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?
How would such habitats be implemented in practice? Could they be built in space and then somehow dropped from orbit into place on Venus?
Could the habitats eventually somehow be fabricated on Venus itself?
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?
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
It would be great if there was even a hair more hydrogen in the atmosphere.It's really unfortunately dry.
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.
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?
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?
Quote from: sanman on 11/30/2018 05:05 pmI'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.
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.
Quote from: Slarty1080 on 12/01/2018 12:38 pmQuote from: sanman on 11/30/2018 05:05 pmI'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 postwhat 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...
Quote from: TripleSeven on 12/01/2018 12:48 pmQuote from: Slarty1080 on 12/01/2018 12:38 pmQuote from: sanman on 11/30/2018 05:05 pmI'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 postwhat 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.svgAt 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/
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.
Quote from: Slarty1080 on 12/01/2018 12:38 pmAn 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-balloonhttps://www.nature.com/articles/ncomms5843http://science.sciencemag.org/content/335/6067/442Apparently, the only Helium loss that cannot be avoided is through Quantum Tunneling(!) QuoteAnother 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.
'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.
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?
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?
Quote from: Slarty1080 on 12/03/2018 12:56 amI 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?
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.
Quote from: sanman on 12/02/2018 04:17 amThe 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.
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.
Quote from: Crispy on 12/03/2018 12:30 pmHow 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.
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)
Quote from: high road on 12/04/2018 09:38 amQuote from: Crispy on 12/03/2018 12:30 pmHow 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.
How do you refuel it without sinking?
Quote from: indaco1 on 12/15/2018 02:34 pmHow 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.
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.
Quote from: mikelepage on 02/01/2019 12:55 pmHad 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.
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.
Quote from: Lemurion on 02/05/2019 07:30 pmThe 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.
Quote from: mikelepage on 02/06/2019 04:19 amQuote from: Lemurion on 02/05/2019 07:30 pmThe 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).
Quote from: high road on 02/06/2019 07:57 amQuote from: mikelepage on 02/06/2019 04:19 amQuote from: Lemurion on 02/05/2019 07:30 pmThe 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 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.
I always confuse the Skyhook and Rotovator concepts. How much would that be made easier by the superrotating atmosphere?
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.
Inhabited floating islands will be after an increase in the albedo of Venus.Manned missions are incomparably more expensiveThe main thing is why Many airship dronesMany 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.
Quote from: WIgorN on 09/07/2019 07:35 pmInhabited floating islands will be after an increase in the albedo of Venus.Manned missions are incomparably more expensiveThe main thing is why Many airship dronesMany 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.
Quote from: Lemurion on 02/05/2019 07:30 pmThe 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
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?...
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 from: high road on 11/18/2019 06:27 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. 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.
Quote from: high road on 11/18/2019 06:27 pmActually, 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 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.
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?
...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.
Quote from: Shevek23 on 11/20/2019 06:15 amSeriously, 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).
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?
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.
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 usual 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.
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.
Meanwhile we had better be obtaining hydrogen in truckload amounts, or might as well stay home. So the slow leak rate is easily compensated.
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.
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).
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 something else? Some kind of bacterial action or what?
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.
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.
QuoteBut 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?)
QuoteEdit: 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
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.
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.htmlShould 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.
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.
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
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-c490d14c0531This one has a nice 'airship' (or habitat) lifting capacity calculator:https://medium.com/@Jernfrost/calculating-lifting-capacity-of-airships-48df5cd7d147And this one compares the various types of lifting gas that can be used:https://medium.com/@Jernfrost/lifting-gases-in-a-venus-aerostat-habitat-69aae6fb990And takes on such subjects as mid-air construction:https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454And transportation and logistics for the colonies:https://medium.com/@Jernfrost/transport-and-logistics-on-a-venus-cloud-colony-62e33e025f23
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.
And takes on such subjects as mid-air construction:https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454
QuoteQuote from: RanulfC on 06/15/2020 08:40 pmAnd takes on such subjects as mid-air construction:https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454Now 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.
Quote from: RanulfC on 06/15/2020 08:40 pmAnd takes on such subjects as mid-air construction:https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454Now 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 from: daedalus1 on 06/16/2020 01:02 pmQuoteQuote from: RanulfC on 06/15/2020 08:40 pmAnd takes on such subjects as mid-air construction:https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454Now 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.
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
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.
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).
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.
No why did I see this on a tuesday morning. There goes my focus for the rest of the day.
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).
Quote from: RanulfC on 06/15/2020 08:40 pmAnd takes on such subjects as mid-air construction:https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454Now 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 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.
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?
Quote from: high road on 06/16/2020 12:18 pmQuote from: RanulfC on 06/15/2020 08:40 pmAnd takes on such subjects as mid-air construction:https://medium.com/@Jernfrost/thoughts-on-building-new-aerostat-habitats-mid-air-on-venus-ffff0ee58454Now 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.
(snip)
Quote from: high road on 06/12/2020 08:28 amOh, 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 QuoteI 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
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?
Quote from: mikelepage on 06/17/2020 05:21 am(snip)So no superheavy launcher, but a 10km long launch infrastructure is acceptable? I like the way you think
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.
Quote from: rsdavis9 on 06/16/2020 03:38 pmHow 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.
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?
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?
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.
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 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.
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.
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
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.
Neither is actually a good solution and I really have to stop pitching railguns 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
Huh, I always imagined them being built like an igloo. If you already have a mast supporting the structure, why would you remove it?
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.
So no superheavy launcher, but a 10km long launch infrastructure is acceptable? I like the way you think
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.
Quote from: high road on 06/17/2020 10:09 amHuh, 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.
QuoteIt'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.
Quote from: high road on 06/12/2020 08:28 amGas-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
Interesting. So why remove the mast once you're done? Seems extra stable to just leave it there.
You're putting some awesome images in my head. So many options!I repeat: that looks awesome in my head.
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.
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.
You don't even need asteroid materials to have an essentially limitless radius. They might help to reduce cost, but at a potential 20$/kg to Earth orbit (Elon Musks rosy estimate), asteroid mining for basic construction materials becomes far less of a gating technology.
Quote from: high road on 06/18/2020 07:33 amYou don't even need asteroid materials to have an essentially limitless radius. They might help to reduce cost, but at a potential 20$/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.
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.
Quote from: high road on 06/21/2020 10:14 amWell, 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.QuoteIt 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
Oh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition,
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...
Quote from: mikelepage on 06/17/2020 05:21 amThe 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.
Quote from: high road on 06/29/2020 08:25 amOh 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.
Quote from: Pete on 06/30/2020 10:19 amQuote from: high road on 06/29/2020 08:25 amOh 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.
Quote from: high road on 07/01/2020 06:30 amQuote from: Pete on 06/30/2020 10:19 amQuote from: high road on 06/29/2020 08:25 amOh 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 ofQuote from: high road on 06/29/2020 08:25 amOh yes. And let's for a minute assume that SpaceX has no interest in dropping their prices below the competition,
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.
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.
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.
Quote from: high road on 07/03/2020 05:52 amYou'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 saysQuote from: high road on 06/29/2020 08:25 amOh 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)
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.
QuoteOh 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
Quote from: high road on 06/18/2020 07:33 amYou 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.
Quote from: RanulfC on 07/09/2020 10:07 pmWell 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.
QuoteOh 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
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.
http://spaceflighthistory.blogspot.com/2020/08/venus-is-best-place-in-solar-system-to.html#comment-formQuoteVenus 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 ?
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: MumPeasant 3: Churches, churchesPeasant 2: Lead, lead.Arthur: A duck.
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).
... (plus Venus gravity is only 90% that of Earth so a "little" bonus there ...
...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...
I see that I'm not the only one, having thought about this thread in the light of yesterday "event". 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.
Quote from: libra on 09/15/2020 01:47 pmI see that I'm not the only one, having thought about this thread in the light of yesterday "event". 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)
Quote from: leovinus on 09/15/2020 02:57 pmQuote from: libra on 09/15/2020 01:47 pmI see that I'm not the only one, having thought about this thread in the light of yesterday "event". 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?
Case in point 1: Shoemaker Levy 9 1994 impact on Jupiter triggered Armaggedon and Deep Impact 4 years later, in 1998.
Nah. Don't blame me. Red that at "The space review" a while back. I will check. https://www.thespacereview.com/article/1728/1https://www.thespacereview.com/article/1469/1
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?
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.
... 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.
QuoteMy 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 !
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.
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 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.
Here's a better vid that already puts some of the misleading arguments in the right context.>snip<
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.
Quote from: high road on 10/03/2020 10:06 amHuh, 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.
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.
QuoteBut 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
QuoteQuote from: high road on 10/03/2020 10:06 amthat 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.
Quote from: high road on 10/03/2020 10:06 amthat 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 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.
Clickbait from someone who likes to hear himself talk.
Conclusions: We find that the published 267-GHz ALMA data provide no statistical evidence for phosphine in the atmosphere of Venus.
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
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.
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.
Quote from: high road on 10/31/2021 10:26 amThe 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.
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.
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.
Quote from: Lampyridae on 01/08/2023 07:43 amCarbon 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.
Quote from: Paul451 on 01/08/2023 12:12 pmQuote from: Lampyridae on 01/08/2023 07:43 amCarbon 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?
Quote from: lamontagne on 01/08/2023 02:28 pmQuote from: Paul451 on 01/08/2023 12:12 pmQuote from: Lampyridae on 01/08/2023 07:43 amCarbon 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.
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.
The testing of vacuum vessels thus far, combined with the potential mechanical advantage of the HF-reinforcedPI material suggests that demonstration of an air-buoyant vacuum vessel prototype might be within reach.
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.
...making the whole thing about 300m across. Not bad. We won't see domes of that size on Mars for quite a while.
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.QuoteThe testing of vacuum vessels thus far, combined with the potential mechanical advantage of the HF-reinforcedPI material suggests that demonstration of an air-buoyant vacuum vessel prototype might be within reach.