way" because there are no "Mindless process" running to grow food or produce air to breath. What's that? The Colony can use solar energy to break down the CO2 and Sulfuric acid into things like nitrogen, oxygen and hydrogen to make air, water and food? But that can't be YOU said it wasn't possible nor did it work that way.... Which is it?

We should use hydrogen as lifting gas you say? Why since it is needed to make that water you mention as well as methane for rocket fuel?

The whole "problem" here is you're stuck on a 'binary' solution in that the colony can use one, and only one, lifting gas forever. Which is no where near correct.
Look I understand where you're coming from but how about you make an effort to do the same and look a little further ahead than a couple of months after the colony is started?

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The last guy who tried to insist that Venus colonies should use air and not hydrogen said "I didn't get it" and then proceeded to talk about the colony getting large and just growing itself seamlessly somehow, like he thought it was one big organism or something.

So, the colony will never grow any bigger than it is? They will never produce any materials that can be used to expand the colony? The ONLY means of growth is a steady supply of arriving one-way Venus Starships to use as habitat space? I can see why you need a new shipment every couple of months as you're going to be in constant need of replacement parts to keep the colony going.

I KNOW you're smarter than this so I'm going to assume you see how silly your 'argument' is in context. Yes the colony WILL grow in a rather organic nature. They will need to produce goods and materials on Venus, that's what ISRU is all about after all. They are going to have to make plastics, metals and composites and build new and larger structures as time goes on. Past a certain size of structure, (and it's actually NOT that large) it becomes an asset to use breathing air as a lifting gas because it allows you to expand your living space in a self supporting manner. NO you do not start OUT that way but work up to it. But that IS how it works.

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Broadly speaking, I think the rather magical seeming processes you are talking about come under the rubric of "growth and expansion." But it seems someone has done a sleight of hand, making it seem reasonable that nitrogen and oxygen will just come along naturally, but hydrogen is unnatural or something.

Nobody has said any such thing except for you and I'm pretty sure you know that's not even what anyone might have meant. The point is that while hydrogen is a useful lifting gas it has other uses as well and there is a point where having the air you breath ALSO being a lifting gas means you CAN use it for other purposes and simply add some of the 'gas cell' space to your living space. It does not in any way mean you can not use hydrogen for additional lift, you can always do so but you'll want to separate it from your living space.

Randy
« Last Edit: 06/11/2020 07:29 pm by RanulfC »
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Floating Habitat on Venus
« Reply #70 on: 06/12/2020 08:28 am »
Oh, you bothered. There were so many things in those posts to respond to that I never even got around to it. 'someone on the internet is wrong' and all  ;)

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But using one as a hab, especially if you could disassemble it into multiple parts (take out tanks, plumbing, engines, what have you, float and use them all independently and use the use the entire volume of the Starship as a habitat), that's a nice idea. A few-sizes-fit-all Starship is bound to become cheaper than a custom built module anyway.

That's one thing I didn't bring up but as a point to 'use' a Starship properly it really should be suspended from the a balloon deployed from the nose as it's a 'vertical' interior design and the tanks of propellant in the suggestion are going to require extra lifting bags to put it into a horizontal position. My suggestion is going to have space and the ability to put the expanded lift cells further aft where needed in this scenario. You'd have to have more lift cells to deploy fitted aft towards the propulsion bay if I'm visualizing the original Starship concept correctly? (Shevek 23?)

I always tend to imagine Starship-based architectures vertically. That does mean I'll have to rethink how the propulsion system that prevents the habitat being dragged to the poles would look like.

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Edit: So essentially this means going full on Tatooine Shipyard, with a jumble of reused parts, while floating in the air. Great visual.

Nice visual yes, but inaccurate I'm afraid :) You won't have many (if any) parts floating around as you want to keep the number of things you have to track and control to a minimum so you won't break anything up into parts but find a way to use the parts in place or 'store' them for raw materials or later use.

Randy

Well, I was initially thinking about one lifting envelope per tank (or at least for all tanks used for the same purpose), and one with spare parts, with smaller transport vehicles (a staple in any of my Venus ideas) in between. Not too many to keep track of, but the idea of disassembled tanks being used out of their original context is what gave it a 'Tatooine scrapyard' feel in my head.

However, I now realize that Starship's outer shell is part of its main tanks, so you could only take out the header tanks, which are relatively small so you wouldn't use them for fuel (I really don't like rocket fuel being stored right underneath people). So now I'm thinking just convert the tanks to useful space, or at most take out the domes, plumbing and what not and store where most appropriate. Which I assume is either at the bottom for stability or on a dedicated scrapyard balloon so it's out of the way and available for later usage.

Dang, I'm not going to get any work done today with this churning in the back of my head.  ;D


Offline edzieba

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Re: Floating Habitat on Venus
« Reply #71 on: 06/12/2020 01:50 pm »
How large does the enclosed volume of the ol' floating-sphere-city need to be before you can pump it mostly full of Hydrogen - or Helium if you can't trust colonists with matches and slingshots - and let your breathing gas pool at the bottom without needing to perform any particular precautions to prevent the two mixing other than not setting up any giant fans (or flying internal rotorcraft)?

Offline rsdavis9

Re: Floating Habitat on Venus
« Reply #72 on: 06/12/2020 02:46 pm »
How large does the enclosed volume of the ol' floating-sphere-city need to be before you can pump it mostly full of Hydrogen - or Helium if you can't trust colonists with matches and slingshots - and let your breathing gas pool at the bottom without needing to perform any particular precautions to prevent the two mixing other than not setting up any giant fans (or flying internal rotorcraft)?

Or squatters with cooking fires.
With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
Same engines. Design once. Same vehicle. Design once. Reusable. Build once.

Offline Proponent

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Re: Floating Habitat on Venus
« Reply #73 on: 06/12/2020 03:09 pm »
How large does the enclosed volume of the ol' floating-sphere-city need to be before you can pump it mostly full of Hydrogen - or Helium if you can't trust colonists with matches and slingshots - and let your breathing gas pool at the bottom without needing to perform any particular precautions to prevent the two mixing other than not setting up any giant fans (or flying internal rotorcraft)?

Despite the differences in the gases' densities, I suspect that diffusion will lead to a fairly thick layer in which both are present in significant quantities (consider the fact that oxygen doesn't settle to the bottom of Earth's atmosphere).  Hence, to avoid a combustion hazard, I suspect you would need either a non-permeable membrane between them or a thick layer of a third, inert gas between them.

Offline Lodrig

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Re: Floating Habitat on Venus
« Reply #74 on: 06/14/2020 01:07 am »
Simple calculations of lifting forces are only one aspect of picking a lift-gas.  Availability, leakage rates, flammability and many other factors are likely to be at least equally if not more important.

I think Hydrogen scores poorly on several fronts.  Obviously flammability dictates that it be kept only in oxygen free areas which means it would be either outside the main habitat bubble or enclosed within a secondary cells inside the habitat, likely floating up at the roof of the former.  A balloon within a balloon doesn't lose any lifting power so this is a perfectly reasonable solution.

The more serious issue is leakage, hydrogen is notoriously good at permeating through every known material.  And a balloon lining being necessarily thin is going to leak constantly.  Larger balloons are a major advantage here though, as their surface area to volume ratio is lower, and their skins thicker.  Short of some major improvement in developing a thin light, flexible, hydrogen-impermeable material.  One of the potential breakthrough materials graphene which shows very low permeability for other molecules like helium is unfortunately still quite permeable to hydrogen.

https://phys.org/news/2020-03-impermeable-graphene.html

Should production of graphene based balloon film be possible on Venus it would represent a near ideal solution for containing nearly any other gas as it would be both extremely strong, light and being carbon based it would be sourced from the atmosphere. 

In this scenario we would likely lifting gas would be the Carbon-Monoxide as this is an intermediate step in extracting carbon from CO2.  It's lifting power is equal to N2 by the way.  Though obviously such balloons aren't habitat spaces in themselves your likely to see them used because of their cheapness as exterior lifting balloons for industrial platforms and dirigible type vehicles.  Actual Nitrogen would be used in habitable spaces of course.

Rather then the monolithic 'cloud city' visions that dominate the Venus idea space, I see considerable need for smaller minimally or entirely unmanned platforms to provide the bulk of the services and resources consumed by the manned ones.  In essence the functionality would be more like buildings in a city, with residential and industrial separation and regular commuting between them, either by independent vehicles or gondola cars on cables.  This makes for a more modular system able to grow and adapt to changing needs.
« Last Edit: 06/14/2020 09:40 am by Lodrig »

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #75 on: 06/15/2020 06:16 pm »
And while we're at it, since November is only 5 months a way to the big event, (no not election THE big event) and I still harbor a fantasy about doing a go-fund-me or something to raise the money/interest for a nice prime time ad narrated by the "Real Men" guy I post the link, (because unlike Jon I don't have permission to post the actual piece itself) below:
https://selenianboondocks.com/2013/12/venusian-acid-cooked-turkeys-or-why-i-still-read-blog-comments/

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #76 on: 06/15/2020 08:40 pm »
How large does the enclosed volume of the ol' floating-sphere-city need to be before you can pump it mostly full of Hydrogen - or Helium if you can't trust colonists with matches and slingshots - and let your breathing gas pool at the bottom without needing to perform any particular precautions to prevent the two mixing other than not setting up any giant fans (or flying internal rotorcraft)?

Or squatters with cooking fires.

Despite the differences in the gases' densities, I suspect that diffusion will lead to a fairly thick layer in which both are present in significant quantities (consider the fact that oxygen doesn't settle to the bottom of Earth's atmosphere).  Hence, to avoid a combustion hazard, I suspect you would need either a non-permeable membrane between them or a thick layer of a third, inert gas between them.

Ya there's not going to be a size where 'mixed' gas atmosphere, (beyond maybe helium which has issues in and of itself) is going to be practical. You're going to have to circulate the air and even if YOU don't at the sizes where air as a lifting gas work best there will be 'natural' convection's and currents anyway. As Proponent notes you'll want something to keep the separated and you're best bet will always be a 'mechanical/physical' type barrier.

And since we're starting smaller, (and yes even Starthip is very small for a colony) having separate envelopes is always going to be a bonus both to redundancy and safety

I'd thought I'd posted these prior as reference to some of my above but it doesn't look like I did. Stupid me :)

I don't like the arguments that are based on "either/or" because to be a space-faring or multi-planet species we MUST both traverse and utilize space itself on a regular basis but we also have no valid reason to set up on only one other planet. Go Big or stay home because 'dabbling' (as we've only been doing since human space flight began) gets you nowhere... Fast.

But most articles on Venus colonization tend to take on Mars as a 'comparison'(and it makes sense since Mars is the "other" main contender given general attitudes and outlooks) but the following one is less confrontational and concise than most:
https://medium.com/@Jernfrost/why-colonize-venus-instead-of-mars-c490d14c0531

This one has a nice 'airship' (or habitat) lifting capacity calculator:
https://medium.com/@Jernfrost/calculating-lifting-capacity-of-airships-48df5cd7d147

And this one compares the various types of lifting gas that can be used:
https://medium.com/@Jernfrost/lifting-gases-in-a-venus-aerostat-habitat-69aae6fb990

And takes on such subjects as mid-air construction:
https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454

And transportation and logistics for the colonies:
https://medium.com/@Jernfrost/transport-and-logistics-on-a-venus-cloud-colony-62e33e025f23

Enjoy!

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #77 on: 06/15/2020 10:04 pm »
Simple calculations of lifting forces are only one aspect of picking a lift-gas.  Availability, leakage rates, flammability and many other factors are likely to be at least equally if not more important.

Agreed, there will be a lot of factors that will play into the decisions. We can speculate, suggest and discuss but it'll be the actual colony planners who will make those decisions. Of course as I already noted WE can always discuss the heck out of the subject as that never really hurts ;D

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I think Hydrogen scores poorly on several fronts.  Obviously flammability dictates that it be kept only in oxygen free areas which means it would be either outside the main habitat bubble or enclosed within a secondary cells inside the habitat, likely floating up at the roof of the former.  A balloon within a balloon doesn't lose any lifting power so this is a perfectly reasonable solution.

The more serious issue is leakage, hydrogen is notoriously good at permeating through every known material.  And a balloon lining being necessarily thin is going to leak constantly.  Larger balloons are a major advantage here though, as their surface area to volume ratio is lower, and their skins thicker.

Well yes and also that hydrogen has numerous 'other' uses on Venus that are likely more important over the short-term to a starting colony. But like many ISRU suggestions you'll probably be bringing some along anyway so...

And baring a literal "one-way" mission architecture you'll likely be bringing enough propellant that you can gradually reduce it down for other uses as time goes on.

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Short of some major improvement in developing a thin light, flexible, hydrogen-impermeable material. One of the potential breakthrough materials graphene which shows very low permeability for other molecules like helium is unfortunately still quite permeable to hydrogen.

https://phys.org/news/2020-03-impermeable-graphene.html

Should production of graphene based balloon film be possible on Venus it would represent a near ideal solution for containing nearly any other gas as it would be both extremely strong, light and being carbon based it would be sourced from the atmosphere.

Ya, one thing I didn't correct above was the idea that helium is 'slipperier' than hydrogen when it's not that hydrogen has ever been 'easier' to contain but that it has pretty much always been vastly cheaper to produce so containment wasn't seen as that much of an issue vis-a-vis helium.

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In this scenario we would likely lifting gas would be the Carbon-Monoxide as this is an intermediate step in extracting carbon from CO2.  It's lifting power is equal to N2 by the way.  Though obviously such balloons aren't habitat spaces in themselves your likely to see them used because of their cheapness as exterior lifting balloons for industrial platforms and dirigible type vehicles.  Actual Nitrogen would be used in habitable spaces of course.

CO was a suggestion that came up often in the Moon Minter's Manifesto/Lunar Reclamation Society articles that first got me interested in Venus as a destination. (http://lunar-reclamation.moonsociety.org/papers/venus_rehabpaper.htm) And yes I suspect that there will be different lifting gasses for different design uses. From what I'm seeing many of the industrial process will have CO as a step in the process so why not use it while it's there?

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Rather then the monolithic 'cloud city' visions that dominate the Venus idea space, I see considerable need for smaller minimally or entirely unmanned platforms to provide the bulk of the services and resources consumed by the manned ones.  In essence the functionality would be more like buildings in a city, with residential and industrial separation and regular commuting between them, either by independent vehicles or gondola cars on cables.  This makes for a more modular system able to grow and adapt to changing needs.

For quite a while I see more 'modular' approaches to habitat design but once you get to a certain size for people it makes sense to start using your air for lifting purposes even if it's still not the 'main' contributor to the overall lift. While people DO tend to skip straight to the mega-habitat structures, (and this holds true for most 'colony' visions no matter where they are located :) ) you tend to see a sharp rise in 'cluster' architecture on Venus simply because the more you can cluster the easier your logistics become as things evolve. Power available goes up as does living and working space and having your industrial and ISRU platforms close enough to 'pipe' the results to the user rather than having to transport them separately makes a big difference in costs.

On the other hand the modular rather than monolithic approach allows you, (at some of the 'smaller' larger scales at least) to rearrange and re-cycle older modules and newer ones to ensure you don't have to deal with older and less efficient sections of the colony. Still there's going to be a point where transferring the 'modular' nature from the exterior to the interior is going to make more sense. So rather than having sectional 'Sky-Cities' of large floating modular 'rafts', you will have a 'planned' city inside a single 'outer' structure with the more modular parts being how the interior and surrounding area is arranged. When you'd get there is anybodies guess but I tend to think it will happen pretty soon after the colony is self supporting in the ability to build such structure on-site.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline daedalus1

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Re: Floating Habitat on Venus
« Reply #78 on: 06/15/2020 10:17 pm »
Having a city in orbit around Venus has much more advantages than a floating habitat.
Eg it is easier to move material already constructed from the earth-moon system than mining it on the surface and then manufacturing it. Keeping it floated is much more difficult than keeping something in orbit etc, etc.

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #79 on: 06/15/2020 10:28 pm »
Oh and I had one more thing to say tonight before I sign-off:

It was brought up in one of the internet discussions of HAVOC that while it is technically possible to use hydrogen for lift in such a vehicle it's very likely that the US and specifically a US government sponsored or run project "technically" could NOT use hydrogen as it may be illegal to do so.

Why? When the Helium Act of 1925 was passed, (https://en.wikipedia.org/wiki/Helium_Act_of_1925#:~:text=Helium%20Act%20of%201925%2C%2050,potential%20of%20producing%20helium%20gas.) there was a bit earlier piece of legislation that Congress also passed that mandated that all US Lighter Than Air vehicles would USE only helium as hydrogen was deemed to dangerous. As far as anyone can find that regulatory statute, while probably out-dated, has never actually been rescinded or removed from the books and therefore any government agency that used hydrogen as a lifting gas, (no matter where) might still be held liable for that use :)

It's kind of an oddity really but it was pointed out that since according to the 1969 OST the US government is primarily responsible for and too for all US spaceflight activities a private organization 'could' be held accountable under the same stature. Likely? Not very and frankly it would be likely struck down in court which would force a review and likely modification if not outright dropped from US legal code. But in general the 'fact' is still there and government agencies have to deal with what is actually on the books rather than what is generally ignored or forgotten :)

Fun stuff :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Floating Habitat on Venus
« Reply #80 on: 06/16/2020 07:55 am »
Having a city in orbit around Venus has much more advantages than a floating habitat.
Eg it is easier to move material already constructed from the earth-moon system than mining it on the surface and then manufacturing it. Keeping it floated is much more difficult than keeping something in orbit etc, etc.

I would say that's true for any planet or gravity well. If you're able to get people there, you already have the technology to keep them alive in space for months or years, depending on the destination. ISRU is technologically a higher bar than sending stuff from Earth, and not having to send supplies down a gravity well greatly reduces cost. The question, no matter what planet or moon you're considering, is whether whatever you can do by going down the gravity well is worth the extra effort of sending supplies to the surface. (while the sole purpose of ISRU is reducing the cost and complexity of shipping in those supplies).

And since we're starting smaller, (and yes even Starthip is very small for a colony) having separate envelopes is always going to be a bonus both to redundancy and safety

Small for a colony, but big for a balloon being inflated while free falling down the atmosphere with a 220 ton payload (assuming the Starship is fully loaded) dragging it along. I think some expendable Starships will be necessary to build a landing pad from smaller segments, so the full size Starship-lifting balloon can be inflated in a controllable way.

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But most articles on Venus colonization tend to take on Mars as a 'comparison'(and it makes sense since Mars is the "other" main contender given general attitudes and outlooks) but the following one is less confrontational and concise than most:
https://medium.com/@Jernfrost/why-colonize-venus-instead-of-mars-c490d14c0531

This one has a nice 'airship' (or habitat) lifting capacity calculator:
https://medium.com/@Jernfrost/calculating-lifting-capacity-of-airships-48df5cd7d147

And this one compares the various types of lifting gas that can be used:
https://medium.com/@Jernfrost/lifting-gases-in-a-venus-aerostat-habitat-69aae6fb990

And takes on such subjects as mid-air construction:
https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454

And transportation and logistics for the colonies:
https://medium.com/@Jernfrost/transport-and-logistics-on-a-venus-cloud-colony-62e33e025f23


No why did I see this on a tuesday morning. There goes my focus for the rest of the day.  ;D


In this scenario we would likely lifting gas would be the Carbon-Monoxide as this is an intermediate step in extracting carbon from CO2.  It's lifting power is equal to N2 by the way.  Though obviously such balloons aren't habitat spaces in themselves your likely to see them used because of their cheapness as exterior lifting balloons for industrial platforms and dirigible type vehicles.  Actual Nitrogen would be used in habitable spaces of course.

Ah, but nitrogen can be extracted with a low energy pressure swing, while converting CO2 to CO and O2 requires a thermal step. Which requires more energy, but the energy can be 'recycled'. N2 is going to be a waste product that has to be extracted before you can get anything else from the atmosphere. While CO will need a specific process to get it, that makes it more valuable. You're likely to store the supply as a lifting gas, but it's you would always want easy access to it. So it's likely to be much less prevalent than nitrogen. But yes, definitely going to be used.

Other lifting gasses would be used on lower altitudes. The higher pressure there increases lift per volume, so you can use heavier ones with other benefits. Like phase changing materials that would automatically lift expensive extraction or exploration equipment if the temperature started to get too high. Water might be good on the surface. Ammonia is also under consideration.

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Rather then the monolithic 'cloud city' visions that dominate the Venus idea space, I see considerable need for smaller minimally or entirely unmanned platforms to provide the bulk of the services and resources consumed by the manned ones.  In essence the functionality would be more like buildings in a city, with residential and industrial separation and regular commuting between them, either by independent vehicles or gondola cars on cables.  This makes for a more modular system able to grow and adapt to changing needs.

Hear hear! Totally agree. Although, as on Earth, you would see concentrations of infrastructure, these concentrations will happen at different altitudes. Each altitude is likely to have a different design, and it's unlikely that equipment designed to lift things off the surface would even be able to reach the population area unassisted. (for maintenance and such).

Offline Lodrig

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Re: Floating Habitat on Venus
« Reply #81 on: 06/16/2020 10:55 am »
Actually CO from CO2 is done by electrolysis with O2 as a byproduct.

Here is a company that makes such a device. https://www.topsoe.com/processes/carbon-monoxide#:~:text=Using%20external%20electricity%2C%20SOECs%20are,each%20side%20of%20the%20cell.

It looks like the energy cost is 5-7 kw/h per kg of CO (had to convert from their odd Nm^3 unit).  Don't know if their are better versions around but this is at least industry standard.  I also don't know if sulfur would foul the catalyst, it dose then this solution is likely not be viable without a pre-filtering solution to remove it.  The lack of moving parts is one of the main advantages to such a device as it just needs a small intake fan to pull ambient Venus air into the device.

Now to determine the energy cost for N2 we just need to know the energy needed to liquefy CO2 and then multiply by the ratio in the atmosphere of about 27 to get the cost per kg of the N2, though you would have lots of potentially useful liquid CO2 for ballast as a byproduct. 

The best numbers I could find was for large industrial system which need just .08 kw/h to liquefy CO2, so this would mean ~2 kw/h per kg of recovered N2, meaning that it dose have a lower energy cost, but a far more complex mechanical process as compressors, chillers, pumps, radiators etc are all involved.

The mass of solar-power vs the mass of the compression/liquifacation system would thus need to be considered.
« Last Edit: 06/16/2020 11:47 am by Lodrig »

Offline high road

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Re: Floating Habitat on Venus
« Reply #82 on: 06/16/2020 12:18 pm »
I also don't know if sulfur would foul the catalyst, it dose then this solution is likely not be viable without a pre-filtering solution to remove it.

Uhuh. I did some calculations a long time ago. Its not that hard to filter the SO2 out of the air. It will have to be done anyway for just about anything, as even very small concentrations are nauseating. The energy intensive part is recycling the filter material. As a rule of thumb, the better the filter (or other SO2 removal process) works, the more energy it takes to recycle it.

And takes on such subjects as mid-air construction:
https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454

Now that's just needlessly complex, isn't it? 'Just' build a drydock out of a jigsaw puzzle of elements that can be carried by a 'Skycrane' that can fit in a Starship. Assemble the drydock, use it to make bigger parts for a bigger drydock, rinse and repeat until you have drydock capable of building geodesic domes as experience on Mars has tought you.

Activity on Venus is always going to be small compared to Mars. Far more efficient to copy what can be copied rather than designing everything specifically for Venus.

Offline daedalus1

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Re: Floating Habitat on Venus
« Reply #83 on: 06/16/2020 01:02 pm »


And takes on such subjects as mid-air construction:
https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454

Now that's just needlessly complex, isn't it? 'Just' build a drydock out of a jigsaw puzzle of elements that can be carried by a 'Skycrane' that can fit in a Starship. Assemble the drydock, use it to make bigger parts for a bigger drydock, rinse and repeat until you have drydock capable of building geodesic domes as experience on Mars has tought you.

Activity on Venus is always going to be small compared to Mars. Far more efficient to copy what can be copied rather than designing everything specifically for Venus.
[/quote]

You ain't landing anything on the surface of Venus and expect it to survive for more than a few hours.

Offline high road

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Re: Floating Habitat on Venus
« Reply #84 on: 06/16/2020 01:19 pm »

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And takes on such subjects as mid-air construction:
https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454

Now that's just needlessly complex, isn't it? 'Just' build a drydock out of a jigsaw puzzle of elements that can be carried by a 'Skycrane' that can fit in a Starship. Assemble the drydock, use it to make bigger parts for a bigger drydock, rinse and repeat until you have drydock capable of building geodesic domes as experience on Mars has tought you.

Activity on Venus is always going to be small compared to Mars. Far more efficient to copy what can be copied rather than designing everything specifically for Venus.

You ain't landing anything on the surface of Venus and expect it to survive for more than a few hours.

Yes, all of this floats while under construction. There's a reason the 'just' is in quotation marks ;-) The 'skycrane' moves the elements from the landing craft to the skydock under construction, which inflates as necessary as elements are added. We had a pretty detailed discussion about this a while back, IIRC.

Offline daedalus1

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Re: Floating Habitat on Venus
« Reply #85 on: 06/16/2020 01:46 pm »

Quote
And takes on such subjects as mid-air construction:
https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454

Now that's just needlessly complex, isn't it? 'Just' build a drydock out of a jigsaw puzzle of elements that can be carried by a 'Skycrane' that can fit in a Starship. Assemble the drydock, use it to make bigger parts for a bigger drydock, rinse and repeat until you have drydock capable of building geodesic domes as experience on Mars has tought you.

Activity on Venus is always going to be small compared to Mars. Far more efficient to copy what can be copied rather than designing everything specifically for Venus.

You ain't landing anything on the surface of Venus and expect it to survive for more than a few hours.

Yes, all of this floats while under construction. There's a reason the 'just' is in quotation marks ;-) The 'skycrane' moves the elements from the landing craft to the skydock under construction, which inflates as necessary as elements are added. We had a pretty detailed discussion about this a while back, IIRC.

I reckon you should call it 'pie in the sky'.

Offline high road

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Re: Floating Habitat on Venus
« Reply #86 on: 06/16/2020 02:44 pm »
Yes, like all human exploration of moons and other planets 🙂 just interesting engineering problems we can think through long before there's any chance this is getting funded.

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #87 on: 06/16/2020 02:55 pm »
Oh, you bothered. There were so many things in those posts to respond to that I never even got around to it. 'someone on the internet is wrong' and all  ;)

Just trying to catch up and he's got some good ideas, the fixation on certain aspects just got to me :)

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I always tend to imagine Starship-based architectures vertically. That does mean I'll have to rethink how the propulsion system that prevents the habitat being dragged to the poles would look like.

You're probably more right than I am, but in retrospect it I should have seen that but was stuck on a 'horizontal' attitude for some reason. It's vertically oriented so that's probably the best way to use it, especially since we don't need to get down to the 'base' of the vehicle on a regular basis.

Still that puts a question on how and from where you'd deploy the gas-cells since if only from the dorsal side you WOULD end up horizontal and you'd need to do so from the nose area to get it to hang tail down...

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #88 on: 06/16/2020 03:27 pm »
Having a city in orbit around Venus has much more advantages than a floating habitat.
Eg it is easier to move material already constructed from the earth-moon system than mining it on the surface and then manufacturing it. Keeping it floated is much more difficult than keeping something in orbit etc, etc.

As High Road notes that's actually pretty true for ANY gravity well as once you're out of it it's far easier to send automated equipment to do all the hard work than go up and down yourself. I will argue that keeping it 'floating' isn't all that hard but what IS hard is getting down and back again but you have to figure that out to exploit the resources anyway so it's likely a wash.

Surface mining it a combination between Earth ocean mining technology and high heat resistant systems so it's likely to be less difficult that shipping in items over time. In the early days it will be a truism that shipping in manufactured goods and equipment to a new colony will always be cheaper and easier no matter if it's on the Moon, Mars or Venus but that won't be true forever and the sooner you can exploit the local resources the better.

I would say that's true for any planet or gravity well. If you're able to get people there, you already have the technology to keep them alive in space for months or years, depending on the destination. ISRU is technologically a higher bar than sending stuff from Earth, and not having to send supplies down a gravity well greatly reduces cost. The question, no matter what planet or moon you're considering, is whether whatever you can do by going down the gravity well is worth the extra effort of sending supplies to the surface. (while the sole purpose of ISRU is reducing the cost and complexity of shipping in those supplies).

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Small for a colony, but big for a balloon being inflated while free falling down the atmosphere with a 220 ton payload (assuming the Starship is fully loaded) dragging it along. I think some expendable Starships will be necessary to build a landing pad from smaller segments, so the full size Starship-lifting balloon can be inflated in a controllable way.

One interesting take I've seen is a large hexagonal balloon that are maneuvered together after which the payloads are then connected to build a large colony over time. While it wasn't in that suggestion per-se I DID note that each 'hex' top was about half again as big as the SpaceX drone ships so ... :)
(Not that I'd trust that kind of arrangement mind you)
But you can also imagine a 'drone-ship' landing pad supported by side and bottom mounted lift cells with additional cells that inflate as the pad takes on the extra mass of the landing vehicle. Really though I suspect the powered docking maneuver, much like Shevek proposes is going to be the main contender for "landing" along with vehicle lifting cells and airborne 'hook-on' landings since those would seem to work the best so far that we know.

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No why did I see this on a tuesday morning. There goes my focus for the rest of the day.  ;D

Because I didn't manage to make Monday and ruin your whole week :)

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Hear hear! Totally agree. Although, as on Earth, you would see concentrations of infrastructure, these concentrations will happen at different altitudes. Each altitude is likely to have a different design, and it's unlikely that equipment designed to lift things off the surface would even be able to reach the population area unassisted. (for maintenance and such).

Yep, I'm pretty confident that Venus infrastructure would be 'stratified' since that would also help sort the various activities towards the nearest resources.

Randy
« Last Edit: 06/16/2020 03:27 pm by RanulfC »
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline rsdavis9

Re: Floating Habitat on Venus
« Reply #89 on: 06/16/2020 03:38 pm »
Pardon me for being a neophyte and not reading all the referenced material.

How do you do the first "landing" at the 50 km height?
Rocket reenters and after falling at terminal velocity you rapidly inflate a balloon?

BTW I like the idea of semi rigid dirigibles like the ones we once had on earth. Landing pad is on the top deck. Whats the wind speed at 50km?
With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
Same engines. Design once. Same vehicle. Design once. Reusable. Build once.

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #90 on: 06/16/2020 04:07 pm »
And takes on such subjects as mid-air construction:
https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454

Now that's just needlessly complex, isn't it? 'Just' build a drydock out of a jigsaw puzzle of elements that can be carried by a 'Skycrane' that can fit in a Starship. Assemble the drydock, use it to make bigger parts for a bigger drydock, rinse and repeat until you have drydock capable of building geodesic domes as experience on Mars has taught you.

Activity on Venus is always going to be small compared to Mars. Far more efficient to copy what can be copied rather than designing everything specifically for Venus.

I should point out that in fact that's how "domes" are supposed to be constructed here on Earth let alone anywhere else : Bucky always intended them to be built on a mast and hauled up, (or in this case 'down' :) ) as each new section was completed.

Building with modular sections is likely to be how things are done for the most part even when the 'parts' are manufactured on Venus. But you're going to be restricted to the size of parts that will fit through the 'air-lock' in use so that's always an issue to keep in mind. Of course that also assumes some 'human' interaction as we tend to work better in "shirt-sleeve" environments than in space or pressure suits. Robots on the other hand don't really care and can work in more direct and hostile environments where it's not practical to use humans for most of the labor.

This will in fact be most colony building whether on Mars, Venus or the Moon. But there is a lot to be said over using an inflatable form and some sort of 'spray-on' surface coating as well.

In general the main reason you want to use a 'drydock' type set up, specifically on Venus, is a well known aspect and reasoning found when constructing anything, anywhere; The propensity for there to be "ooops" moments when something is dropped.

On the Moon or Mars if you drop something it's right there in the 'dust' somewhere. On Venus when you drop something it would likely be on a very one-way trip to the surface unless it has a lanyard or something attached, or it's in an enclosed structure of some kind. (You have a similar issue in orbit where if something drifts out of reach it could become difficult to retrieve)

Building inside a structure whether it's just modular components or the whole structure itself allows you to have more freedom to make mistakes than trying to do it outside 'on-air' as it were.

On the other hand there's a bit to be said about constructing a geodesic sphere on a mast hanging from a construction dock... You'll know where all the screws, nuts and bolts got to at the end of the day :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline mikelepage

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Re: Floating Habitat on Venus
« Reply #91 on: 06/17/2020 05:21 am »
I always tend to imagine Starship-based architectures vertically. That does mean I'll have to rethink how the propulsion system that prevents the habitat being dragged to the poles would look like.

...

Dang, I'm not going to get any work done today with this churning in the back of my head.  ;D

Well dang, now I see you guys started this thread up again, my mind is churning again (at least I made it to Wednesday :) )

While I can imagine Starship being modified to be able to come to neutral buoyancy in the upper Venusian atmosphere, I still haven't been able to convince myself that being able to host and fuel a Superheavy-class booster makes sense as the goal for a cloud base on Venus.  It seems to me that all the arguments against air launch / space tethers (that it's more efficient to build a larger launch vehicle) on Earth, go the opposite way on Venus, because we'll be arriving from orbit, and obviously there's no solid ground to launch from.

That's why I always tend to go back to some kind of megastructure being required on Venus, in combination with aiming to minimise the size of the spacecraft actually doing the to-ing and fro-ing, so today's thought bubble is to wonder if it might be easier to build 3 not-quite-as-mega-megastructures:

It consists of a combination of ideas I've toyed with previously on this thread and others:
1) Floating skyscraper, which has the colony built around a central...
2) ~10km railgun, which lobs a small spacecraft on a suborbital trajectory up to a...
3) Orbiting, non-rotating space tether.

The skyscraper-like structure would made up of modular lifting gas segments, each one of which has a Hoberman sphere-like expansive capability so as to allow it to EDF (enter-descend-float) at Venus inside the smallest descent capsule possible, and autonomously assemble into a horn-like structure (wider end of bell facing up) around a cylindrical central hole, so as to maintain vertical orientation.

The rail gun, accelerates what I'm assuming is a Falcon 9 S2+Dragon derivative (~6km/s dV onboard) spacecraft at 4Gs over 10km, will give it a final velocity close to 300m/s and put it on a suborbital trajectory with an apogee of about 160km (I know Falcon 9 stages considerably faster than this but this is for the exercise). A 160km circular orbit around Venus requires 7.2km/s orbit velocity by my calcs, so if the spacecraft started thrusting upon exiting the railgun, it would still be 1.2km/s short of orbital velocity.  The rotation of equatorial winds on Venus are 360m/s, so that should reduce this amount, but I'm not accounting for gravity drag, wind resistance, or modifications needed to be a railgun projectile  ::) so I'm calling it even and assuming a 1.2km/s difference.

In order to move slowly enough to catch the craft, a space tether would need a CoM located in an orbit with a= 8972km (2920km above surface), and would need to be 5520km long so as to hang down to that 160km altitude.  To repeat, the tether isn't rotating or sweeping through space, it is just hanging there, so while the rendezvous is time-critical, it's not completely crazy. Once you account for there only being <10 metric tons of capsule to hoist up, it's looking pretty benign by tether proposal standards, but still a significant structure.

Key saving of this setup is that the mass/volume of the floating skyscraper structure only has to compensate for a mass change of 125 metric tons with each launch, rather than the 4400 metric tons of Starship Superheavy, and you could reduce that still further if you're willing to make a longer tether. Seems important to minimise the amount of lifting gas required just to get two way transit happening :o

EDIT: the other consideration is if you want to eliminate the space tether entirely, but that means your spacecraft either has to get considerably bigger, or your tower/railgun has to get considerably taller - and 10km tall is already pushing it for me.   ;D 
« Last Edit: 06/17/2020 05:27 am by mikelepage »

Offline high road

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Re: Floating Habitat on Venus
« Reply #92 on: 06/17/2020 10:09 am »
Pardon me for being a neophyte and not reading all the referenced material.

How do you do the first "landing" at the 50 km height?
Rocket reenters and after falling at terminal velocity you rapidly inflate a balloon?

That is what is currently being talked about. There have been other suggestions.

Quote
BTW I like the idea of semi rigid dirigibles like the ones we once had on earth. Landing pad is on the top deck. Whats the wind speed at 50km?

The landing pad is moving with the wind, so does it matter?

And takes on such subjects as mid-air construction:
https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454

Now that's just needlessly complex, isn't it? 'Just' build a drydock out of a jigsaw puzzle of elements that can be carried by a 'Skycrane' that can fit in a Starship. Assemble the drydock, use it to make bigger parts for a bigger drydock, rinse and repeat until you have drydock capable of building geodesic domes as experience on Mars has taught you.

Activity on Venus is always going to be small compared to Mars. Far more efficient to copy what can be copied rather than designing everything specifically for Venus.

I should point out that in fact that's how "domes" are supposed to be constructed here on Earth let alone anywhere else : Bucky always intended them to be built on a mast and hauled up, (or in this case 'down' :) ) as each new section was completed.

Huh, I always imagined them being built like an igloo. If you already have a mast supporting the structure, why would you remove it?

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Building with modular sections is likely to be how things are done for the most part even when the 'parts' are manufactured on Venus. But you're going to be restricted to the size of parts that will fit through the 'air-lock' in use so that's always an issue to keep in mind. Of course that also assumes some 'human' interaction as we tend to work better in "shirt-sleeve" environments than in space or pressure suits. Robots on the other hand don't really care and can work in more direct and hostile environments where it's not practical to use humans for most of the labor.

It's probably the Starship-theme getting to me, but now I'm trending towards the dock being an 'onion tent'. When the section is finished, the tent is cut open along a seam in the middle, and the roof and the support structure folds to the sides. After the section (or the complete structure) has been carried away (or lifted off) from the platform, the tent is closed again, an the seam is covered with a plastic tape that melts when heated to create an airtight seam.

(snip)

So no superheavy launcher, but a 10km long launch infrastructure is acceptable? I like the way you think  ;D

Oh, you bothered. There were so many things in those posts to respond to that I never even got around to it. 'someone on the internet is wrong' and all  ;)

Just trying to catch up and he's got some good ideas, the fixation on certain aspects just got to me :)

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I always tend to imagine Starship-based architectures vertically. That does mean I'll have to rethink how the propulsion system that prevents the habitat being dragged to the poles would look like.

You're probably more right than I am, but in retrospect it I should have seen that but was stuck on a 'horizontal' attitude for some reason. It's vertically oriented so that's probably the best way to use it, especially since we don't need to get down to the 'base' of the vehicle on a regular basis.

Still that puts a question on how and from where you'd deploy the gas-cells since if only from the dorsal side you WOULD end up horizontal and you'd need to do so from the nose area to get it to hang tail down...

Randy

Gas-cells you say? A 220 ton vehicle (assuming fully loaded) requires a Hindenburg sized aerostat to lift it.

Given the difficulties SpaceX and RocketLab say they've experienced with parashute development, inflating a huge structure while hurtling down seems a tad dangerous. However, if we could fill Starship with a couple of 8*40 craft (which would inflate along the long axis, with the internal support structure locking into position when fully inflated), Starship could do its crazy flip (less dangerous on Venus than on Earth) and come to a near-stop so the modules can be deployed more easily. Sacrifice the Starship when done. That's about 1.3 tons of total lift per module. Combine as necessary for all your needs.
« Last Edit: 06/17/2020 10:16 am by high road »

Offline stefan r

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Re: Floating Habitat on Venus
« Reply #93 on: 06/18/2020 03:19 am »


How do you do the first "landing" at the 50 km height?
Rocket reenters and after falling at terminal velocity you rapidly inflate a balloon?

BTW I like the idea of semi rigid dirigibles like the ones we once had on earth. Landing pad is on the top deck. Whats the wind speed at 50km?

I would inflate in space.  Perhaps a shape similar to Apollo re-entry vehicle unless there is a known reason to modify the shape.  The heat damage to a heat shield is proportional to the area density.  Metal sheets that are relatively thin might not even need a ceramic coating.  The Apollo vessel needed to avoid cooking meat. 

The Apollo designers/engineers had to work within a radius of the Saturn V rockets.  If constructed in space using asteroid materials there isn't much limit to the radius. 

Offline mikelepage

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Re: Floating Habitat on Venus
« Reply #94 on: 06/18/2020 05:23 am »
(snip)

So no superheavy launcher, but a 10km long launch infrastructure is acceptable? I like the way you think  ;D


The comparison isn't superheavy booster versus 10km tower... it's superheavy booster (plus associated launch complex and propellent refining/handling infrastructure) versus a 10km tower (plus railgun  ::) ) Neither is actually a good solution and I really have to stop pitching railguns  ;D when all I actually want is a long enough (low-G) acceleration run up to a suborbital trajectory so a lightweight spacecraft can go chasing the tether. 

Here's another take on it:

I've simplified the idea here into a catapult arrangement that uses the differential weights between the gas envelopes and the more dense parts of the structure to drive a series of pulley assemblies which are linked to the launch platform.  The catapulted spacecraft still goes through a 10km acceleration run to get to ~300m/s, but the habitat modules/counterweights only need fall 250-500m relative to the gas envelopes. If you have a floating ring of gas envelopes as depicted here, the central platform could double as a landing platform for capsules.

That way you could always have two of these working in tandem, with a "catcher" downrange from the "launcher" in case the spacecraft failed to make the rendezvous with the tether. Also fwiw I'm imagining a separate cable robot would be used to place rockets on, and pick up capsules from, the central platform.
« Last Edit: 06/18/2020 05:29 am by mikelepage »

Offline Lodrig

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Re: Floating Habitat on Venus
« Reply #95 on: 06/18/2020 06:30 am »
Honestly I think launching a rocket from a balloon platform is probably best done by dropping the rocket and lighting it in mid-air.  It can then easily steer laterally and avoid the platform, this makes the platform far simpler, the rocket can also be on the bottom of a long tether giving it plenty of room.

Offline high road

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Re: Floating Habitat on Venus
« Reply #96 on: 06/18/2020 07:33 am »
Honestly I think launching a rocket from a balloon platform is probably best done by dropping the rocket and lighting it in mid-air.  It can then easily steer laterally and avoid the platform, this makes the platform far simpler, the rocket can also be on the bottom of a long tether giving it plenty of room.

Laterally or even just on a vector that avoids it colliding with the platform on the way up. And you could have the engines start up before disconnecting it from the platform, and throttle up after disconnecting. Assuming the platform only supports the rocket (which is not the only alternative), it will get out of dodge quickly when the rocket releases, allowing the rocket an even closer to vertical trajectory.

But how would you retrieve the rocket when it lands? Freefloat on its own in the hotter, denser parts of the atmosphere? Or does it have its own balloon that can keep it aloft at higher altitudes until it can be picked up?



How do you do the first "landing" at the 50 km height?
Rocket reenters and after falling at terminal velocity you rapidly inflate a balloon?

BTW I like the idea of semi rigid dirigibles like the ones we once had on earth. Landing pad is on the top deck. Whats the wind speed at 50km?

I would inflate in space.  Perhaps a shape similar to Apollo re-entry vehicle unless there is a known reason to modify the shape.  The heat damage to a heat shield is proportional to the area density.  Metal sheets that are relatively thin might not even need a ceramic coating.  The Apollo vessel needed to avoid cooking meat. 

The Apollo designers/engineers had to work within a radius of the Saturn V rockets.  If constructed in space using asteroid materials there isn't much limit to the radius. 

You don't even need asteroid materials to have an essentially limitless radius. They might help to reduce cost, but at a potential 20$/kg to Earth orbit (Elon Musks rosy estimate), asteroid mining for basic construction materials becomes far less of a gating technology.

Offline Lodrig

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Re: Floating Habitat on Venus
« Reply #97 on: 06/18/2020 09:53 am »

Laterally or even just on a vector that avoids it colliding with the platform on the way up. And you could have the engines start up before disconnecting it from the platform, and throttle up after disconnecting. Assuming the platform only supports the rocket (which is not the only alternative), it will get out of dodge quickly when the rocket releases, allowing the rocket an even closer to vertical trajectory.

But how would you retrieve the rocket when it lands? Freefloat on its own in the hotter, denser parts of the atmosphere? Or does it have its own balloon that can keep it aloft at higher altitudes until it can be picked up?


Probably just have to grab or be lassoed at the bottom of the same type of tether.  If you have the precision of the F-9's drone ship landing then it's simple to envision that point of zero velocity just being a point in mid-air which is where the tether ends.  Thus just have the vehicle go upward a bit, sticking it's nose through a lasso and close it, hooks on the top of the vehicle give a secure hold.  The end of the tether can actually be attached to a small helicopter drone so it can actively seek to engage the vehicle should it be out of position.

Now you can pull the whole vehicle up into a servicing and reintegration bay if it's multi-stage.  When it's ready and fueled lower it again (probably a much larger tether which supports the vehicle from it's base).  Rinse and repeat.  Think of it like how a small submarine is retrieved and launched from a moon pool on a ship.

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #98 on: 06/18/2020 04:56 pm »
Pardon me for being a neophyte and not reading all the referenced material.

We will 'provisionally' forgive you this ONE time but please have all the pertinent material read and summeries prepared with highlighted talking points and relevent charts by the next conversation or we will be forced to ...

Well admit we were kidding, but on reflection if you actually manage to DO all that I for one will be highly impressed and willing to extend you extra "nerd-cred"...

Seriously, (shut-up everyone, it DOES happen on occasion :) ) welcome and have fun!

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How do you do the first "landing" at the 50 km height?
Rocket reenters and after falling at terminal velocity you rapidly inflate a balloon?

Possibly. In theory, (see: https://selenianboondocks.com/2013/11/venusian-rocket-floaties/, for how to float without a balloon but at a less comfortable level for the most part :) ) you can float and empty rocket all by itself but since we're talking something 'manned' and/or living space for same you'd want to have a more active role in your altitude control.

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BTW I like the idea of semi rigid dirigibles like the ones we once had on earth. Landing pad is on the top deck.

Not exactly like the early ones as a lot of the 'rigid' structure would extend around or through the lifting cells to support and stabilize the pad on top as well as provide interconnects and structural connections to the sides for making larger structures. At least the one I saw.

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Whats the wind speed at 50km?

IIRC about 400km per hour but as high road notes you'd be travelling with it so wouldn't notice the velocity other than gusts and up/down drafts

Same way you can really feel that 1,000mph 'wind' every time you step outside here on Earth :)

I would inflate in space.  Perhaps a shape similar to Apollo re-entry vehicle unless there is a known reason to modify the shape.  The heat damage to a heat shield is proportional to the area density.  Metal sheets that are relatively thin might not even need a ceramic coating.  The Apollo vessel needed to avoid cooking meat. 

The Apollo designers/engineers had to work within a radius of the Saturn V rockets.  If constructed in space using asteroid materials there isn't much limit to the radius.

Did I mention the infamous "Hamster-Hab" incident? :) My original suggestion was based on the "Mars Direct" architecture for equipment, (not the actual plan which had/has issue) so I had a "tuna-can" hab inside and centered in a large spherical outer envelope that was both a habitat extension, auxiliary lift production device, and reentry heat shield. (Once 'down' a hydrogen balloon was the main means of lift)

Then I was informed of what happens when a sphere with the main mass in the center meets a situation of high drag... Hmmm, re-design! :)

It would, I think be more like a 'shuttle-cock' set up than an "Apollo" configuration because if it provides any lift at all once in the atmosphere the main 'mass' has to be on the lower volume point. Hence an Apollo shaped lifting device would try to float 'broad' end up. Does that make sense? Part of my 're-design' above was putting the "tuna-can" at the 'bottom' of the sphere and adding an actual heat-shield to help protect that point of higher than average mass. The rest of the balloon should get off pretty light given the right materials for an outer envelope.

Another idea is a "Lenticular" or saucer shaped habitat.
Well dang, now I see you guys started this thread up again, my mind is churning again (at least I made it to Wednesday :) )

Resistance is feudal, you will be assimilated into the discussion. We are... Way to into this stuff sometimes it seems :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #99 on: 06/18/2020 07:10 pm »
While I can imagine Starship being modified to be able to come to neutral buoyancy in the upper Venusian atmosphere, I still haven't been able to convince myself that being able to host and fuel a Superheavy-class booster makes sense as the goal for a cloud base on Venus.

Well to be clear, "a" cloud base or "THE" Cloud Base as context matters ;)

I agree as the 'problem' is the same as to why you don't use "Superheavy/Starship" to move people and supplies on Mars. It may be economical for a while but in the end what they can and will build and use on Mars (and Venus and the Moon, etc) will likely be something more suited to their actual needs as you have few, (if any) of the same incentives and drivers you had on Earth to develop them in the first place.

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It seems to me that all the arguments against air launch / space tethers (that it's more efficient to build a larger launch vehicle) on Earth, go the opposite way on Venus, because we'll be arriving from orbit, and obviously there's no solid ground to launch from.

I'm actually seeing this in the "air-breathing stage" thread and the thing is it simply isn't true as presented because having a 'larger' launch vehicle only works for certain situations. It 'works' on Earth currently because it has the ability to tap into Earth's vast (and cheap) transportation, communications and infrastructure networks. That makes it arguably cheap to build and maintain but leaves the question of actual marketability up in the air. (Pardon the pun) As one excitable person made the claim that a single Starship/Superheavy could fly ALL the worlds satellite launches in ONE flight and seemed confused when someone pointed out, "And then what?" :)

While granting that when we get to the point of considering colonization of other worlds we'll need some serious cargo capacity throughput from Earth to the new colony for quite a while there still remains the question of the best and most economical means of doing the job. Starship specifically though "designed" as an interplanetary transport is actually only marginally qualified to do the job on an active and economic basis. There are numerous OTHER means of doing so at a much lower cost with a much higher 'throughput' total and quite frankly at the point where we're building actual colonies then Starships main job will be simply hauling cargo and passengers into Low Earth Orbit rather than taking them all the way to the Colony. (Keep in mind we're not talking the "first" colony and it's support but the point when multiple colonies are building and expanding)

While each air-launch/tether combination only puts up a pretty small cargo on each flight it can in effect put up a LOT of cargo in a single 'day' of the Earth and from all over the Earth as well. The economic and optics get MUCH worse should be manage a Space Elevator eventually. Starship on the other hand is very much dependent on the "build-it-and-they-will-come" philosophy.

I understand the 'frustration' that drove "Starship" into being but historically and arguably it's not actually the correct conclusion to have come to. We may have been going into space for almost 60 years, (closer to 65 if you start from Sputnik) but we've only done it for specific purposes and in very focused and narrow ways. The comparison of where we went from the first powered flight to the Moon in only 66 years is actually false since we never 'dabbled' in powered flight like we do normally in space travel. The idea that there are millions of people, payloads and projects that have just been waiting for the 'right' ride to space to come along is demonstrably not true. If you're going to try and make a historic comparison then we JUST had our "Wright Brothers" moment about a month ago!

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That's why I always tend to go back to some kind of megastructure being required on Venus, in combination with aiming to minimize the size of the spacecraft actually doing the to-ing and fro-ing, so today's thought bubble is to wonder if it might be easier to build 3 not-quite-as-mega-megastructures:

It consists of a combination of ideas I've toyed with previously on this thread and others:
1) Floating skyscraper, which has the colony built around a central...
2) ~10km railgun, which lobs a small spacecraft on a suborbital trajectory up to a...
3) Orbiting, non-rotating space tether.

Preferably more than one so you can 'use' a majority of the skyhooks orbit? I'd also probably suggest not having the "colony" itself clustered around the Launch System. Probably it would have an industrial basis.

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The skyscraper-like structure would made up of modular lifting gas segments, each one of which has a Hoberman sphere-like expansive capability so as to allow it to EDF (enter-descend-float) at Venus inside the smallest descent capsule possible, and autonomously assemble into a horn-like structure (wider end of bell facing up) around a cylindrical central hole, so as to maintain vertical orientation.

Ah, I love those things! (https://en.wikipedia.org/wiki/Hoberman_mechanism) I suspect they'd be torus rather than sphere's though and you'd just add some external lift cells towards the top

>snip<
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Key saving of this setup is that the mass/volume of the floating skyscraper structure only has to compensate for a mass change of 125 metric tons with each launch, rather than the 4400 metric tons of Starship Superheavy, and you could reduce that still further if you're willing to make a longer tether. Seems important to minimise the amount of lifting gas required just to get two way transit happening :o

Ya minimizing the 'shift' will be a good thing :)

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EDIT: the other consideration is if you want to eliminate the space tether entirely, but that means your spacecraft either has to get considerably bigger, or your tower/railgun has to get considerably taller - and 10km tall is already pushing it for me.   ;D

You also wrote:
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Neither is actually a good solution and I really have to stop pitching railguns  ;D when all I actually want is a long enough (low-G) acceleration run up to a suborbital trajectory so a lightweight spacecraft can go chasing the tether

Well I won't say it will be 'light' but it's a 'steady' mass that won't overly react to tossing out a couple of hundred tons every couple of minutes :)

May I present CELT?
(Ignore the cockeyed first "abstract" page, someone was having a bad day scanning I suspect: https://ntrs.nasa.gov/archive/nasa/casi.ntrs.nasa.gov/20010027422.pdf)

"Closed End Launch Tube" Not actually a 'tube' per-se but just a giant air-pressure accelerator system to push a payload to around 300 m/s. Mechanically and systematically rather simple and direct, using readily available resources, (Venus 'air' and electricity) and good news it's 'only' about 6 or 7km long :) (And as it's sized for a nominal 450 tonnes tossing 125 tonne loads shouldn't be an issue : ) )

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #100 on: 06/18/2020 07:33 pm »
Huh, I always imagined them being built like an igloo. If you already have a mast supporting the structure, why would you remove it?

Domes are NOT built like this which was always a pet-peeve with Bucky because he had it all planned out and nobody listened :)

We build domes by building panels and then attaching them to other panels from the ground 'up' to the top. Bucky had always planned to start at the "top" at ground level and the hoist the finished pieces on as it rose up the mast. (The idea was to get a 'roof' up as soon as possilbe) The mast would anchor and support the rising dome while guy-lines kept the dome stable as new panels were added, all from the 'safety' of solid ground.

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It's probably the Starship-theme getting to me, but now I'm trending towards the dock being an 'onion tent'. When the section is finished, the tent is cut open along a seam in the middle, and the roof and the support structure folds to the sides. After the section (or the complete structure) has been carried away (or lifted off) from the platform, the tent is closed again, an the seam is covered with a plastic tape that melts when heated to create an airtight seam.

Around here there's a lot of year round construction you see a lot of 'bubble' domes over construction work and quite a few have an inner structure that allows them to be picked up so whatever you're working on can be slide in and out of 'cover' when needed.

Personally I'm thinking you'd just have a 'square' Air-Raft dock with lifting cells on each side and spots for supplementary cell attachment and a two level structure where the parts come in the 'top', get mostly assembled before it is lowered into the bottom structure and an air-tight-ish, (it's an industrial process so total sealing isn't likely to happen) seal is run across the space. It's completed there and once done the bottom opens up and the structure is lowered to meet an 'air-tug' to tow it to the assembly site.

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So no superheavy launcher, but a 10km long launch infrastructure is acceptable? I like the way you think  ;D

Size matters, even if they tell you different :D

Gas-cells you say? A 220 ton vehicle (assuming fully loaded) requires a Hindenburg sized aerostat to lift it.

Well not quite on Venus but I get your point :)
But don't think the Hindenburg but multiple Goodyear blimps from each 'port' to equal the lift needed

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Given the difficulties SpaceX and RocketLab say they've experienced with parashute development, inflating a huge structure while hurtling down seems a tad dangerous. However, if we could fill Starship with a couple of 8*40 craft (which would inflate along the long axis, with the internal support structure locking into position when fully inflated), Starship could do its crazy flip (less dangerous on Venus than on Earth) and come to a near-stop so the modules can be deployed more easily. Sacrifice the Starship when done. That's about 1.3 tons of total lift per module. Combine as necessary for all your needs.

You've likely seen the HAVOC video's so it's several 'blimp' envelopes that deploy from bays with cables to the hull outside the bays.  Going to be 'interesting' but actually easier than parachutes due to the self-inflation.

Point was that getting it to 'stand' upright is going to require bays on the reentry side as well as the down-wind side. That might be an issue.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Floating Habitat on Venus
« Reply #101 on: 06/19/2020 08:07 am »
Huh, I always imagined them being built like an igloo. If you already have a mast supporting the structure, why would you remove it?

Domes are NOT built like this which was always a pet-peeve with Bucky because he had it all planned out and nobody listened :)

We build domes by building panels and then attaching them to other panels from the ground 'up' to the top. Bucky had always planned to start at the "top" at ground level and the hoist the finished pieces on as it rose up the mast. (The idea was to get a 'roof' up as soon as possilbe) The mast would anchor and support the rising dome while guy-lines kept the dome stable as new panels were added, all from the 'safety' of solid ground.

Interesting. So why remove the mast once you're done? Seems extra stable to just leave it there.

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It's probably the Starship-theme getting to me, but now I'm trending towards the dock being an 'onion tent'. When the section is finished, the tent is cut open along a seam in the middle, and the roof and the support structure folds to the sides. After the section (or the complete structure) has been carried away (or lifted off) from the platform, the tent is closed again, an the seam is covered with a plastic tape that melts when heated to create an airtight seam.

Around here there's a lot of year round construction you see a lot of 'bubble' domes over construction work and quite a few have an inner structure that allows them to be picked up so whatever you're working on can be slide in and out of 'cover' when needed.

You're putting some awesome images in my head. So many options!

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Personally I'm thinking you'd just have a 'square' Air-Raft dock with lifting cells on each side and spots for supplementary cell attachment and a two level structure where the parts come in the 'top', get mostly assembled before it is lowered into the bottom structure and an air-tight-ish, (it's an industrial process so total sealing isn't likely to happen) seal is run across the space. It's completed there and once done the bottom opens up and the structure is lowered to meet an 'air-tug' to tow it to the assembly site.

I repeat: that looks awesome in my head.

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Gas-cells you say? A 220 ton vehicle (assuming fully loaded) requires a Hindenburg sized aerostat to lift it.

Well not quite on Venus but I get your point :)
But don't think the Hindenburg but multiple Goodyear blimps from each 'port' to equal the lift needed

Ah, I was in an all-methane setup. Hydrogen/helium would give you 50% more lift, so 2/3 of the volume are still required. That's almost 90% of the radius, unfortunately.

But I had interpreted your design wrong. So assuming, for simplicity's sake, that the blimps would neatly fill up a cilinder around the Starship, that's a 33m diameter tube. Seems comparable to the 8*40 idea. And you'd have more time and be able to inflate them much quicker.

So yeah, like this it becomes arguable whether you would go for somewhat longer blimps and stay horizontal, or go for a (partially) disposable heat shield to protect the ports on that side. The Starship could drop to lower, denser and hotter areas before inflating those 'downward' gas cells, turning vertical and rising to operational altitude.

Offline edzieba

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Re: Floating Habitat on Venus
« Reply #102 on: 06/19/2020 11:30 am »
Interesting. So why remove the mast once you're done? Seems extra stable to just leave it there.
The mast makes it less stable. A Thinwall dome is stable because the entire dome 'skin' is under compression, like in an archway. Adding a mast poking up the centre and actually doing anything to bear vertical load means there is now part in tension, part in compression, and a transition zone where the skin is flapping in the breeze.

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #103 on: 06/19/2020 08:45 pm »
Interesting. So why remove the mast once you're done? Seems extra stable to just leave it there.

As edzieba notes the dome is meant to spread the load around the structure where as keeping the mast concentrates loads on that mast instead and removes the perimeter loading as a basis for stability. One thing a central 'mast' might do in a free-floating habitat would be a connection point for a tensegrity cable network to tie too and to add tension loading to the 'poles' of the sphere. But in general that's the whole reason to use geodesic space-frames is to allow as much "open/free" space as possible.

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You're putting some awesome images in my head. So many options!
I repeat: that looks awesome in my head.

You're welcome :)

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Ah, I was in an all-methane setup. Hydrogen/helium would give you 50% more lift, so 2/3 of the volume are still required. That's almost 90% of the radius, unfortunately.

But I had interpreted your design wrong. So assuming, for simplicity's sake, that the blimps would neatly fill up a cylinder around the Starship, that's a 33m diameter tube. Seems comparable to the 8*40 idea. And you'd have more time and be able to inflate them much quicker.

Well still assuming "Starship" then yes it would still be methane, and ya, deployment and arrangement is going to be an issue that I'd like to get into. But probably in a separate post :)

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So yeah, like this it becomes arguable whether you would go for somewhat longer blimps and stay horizontal, or go for a (partially) disposable heat shield to protect the ports on that side. The Starship could drop to lower, denser and hotter areas before inflating those 'downward' gas cells, turning vertical and rising to operational altitude.

I have to be honest in that this is going to be less and less 'Starship' as we go along and that makes me compare this to the "Green Dragon" concept. (Green-Starship? Lincoln-Green-Starship? Oh heck just admit it, we'll call it Jefferson Starship because after all, "We built this City"! Oh look, a door and my hat and coat... Hmmm, hint maybe? : ) )

Ok back on point but like the idea of 're-purposing' a used-Dragon 1 for a Venus floating prototype we're essentially taking a 'used' Starship and gutting it and the refitting it for the intended purpose so any idea that this will be 'cheap' because we're using an existing hull isn't true. This is especially true with trying to deploy one or more 'balloon' lifting cells.

And speaking of deployment...

I originally envisioned something like hatches around the Starship which each pushed out a 'cylinder' or 'spherical' balloon that was assisted by cables and attachments along the hull. (Similar to how the HAVOC blimp envelope is deployed) Problem is the windward side of that means you'd need to do something about the heat shield. (And something I meant to bring up to Shevek is that his numbers are assuming a VERY heavy "Starship" on entry and lot heavier than any planned configuration on "landing") Now if we modify the downwind side of the Starship to house the cells and deployment systems in what amounts to an 'external' housing this reduces a lot of the problems but means we're going to gain a few more and end up being 'horizontal' rather than vertical.

The other problem is that Starship is 'big' but not that big in context but let's take the main dimensions:
(Source: https://www.spacex.com/vehicles/starship/, https://www.spacex.com/media/starship_users_guide_v1.pdf)
 
Height: 50m/160ft
Diameter: 9m/38ft

I don't think any arrangment of 'lift cells' is going to be able to fit around this hull. So we may have only a limited number of options for placement.

To avoid having to deal with ripping out the 'passenger' section and re-building it lets assume a "cargo-tanker" version so the area we have to work with is shown in figure 4 of the users guide. So if I'm reading this right we've got an area of 8m in diameter by 22m in length within which we're going to have to fit the deployment mechanisms and the lift cell storage.

Now if my math is right, (which isn't likely a valid assumption, but...) as Shevek23 noted we'd be needing around 146 tonnes of methane for lift, which at 0.554kg per cubic meter should work out to a total of 80,884 cubic meters of gas we have to contain to keep this in the 'air' as it were.
(Calculator: https://www.calculatorsoup.com/calculators/geometry-solids/)

Assuming something like a 'single' outer envelope or such structure (you'd still have individual 'cells' but they are build in) we're looking at a sphere 54m in diameter, or a cylinder of something like, (assuming I can get a diameter of around 20m) 258m long/tall as a "single-unit" design. If we're stuck with a smaller diameter the length gets too ridiculous and frankly we'd be pushing it with the current 5 times the length of the Starship we have here.

Assuming a non-rigid envelope somewhat similar to the Zepplin NT envelope which can hold about 8,500 cubic feet of gas that means we'd need about ten (10) 55m long and 25m diameter cylinder or 14m diameter spherical lifting cells that we have to deploy individually to lift the beast.

I'm not seeing any real way to deploy this from a side cargo bay and even opening the 'standard' Starship payload fairing isn't an option so we're looking at some sort of installed deployment system around the 'nose' of the vehicle. Essentially a number of giant "parachute-mortar" tubes that fire the cells out to inflate and fight for space around the nose of the ship. In any case it's looking like we pretty much 'lose' most of the forward cargo space to the lift cell storage and deployment system or we mount it externally somehow. The former case means we'd likely convert the LOX tank to storage space but that brings into question the weight and balance of the vehicle, the latter case avoids those problems but we're faced with heating and aerodynamic unknowns and horizontal living.

And btw my "FIRST" concept won't work either because you'd have to deploy two cylinders along the sides that were around 20m in diameter and 130m long. Only a bit over twice as long as the Starship hull ...

Randy

From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Floating Habitat on Venus
« Reply #104 on: 06/21/2020 10:14 am »
Well, that seems a lot of effort. So basically a Green Starship would be an entirely new vehicle that is Starship shaped and can be launched as a starship.

It appeals a bit less to me, as I don't see the advantages over other architectures. Sacrificing an end of life Starship to deploy 8 by 40 rigid body aerostats gives you a simple way of using Starships massive capabilities. With just inflatable envelopes, you might be able to go bigger if they can deploy safely. And you might deploy even bigger 'hamsterballs' from orbit using Starship. Send a tanker along of you want the Starship back. (If a tanker holds enough fuel to bring back 2 Starships from Venus orbit)

Offline stefan r

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Re: Floating Habitat on Venus
« Reply #105 on: 06/23/2020 04:19 pm »


You don't even need asteroid materials to have an essentially limitless radius. They might help to reduce cost, but at a potential 20$/kg to Earth orbit (Elon Musks rosy estimate), asteroid mining for basic construction materials becomes far less of a gating technology.

Reduced launch costs enable all types of space projects launched from Earth.  That lowers the barrier to both asteroid mining and planetary missions.

In the overall timeline I believe colonists moving to Venus (or any planet) will be somewhat later.  There is a strong economic motive for people on Earth to mine asteroids.  The incentive to relocate and build a residence on another planet is much weaker.  We can probably count on political support from large groups that want to see terrestrial mines on Earth shut down.  So at the time when Venus habitats are being constructed the I-beams for skyscrapers in Manhattan and the rebar for Earth's roads will be built using asteroid sourced iron. 

Under those circumstances the advanced components like control machinery and computer systems may still be manufactured on Earth.  For a really big metal bubble I do not see enough advantages building it on the ground.  The stress from launching off Earth would do more damage than what we could gain from better processing facilities.  Welding lots of little pieces in orbit may be more effort than just rolling large sheets of steel or Nickle. 

It is plausible that asteroid mining will be done using the Mond process.  The iron and nickel would be removed as carbonyls so that the dissolved precious metals are accessible and can be launched back to Earth.  That makes steel sheet metal is an unused by-product.  The acceleration from solar sailing would be measured in microns per second2 but that is good enough aim it at multiple gravity assists.  When some of that material starts drifting toward Venus it might be realistic to consider making some Venetian habitats.  I do realize multiple gravity assists could take multiple decades.

Offline high road

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Re: Floating Habitat on Venus
« Reply #106 on: 06/24/2020 09:26 am »


You don't even need asteroid materials to have an essentially limitless radius. They might help to reduce cost, but at a potential 20$/kg to Earth orbit (Elon Musks rosy estimate), asteroid mining for basic construction materials becomes far less of a gating technology.

Reduced launch costs enable all types of space projects launched from Earth.  That lowers the barrier to both asteroid mining and planetary missions.

In the overall timeline I believe colonists moving to Venus (or any planet) will be somewhat later.  There is a strong economic motive for people on Earth to mine asteroids.  The incentive to relocate and build a residence on another planet is much weaker.  We can probably count on political support from large groups that want to see terrestrial mines on Earth shut down.  So at the time when Venus habitats are being constructed the I-beams for skyscrapers in Manhattan and the rebar for Earth's roads will be built using asteroid sourced iron. 

Under those circumstances the advanced components like control machinery and computer systems may still be manufactured on Earth.  For a really big metal bubble I do not see enough advantages building it on the ground.  The stress from launching off Earth would do more damage than what we could gain from better processing facilities.  Welding lots of little pieces in orbit may be more effort than just rolling large sheets of steel or Nickle. 

It is plausible that asteroid mining will be done using the Mond process.  The iron and nickel would be removed as carbonyls so that the dissolved precious metals are accessible and can be launched back to Earth.  That makes steel sheet metal is an unused by-product.  The acceleration from solar sailing would be measured in microns per second2 but that is good enough aim it at multiple gravity assists.  When some of that material starts drifting toward Venus it might be realistic to consider making some Venetian habitats.  I do realize multiple gravity assists could take multiple decades.

Ah, yes. I was talking about the cost of sending infrastructure there to study the planet and get Venus beyond its 'Viking Lander moment' at the time. Launch costs are not as relevant for that, especially if you're using Starship as a reference. For future setlement, the economics are more shaky for Venus. (why you bother going there determines the architecture choices). But that is an interesting discussion in itself.

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #107 on: 06/25/2020 11:06 pm »
Well, that seems a lot of effort. So basically a Green Starship would be an entirely new vehicle that is Starship shaped and can be launched as a starship.

Eh, "It depends" is actually a valid answer here as I DID point out you can essentially use a "Cargo/Tanker" Starship as a basis but you get a lot of (pardon the pun) unintended and unnecessary baggage along with what you actually need. So the question becomes not only do you really NEED "Green Starship" but do you WANT "Green Starship" because by the time you're done you have a marginal 'habitat' at best with more than few compromise issues and problems.

One thing I failed to point out but should have is the TVI figures seem to assume that the "Green Starship" doesn't do any of the 'work' since it's filled most of the tankage with methane and has what appears to be no room for LOX? Granted you need 'something' of the approximate mass of the engines on Starship to balance out the ship on entry but you don't NEED the engines themselves and ripping them out is not going to be a trivial or cheap thing to do.

So while you essentially START with a "Starship" the same way I started Green Dragon by basing it on a Dragon-1 capsule by the time you're done it's not going to be anything really close to what you started with so is it really a good choice to base the concept on?

 At the time and in context, for Green Dragon yes it still makes sense because it gives you a known basis to work with towards a specific and plausible concept. "Green Starship" without some significant changes is maybe not the best way to go.

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It appeals a bit less to me, as I don't see the advantages over other architectures. Sacrificing an end of life Starship to deploy 8 by 40 rigid body aerostats gives you a simple way of using Starships massive capabilities. With just inflatable envelopes, you might be able to go bigger if they can deploy safely. And you might deploy even bigger 'hamsterballs' from orbit using Starship. Send a tanker along of you want the Starship back. (If a tanker holds enough fuel to bring back 2 Starships from Venus orbit.

The first part is my main issue as it does not in fact seem to have any advantages over a more dedicated architecture. Yes sacrificing a couple of "end-of-life" Starships to form the core of a Venus space station 'might' make sense but I have to point out "end-of-life" is a term with a specific meaning and would you really want to start off with inherited and longer term issues of what is essentially a near-worn-out hull?

And lest we forget this all assumed you (or anyone) can even get one used or not because in the very end that's NOT part of the plan. These are not 'aircraft' that get sold down the line to lower and lower tier airlines. These are spacecraft that SpaceX will build, SpaceX will operate, and likely SpaceX will scrap to keep someone from 'ruining' SpaceX's reputation by crashing one and killing people. (Never mind that the concept of a "Ryder-Rent-A-Rocket" wasn't every really feasible after 9/11 this is a possible "thing" that governments specifically and people in general take VERY seriously)

I'm pretty sure at this point that when the time comes anyone can buy a "flight" (crew included but likely "options" like air to breath might cost extra :) ) who wants one and can pay for it but you won't see private Starships anymore than we'll likely see someone other than SpaceX flying Falcon/FH/Dragon.

People seem to ignore/forget that Musk has been very open about NOT going to be all-in for planning a Mars colony, (he's dabbling atm but that's to be expected given his actual goal.. he's got to know the bounds of cargo and passenger requirements he's going to be servicing after all) but he is FULLY committed to build an interplanetary transportation service/system. It might not be obvious, though I personally can't see why it's not VERY obvious, but that pretty explicitly means that he (and SpaceX) will be RUNNING it as well. In essence if you want to go to Mars you will have to go through SpaceX. The Moon? SpaceX. Venus? You get the idea...

There is always the possibility of competition but it's pretty apparent that neither Musk nor most of his fans see that happening and that they 'assume' that's a good thing for some reason is rather worrisome at times :)

Should a miracle occur and I every get "Green Dragon" off the ground, (pun intended) it will fly on a SpaceX flight. That's pretty much a given considering all that's needed to make it happen I would REQUIRE SpaceX's good will and blessings so anything else isn't really an option. But it doesn't mean that even if it shakes out that way it will always be that way. The odds are long however that it will be quite a while before anything changes.

Part of the reason I choose Venus and why I oppose the demand that I "choose" to follow a "majority" (btw: you aren't, at all) and place all my hopes on Mars is BECAUSE I understand how easy it would be to fall into that trap.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Floating Habitat on Venus
« Reply #108 on: 06/29/2020 08:25 am »
Well, that seems a lot of effort. So basically a Green Starship would be an entirely new vehicle that is Starship shaped and can be launched as a starship.

Quote
It appeals a bit less to me, as I don't see the advantages over other architectures. Sacrificing an end of life Starship to deploy 8 by 40 rigid body aerostats gives you a simple way of using Starships massive capabilities. With just inflatable envelopes, you might be able to go bigger if they can deploy safely. And you might deploy even bigger 'hamsterballs' from orbit using Starship. Send a tanker along of you want the Starship back. (If a tanker holds enough fuel to bring back 2 Starships from Venus orbit.

The first part is my main issue as it does not in fact seem to have any advantages over a more dedicated architecture. Yes sacrificing a couple of "end-of-life" Starships to form the core of a Venus space station 'might' make sense but I have to point out "end-of-life" is a term with a specific meaning and would you really want to start off with inherited and longer term issues of what is essentially a near-worn-out hull?

Ah, that's not what I meant. These are some alternatives to your approach that appeal to me more (which is entirely personal and not based on anything, really). I meant not fiddling with Starship, just design a craft that fits inside a Starship. The Starship is sacrificed because it falls to the surface after deploying its cargo. And if it's a craft that is nearing end of life, it would be easier to get SpaceX to agree. They might even prefer their rockets to meet their end on a distant planet, rather than somewhat more spectacularly on Earth, or with more dramatic consequences on Mars. But they could prefer to retire and scrap their rockets, that's also a likely outcome.

Quote
And lest we forget this all assumed you (or anyone) can even get one used or not because in the very end that's NOT part of the plan. These are not 'aircraft' that get sold down the line to lower and lower tier airlines. These are spacecraft that SpaceX will build, SpaceX will operate, and likely SpaceX will scrap to keep someone from 'ruining' SpaceX's reputation by crashing one and killing people. (Never mind that the concept of a "Ryder-Rent-A-Rocket" wasn't every really feasible after 9/11 this is a possible "thing" that governments specifically and people in general take VERY seriously)

I'm pretty sure at this point that when the time comes anyone can buy a "flight" (crew included but likely "options" like air to breath might cost extra :) ) who wants one and can pay for it but you won't see private Starships anymore than we'll likely see someone other than SpaceX flying Falcon/FH/Dragon.

People seem to ignore/forget that Musk has been very open about NOT going to be all-in for planning a Mars colony, (he's dabbling atm but that's to be expected given his actual goal.. he's got to know the bounds of cargo and passenger requirements he's going to be servicing after all) but he is FULLY committed to build an interplanetary transportation service/system. It might not be obvious, though I personally can't see why it's not VERY obvious, but that pretty explicitly means that he (and SpaceX) will be RUNNING it as well. In essence if you want to go to Mars you will have to go through SpaceX. The Moon? SpaceX. Venus? You get the idea...

There is always the possibility of competition but it's pretty apparent that neither Musk nor most of his fans see that happening and that they 'assume' that's a good thing for some reason is rather worrisome at times :)

Should a miracle occur and I every get "Green Dragon" off the ground, (pun intended) it will fly on a SpaceX flight. That's pretty much a given considering all that's needed to make it happen I would REQUIRE SpaceX's good will and blessings so anything else isn't really an option. But it doesn't mean that even if it shakes out that way it will always be that way. The odds are long however that it will be quite a while before anything changes.

Part of the reason I choose Venus and why I oppose the demand that I "choose" to follow a "majority" (btw: you aren't, at all) and place all my hopes on Mars is BECAUSE I understand how easy it would be to fall into that trap.

Randy

Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition, even as Starship reduces their costs, that pretty much means that SpaceX now has an easy way to finance any economic activity in space. Pretty much Vanderbilt in space. With the next John D. Rockefeller spinning out of those activities. Not entirely sure how I feel about that. But a little off topic for this thread.

Offline Pete

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Re: Floating Habitat on Venus
« Reply #109 on: 06/30/2020 10:19 am »
Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition,

Do you have any reason to suspect that SpaceX will drastically alter their current pricing model?
Because they have ALREADY dropped their prices below the competition.

Offline Twark_Main

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Re: Floating Habitat on Venus
« Reply #110 on: 06/30/2020 01:29 pm »
The rail gun, accelerates what I'm assuming is a Falcon 9 S2+Dragon derivative (~6km/s dV onboard) spacecraft at 4Gs over 10km, will give it a final velocity close to 300m/s and put it on a suborbital trajectory with an apogee of about 160km...

I get different numbers, so someone check my math.

4 g acceleration (relative to the Venusian surface, so including gravity the vehicle is experiencing 4.9 g inertial) for 10 km yields exit velocity of 886 m/s, by v = sqrt(2ad). But I got a vacuum apogee of only 44 km, by h = 1/2 v2/g = ad/g, where g = 8.87 m/s2.
« Last Edit: 06/30/2020 02:19 pm by Twark_Main »
"The search for a universal design which suits all sites, people, and situations is obviously impossible. What is possible is well designed examples of the application of universal principles." ~~ David Holmgren

Offline Pete

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Re: Floating Habitat on Venus
« Reply #111 on: 06/30/2020 04:39 pm »
The rail gun, accelerates what I'm assuming is a Falcon 9 S2+Dragon derivative (~6km/s dV onboard) spacecraft at 4Gs over 10km, will give it a final velocity close to 300m/s and put it on a suborbital trajectory with an apogee of about 160km...

I get different numbers, so someone check my math.

4 g acceleration (relative to the Venusian surface, so including gravity the vehicle is experiencing 4.9 g inertial) for 10 km yields exit velocity of 886 m/s, by v = sqrt(2ad). But I got a vacuum apogee of only 44 km, by h = 1/2 v2/g = ad/g, where g = 8.87 m/s2.
yarp, your numbers are correct, but you are missing some assumptions.
The launch begins from a floating base at altitude 50km.
The launch exits launcher at base+10km = 60km. So to get to 160km alt, it just needs to go up another 100.
This needs about 1332m/s exit from the launcher.
And *that*, on a 10km launch, needs acceleration of 88.7+gravity = 97.6m/s2 (about 10 earth-g)

Offline high road

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Re: Floating Habitat on Venus
« Reply #112 on: 07/01/2020 06:30 am »
Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition,

Do you have any reason to suspect that SpaceX will drastically alter their current pricing model?
Because they have ALREADY dropped their prices below the competition.

Yes, to a pricepoint where they can get about all of the commercial launches, with little relation to their own costs. Most of the money they save by reusing rockets is profit for them rather than lowering their prices. (And it's probably a good thing, as they seem to be the best bang for your buck by far).

If the competition doesn't keep up with dropping prices, and it doesn't look like it, prices will not drop that much. SpaceX still needs all the money it can get to finance all of their upcoming projects.

Offline Pete

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Re: Floating Habitat on Venus
« Reply #113 on: 07/01/2020 07:10 am »
Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition,

Do you have any reason to suspect that SpaceX will drastically alter their current pricing model?
Because they have ALREADY dropped their prices below the competition.

Yes, to a pricepoint where they can get about all of the commercial launches, with little relation to their own costs. Most of the money they save by reusing rockets is profit for them rather than lowering their prices. (And it's probably a good thing, as they seem to be the best bang for your buck by far).

If the competition doesn't keep up with dropping prices, and it doesn't look like it, prices will not drop that much. SpaceX still needs all the money it can get to finance all of their upcoming projects.
Yes.
And this IN NO WAYS implies "no interest in dropping their prices below the competition"
Indeed, it shows the *exact opposite*. SpaceX ****has**** dropped their prices below the competition. And you yourself affirm that.
Which makes a bit of a mockery of your own statement of
Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition,

« Last Edit: 07/01/2020 07:11 am by Pete »

Offline high road

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Re: Floating Habitat on Venus
« Reply #114 on: 07/03/2020 05:52 am »
Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition,

Do you have any reason to suspect that SpaceX will drastically alter their current pricing model?
Because they have ALREADY dropped their prices below the competition.

Yes, to a pricepoint where they can get about all of the commercial launches, with little relation to their own costs. Most of the money they save by reusing rockets is profit for them rather than lowering their prices. (And it's probably a good thing, as they seem to be the best bang for your buck by far).

If the competition doesn't keep up with dropping prices, and it doesn't look like it, prices will not drop that much. SpaceX still needs all the money it can get to finance all of their upcoming projects.
Yes.
And this IN NO WAYS implies "no interest in dropping their prices below the competition"
Indeed, it shows the *exact opposite*. SpaceX ****has**** dropped their prices below the competition. And you yourself affirm that.
Which makes a bit of a mockery of your own statement of
Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition,

You're making a strawman out of it. SpaceX sets its prices relative to competitors. If they don't drop their prices further, SpaceX won't either. Most of their savings on reusability and Starship are reinvested.

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #115 on: 07/09/2020 10:07 pm »
Ah, that's not what I meant.

Ahh, but who cares what you 'meant' as it allows more discussion on other widely varying topics to crop up? ;)

Quote
These are some alternatives to your approach that appeal to me more (which is entirely personal and not based on anything, really). I meant not fiddling with Starship, just design a craft that fits inside a Starship. The Starship is sacrificed because it falls to the surface after deploying its cargo. And if it's a craft that is nearing end of life, it would be easier to get SpaceX to agree. They might even prefer their rockets to meet their end on a distant planet, rather than somewhat more spectacularly on Earth, or with more dramatic consequences on Mars. But they could prefer to retire and scrap their rockets, that's also a likely outcome.

Well to be honest IF you're going to drag a Starship all the way to Venus, (even one way) then at least get SOME use out of it is my take. Deploy the 'payload' from orbit sure but keep the Starship hull(s) as part of a Venus Station or something.
(And if you can imagine a METEOR space station created using Starships as a core element: http://www.projectrho.com/public_html/rocket/spacestations.php#id--Designs--Meteor_Space_Station, https://www.secretprojects.co.uk/threads/meteor-city-in-space.5876/, you're welcome :) )

My main point was it's not likely they would underwrite such an effort mostly due to the "Mars First/Last/Only" sub-text in Musk's plans.

Quote
Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition, even as Starship reduces their costs, that pretty much means that SpaceX now has an easy way to finance any economic activity in space. Pretty much Vanderbilt in space. With the next John D. Rockefeller spinning out of those activities. Not entirely sure how I feel about that. But a little off topic for this thread.

Which as you note is likely the whole POINT of the exercise in the first place :)

And I have to point out it's NOT actually off-topic because there's a LOT of 'push-back' to colonization efforts OTHER than Mars from a lot of people who support SpaceX/Musk BECAUSE he's so focused on Mars. And it's not an accident since they as a general rule tend to see no other place that SHOULD be considered or planned to be colonized OTHER than Mars. Keeping them honest and keeping the idea open that it in no way should be implied or assumed that you can only do ONE thing with the technology is always a good idea :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline Pete

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Re: Floating Habitat on Venus
« Reply #116 on: 07/10/2020 10:43 am »
You're making a strawman out of it. SpaceX sets its prices relative to competitors. If they don't drop their prices further, SpaceX won't either. Most of their savings on reusability and Starship are reinvested.
HUnnybun.*****YOU***** are the one that says

Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition,

So Either you are arguing with YOURSELF (which is a sign of severe mental illness)
or you are just a troll (which is also a bit negative, on the mental health scale)

Offline high road

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Re: Floating Habitat on Venus
« Reply #117 on: 07/10/2020 11:44 am »
You're making a strawman out of it. SpaceX sets its prices relative to competitors. If they don't drop their prices further, SpaceX won't either. Most of their savings on reusability and Starship are reinvested.
HUnnybun.*****YOU***** are the one that says

Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition,

So Either you are arguing with YOURSELF (which is a sign of severe mental illness)
or you are just a troll (which is also a bit negative, on the mental health scale)

Other than that you're taking the second quote out of context (making a strawman out of it), these quotes are not in conflict with each other. They're in conflict with your interpretation of my shorthand. Which admittedly, is an unfortunate shorthand in hindsight, but given the context I assumed it was clear. It was already off topic without going into market elasticity.


Well to be honest IF you're going to drag a Starship all the way to Venus, (even one way) then at least get SOME use out of it is my take. Deploy the 'payload' from orbit sure but keep the Starship hull(s) as part of a Venus Station or something.
(And if you can imagine a METEOR space station created using Starships as a core element: http://www.projectrho.com/public_html/rocket/spacestations.php#id--Designs--Meteor_Space_Station, https://www.secretprojects.co.uk/threads/meteor-city-in-space.5876/, you're welcome :) )

My main point was it's not likely they would underwrite such an effort mostly due to the "Mars First/Last/Only" sub-text in Musk's plans.

Seeing this imagery, I now realize that the artists making the drawings for the books and comics I loved the most as I child got their inspiration from this. So even as a child I prefered realism (after a fashion) over pure fantasy, apparently. That's new. I assumed my aversion of Star Trek's plot-dependent technobabble vs Star Wars' fantastic yet simple and consistent - for my ten year old mind - story meant I was more into fantasy back then.


Quote
Quote
Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition, even as Starship reduces their costs, that pretty much means that SpaceX now has an easy way to finance any economic activity in space. Pretty much Vanderbilt in space. With the next John D. Rockefeller spinning out of those activities. Not entirely sure how I feel about that. But a little off topic for this thread.

Which as you note is likely the whole POINT of the exercise in the first place :)

And I have to point out it's NOT actually off-topic because there's a LOT of 'push-back' to colonization efforts OTHER than Mars from a lot of people who support SpaceX/Musk BECAUSE he's so focused on Mars. And it's not an accident since they as a general rule tend to see no other place that SHOULD be considered or planned to be colonized OTHER than Mars. Keeping them honest and keeping the idea open that it in no way should be implied or assumed that you can only do ONE thing with the technology is always a good idea :)

Randy

Well, they're not going to actively block any Venus initiatives only because SpaceX prefers focusing on Mars. Just no free or at-cost rides. Nothing wrong with concentrating efforts on one planet, and have all other activities benefit from that. If Mars ultimately gets financed by a space transportation, electric car, tunnel boring and solar power mogul, Venus might just need a sponsor from the mining/chemistry sector (sulfur capture) or LTA transport sector (still waiting for Airlander to happen). They can start small scale on Photon, if need be. Peter Beck might be motivated to be a sponsor of such a mission ;-)


Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #118 on: 07/16/2020 02:29 pm »

You don't even need asteroid materials to have an essentially limitless radius. They might help to reduce cost, but at a potential 20$/kg to Earth orbit (Elon Musks rosy estimate), asteroid mining for basic construction materials becomes far less of a gating technology.

Reduced launch costs enable all types of space projects launched from Earth.  That lowers the barrier to both asteroid mining and planetary missions.

Meant to address this a bit earlier but it got lost in the shuffle :)

It likely really needs it's own topic but in general there's a lot of truth in the former statement but a lot of the truth of the second rests on a HUGE number of "it depends" details that are not as clear cut as it may seem. There's more than a little flawed logic that arguably makes 'sense' but has not been shown to be supported by historically similar circumstances to a large extent.

Yes reduced launch costs enable all sorts of space projects from Earth and lower the barrier for planetary missions. What they do NOT do is automatically make space resource extraction for "export" more viable nor does it automatically confer sustainable operations or planning on such endeavors. What often is forgotten in the equation is that the use of "in-space" resources makes economic sense when launch costs are high because it pretty directly impacts the finished and material goods costs going up a gravity well. Extracting, processing and using "local" materials in space has a higher 'value' and it tends to retain that 'value' even when launch cost drop significantly but ONLY for local use. The cost of moving those materials any distance rapidly exceeds the possible value once the costs of lifting materials out of a gravity well drops significantly due to the depth of Earths resource/processing/transportation and manufacturing infrastructure is taken into account.

It's often hard to understand why cheap launch won't always lead to cheap interplanetary transportation but you have to keep in mind that space isn't Earth or spaceflight, as a transportation system, anything like how transportation was organized and built on Earth. Space has no existing destinations with in-place infrastructure and amenities that can be exploited by business and people. You have to bring a lot if not all of it with you (or at least the equipment to get the local resources and construct it) and build it on-site in a place where human labor costs are fantastically high. So it will likely be automated and most of those who come first will tend and repair that automation.

This process will likely build up a stockpile of resources the base/outpost/colony can't use at this point so rather than sending a transport back empty some will be loaded on the returning spacecraft. (This happened in America where original settlers would harvest wood and metals that they mined and send a portion back 'home' to be sold to raise money but the majority was used in place because it wasn't really worth shipping it. Now there WERE some companies set up to do just that but the profit margin was very thin and we have a modern day example of such an operation I'll get to in a bit)

Now if the place has something that is actually of a fairly high value then that will of course replace the more mundane resources. But did you note that at no point was the main goal the extraction and shipment of those local resources someplace else? It's because at no point is that going to be 'cost-effective' in and of itself. Not for a 'colony' type settlement.

"Low" launch costs allow people to put stations in Earth orbit, on the Moon and more marginally on Mars and Venus but those "settlements" will have been optimized to build and expand using local resources and conversely have no 'capital' to expend in obtaining resources from somewhere else even if those other place could really afford to ship them.
Metals, rare-earths, some chemicals, (rocket propellant would be an 'export' item but it is arguable that having excess production capacity would not be justifiable as it could not compete with any 'locally' produced propellants) and likely water but keep in mind the price at delivery will always have to be lower than that of the "local" resource.

And you have cheap launch which means anywhere in the Cis-Lunar area water imported from Earth is cheaper than bringing it from anywhere else. Water from the Moon you say? Yes that would be used on the Moon but it would make no sense to try and send it anywhere else. The factors that are required to harvest and prepare the water automatically make it more expensive than local sources or shipping it from Earth.

This all works out great for people who want to colonize the Moon, Mars or even Venus because the cost barrier to set things up and get them 'self-supporting' are going to be affordable and plausible with the right plan and effort. It has issues with having any real economic means of support itself nor much ability to create an export system but if we're honest that's usually a low priority for such groups at best so no real issue.

Those that DO have such an economic interest, (asteroid mining being one of these groups) then quite obviously the FIRST thing you toss out is "colonization" or really generally sustainable operations. Cheap launch allows the space-going equivalent of off-shore drilling/mining as a viable means of making an actual profit. But without the 'people' since they are so expensive and delicate. Which is essentially what all current asteroid mining programs are based on. Sustainability, deep-space infrastructure and "colonization" if you will are not even remotely factors in the discussion or planning.

And no whatever "other" resources come from an asteroid or other off-planet mine are if they can't be delivered in less than a decade they are not worth even bothering with in most reasonable planning. Market volatility, business shifts and consumer fickleness are a legitimate business plan concern and planning anything over decade in the future has a too high chance of failure due to too many circumstances outside your control. You CAN set up and operate such a business scheme but it literally takes a very non-standard business model with extreme long range planning and a very stable structure to even contemplate. (It's less a business and more of an institution/foundation that has to encompass not only NGO's but governments and deep political and private interconnections. Why? Because once in operation this is a process that literally CAN NOT FAIL because of the consequences involved in any failure or disruption.)

And let’s be honest because we really NEED to look at things honestly and not kid ourselves, (a massively bad habit that stretches all the back to the first ideas and concepts of space travel to today) if we allow that cheap launch enables those of us who dream of cities on Mars, the Moon or even Venus to achieve those dreams then by far we're going to be outnumbered by those who simply dream of making a lot of cash and getting out. The concept that cheap launch will open a flood gate of people who want to colonize space isn't true nor has that been true every in history. History, (especially more modern history which is actually more applicable than earlier) says you get more tourists than settlers at a ratio that correlates with how difficult and expensive "settling" versus "tourism" is. And space is VERY hard and expensive to "settle" but relatively cheap to visit in this context. The Moon, Mars, et-al will be vastly more popular to visit than live on and the majority of the population will always find it more comfortable to stay on Earth

Cheap launch does in no way guarantee the building of infrastructure of sustainable operations, in fact outside some specifics circumstances it actually incentivizes the opposite! Anyone remember that THE thing that made "Mars Direct" such a paradigm shift was ISRU to reduce the resources you needed to ship UP from the Earth. It essentially made doing "Apollo-to-Mars" (Zubrin himself stated that repeating Apollo was exactly what he'd based the concept on) cheap enough it could plausibly be pitched to Congress. That's it. The "sustainability" and other stuff was tacked on later but really it was making flags-and-footprints no Mars plausible to pitch to politicians who had no interest or desire for a 'sustainable' space program.

Any close examination of Elon Musk's Mars plans show it is based directly on Mars Direct and has the same built-in non-requirement for sustainable operations or infrastructure building. You only need to stay on Mars long enough to make the fuel to go home and once you have things set up you don't even have to stay that long. You CAN of course there's no doubt about that, but there is nothing there you can plausibly exploit to export back to Earth to actually 'pay' the way for expansion and settlement.

And your "market" and industry is literally making more space for people from Earth who want to come to visit rather than live on Mars. The number of people who are willing to do what would be needed to actually settle and live long-term anywhere in space is a very finite number and a minority not a majority. More so when you factor in that within that number will be others that want to live on the Moon or on Venus, etc and they will be willing to pay to do that but specifically NOT willing to pay a cent for settling Mars.

Once a certain tipping point in overall, (not just launch) costs is reached then yes interplanetary materials economics would make sense but keep in mind that's NOT predicated on launch costs from Earth, (or any other gravity well) as much as it is on actual interplanetary transportation technology. Like most things it's a lot more complicated than it would appear :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #119 on: 07/16/2020 04:01 pm »

Well to be honest IF you're going to drag a Starship all the way to Venus, (even one way) then at least get SOME use out of it is my take. Deploy the 'payload' from orbit sure but keep the Starship hull(s) as part of a Venus Station or something.
(And if you can imagine a METEOR space station created using Starships as a core element: http://www.projectrho.com/public_html/rocket/spacestations.php#id--Designs--Meteor_Space_Station, https://www.secretprojects.co.uk/threads/meteor-city-in-space.5876/, you're welcome :) )

My main point was it's not likely they would underwrite such an effort mostly due to the "Mars First/Last/Only" sub-text in Musk's plans.

Seeing this imagery, I now realize that the artists making the drawings for the books and comics I loved the most as I child got their inspiration from this. So even as a child I preferred realism (after a fashion) over pure fantasy, apparently. That's new. I assumed my aversion of Star Trek's plot-dependent technobabble vs Star Wars' fantastic yet simple and consistent - for my ten year old mind - story meant I was more into fantasy back then.

If we're being honest Star Trek/Wars is literally "western/swashbuckling/samurai/etc-Earth-bound" adventures with fantasy "space" as a backdrop and that's the reason they tend to be more popular than "hard" science fiction because living/working/adventuring in that kind of 'space' is so much more easy and relatable than the real thing. You can more easily relate to Duck Dodgers not having to pre-breath pure O2 for two hours before he jumps into his spacesuit to go outside and repair the ship because that's what YOU do when you repair the car or house. The reality tends to bog down the 'story' and immersive feeling of things :)

At the same time humans DO tend to be story tellers and in that regard we're more likely to lean towards consistency in our background but less to the point where the background details get to complex.

More in context to early concepts like METEOR once you realize that the people working on the concept often literally didn't know what they didn't know and were working from the best ideas and knowledge at the time you can more easily cut them some slack. On the converse side that understanding can also cause you more than a little stress when comparing those concepts and especially the assumptions behind them to what we "know" today and the huge amount of short-sighted and logically false 'assumptions' are piled on today's concepts and bias.

More directly, something like METEOR would not even be a consideration today not for any real 'technical' or economic reason but because it would require a vast amount of expensive and risky EVA work and therefore a more focused, cheaper and modular approach would obviously more logical. I call that false because the truth is that EVA is expensive and risky because we avoid it as much as possible because it's expensive and risky.
Back in the day the assumption was if that were true you'd develop and find ways to reduce the expense and risk not find ways to avoid doing it all together. Inherent in the ability to perform economic and safe EVA construction and assembly is the ability to repair and expand, meanwhile with the "plug-and-play" method you are limited by the lifetime and mean-time-between-failure extent of your original construction. It may be decades from now but you STARTED with the premise you were going to expend the asset from the very start and that colors the whole endeavor and self limits your options.

METEOR may be quaint and seem a retro-naive concept but it's very basis speaks of an assumption of broad, long-term goals and ideals rather than laser-focused, short-term and limited vision.

Quote
Quote
Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition, even as Starship reduces their costs, that pretty much means that SpaceX now has an easy way to finance any economic activity in space. Pretty much Vanderbilt in space. With the next John D. Rockefeller spinning out of those activities. Not entirely sure how I feel about that. But a little off topic for this thread.

Which as you note is likely the whole POINT of the exercise in the first place :)

And I have to point out it's NOT actually off-topic because there's a LOT of 'push-back' to colonization efforts OTHER than Mars from a lot of people who support SpaceX/Musk BECAUSE he's so focused on Mars. And it's not an accident since they as a general rule tend to see no other place that SHOULD be considered or planned to be colonized OTHER than Mars. Keeping them honest and keeping the idea open that it in no way should be implied or assumed that you can only do ONE thing with the technology is always a good idea :)

Well, they're not going to actively block any Venus initiatives only because SpaceX prefers focusing on Mars. Just no free or at-cost rides. Nothing wrong with concentrating efforts on one planet, and have all other activities benefit from that. If Mars ultimately gets financed by a space transportation, electric car, tunnel boring and solar power mogul, Venus might just need a sponsor from the mining/chemistry sector (sulfur capture) or LTA transport sector (still waiting for Airlander to happen). They can start small scale on Photon, if need be. Peter Beck might be motivated to be a sponsor of such a mission ;-)
[/quote]

While admitting I've not been to many conferences and other gatherings in a good while, (about a decade :( ) I have first hand experience with what we used to call the "Mars (sorry, need to stop here for a second and just say that I have to use stupid words to get my point across. I know that means I must have a weak argument, but that's why I use bad words)." who are often very much SpaceX fans these days as they were "Mars Direct" fans (specifically) then. And boy howdy if they COULD do so they would gladly block any and all "other" options than Mars simply because they DO see Mars as the only viable option and believe that ANY distraction from that single goal will doom humanity. (Yes these are the 'fans' that question and complain about Musk anytime he so much as mentions "other" applications for Starship so I know they are still out there :) )

I agree it's not likely that SpaceX/Musk would actively oppose "other" uses and abuses for Starship as it would make no business sense at the end of the day that will still have to be the 'main' driver for Starsthip. The problem is that it is still a non-zero chance that COULD happen and frankly when you consider how much focus there is on Mars and the needs specifically driven by that goal that has gone into Starship it's not all all as low a percentage as one might think.

"Worse" in some ways is the other scenario you mention in that it is actually very likely, (arguably a certainty given the quoted tourism prices for Falcon-9/Dragon vis-a-vis the official government price per seat) SpaceX is going to roll any 'savings' back into supporting a Mars colonization and infrastructure plan and by that very fact are going to have a hugely disproportionate influence on that planning. There is really no way around it unless Starship is delayed enough that say Blue Origin gets into the market at least at the same level.

And that's worrying because as I've pointed out the current direction and planning is aimed at essentially building a commercial version of Mars Direct with all that implied towards activities and infrastructure not directly tied to getting to and from Mars. There are a huge number of assumptions and bias' that come with that path and in the end while it has some practicality outside the focus of Mars it really is of highly limited value to more general goals. Further while it might drop launch costs low enough that one would assume a huge expansion of space projects you also need to keep in mind that there in fact IS an overarching and focused goal towards which that capability is aimed. That matters.

As an example I was flooded a couple months ago with a youtube video from my various sources that waxed eloquently on how elegant it was that 1000 person Mars colony would be so simple using "just" 100 Starships during every synodic period which would allow millions of people to settle Mars in just a few decades. Much like another comment I'd heard where it was stated that a single Starship could fly-off every waiting and planned orbital mission for the next decade in a single year I asked the (to me) obvious question. And then what?

More specifically for the Mars colony the question of where those 100 Starships come from is something that doesn't seem to occur to anyone. If those have been built to service the orbital, suborbital and Cis-Lunar market then how do you find a way to justify taking them out of service in those areas for about a two year period and what replaces them? If those are dedicated to the Mars colony, (and that in and of itself raises some huge questions) then how many MORE Starthips are servicing the afore mentioned markets and what do those 100 Starships do in the 'off-season' between synodic's?
It's literally an unworkable idea yet none of the comments questioned it but simply assumed 'something' like that was obviously the way to go.

In many ways you have to give Musk credit for at least trying to address some of the issues that are likely to be created by cheap launch costs but if you're paying attention you quickly realize he's not trying very hard and frankly he's likely realized that none of the ideas will really work. But they are all he's got and no one else seems to be looking at all.

If that's not clear let me point out how he's been talking up the idea of "Point-to-Point" (P2P) travel on Earth as a market for Starship. This is directly because the "market" for passenger SPACE travel will remain pretty small unless prices are to a point where they compare with air travel. And as we've already noted going that low will not allow the profit margin required to support the Mars missions. To be able to charge those type of prices and NOT destroy the profit margin for actual space travel the idea is to use the Starship for P2P to tap into the general air-travel market itself. Neat and simple because it's not "actually" space travel so the lower prices make an "obvious" sense even though you are literally using a spaceship as a terrestrial transport.

The problem is that even if the economic planning can be made to close that's NOT really the most important factor in passenger transport. Time, per-se, is no longer "money" in passenger transport so saving double-digit hours in transit time is vastly less of a factor than convenience and simplicity to the average traveler. Anyone who's been following the ups and downs of P2P travel has noted the shift back towards finding ways to integrate with "standard" Airport infrastructure and the reasoning is quite sound. Airports are already heavily and deeply interconnected with the entire Earth transportation network and already have a deep and paid-off infrastructure and organization system that is highly effective and economic.

When you take into account the physical and regulator needs for something like Superheavy/Starship there is simply no way to close the planning in a plausible way. But at least you can say Musk is aware of the issues and trying to address them... But is that true? I'd say not because it seems much more likely that what Musk is doing is trying to appear to address the problem so that no one looks any deeper AT those problems. Again Musk is focused on Mars and from that perspective anything NOT able to be directly  related to Mars appears to be a sideline. (Yes Tesla is a 'sideline', Musk has already said more than once it's what pays the bills till SpaceX got going)

So yes it turns out that things are a LOT more complex than we really want them to be but life is messy. Right? :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline libra

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Re: Floating Habitat on Venus
« Reply #120 on: 08/31/2020 05:14 pm »
http://spaceflighthistory.blogspot.com/2020/08/venus-is-best-place-in-solar-system-to.html#comment-form

Quote
Venus settlers would float where Vega 1 and Vega 2 floated, but Landis rejected helium balloons. He noted that, on Venus, a human-breathable nitrogen/oxygen air mix is a lifting gas.

A balloon containing a cubic meter of breathable air would be capable of hoisting about half a kilogram, or about half as much weight as a balloon containing a cubic meter of helium.

A kilometer-wide spherical balloon filled only with breathable air could in the Venusian atmosphere lift 700,000 tons, or roughly the weight of 230 fully-fueled Saturn V rockets.

Settlers could build and live inside the air envelope.

My mind is completely blown (lame pun assumed).

I was wondering one simple thing... let's suppose we take a Bigelow 2100 or even a smaller 330. We fill and inflate that thing, with breathable air.
And then we drop it into Venus atmosphere.

Would it float ?  :o :o :o

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #121 on: 08/31/2020 08:51 pm »
http://spaceflighthistory.blogspot.com/2020/08/venus-is-best-place-in-solar-system-to.html#comment-form

Quote
Venus settlers would float where Vega 1 and Vega 2 floated, but Landis rejected helium balloons. He noted that, on Venus, a human-breathable nitrogen/oxygen air mix is a lifting gas.

A balloon containing a cubic meter of breathable air would be capable of hoisting about half a kilogram, or about half as much weight as a balloon containing a cubic meter of helium.

A kilometer-wide spherical balloon filled only with breathable air could in the Venusian atmosphere lift 700,000 tons, or roughly the weight of 230 fully-fueled Saturn V rockets.

Settlers could build and live inside the air envelope.

My mind is completely blown (lame pun assumed).

I was wondering one simple thing... let's suppose we take a Bigelow 2100 or even a smaller 330. We fill and inflate that thing, with breathable air.
And then we drop it into Venus atmosphere.

Would it float ?  :o :o :o

Yes it would float, even a "empty" rocket stage will do that on Venus:
https://selenianboondocks.com/2013/11/venusian-rocket-floaties/

The question is of course WHERE will it float? Air has about half the lifting power of helium on Earth, (plus Venus gravity is only 90% that of Earth so a "little" bonus there :) ) but you also have a volume packed with equipment and supports and the outer envelope is pretty thick and won't really contribute to the lift. (And this is all before we have to add on an outer layer of acid resistant plastic as well) And you don't really need that thick of an outer layer which generally would point to wanting a specific design for Venus use rather than trying to directly adapt a Bigelow module in and of itself. Removing most of the internal layers of fabric to expand your internal air space is probable and will reduce the overall module 'inert' mass which will help.

I'm going to have to run some numbers but right off hand my gut-feeling is it won't have enough lift to be at a level where you don't need a significant over-pressure inside to resist the outside pressure. That would likely mean a level where the temperature is excessive as well since you want to float at about 50km or so and as near Earth Sea-Level pressure as you can get.

So while it would in theory 'help' somewhat you're still going to need a balloon to offset most of the mass of the Bigelow habitat and systems.

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline libra

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Re: Floating Habitat on Venus
« Reply #122 on: 09/01/2020 06:13 am »
Something bother me... Landis says that every single 1 cubic meter of breathable air, can lift 0.5 kg. So basically, 50%.
So a 1 km diameter balloon could lift 700 000 tons and 2 km diameter, 6 million tons. Their radiuses would be half of that: 500 m and 1 km, respectively.

Except simple volume calculations don't match (see attached) even if they are comparable numbers. I got 4.2 billion cubic meters and 524 million cubic meters, respectively.

Now if I apply the 50% factor, I get 2.1 million tons and 262 000 tons.

Order of magnitude similar, but still big discrepancies. Impressive numbers nonetheless !!!!

Or maybe something is wrong on the Internet (as per the legendary XCKD comic).

Offline libra

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Re: Floating Habitat on Venus
« Reply #123 on: 09/01/2020 06:18 am »
The Selenian boondocks entry is even more astonishing. Rocket stages floating inside Venus atmosphere. Wow.

Venus atmosphere sheer density really brings weird things. Reminds me of that tirade in Monty Pythons Holy Grail
(Bedevere witch science)

Quote
Bedevere: What also floats in water?

Peasant 1: Bread.

Peasant 2: Apples.

Peasant 3: Very small rocks.

Peasant 1: Cider.

Peasant 2: Grape gravy.

Peasant 1: Cherries.

Peasant 2: Mum

Peasant 3: Churches, churches

Peasant 2: Lead, lead.

Arthur: A duck.

What also floats on Venus ?

Rockets !

Balloons !

Cities !

Empire state building !

ROTFL

Offline high road

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Re: Floating Habitat on Venus
« Reply #124 on: 09/01/2020 11:45 pm »
Something bother me... Landis says that every single 1 cubic meter of breathable air, can lift 0.5 kg. So basically, 50%.
So a 1 km diameter balloon could lift 700 000 tons and 2 km diameter, 6 million tons. Their radiuses would be half of that: 500 m and 1 km, respectively.

Except simple volume calculations don't match (see attached) even if they are comparable numbers. I got 4.2 billion cubic meters and 524 million cubic meters, respectively.

Now if I apply the 50% factor, I get 2.1 million tons and 262 000 tons.

Order of magnitude similar, but still big discrepancies. Impressive numbers nonetheless !!!!

Or maybe something is wrong on the Internet (as per the legendary XCKD comic).

That's because 'half' is rounded down. It's closer to 60%. But the ideal gas law also has temperature and pressure as inputs, so it varies significantly depending on the altitude you want to operate on.. And we don't really have enough data to know the exact pressures and temperatures on all altitudes. And you might want to actively cool the hab or keep it at a higher pressure than the surrounding air. Both decrease lift per volume, but allow the hab to provide comfortable living conditions at a lower or higher altitude respectively.

Offline GWH

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Re: Floating Habitat on Venus
« Reply #125 on: 09/02/2020 03:46 pm »
Reading the old Selenian Boondocks blog post has me thinking of rocket reuse in the Venus atmosphere.  The old Atlas stainless steel baloon tanks and engine staging coupled with Arianespace's Adeline fly back engine module would be a perfect reusable architecture.

Fly the heavy engines back and drop the tanks into the atmosphere with a couple ballutes to further increase boyancy for later recovery.

Offline stefan r

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Re: Floating Habitat on Venus
« Reply #126 on: 09/03/2020 02:49 am »

... (plus Venus gravity is only 90% that of Earth so a "little" bonus there :) ...

No bonus.  Lower gravity means less force from buoyancy too. 




...So while it would in theory 'help' somewhat you're still going to need a balloon to offset most of the mass of the Bigelow habitat and systems...

You want some big methane balloons anyway.  We will need the hydrogen for a colony or for a launch.  The polymer in the balloon delivers have half as much hydrogen as the methane.

For long term urban planning I'm imagining something like aerographite foundations.  Venus has unlimited carbon supplies.  Composites structured like typical camping mats should work well too. 


Offline high road

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Re: Floating Habitat on Venus
« Reply #127 on: 09/15/2020 11:50 am »
A quick glance at a periodic table tells me phosphine has about as much lift as oxygen or nitrogen. While not breathable, harvesting phosphine by growing local bacteria might need a far less complex chemistry set than extracting hydrogen from sulfuric acid (resetting for the next cycle is complex) or getting rid of trace amounts of SO2 when getting nitrogen or CO2 from the air. So any industrial infrastructure might as well use it to avoid the cost of sustaining too many advanced chemistry facilities 2.5 years away from spare parts. Or a launch platform that needs to be able to dump large amounts of lift gas.

Agriculture on Venus, I love the idea. I don't know if any of you play the Terraforming Mars board game, but 'floaters' will now have some extra significance for me 😋

Edit: and for those buzzkillers pointing out that it's probably not a biological process, a chemical plant to augment a reaction that's already happening naturally will probably still be quite a lot simpler than a chemical plant that tries to run processes we developed in the comfort of our own planet and preexisting production chains. ;-)

Edit 2: and hello, lower energy H2O from H2SO4 process that I didn't consider before. (and hello, process that would likely be used by a bacteria floating in sulfuric acid clouds).
« Last Edit: 09/15/2020 12:49 pm by high road »

Offline libra

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Re: Floating Habitat on Venus
« Reply #128 on: 09/15/2020 01:47 pm »
I see that I'm not the only one, having thought about this thread in the light of yesterday "event".  :P

Now that could make one hell of sci-fi or horror movie. Part-Alien, part-Interstellar.

Humans go to Venus to try and solve that phosphine mystery.

They live inside a 2 km wide inflatable habitat, filled with... the air they breath (!) and able to support a 6 million ton infrastructure.

... and then the extremophiles attack them with phosgen chemical weapon & poison. 

And of course of the crew goes rogue (dr. Mann style) and plan to use the same phosgen weapon to spread havoc on Earth.

Offline high road

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Re: Floating Habitat on Venus
« Reply #129 on: 09/15/2020 01:53 pm »
War of the worlds in reverse  :P

Offline leovinus

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Re: Floating Habitat on Venus
« Reply #130 on: 09/15/2020 02:57 pm »
I see that I'm not the only one, having thought about this thread in the light of yesterday "event".  :P

Now that could make one hell of sci-fi or horror movie. Part-Alien, part-Interstellar.

Humans go to Venus to try and solve that phosphine mystery.

They live inside a 2 km wide inflatable habitat, filled with... the air they breath (!) and able to support a 6 million ton infrastructure.

... and then the extremophiles attack them with phosgen chemical weapon & poison. 

And of course of the crew goes rogue (dr. Mann style) and plan to use the same phosgen weapon to spread havoc on Earth.

https://en.wikipedia.org/wiki/Venus_(novel)

Offline libra

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Re: Floating Habitat on Venus
« Reply #131 on: 09/15/2020 03:44 pm »
https://en.wikipedia.org/wiki/Venus_(novel)

Pretty amusing.

Now imagine if Hollywood get wind of all this, and decides to adapt the novel, say, in  four years.

(note: it happened in the past.

 Case in point 1: Shoemaker Levy 9 1994 impact on Jupiter  triggered Armaggedon and Deep Impact  4 years later, in 1998.

Case in point 2: ALH meteorit, 1996, was the root cause of Red Planet and Mission to Mars movies, in 2000.

Aparently Hollywood needs 4 years to turns real world events into movie scripts. Alas, in all four cases above, the movies were very, very bad).

(The only exception is Contact... the scene where President Clinton is seen on TV discussing Ellie Arroway discovery... is actually stock footage from his August 1996 ALH Mars announcement. The movie producers acknowledged this and said "it had been a godsend to us")
« Last Edit: 09/15/2020 03:52 pm by libra »

Offline high road

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Re: Floating Habitat on Venus
« Reply #132 on: 09/15/2020 04:33 pm »
I see that I'm not the only one, having thought about this thread in the light of yesterday "event".  :P

Now that could make one hell of sci-fi or horror movie. Part-Alien, part-Interstellar.

Humans go to Venus to try and solve that phosphine mystery.

They live inside a 2 km wide inflatable habitat, filled with... the air they breath (!) and able to support a 6 million ton infrastructure.

... and then the extremophiles attack them with phosgen chemical weapon & poison. 

And of course of the crew goes rogue (dr. Mann style) and plan to use the same phosgen weapon to spread havoc on Earth.

https://en.wikipedia.org/wiki/Venus_(novel)

Ah, Ben Bova. I wanted to read his grand tour series, and started with powersat, which is supposed to be 'first' in that setting. But it was such a sexist, racist book where every single character is a boring onedimensional stereotype that I gave up after that one. Is the Venus novel any better in style?

Offline leovinus

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Re: Floating Habitat on Venus
« Reply #133 on: 09/15/2020 05:05 pm »
I see that I'm not the only one, having thought about this thread in the light of yesterday "event".  :P

Now that could make one hell of sci-fi or horror movie. Part-Alien, part-Interstellar.

Humans go to Venus to try and solve that phosphine mystery.

They live inside a 2 km wide inflatable habitat, filled with... the air they breath (!) and able to support a 6 million ton infrastructure.

... and then the extremophiles attack them with phosgen chemical weapon & poison. 

And of course of the crew goes rogue (dr. Mann style) and plan to use the same phosgen weapon to spread havoc on Earth.

https://en.wikipedia.org/wiki/Venus_(novel)

Ah, Ben Bova. I wanted to read his grand tour series, and started with powersat, which is supposed to be 'first' in that setting. But it was such a sexist, racist book where every single character is a boring onedimensional stereotype that I gave up after that one. Is the Venus novel any better in style?

IMHO, nope. I liked the idea about microbes in the Venus atmosphere. The planet is so devoid from details in a small telescope which was all I had at the time I read it many moons ago. At that time, I did not know that Carl Sagan (and probably others) were there first with the idea. Anyway, sorry for the distraction, back on topic :)

Offline Pete

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Re: Floating Habitat on Venus
« Reply #134 on: 09/16/2020 07:05 am »
Case in point 1: Shoemaker Levy 9 1994 impact on Jupiter  triggered Armaggedon and Deep Impact  4 years later, in 1998.
For convenience, let's ignore the fact that the "Deep Impact" movie was based on a 1993 script which was a revamp of a 1951 movie mated to the 1993 book by Arthur C Clarke.

Let's also ignore that there have been more movies about cataclysmic Asteroid Impacts than there have been KingKong movies. And there have been many KIngKong movies. A couple *dozen* Impact movies, actually.

TL;DR:
You are seeing causality in coincidence.
« Last Edit: 09/16/2020 08:14 am by Pete »

Offline libra

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Re: Floating Habitat on Venus
« Reply #135 on: 09/16/2020 11:44 am »
Nah. Don't blame me. Red that at "The space review" a while back. I will check.

https://www.thespacereview.com/article/1728/1

https://www.thespacereview.com/article/1469/1

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #136 on: 09/16/2020 08:31 pm »
Nah. Don't blame me. Red that at "The space review" a while back. I will check.

https://www.thespacereview.com/article/1728/1

https://www.thespacereview.com/article/1469/1

Nope, we're blaming you... Even voted on it all democratic like and everything! :D

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Floating Habitat on Venus
« Reply #137 on: 09/16/2020 09:53 pm »
Ah Randy. Any thoughts on what the phosphine discovery might have on your ideas? Sending hamsterballs for the pleasure of alien critters? Phosphine-based power production and mining? Environmental impact of rocket floaties on phosphene-bacteria populations? 😉

I don't know if Jon Goff reads this thread, but I wouldn't mind some culinary advice using phosphoric acid on Selenian Boondocks. Would it even help against mold there, or just make the local shrooms grow faster?

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #138 on: 09/17/2020 03:09 pm »
Ah Randy. Any thoughts on what the phosphine discovery might have on your ideas?

Yes.... What? You want to know more? What do I look like? An interactive ad for Federal Service? Wait... don't answer that one...


Quote
Sending hamsterballs for the pleasure of alien critters? Phosphine-based power production and mining? Environmental impact of rocket floaties on phosphene-bacteria populations? 😉

My personal take is that this pretty much seals the deal in the need for a long-term Venus atmospheric probe with a pretty extensive instrument set. (Tuba? French Horn's? A Sax? NO not those kind of instruments! :) ) If it's life we need to know all we can about it, if it's not we need to know where this comes from and how.

It's still diffuse, (5 to 20 parts per billion where as the danger level if 1 part per million) but it has industrial uses if we can get enough of it. And all joking aside we need to find out if having an "object" hanging around, like say a balloon probe or manned habitat, is going to effect for better or worse. (Finding out that whatever produces the phosphene REALLY-REALLY likes the materials of your outer hull and/or envelope could be argued to be FAR better to find out sooner rather than later :) )

Given how hard we've been looking for life "out-there" there's really no excuse not to use this as a driver for more comprehensive exploration of Venus.

Quote
I don't know if Jon Goff reads this thread, but I wouldn't mind some culinary advice using phosphoric acid on Selenian Boondocks. Would it even help against mold there, or just make the local shrooms grow faster?

Maybe it will help make the Turkey (https://selenianboondocks.com/2013/12/venusian-acid-cooked-turkeys-or-why-i-still-read-blog-comments/) a bit more tasty or the ale a bit less bitter :) And it's used to fumigate and control animal infestations but I don't see where it actually effects molds or such. Which could be an issue if the microorganism turns out to be some type of mold-like form.

At the very end of the day we NEED to go to Venus as well as Mars and everywhere else because there is NO one destination best suited for inspiring people, performing science and/or one day settling. Go Big or Stay Home...

And speaking of "inspiring" ideas:
https://selenianboondocks.com/2013/12/random-thoughts-inspiration-venus/

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline libra

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Re: Floating Habitat on Venus
« Reply #139 on: 09/20/2020 06:04 am »
Quote

My personal take is that this pretty much seals the deal in the need for a long-term Venus atmospheric probe with a pretty extensive instrument set. (Tuba? French Horn's? A Sax? NO not those kind of instruments! :) ) If it's life we need to know all we can about it, if it's not we need to know where this comes from and how.


They are on instruments !




Offline stefan r

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Re: Floating Habitat on Venus
« Reply #140 on: 09/22/2020 03:06 pm »

... and then the extremophiles attack them with phosgen chemical weapon & poison. 

And of course of the crew goes rogue (dr. Mann style) and plan to use the same phosgen weapon to spread havoc on Earth.

Phosgene: Cl2CO
Phosphene: not a chemical (usually)
Phosphine: PH3



« Last Edit: 09/22/2020 03:06 pm by stefan r »

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #141 on: 09/22/2020 05:45 pm »
Quote

My personal take is that this pretty much seals the deal in the need for a long-term Venus atmospheric probe with a pretty extensive instrument set. (Tuba? French Horn's? A Sax? NO not those kind of instruments! :) ) If it's life we need to know all we can about it, if it's not we need to know where this comes from and how.


They are on instruments !


The reference joke I was alluding to :)

The other thing I was alluding to was the 'fact' that by design any such floating probe would be by definition would be granting a much larger and more 'stable' surface area to any floating beasties which can in and of itself be argued to be a major change in the atmospheric environment. Which again would be something it's better to know sooner rather than later.

Randy


From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Floating Habitat on Venus
« Reply #142 on: 09/23/2020 11:29 am »
And you thought I was joking with my hamsterballs for Venusian critters suggestion ;)

On a more serious-ish note, you would like to know whether Venusian biofilms growing prolifically risks changing buoyancy, interfering with instruments or even considers your infrastructure to be a good source of nutrients. If something exists that can cling to life in the Venusian acid clouds, I would not dare underestimate it.

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #143 on: 10/01/2020 09:49 pm »
And you thought I was joking with my hamsterballs for Venusian critters suggestion ;)

On a more serious-ish note, you would like to know whether Venusian biofilms growing prolifically risks changing buoyancy, interfering with instruments or even considers your infrastructure to be a good source of nutrients. If something exists that can cling to life in the Venusian acid clouds, I would not dare underestimate it.

Not to rain on the parade, (I'm all for justification for more science) but:
https://twitter.com/thunderf00t/status/1310987466791358464

In context "life" might not be the most plausible answer. Then again isn't it better to actually KNOW? Go Green Dragon! :)

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Floating Habitat on Venus
« Reply #144 on: 10/03/2020 10:06 am »
Huh, that vid is a bunch of strawmen, red herrings and gaslighting with inaccurate science from start to end. Don't put too much faith in it. Clickbait from someone who likes to hear himself talk.

Lightning does create phosphine, but the lightning detected by Venus Express was too little to explain the concentration OF 20 BPM. And once you have phosphine, you can get all the water you need from sulphuric acid. No need for water vapor. And while it's unlinkely for lofe to have started from scratch at 50 km up, it might have had time to start when Venus was Earthlike, and evolve to adapt to the changing conditions.

Here's a better vid that already puts some of the misleading arguments in the right context.



But I agree that unknown chemistry is more likely than life. And the Martian Colonist, who's doing his doctorate in detecting signs of life on explanets, said in a reaction to one of his videos that a single absorption line is scant evidence for phosphine.

Offline RanulfC

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Re: Floating Habitat on Venus
« Reply #145 on: 10/16/2020 03:26 am »
Huh, that vid is a bunch of strawmen, red herrings and gaslighting with inaccurate science from start to end. Don't put too much faith in it. Clickbait from someone who likes to hear himself talk.

That's a bit hard to support considering he's a competent scientist himself. And the arguments are actually more solid than you give it credit for. Specifically it's a LOT less likely to be life than any other reason and the papers authors actually make that point.

Quote
Lightning does create phosphine, but the lightning detected by Venus Express was too little to explain the concentration OF 20 BPM. And once you have phosphine, you can get all the water you need from sulphuric acid. No need for water vapor. And while it's unlikely for life to have started from scratch at 50 km up, it might have had time to start when Venus was Earthlike, and evolve to adapt to the changing conditions.

"Lightning" as postited was suggested as a possible means with a much higher chance than life but it was only one possible way and he points out that it's actually less likely than other sources but it's MUCH higher than the chance it's produced by life. The problem with evolved life in the atmosphere, (and I'll get a bit more into this below or the link will at any rate) is that the paper and the authors are using the result to speculate (and I can't stress enough that this IS speculation and more being fed by the media and when the authors are interviewed by the same whereas the paper itself STRESSES they think that life is a VERY low probability source) that the possible 'life' no longer needs water vapor at all and the examples that are used to suggest this all live in high water vapor areas. In other words it's "life but not as we know it" with no plausible way to get from point A to point B given that life on Earth doesn't even fill such niches ON Earth.

Quote
Here's a better vid that already puts some of the misleading arguments in the right context.
>snip<

That was literally an Astrophysicist saying the exact same thing the media has been saying with no different context or information. She literally quoted the paper and interviews and doesn't address any of the 'issues'. She specifically says the "authors" were the ones who considered the possible sources and are giving "life" a vaguely possible nod as to being the source.

Quote
But I agree that unknown chemistry is more likely than life. And the Martian Colonist, who's doing his doctorate in detecting signs of life on explanets, said in a reaction to one of his videos that a single absorption line is scant evidence for phosphine.

Actually gets worse as a "Deep Dive" video by Thunderfoot (, phew, good thing I caught that I almost sent the link for the new "Monster Hunter" movie :) ) actually dug deeper into what information we do have on the Venusian atmosphere and there's a major possible source for the phosphine that I don't think I saw anywhere else...

The clouds are dominated by Sulphuric acid but a major component turns out to be H3PO4 or phosphorus oxides, (25:54) which is unstable and tends to break down... Into (28:27) phosphine... So a KNOWN chemical answer is actually the most plausible given what we know of Venus' atmosphere.

And here's where the optimists/pessimist in me (and for those keeping track I'll point out the glass is TECHNICALLY 100% full being 50% water and 50% air and it is only your insistence for a arbitrary binary answer that is the actual problem, and yes I DO wear a T-shirt with that on it :) ) has a conflict because having read the paper itself I note the authors really DID try and downplay the idea that it is produced by 'life' but as that was quite obviously going to get SOME attention when it did they ran with it which makes me question why include it when the possibility was so low and other possibilities, (including a known chemical process from an obvious chemical source in the atmosphere) was actually higher?

Randy
From The Amazing Catstronaut on the Black Arrow LV:
British physics, old chap. It's undignified to belch flames and effluvia all over the pad, what. A true gentlemen's orbital conveyance lifts itself into the air unostentatiously, with the minimum of spectacle and a modicum of grace. Not like our American cousins' launch vehicles, eh?

Offline high road

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Re: Floating Habitat on Venus
« Reply #146 on: 10/19/2020 11:00 am »
Huh, that vid is a bunch of strawmen, red herrings and gaslighting with inaccurate science from start to end. Don't put too much faith in it. Clickbait from someone who likes to hear himself talk.

That's a bit hard to support considering he's a competent scientist himself. And the arguments are actually more solid than you give it credit for. Specifically it's a LOT less likely to be life than any other reason and the papers authors actually make that point.

I'm not saying his arguments are bad. I'm saying he starts off by setting up a lot of red herrings that he found somewhere online. That's about as useful as a detailed explanation of the individual issues with the QAnon conspiracy theory... Once you go down to that poor quality, it's very hard to recover from that. It seems like you're setting up easy targets, without identifying them as easy targets before getting to more interesting points. It's not the first time he does this. I prefer to start from an accurate representation of what was in the article, and start pointing out issues from there.

Quote
That was literally an Astrophysicist saying the exact same thing the media has been saying with no different context or information. She literally quoted the paper and interviews and doesn't address any of the 'issues'. She specifically says the "authors" were the ones who considered the possible sources and are giving "life" a vaguely possible nod as to being the source.

exactly, and none of the claims and out of context statements that were in the thunderfoot vid. Start from what was actually in the article, then disect and analyse. That's my prefered approach anyway.

Quote
Quote
But I agree that unknown chemistry is more likely than life. And the Martian Colonist, who's doing his doctorate in detecting signs of life on explanets, said in a reaction to one of his videos that a single absorption line is scant evidence for phosphine.

Actually gets worse as a "Deep Dive" video by Thunderfoot (, phew, good thing I caught that I almost sent the link for the new "Monster Hunter" movie :) ) actually dug deeper into what information we do have on the Venusian atmosphere and there's a major possible source for the phosphine that I don't think I saw anywhere else...

The clouds are dominated by Sulphuric acid but a major component turns out to be H3PO4 or phosphorus oxides, (25:54) which is unstable and tends to break down... Into (28:27) phosphine... So a KNOWN chemical answer is actually the most plausible given what we know of Venus' atmosphere.

And here's where the optimists/pessimist in me (and for those keeping track I'll point out the glass is TECHNICALLY 100% full being 50% water and 50% air and it is only your insistence for a arbitrary binary answer that is the actual problem, and yes I DO wear a T-shirt with that on it :) ) has a conflict because having read the paper itself I note the authors really DID try and downplay the idea that it is produced by 'life' but as that was quite obviously going to get SOME attention when it did they ran with it which makes me question why include it when the possibility was so low and other possibilities, (including a known chemical process from an obvious chemical source in the atmosphere) was actually higher?

Randy
[/quote]

Ah, I haven't gotten around to that one. Good to know there's interesting new info (for me) in it.

The reason they mentioned it is because the whole point of looking for phosphine in Venus was to do a verifiable test before using it as a biosignature for life on exoplanets. It seems to me we won't be able to use it that way anymore.

edit: I'm making my way through it. Much better quality already. Lots of interesting stuff. The first flaw in logic, which IMO the other vid was full of, is that life can be written off off the bat because there's not enough hydrogen. In my opinion, life 'only' needs a way to extract and concentrate the available hydrogen. Any spare hydrogen or water not absorbed or excreted again, would quickly be absorbed by the sulfuric acid clouds. That does not make life likely. But it does mean you can't write it off like that either. This kind of leaps in logic is what irks me about this guy. It's like saying life can't survive without sunlight.

On the other hand, when going through the usual, 'pressure on the surface is as high as a kilometer beneath the ocean surface' soundbyte, he did show a graph with life forms on that depth. He didn't actually go into that, which would have been nice, but I'll write it down on the positive side  ;)

edit2: aaand here we go.

'loads of life' --> not what is claimed.
'would have been detected' --> The 40 year old probes explained at the beginning of the video to explain how little we know about Venus, are also ill equiped to detect traces of sparse amounts of microbes floating around in clouds, even if they did suck up small samples of the air.
'elements for life are simply not there' --> well, except for the carbon, nitrogen, oxygen you just mentioned ten minutes ago being there on the graph, and there is quite a lot of sulfur and hydrogen, and later on we get to phosporous. All the elements are right there. There's still the huuuge leap of converting all of that into useful substances, and microbes would need to contain a lot of free nitrogen (my favourite because it's the easiest to get) oxygen, phosphine, ammonia or whatever to stay afloat. Swimming bladders that do exactly that are a thing in fish, but I have no idea how that would look like in a microbe.

Other than that, his alternative explanation is quite attractive. Now had he just gotten there without leaps in logic of himself (which are jarring to me given his usual condescending tone about people making those mistakes), that would have been great. Condescending people is never a good way to get your point across, and is usually only a tactic to discourage people from debating you. Eg don't condescend flat earthers like he does in his other videos, just give them am experiment that they cam do themselves, like travelling west or east a few hundred miles and calling home around sunset.

and he finishes on a dishonest representation. The whole idea was to look for phosphine as a biosignature on exoplanets. The only conclusion of this video should have been that phosphine is not a biosignature. But that would not have suited his dramatic style that he gets his clicks with  ::) He's doing the same thing as the reporters editing the interviews to be all about the potential of life.

aaaand surfacism. yes, no leaps in logic at all  ::)
« Last Edit: 10/21/2020 08:58 am by high road »

Offline Paul451

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Re: Floating Habitat on Venus
« Reply #147 on: 10/29/2020 12:43 pm »
Quote
that vid is a bunch of strawmen, red herrings and gaslighting with inaccurate science from start to end. Don't put too much faith in it. Clickbait from someone who likes to hear himself talk.
[...]
I'm not saying his arguments are bad.

Offline endlesslimitation

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Re: Floating Habitat on Venus
« Reply #148 on: 11/11/2020 07:19 pm »
Quote
Clickbait from someone who likes to hear himself talk.
100% agree with this succinct summary of Thunderf00t's channel. Can't stand the guy... (and scientists are at least as likely to be in love with the sound of their own voice as anyone). His videos usually seem like a mish mash of reasonable skepticism overlaid with self-serving pwnage of more absurd takes from tangential statements related to the main topic.

Regardless of all that, I thought it was worth mentioning that an even bigger problem for the phosphine detection thing is that it's probably totally spurious. This paper https://arxiv.org/abs/2010.09761 (not yet peer reviewed, but authored by the gurus of data reduction at the telescope used) says that a more careful handling of the data doesn't show any phosphine absorption line.

Quote
Conclusions: We find that the published 267-GHz ALMA data provide no statistical evidence for phosphine in the atmosphere of Venus.

Also, apparently the original line detection used a 12th order polynomial to fit the underlying baseline. (IE not a straight line - a first order polynomial, nor a parabola - a second order polynomial, but a twelfth order polynomial). That's not necessarily disqualifying, but it should really give us pause. It's awfully easy to get extra 'wiggles' out of a 12th order polynomial.

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #149 on: 10/18/2021 12:04 pm »
Linking to another related thread here:
https://forum.nasaspaceflight.com/index.php?topic=55011.0
This concerns Starships and Venus habitation

And while I'm here I might as well add that one major issue with a base in the atmosphere of Venus, whether deployed by Starship or not would be the winds and "docking". Such a base would be continuously on the move at relatively high speed. Although it would travel around the planet with the wind it would also be subject to vast storm system eddies that would probably send it thousands of miles off course.

https://www.globalweatherclimatecenter.com/space-weather-topics/the-immortal-double-eye-storm-of-venus
This phenomena is based near the south pole, but the atmosphere of Venus undoubtedly turbulent.
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Offline high road

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Re: Floating Habitat on Venus
« Reply #150 on: 10/30/2021 11:56 am »
Actually, no. It seems to be relatively calm, with the high pressures having equalized temperatures, and the clouds combined reflection and isolation further stabilizing temperature. That's why the atmosphere is so featureless. You don't want to be at the poles and crossing the day-night terminal is probably decidedly sporty, but the average turbulence should be okay.

Docking ships are floating along with the same winds, so it should be far easier than refueling fighter jets while traveling at a high airspeed in the turbulence of another aircraft. More like ships rather than aircraft on Earth. And no bulky pressure suits or pressure vessels to do the finer jobs, just 'wetsuits' and breathing masks.

Offline high road

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Re: Floating Habitat on Venus
« Reply #151 on: 10/30/2021 12:05 pm »
How dense are the cloud layers on Venus. Could a base at 50km occasionally see the surface ?
If not visible from 50km, at what altitude do the clouds give 100% coverage. It would be nice to have some way of seeing the surface even if it is only with cameras on cables or FPV remote control planes.

With the acidic atmosphere at 50km, is this at a level where unprotected eyes are severely damaged in seconds, or is it more like the air in indoor swimming pools (SO2 on Venus rather than HCL). Is exposed skin damaged quickly ?

https://pdf.sciencedirectassets.com

Given the constant dusk and content of the atmosphere, you'd have to be pretty close to the surface to see it in visible light in detail. But once you have a platform at the 50 km altitude (54 actually if I remember well, 50 km is still uncomfortably warm), you have plenty of resources and energy to produce coolant and storable energy to send robotic explorers and humans in pressure vessels to the surface for missions.

Offline colbourne

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Re: Floating Habitat on Venus
« Reply #152 on: 10/31/2021 02:49 am »
Instead of visible light , we could use either radar or infra-red cameras ?  This way the people living in the base could have a real time view of the surface as they drifted over. I think this would be important psychologically for the crew removing the claustrophobic effect  of  feeling very isolated seeing only clouds.

Offline high road

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Re: Floating Habitat on Venus
« Reply #153 on: 10/31/2021 10:26 am »
The surface of Venus is pretty depressing and static to look at. If looking at the miles and miles of cloud landscapes (a view comparable to beachfront properties that people pay a lot for), having large screens to change the scenery is probably a good idea. No reason to limit them to imagery of the surface though.

Offline Slarty1080

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Re: Floating Habitat on Venus
« Reply #154 on: 11/18/2021 04:43 pm »
Actually, no. It seems to be relatively calm, with the high pressures having equalized temperatures, and the clouds combined reflection and isolation further stabilizing temperature. That's why the atmosphere is so featureless. You don't want to be at the poles and crossing the day-night terminal is probably decidedly sporty, but the average turbulence should be okay.

Docking ships are floating along with the same winds, so it should be far easier than refueling fighter jets while traveling at a high airspeed in the turbulence of another aircraft. More like ships rather than aircraft on Earth. And no bulky pressure suits or pressure vessels to do the finer jobs, just 'wetsuits' and breathing masks.
I'm not so sure. I think the best that can be said is that a lot more investigation is required.

https://global.jaxa.jp/projects/sat/planet_c/topics.html#topics10633

https://www.science.org/doi/10.1126/science.328.5979.677-a
My optimistic hope is that it will become cool to really think about things... rather than just doing reactive bullsh*t based on no knowledge (Brian Cox)

Offline stefan r

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Re: Floating Habitat on Venus
« Reply #155 on: 11/30/2021 03:10 pm »
The surface of Venus is pretty depressing and static to look at. If looking at the miles and miles of cloud landscapes (a view comparable to beachfront properties that people pay a lot for), having large screens to change the scenery is probably a good idea. No reason to limit them to imagery of the surface though.

Need to think bigger.  Nitrogen is extremely abundant and easy to separate from carbon dioxide. You would feel more claustrophobic in a sports stadium. 

Water is more challenging at 20 ppm.  The sulfuric acid condenses in cloud droplets.  This needs to be removed from gas in the outer buffer barriers to protect inner regions from corrosion.  Liquid sulfuric acid can be separated into water and SO3 or SO2 and oxygen.  The global water resources total 96 trillion tons.  An Olympic swimming pool is 2500 tons of water.  With a billion human inhabitants we are limited to 38.4 Olympic pools per person.  A large fraction of the hydrogen will be incorporated into plastic, carbohydrate, or other organic compounds. 

If the competition is O'Neil habitats at L5 then Venus habitats are obviously cheaper.  Venus can build much larger decks.  The L5 colony has to import both their air and their water.  The air mass in a full-sized cylinder is close to the mass of the cylinder itself. 

Large open spaces are challenging in all pressurized locations because stress from air pressure increases with circumference.  On Venus the surface deck rides on a flexible foam pad and the ceiling only holds back the pressure from a column.  The deck can span over the horizon. 

Offline Roy_H

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Re: Floating Habitat on Venus
« Reply #156 on: 04/20/2022 07:24 pm »
I think this is a great idea and worthy of promotion. A better option than trying to live on Mars as people would experience Earth normal gravity.
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Re: Floating Habitat on Venus
« Reply #157 on: 07/30/2022 11:06 pm »
It seems to me that a big floating probe or two could provide so much useful information at this stage, as Randy suggests.

Does anyone know of any current plans for a mission to Venus in the near future ?

Offline jdon759

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Re: Floating Habitat on Venus
« Reply #158 on: 08/01/2022 09:18 am »
Rocket lab is planning one next year (or the year after?).  NASA and ESA both have at least one Venus probe planned each. One of  those has an atmospheric probe as well as an orbital platform.  The rocket lab mission is exclusively atmospheric (though will probably have minimal instrumentation on the flyby photon that acts as comms relay).

Offline Lampyridae

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Re: Floating Habitat on Venus
« Reply #159 on: 08/05/2022 09:11 am »
The surface of Venus is pretty depressing and static to look at. If looking at the miles and miles of cloud landscapes (a view comparable to beachfront properties that people pay a lot for), having large screens to change the scenery is probably a good idea. No reason to limit them to imagery of the surface though.

Need to think bigger.  Nitrogen is extremely abundant and easy to separate from carbon dioxide. You would feel more claustrophobic in a sports stadium. 

Water is more challenging at 20 ppm.  The sulfuric acid condenses in cloud droplets.  This needs to be removed from gas in the outer buffer barriers to protect inner regions from corrosion.  Liquid sulfuric acid can be separated into water and SO3 or SO2 and oxygen.  The global water resources total 96 trillion tons.  An Olympic swimming pool is 2500 tons of water.  With a billion human inhabitants we are limited to 38.4 Olympic pools per person.  A large fraction of the hydrogen will be incorporated into plastic, carbohydrate, or other organic compounds. 

If the competition is O'Neil habitats at L5 then Venus habitats are obviously cheaper.  Venus can build much larger decks.  The L5 colony has to import both their air and their water.  The air mass in a full-sized cylinder is close to the mass of the cylinder itself. 

Large open spaces are challenging in all pressurized locations because stress from air pressure increases with circumference.  On Venus the surface deck rides on a flexible foam pad and the ceiling only holds back the pressure from a column.  The deck can span over the horizon. 

Wow, it's been a long time since I've visited this thread.

For perspective, 96 trillion tonnes is not too far out compared to the current fossil fuel burn of 12 billion tonnes/annum. When we think in terms of that water's hydrogen, roughly 10 trillion tonnes, it starts to close up with what a fully industrialised solar system could consider as an import product.

Let's consider that interplanetary colonies will have access to interplanetary trade. So hydrogen could be a major trade import, sourced perhaps from Ceres as massive, insulated spheres of hydrogen ice. Oil, coal and gas are the lifeblood of our economies and we trade them in vast volumes. While hydrogen could be sourced from the atmosphere, it will get more and more challenging to get all of it. At some point, you are going to mess up the climate and cloud formation, but when you have a billion people living there in aerostats, that's to be expected.

From this chart, we see that the average annual US fossil consumption per capita is 63MWh, translated into kg of petrol comes to 4.8 tonnes. Substituting for hydrogen. the same mass of petrol import would make 43 tonnes of water, or a similar mass of polyethylene. At notional Starship costs of $200/kg that's $1 million a year for the hydrogen. Meanwhile bulk HDPE costs hover around $1/kg and we don't need to add the hydrogen to carbon at the end, nature has (partly) done this for us.

The O'Neill colonies require the full H2O, so either they keep the O2 from metal refining, or else they pay to import the O part of the H2O as well. The H2/H2O imports also have to match orbits with wherever the colonies are, whereas H2 shipments to Venus can theoretically just get a free aerobrake down to the surface.

Online Solarsail

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Re: Floating Habitat on Venus
« Reply #160 on: 08/19/2022 09:30 am »
On orbital launch from Venus:  I would expect that we would moreso see the Starship upper stage used as a first stage on Venus, with a bespoke upper stage, rather than trying to turn the Super Heavy into a reentry capable vehicle.  A reentry capable Super Heavy would likely be far more bespoke work than a small(er) upper stage for inside a Starship payload bay.  Though this does not provide the full size habitat during ascent to orbit, it does allow the Starship to reenter, and return to launch site under balloon.

Overthinking a different aspect of settling Venus, I wonder if we could use all of that waste Sulfur as a building material.  Apparently you can make a 'plastic' formation of Sulfur in specific manufacturing processes;  There already are construction projects here using a 'Sulfur concrete', with Sulfur as a binding material for aggregate.  Perhaps Venusian regolith would be too scarce & valuable to be using much making concrete, & that's pretty heavy.  I wonder if anybody's tried plastic Sulfur in a fiber reinforced plastic?  Those would be pretty weight appropriate for an aerostat.

Offline Lampyridae

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Re: Floating Habitat on Venus
« Reply #161 on: 01/08/2023 07:43 am »
Regarding building materials, aerogels can be made with a lower density than air (minus the pore space). On Venus, an aerogel could be filled with oxygen/nitrogen and be buoyant. Entire aerogel clouds could be made in this way. Carbon nanotube aerogels have also been made that keep a vacuum inside the >99.99% empty pore spaces, effectively making a lifting solid with performance better even than helium. Air eventually seeps in but this is quite remarkable. I'll add in the abstract when I find it again. If properly sealed, you could fill a dirigible with this stuff and have a high-performance lifter with no helium input (though it is available in uneconomical ppm quantities).

Metal oxide aerogels can resist over 1000°C, so could insulate landers, provide bouyant lift or even be used as sponges in the lower atmosphere to collect lofted dust.
« Last Edit: 01/08/2023 07:44 am by Lampyridae »

Offline TrevorMonty

Re: Floating Habitat on Venus
« Reply #162 on: 01/08/2023 08:33 am »
Regarding building materials, aerogels can be made with a lower density than air (minus the pore space). On Venus, an aerogel could be filled with oxygen/nitrogen and be buoyant. Entire aerogel clouds could be made in this way. Carbon nanotube aerogels have also been made that keep a vacuum inside the >99.99% empty pore spaces, effectively making a lifting solid with performance better even than helium. Air eventually seeps in but this is quite remarkable. I'll add in the abstract when I find it again. If properly sealed, you could fill a dirigible with this stuff and have a high-performance lifter with no helium input (though it is available in uneconomical ppm quantities).

Metal oxide aerogels can resist over 1000°C, so could insulate landers, provide bouyant lift or even be used as sponges in the lower atmosphere to collect lofted dust.
Could use hydrogen extracted from sulphuric acid along with oxygen for breathing.
« Last Edit: 01/08/2023 03:20 pm by TrevorMonty »

Offline Paul451

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Re: Floating Habitat on Venus
« Reply #163 on: 01/08/2023 12:12 pm »
Carbon nanotube aerogels have also been made that keep a vacuum inside the >99.99% empty pore spaces, effectively making a lifting solid with performance better even than helium. Air eventually seeps in but this is quite remarkable. I'll add in the abstract when I find it again.

Please do. I did a quick search and found nothing like that. (Lots of references to aerogels in vacuum, but that doesn't mean they can retain the intracell vacuum when surrounded by air, it just means they are formed in a vacuum.)

If an evacuated aerogel can support the 10 tonnes / sq_metre pressure from the atmosphere without crushing, that would be huge.

It doesn't actually matter if the aerogel itself can keep the surrounding gas out. You can put the aerogel in a gas-tight envelope. The issue is having it withstand the crushing pressuring on that envelope.

Offline lamontagne

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Re: Floating Habitat on Venus
« Reply #164 on: 01/08/2023 02:28 pm »
Carbon nanotube aerogels have also been made that keep a vacuum inside the >99.99% empty pore spaces, effectively making a lifting solid with performance better even than helium. Air eventually seeps in but this is quite remarkable. I'll add in the abstract when I find it again.

Please do. I did a quick search and found nothing like that. (Lots of references to aerogels in vacuum, but that doesn't mean they can retain the intracell vacuum when surrounded by air, it just means they are formed in a vacuum.)

If an evacuated aerogel can support the 10 tonnes / sq_metre pressure from the atmosphere without crushing, that would be huge.

It doesn't actually matter if the aerogel itself can keep the surrounding gas out. You can put the aerogel in a gas-tight envelope. The issue is having it withstand the crushing pressuring on that envelope.
As far as I can see they would need to be surrounded by a continuous shell, like vacuum insulation board, since they are highly porous.  But perhaps a new development?

Online DanClemmensen

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Re: Floating Habitat on Venus
« Reply #165 on: 01/08/2023 03:00 pm »
Carbon nanotube aerogels have also been made that keep a vacuum inside the >99.99% empty pore spaces, effectively making a lifting solid with performance better even than helium. Air eventually seeps in but this is quite remarkable. I'll add in the abstract when I find it again.

Please do. I did a quick search and found nothing like that. (Lots of references to aerogels in vacuum, but that doesn't mean they can retain the intracell vacuum when surrounded by air, it just means they are formed in a vacuum.)

If an evacuated aerogel can support the 10 tonnes / sq_metre pressure from the atmosphere without crushing, that would be huge.

It doesn't actually matter if the aerogel itself can keep the surrounding gas out. You can put the aerogel in a gas-tight envelope. The issue is having it withstand the crushing pressuring on that envelope.
As far as I can see they would need to be surrounded by a continuous shell, like vacuum insulation board, since they are highly porous.  But perhaps a new development?
A helium or Hydrogen balloon is "surrounded by a continuous shell", so this is not a new requirement. The difference is that new "shell" does not need to be strong in tension and can therefore be lighter: probably a thin film applied as a coating.

Leaks or other loss of hydrogen or helium must be replaced today, and this is a fairly easy operation. "leaks" of vacuum (i.e., air infiltration into the aerogel) will require an entirely new support infrastructure. maybe an enormous hanger that can act as a vacuum oven. Since this is infeasible, maybe the aerogel can be divided into blocks that can be so treated. managing these blocks during handling will be a challenge since they will try to float away.

Offline rsdavis9

Re: Floating Habitat on Venus
« Reply #166 on: 01/08/2023 03:19 pm »
Carbon nanotube aerogels have also been made that keep a vacuum inside the >99.99% empty pore spaces, effectively making a lifting solid with performance better even than helium. Air eventually seeps in but this is quite remarkable. I'll add in the abstract when I find it again.

Please do. I did a quick search and found nothing like that. (Lots of references to aerogels in vacuum, but that doesn't mean they can retain the intracell vacuum when surrounded by air, it just means they are formed in a vacuum.)

If an evacuated aerogel can support the 10 tonnes / sq_metre pressure from the atmosphere without crushing, that would be huge.

It doesn't actually matter if the aerogel itself can keep the surrounding gas out. You can put the aerogel in a gas-tight envelope. The issue is having it withstand the crushing pressuring on that envelope.
As far as I can see they would need to be surrounded by a continuous shell, like vacuum insulation board, since they are highly porous.  But perhaps a new development?
A helium or Hydrogen balloon is "surrounded by a continuous shell", so this is not a new requirement. The difference is that new "shell" does not need to be strong in tension and can therefore be lighter: probably a thin film applied as a coating.

Leaks or other loss of hydrogen or helium must be replaced today, and this is a fairly easy operation. "leaks" of vacuum (i.e., air infiltration into the aerogel) will require an entirely new support infrastructure. maybe an enormous hanger that can act as a vacuum oven. Since this is infeasible, maybe the aerogel can be divided into blocks that can be so treated. managing these blocks during handling will be a challenge since they will try to float away.

You could imagine vacuum aerogels being rotated to space for regular recharging. If they spend a equal time in orbit in vacuum they should keep their charge.

With ELV best efficiency was the paradigm. The new paradigm is reusable, good enough, and commonality of design.
Same engines. Design once. Same vehicle. Design once. Reusable. Build once.

Offline Lampyridae

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Re: Floating Habitat on Venus
« Reply #167 on: 01/08/2023 03:33 pm »
Thanks lamontagne for that other paper. I found the actual paper and discovered that I misinterpreted the abstract when I glanced over it. Firstly, the aerogel was not yet buoyant in vacuum (34 times more dense than air for the first one), but rather more importantly, the aerogel was used to form a shell containing the vacuum. A vacuum dirigible. Not only that, but the performance seems to get better the less dense the aerogel shell material is. They speculate it has something to do with the pressure differential elastically compressing the aerogel, making it impermeable.

Of course, this has absolutely crazy implications for our space-addled brains. Emergency pressure bubbles, single-use airlock doors and so on. You would have to prove the reverse works for containing pressure, or else make the structures compressive (eg a concave airlock door/window). It probably deserves its own thread in Advanced Concepts.

Quote
Air impermeability has been observed in low-density aerogel and cryogel materials, which has led to a series of experiments to investigate the feasibility of an air buoyant vacuum vessel, as well as the fabrication and testing of sub-buoyant prototypes. Bulk samples of silica aerogel were shown to isolate vacuum from ambient air for several hours with optimal vacuum isolation occurring at a density of approximately 85 mg cm−3. It was demonstrated using polyimide aerogel and cryogel materials that the ability of these foam materials to provide an air impermeable layer between vacuum and atmosphere, in spite of being comprised of mostly void space, is related to material stiffness. It is hypothesized that this behavior is due to local deformation of the random nanostructure of the material. Spherical shell vacuum vessels were produced using the polyimide cryogel, and less than 133 Pa vacuum containment was demonstrated under active pumping. In order to approach the non-buoyant to buoyant transition for these vacuum vessels, a polyimide composite was produced using helical fibers for which preliminary mechanical testing was performed.

Oh yeah, as a vacuum dirigible it seems it would just need a vacuum pump for leaks if they get the density low enough for it to work.

Quote
The testing of vacuum vessels thus far, combined with the potential mechanical advantage of the HF-reinforced
PI material suggests that demonstration of an air-buoyant vacuum vessel prototype might be within reach.
« Last Edit: 01/08/2023 03:41 pm by Lampyridae »

Offline JohnFornaro

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Re: Floating Habitat on Venus
« Reply #168 on: 01/09/2023 11:29 am »
Just a reminder that the HAVOC blimp shown in the OP is only 31m long.

The illustration is designed to look like Cloud City in StarWars, but it is not.
« Last Edit: 01/09/2023 11:30 am by JohnFornaro »
Sometimes I just flat out don't get it.

Offline Lampyridae

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Re: Floating Habitat on Venus
« Reply #169 on: 01/09/2023 04:50 pm »
Just a reminder that the HAVOC blimp shown in the OP is only 31m long.

The illustration is designed to look like Cloud City in StarWars, but it is not.

Given the docked blimps for scale, each of the aerostats appears to be 100-150m across, making the whole thing about 300m across. Not bad. We won't see domes of that size on Mars for quite a while.


Offline JohnFornaro

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Re: Floating Habitat on Venus
« Reply #170 on: 01/10/2023 05:34 pm »
[
Given the docked blimps for scale, each of the aerostats appears to be 100-150m across, making the whole thing about 300m across. Not bad. We won't see domes of that size on Mars for quite a while.


Good catch!
Sometimes I just flat out don't get it.

Offline LMT

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Re: Floating Habitat on Venus
« Reply #171 on: 01/11/2023 02:40 am »
...making the whole thing about 300m across. Not bad. We won't see domes of that size on Mars for quite a while.

 ;)

Offline lamontagne

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Re: Floating Habitat on Venus
« Reply #172 on: 01/11/2023 08:57 pm »


Oh yeah, as a vacuum dirigible it seems it would just need a vacuum pump for leaks if they get the density low enough for it to work.

Quote
The testing of vacuum vessels thus far, combined with the potential mechanical advantage of the HF-reinforced
PI material suggests that demonstration of an air-buoyant vacuum vessel prototype might be within reach.
Here is the supplementary material the report refers to. i.e. pictures of the aerogel balls and test equipment!
« Last Edit: 01/11/2023 08:59 pm by lamontagne »

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