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Title: Terraforming of Mars Ideas (and questions!)
Post by: aris2270 on 10/22/2019 07:19 am
Hi! I'm not sure if this is the right place to post this, but I just need some scientific points of view.
I'm going to start drawing/writing a mini webcomic series based around space exploration in the Solar System in 2270 (just for fun). This future boasts a fully terraformed Mars. I've come up with a little timeline for the terraforming process, but I just wanted to confirm something. (I'm by no means a scientist of any sort, just really fascinated with hominization.)
Basically, in 2120, a high-efficiency route between Mars and Venus was established. This featured antimatter rockets that would fly between the two planets. Vast amounts of Carbon Dioxide was sequestered in the Venusian atmosphere, shipped to Mars and burnt off on the surface, increasing atmospheric pressure greatly.
The timeline meant that after this was established, there was a ~100 kPa (still haven't decided on an actual number yet) Carbon Dioxide atmosphere in 50 years. Adding on the Boreholes, Orbital Mirrors and burning of carbon composites established beforehand, it took a total of 120 years to achieve this after beginning in 2050.
Is this antimatter-rocket-route feasible, and does the timeline appear realistic?
Thanks!
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Owlon on 10/23/2019 03:57 am
Hi! I'm not sure if this is the right place to post this, but I just need some scientific points of view.
I'm going to start drawing/writing a mini webcomic series based around space exploration in the Solar System in 2270 (just for fun). This future boasts a fully terraformed Mars. I've come up with a little timeline for the terraforming process, but I just wanted to confirm something. (I'm by no means a scientist of any sort, just really fascinated with hominization.)
Basically, in 2120, a high-efficiency route between Mars and Venus was established. This featured antimatter rockets that would fly between the two planets. Vast amounts of Carbon Dioxide was sequestered in the Venusian atmosphere, shipped to Mars and burnt off on the surface, increasing atmospheric pressure greatly.
The timeline meant that after this was established, there was a ~100 kPa (still haven't decided on an actual number yet) Carbon Dioxide atmosphere in 50 years. Adding on the Boreholes, Orbital Mirrors and burning of carbon composites established beforehand, it took a total of 120 years to achieve this after beginning in 2050.
Is this antimatter-rocket-route feasible, and does the timeline appear realistic?
Thanks!

Just to give a ballpark estimate, the kinetic energy needed to accelerate all that mass out of the gravity well of Venus and throw it at Mars would be on the order of 100,000 times the current global annual energy production (assuming I haven't made any gross calculation errors). As to whether that is feasible or realistic--who knows where energy production technology will lead in the next century?

I'll point out that a pretty significant amount of the CO2 needed already exists on Mars in the polar ice caps and frozen in regolith, which would be released if the global temperature was increased. Going by hazy memory, I think I've seen estimates that this would add up to anywhere from 5 to 50% of Earth's atmospheric pressure.

EDIT: Also, welcome to the forum!
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: _MECO on 10/23/2019 07:00 am
Hi! I'm not sure if this is the right place to post this, but I just need some scientific points of view.
I'm going to start drawing/writing a mini webcomic series based around space exploration in the Solar System in 2270 (just for fun). This future boasts a fully terraformed Mars. I've come up with a little timeline for the terraforming process, but I just wanted to confirm something. (I'm by no means a scientist of any sort, just really fascinated with hominization.)
Basically, in 2120, a high-efficiency route between Mars and Venus was established. This featured antimatter rockets that would fly between the two planets. Vast amounts of Carbon Dioxide was sequestered in the Venusian atmosphere, shipped to Mars and burnt off on the surface, increasing atmospheric pressure greatly.
The timeline meant that after this was established, there was a ~100 kPa (still haven't decided on an actual number yet) Carbon Dioxide atmosphere in 50 years. Adding on the Boreholes, Orbital Mirrors and burning of carbon composites established beforehand, it took a total of 120 years to achieve this after beginning in 2050.
Is this antimatter-rocket-route feasible, and does the timeline appear realistic?
Thanks!

Just to give a ballpark estimate, the kinetic energy needed to accelerate all that mass out of the gravity well of Venus and throw it at Mars would be on the order of 100,000 times the current global annual energy production (assuming I haven't made any gross calculation errors). As to whether that is feasible or realistic--who knows where energy production technology will lead in the next century?

I'll point out that a pretty significant amount of the CO2 needed already exists on Mars in the polar ice caps and frozen in regolith, which would be released if the global temperature was increased. Going by hazy memory, I think I've seen estimates that this would add up to anywhere from 5 to 50% of Earth's atmospheric pressure.

EDIT: Also, welcome to the forum!

This. You'd be surprised how cheap gigaton-range nuclear weapons become when you start talking about importing CO2 from Venus.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: AnalogMan on 10/23/2019 10:31 am
This currently active thread may also be of interest:

Mars Terraforming discussion
https://forum.nasaspaceflight.com/index.php?topic=31113.0 (https://forum.nasaspaceflight.com/index.php?topic=31113.0)
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: MATTBLAK on 10/23/2019 11:17 am
Venus might be cooled with a combination of CO2 conversion and a huge, manufactured in space 'sunshield'. But the darn place rotates so terribly slowly this contributes to it's lackluster magnetic field - and who wants permanent daylight anyhow?! Mars is a better candidate for Terraforming. But I've always been very lukewarm for the idea. It would take a hell of a lot of money, energy and centuries of time to change it. Why bother? All the trillions spent on it and centuries to Terraform might instead be better used Terraforming Earth back to the 'ideal' state and building Starships to travel to other systems where Earth like planets had been discovered.

We already build gigantic sports stadiums and enclosed communities on Earth. Why not just use our Civil Engineering Super-know how to build pressurized Super-Domed cities on Mars? And if Mars does turn out to have a residual, albeit dying ecosystem left there - I don't think we have the ethical right to decimate it. Just my two cents worth of opinions...
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: whitelancer64 on 10/23/2019 03:02 pm
Hi! I'm not sure if this is the right place to post this, but I just need some scientific points of view.
I'm going to start drawing/writing a mini webcomic series based around space exploration in the Solar System in 2270 (just for fun). This future boasts a fully terraformed Mars. I've come up with a little timeline for the terraforming process, but I just wanted to confirm something. (I'm by no means a scientist of any sort, just really fascinated with hominization.)
Basically, in 2120, a high-efficiency route between Mars and Venus was established. This featured antimatter rockets that would fly between the two planets. Vast amounts of Carbon Dioxide was sequestered in the Venusian atmosphere, shipped to Mars and burnt off on the surface, increasing atmospheric pressure greatly.
The timeline meant that after this was established, there was a ~100 kPa (still haven't decided on an actual number yet) Carbon Dioxide atmosphere in 50 years. Adding on the Boreholes, Orbital Mirrors and burning of carbon composites established beforehand, it took a total of 120 years to achieve this after beginning in 2050.
Is this antimatter-rocket-route feasible, and does the timeline appear realistic?
Thanks!

I'm assuming these antimatter rockets are constantly firing during the trip. If they're accelerating at a significant fraction of g, then the trip time between the inner solar system planets is measured in single-digit days, no matter which two planets you select or where they are in their orbits. So a "high efficiency route" isn't needed, that issue is solved with brute force.

That being the case, I think it would be better to transport nitrogen and oxygen from the atmosphere of Jupiter to Mars. There they would require little to no refining / processing before transport to Mars, and the resulting atmosphere would be far more comfortable for Earth life. As already mentioned, Mars already has plenty of CO2. Depending on the size of these antimatter ships (how much is being transported per trip?) that might be the better option.

If this isn't a major plot point for your story, you might not have to worry too much about these details (though the readers certainly will).
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: mlorrey on 10/24/2019 03:27 am
You could get a Tibetan climate on Mars within about 30 years, at 300-400 millibars pressure, but pure CO2, by building automated production facilities to produce CFCs from raw native flourine and chlorine based chemical compounds and minerals, and dump said CFCs into the atmosphere. You'd need to produce them at the level the developed nations were producing them before the Montreal Protocol. This would trigger enough warming to cause all the CO2 to melt and outgass from the regolith, leading to temperate climate over 75% of Mars surface. No pressure suits needed, but O2 masks would be required still.
After  that, its just a whole lot of plant growth, releasing algae into the northern sea (yes all the ice will melt and fill the northern third of the planets surface  with  ocean), to convert a lot of the CO2 to O2.
Then you need a whole lot of  nitrogen, which isn't on Venus,  or Earth, or anywhere in the Asteroids. Its on Titan, where there are high levels of Ammonia (NH3). You can send rockets out there to collect ammonia in tanks, which they can then crack it into N2 and H2 to supply their rockets to get back to Mars. Or... you can hope Mach Effects really work, cause the Mach Effect equation will, at a high  enough energy density and operating frequency, enable stargates. Imagine having a stargate connection between Mars surface and Titan surface. You'd have it gushing ammonia and methane into Mars til pressure equalizes or you shut the gate.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Elmar Moelzer on 10/24/2019 05:17 am
In addition to the CFCs, a good idea seems to be an artificial magnetic field for Mars, which is not unthinkable even with today's technology. I believe NASA had a paper on this idea, not too long ago. The existence of a magnetic field alone (even without additional terraforming operations) would increase pressure and temperatures on Mars relatively quickly (but from what I understand only up to a certain point).
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: MATTBLAK on 10/24/2019 06:48 am
Mars is losing several kilos of atmospheric gases per day - so any way this could be arrested would be a good thing. Any improvements to the magnetic field would only be a good thing, too.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: edzieba on 10/24/2019 09:55 am
If you have a copious antimatter source, it would probably make more sense to fly that antimatter to Mars and use it for energy production to produce CO2 (or more effective greenhouse gases) in-situ - e.g. crushing up rocks for Carbon and melting and electrolysing ice for Oxygen - than to cart that CO2 up out of a gravity well and fling it across the solar system.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Elmar Moelzer on 10/24/2019 05:14 pm
This here:
https://www.extremetech.com/extreme/245369-nasa-proposes-building-artificial-magnetic-field-restore-mars-atmosphere
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: QuantumG on 10/24/2019 09:50 pm
Cover the poles with a travelling wave nuclear reactor (https://en.wikipedia.org/wiki/Traveling_wave_reactor) (thanks Bill Gates!) and melt them.

Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Spaniard on 10/25/2019 12:47 pm
Well... Instead of antimatter rockets, because we are talking about a huge amount of matter in any case, I suggest to make an orbital ring around venus and use it to suck the atmosphere directly. Using the ring as a big energy collector too (surrounded by pv panels), pipe the gases, turn into solid CO2, and in cold ships, launch to Mars in a "cycler like" trajectory.

Just with minimal separation, you could send the cargo to Mars collision while the ship goes to Venus again (remember... cycler trajectory)

Using aerobraking and minimal propulsion, the ship could reach Low Venus Orbit and reattach to the ring again.

The launch of the ship could be using tethers on the ring. The result is MINIMAL need of propulsion and reusing ships over and over and over.

Probably it would be need minimal propulsion that, based on electrical propulsion, could use some of the cargo as a propollant. Just a tiny fraction.

There is more atmosphere on Venus that needed on Mars.

We don't need to replicate Earth atmosphere on Mars. We just need a enough thick atmosphere to reach the liquid point of water on the whole Mars, some nitrogen, and some oxygen.

The species could adapt to this levels, so life colonization could start from this point without need to stop the terraforming.

Because build a ring (even if it's close to cables only) around a planet is a very expensive project, we should probably with more traditional approach like producing supergreenhouse gasses and mirrors for Mars. This would have sense later, when most of ices has been released and we have checked that there is no enough ice on Mars to build or ideal terraforming project.

Import some ammonia comets will be needed too, because we need to import nitrogen and we don't want to decrease nitrogen levels on Venus, for later Venus terraforming project.
The idea is to bring two projects into one. Strip down Venus atmosphere and use it on Mars. Two for the price of one.

The "suck atmosphere" part could use the technique of the ring at a different speed to Venus land or atmosphere. On the ring, you have "magnetic rails" and a "train" with the pipe to the atmosphere. It close to a elevator, but the elevator requires very far (unrealistic on Venus) counterweight. Here, instead, the counterweight push the ring and the ring could maintain the position because its orbital speed is different and faster.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Paul451 on 10/27/2019 06:35 am
You could get a Tibetan climate on Mars within about 30 years, at 300-400 millibars pressure, but pure CO2

For the people who think the only thing wrong with the climate of Tibet is all that damn oxygen.

at 300-400 millibars pressure

Is the top of Mt Everest. Most of Tibet is in the 500-700 millibar range. (You don't drop below 400mb until you get above 7km.)

Then you need a whole lot of  nitrogen, which isn't on Venus,

3.5% at 90+ atmospheres gives Venus nearly 4 times as much nitrogen as on Earth. Hence if you were trying to thin Venus' atmosphere down to 100kPa, you'd need to eliminate a bit over 3 atmospheres' worth of nitrogen.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Paul451 on 10/27/2019 07:00 am
If you have a copious antimatter source, it would probably make more sense to fly that antimatter to Mars and use it for energy production to produce CO2 (or more effective greenhouse gases) in-situ - e.g. crushing up rocks for Carbon and melting and electrolysing ice for Oxygen - than to cart that CO2 up out of a gravity well and fling it across the solar system.

My guess is that the energy cost and resources required to terraform any planet would let you turn the entire mass of the asteroid belt into a basic Dyson Swarm. Tens to hundreds of billions of unique tailored environments, capable of housing up to hundreds of millions of times the population of Earth; or giving the current population of Earth tens of Island Three sized habitats each.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: mrhuggy on 10/27/2019 11:28 am
Millions of wind turbines heating up the ice to melt.
Bio engineered Mars resistant plants.
Bio engineer humans to be more Mars resistant and able to breath in high CO2 atmospheres.
Nuking the ice caps.
Build massive industrial chemical plants to produce pollution to increase a greenhouse effect.
Puting mass drivers on asteroids and comets to burn the up in the atmosphere.
Using solar mirrors to heat up Mars.
Using solar mirrors to melt the martian surface, creating those martian canals that we have long sought for.
Covering up vallis to make them in to huge greenhouses to convert CO2 into food, wood and oxygen.

All nearly scientifically possible, now guess which books covers it all.


Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Lar on 10/28/2019 12:37 pm
Millions of wind turbines heating up the ice to melt.
Bio engineered Mars resistant plants.
Bio engineer humans to be more Mars resistant and able to breath in high CO2 atmospheres.
Nuking the ice caps.
Build massive industrial chemical plants to produce pollution to increase a greenhouse effect.
Puting mass drivers on asteroids and comets to burn the up in the atmosphere.
Using solar mirrors to heat up Mars.
Using solar mirrors to melt the martian surface, creating those martian canals that we have long sought for.
Covering up vallis to make them in to huge greenhouses to convert CO2 into food, wood and oxygen.

All nearly scientifically possible, now guess which books covers it all.




Red/Green/Blue Mars (by Kim Stanley Robinson) ???
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Robotbeat on 05/27/2022 03:08 pm
Bump. I think Advanced Concepts is the right place to discuss terraforming.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Robotbeat on 06/17/2022 04:39 pm
Bump. I think Advanced Concepts is the right place to discuss terraforming.
The easiest way to "raise" the pressure would be to dig up a 40km deep hole.
It will basically be deeper than the sea on Earth.
The pressure at the bottom will then be ~33% of Earth.
We can use plants to generate oxygen rather than Sabbatier process.
Although that way we get only about less than 1% of the surface area as a set of colonies.
Disagree. Look up the amount of dirt you need to moveÖ Marsí atmosphere has a mass of 25 terratonnes (and causes a pressure of about 10-15 millibar at the deepest parts of Hellas Basin compared to 62mbar needed for the Armstrong Limit, so about a factor of 5 away). A cone with angle of repose of 26 degrees and 40km deep has a volume approximately 250 trillion cubic meters, which if you have a density of 2g/cc means youíre moving 20 times the mass as the mass of the current atmosphere of Mars & 4 times the amount needed for minimal terraforming, and thatís just a single small cone.

Massive bubble habitats would be a lot less work for the same area and pressure.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: rakaydos on 06/25/2022 06:20 pm
Since it looks like the thread in the mars forum isnt returning...

The biggest problem with domes is that human-habitable pressure is so much higher than mars surface pressure, that "domes" cannot rely on surface anchors and instead  are effectively partially buried pressure spheres. The thickness of glass needed to "float" a dome would be on the order of a meter thick- and issac newton help you if a dome that heavy ever loses pressure.

But what if we could play with atmospheric scale height inside the dome?

There's breathable materials significantly denser than NitrOx, and the hellas basin is pretty deep, which also means that there's significant walls on all sides. Throw a zero-pressure-difference celophane barrier over the basin to prevent martian winds from dispercing our efforts, and fill the basin with those denser breathable mixtures, and how close to the armstrong limit can you reach?
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Paul451 on 06/27/2022 11:48 pm
The thickness of glass needed to "float" a dome would be on the order of a meter thick

On the order of ten metres for 1atm. Which does give you some allowance for self-supporting structural strength.

There's breathable materials significantly denser than NitrOx

I'm amused by the idea that everyone on Mars -- men, women, children, even toddlers -- sounds like an angry Penn Jillette.

Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: edzieba on 06/28/2022 07:44 am
Since it looks like the thread in the mars forum isnt returning...

The biggest problem with domes is that human-habitable pressure is so much higher than mars surface pressure, that "domes" cannot rely on surface anchors and instead  are effectively partially buried pressure spheres. The thickness of glass needed to "float" a dome would be on the order of a meter thick- and issac newton help you if a dome that heavy ever loses pressure.

But what if we could play with atmospheric scale height inside the dome?

There's breathable materials significantly denser than NitrOx, and the hellas basin is pretty deep, which also means that there's significant walls on all sides. Throw a zero-pressure-difference celophane barrier over the basin to prevent martian winds from dispercing our efforts, and fill the basin with those denser breathable mixtures, and how close to the armstrong limit can you reach?
I don't think denser mixes really gain you anything. You care about ppO2, and the highest ppO2 you can get with the lowest absolute gas pressure is a pure O2 atmosphere - because at the same pressure, any diluent gasses added are just displacing some O2 (and thus reducing ppO2) or adding to total pressure (because you're shoving extra molecules into the same volume).
For a 0.17 Bar ppO2 (nearly hypoxic but survivable) that's a density of 0.24g/l for a pure O2 environment. Mars' atmospheric density is 0.02g/l. That means regardless of the diluent added, you're going to need to be well above atmospheric pressure (~10x) to sustain life.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: rakaydos on 07/01/2022 02:29 pm
Since it looks like the thread in the mars forum isnt returning...

The biggest problem with domes is that human-habitable pressure is so much higher than mars surface pressure, that "domes" cannot rely on surface anchors and instead  are effectively partially buried pressure spheres. The thickness of glass needed to "float" a dome would be on the order of a meter thick- and issac newton help you if a dome that heavy ever loses pressure.

But what if we could play with atmospheric scale height inside the dome?

There's breathable materials significantly denser than NitrOx, and the hellas basin is pretty deep, which also means that there's significant walls on all sides. Throw a zero-pressure-difference celophane barrier over the basin to prevent martian winds from dispercing our efforts, and fill the basin with those denser breathable mixtures, and how close to the armstrong limit can you reach?
I don't think denser mixes really gain you anything. You care about ppO2, and the highest ppO2 you can get with the lowest absolute gas pressure is a pure O2 atmosphere - because at the same pressure, any diluent gasses added are just displacing some O2 (and thus reducing ppO2) or adding to total pressure (because you're shoving extra molecules into the same volume).
For a 0.17 Bar ppO2 (nearly hypoxic but survivable) that's a density of 0.24g/l for a pure O2 environment. Mars' atmospheric density is 0.02g/l. That means regardless of the diluent added, you're going to need to be well above atmospheric pressure (~10x) to sustain life.
It's not about the narrow breathable volume at the bottom of the basin. Its's about the composition of the uninhabitable-but-isolated bondary layer between the bottom on the basin and the rim of the basin. By changing the composition in this region to have a lower scale height, the top of this pillar of air can remain mars pressure while the bottom of the pillar of air can be... higher than it is currently.

High enough to be useful? I dont know enough to say.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Paul451 on 07/02/2022 02:23 pm
By changing the composition in this region to have a lower scale height, the top of this pillar of air can remain mars pressure while the bottom of the pillar of air can be... higher than it is currently.
High enough to be useful? I dont know enough to say.

Scale height is inversely proportional to molar mass of the gas. Hence, sulphur hexafluoride would have a scale-height 3.32x smaller than Mars' current 11.1km (so 3.34km.)

So picking a fairly arbitrary 10km between bottom of Hellas-deep and the membrane cap, that would give you 3 SH6 "scales", so 20 times (e^3) increase in pressure at the bottom compared to the top. Assuming Mars ambient pressure at the top (roughly 600pa), gives you around 12kpa at the bottom. So, 12% of Earth normal, around 1/8th SL. Equiv of 15km altitude. That's lower than the operating pressure of a pure-oxygen EVA suit, so you still need a pressure suit.

Sulphur hexafluoride is a potent (crazy potent) greenhouse gas, which might seem like a good idea, keeping temps above freezing and a much reduced day/night thermal cycle. But it might be too potent a GHG, making the basin too hot, even with the conductive/convective cooling through the membrane.

It's also an anaesthetic gas, so you can't just mix it with oxygen. But at that pressure, you'd still be living in pressurised habs and wearing pressure suits when outside, so it's not an issue.

However... Using Perfluorobutane as the fill gas, you nearly double the molar mass, which nearly halves the scale height again and increases bottom pressure (by e^6) to higher-that-Earth-SL. Which is starting to get interesting.

It's also still a stupidly potent greenhouse gas, but not as crazy as SF6, and given the high pressure, can be diluted with any arbitrary gas, like nitrogen, to lower the pressure, so might be more useful. It is, however, much harder to produce than SF6 AIUI. Same issue with SH6 in being an anaesthetic and nervous system depressant, so you still need a separate breather and good seals. However, being at high pressure means your habs can be unpressurised, and there's a greater risk of outside atmosphere flowing inwards through leaky seals, instead of outwards. It's still vastly safer than a pressure vessel in a near-vacuum, but now adds its own special risk. So you might aim to keep the outside pressure at 3/4 SL (via mix gases to dilute the perflurobutane) with the habs at a full 1atm, in order to ensure positive pressure. Likewise, when working outside, have your breathing mask or hood pressurised just slightly above that outside 3/4 SL, just enough positive pressure to give some protection against suffocation if your mask-seals are crappy. (No pre-breath required.)

Downside of all the fluorides is that when used around, say, arcing electrical equipment and high-temp industrial equipment, can break down into fluorine gas or hydrogen fluoride. Which is super unfun, yo. But I don't know how big a risk that is. Worst case, you put those systems in a nitrogen or CO2 bubble.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Barley on 07/02/2022 04:36 pm
How flat is the floor of the basin?

If the atmosphere has a scale height of 2km then a 400m elevation gain is the equivalent of sea level to Denver.  Not a show stopper, but enough to get some noticeable effects.  Particularly if a settlement is large enough to be space limited, which seems likely if you get to this stage of terraforming.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Lampyridae on 07/03/2022 04:15 pm
Since it looks like the thread in the mars forum isnt returning...

The biggest problem with domes is that human-habitable pressure is so much higher than mars surface pressure, that "domes" cannot rely on surface anchors and instead  are effectively partially buried pressure spheres. The thickness of glass needed to "float" a dome would be on the order of a meter thick- and issac newton help you if a dome that heavy ever loses pressure.

But what if we could play with atmospheric scale height inside the dome?

There's breathable materials significantly denser than NitrOx, and the hellas basin is pretty deep, which also means that there's significant walls on all sides. Throw a zero-pressure-difference celophane barrier over the basin to prevent martian winds from dispercing our efforts, and fill the basin with those denser breathable mixtures, and how close to the armstrong limit can you reach?
I don't think denser mixes really gain you anything. You care about ppO2, and the highest ppO2 you can get with the lowest absolute gas pressure is a pure O2 atmosphere - because at the same pressure, any diluent gasses added are just displacing some O2 (and thus reducing ppO2) or adding to total pressure (because you're shoving extra molecules into the same volume).
For a 0.17 Bar ppO2 (nearly hypoxic but survivable) that's a density of 0.24g/l for a pure O2 environment. Mars' atmospheric density is 0.02g/l. That means regardless of the diluent added, you're going to need to be well above atmospheric pressure (~10x) to sustain life.
It's not about the narrow breathable volume at the bottom of the basin. Its's about the composition of the uninhabitable-but-isolated bondary layer between the bottom on the basin and the rim of the basin. By changing the composition in this region to have a lower scale height, the top of this pillar of air can remain mars pressure while the bottom of the pillar of air can be... higher than it is currently.

High enough to be useful? I dont know enough to say.

Makes me think of the Shell World discussions a while ago: https://forum.nasaspaceflight.com/index.php?topic=49788.0

I'm sure there's a space for an intermediate application where you can have a massive air dam which is inward leaning, partly floating on the enclosed air, extending up in altitude to a hundred kilometres or so. At this scale, air behaves like weather systems, not necessarily a tyre filled with gas. The dam has a double wall, filled with SF6.

Scale height on Mars for warm breathable air is 22km. We fill it up with O2 to get 1/3 bar on the floor so that we can breathe and have Smokey the Bear warning signs everywhere. At the top of a 110km column (Hellas basin gives us 8km free), the air pressure is 0.007 bar, or ~200kg per square metre. We let it blast over the side, and it falls into the SF6 because there is a huge pressure differential (SF6 scale height is 8km; at the top of a 100km column the air pressure is basically vacuum. Process the lost oxygen from the SF6 moat and pump back into Hellas. The larger the area, the slower the leak rate into the moat. Opt for a higher leak rate and the air dam can be smaller.

Or you can forgo the SF6 and make the temperature in the moat just above liquid air temps; the moat still catches air and you pump it (or just let it flow) back into the reservoir. Adiabatic compression will heat the surrounding air somewhat but it has a big shade or something to keep it cool.

Somewhat further afield I note that imperfectly conducting gas disks around stars rotating through a magnetic field create a toroidal field that pinches it. I wonder if that could be applied to a toroidal basin/moat setup to squash the scale height.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: rakaydos on 07/04/2022 02:19 pm
Since it looks like the thread in the mars forum isnt returning...

The biggest problem with domes is that human-habitable pressure is so much higher than mars surface pressure, that "domes" cannot rely on surface anchors and instead  are effectively partially buried pressure spheres. The thickness of glass needed to "float" a dome would be on the order of a meter thick- and issac newton help you if a dome that heavy ever loses pressure.

But what if we could play with atmospheric scale height inside the dome?

There's breathable materials significantly denser than NitrOx, and the hellas basin is pretty deep, which also means that there's significant walls on all sides. Throw a zero-pressure-difference celophane barrier over the basin to prevent martian winds from dispercing our efforts, and fill the basin with those denser breathable mixtures, and how close to the armstrong limit can you reach?
I don't think denser mixes really gain you anything. You care about ppO2, and the highest ppO2 you can get with the lowest absolute gas pressure is a pure O2 atmosphere - because at the same pressure, any diluent gasses added are just displacing some O2 (and thus reducing ppO2) or adding to total pressure (because you're shoving extra molecules into the same volume).
For a 0.17 Bar ppO2 (nearly hypoxic but survivable) that's a density of 0.24g/l for a pure O2 environment. Mars' atmospheric density is 0.02g/l. That means regardless of the diluent added, you're going to need to be well above atmospheric pressure (~10x) to sustain life.
It's not about the narrow breathable volume at the bottom of the basin. Its's about the composition of the uninhabitable-but-isolated bondary layer between the bottom on the basin and the rim of the basin. By changing the composition in this region to have a lower scale height, the top of this pillar of air can remain mars pressure while the bottom of the pillar of air can be... higher than it is currently.

High enough to be useful? I dont know enough to say.

Makes me think of the Shell World discussions a while ago: https://forum.nasaspaceflight.com/index.php?topic=49788.0

I'm sure there's a space for an intermediate application where you can have a massive air dam which is inward leaning, partly floating on the enclosed air, extending up in altitude to a hundred kilometres or so. At this scale, air behaves like weather systems, not necessarily a tyre filled with gas. The dam has a double wall, filled with SF6.

Scale height on Mars for warm breathable air is 22km. We fill it up with O2 to get 1/3 bar on the floor so that we can breathe and have Smokey the Bear warning signs everywhere. At the top of a 110km column (Hellas basin gives us 8km free), the air pressure is 0.007 bar, or ~200kg per square metre. We let it blast over the side, and it falls into the SF6 because there is a huge pressure differential (SF6 scale height is 8km; at the top of a 100km column the air pressure is basically vacuum. Process the lost oxygen from the SF6 moat and pump back into Hellas. The larger the area, the slower the leak rate into the moat. Opt for a higher leak rate and the air dam can be smaller.

Or you can forgo the SF6 and make the temperature in the moat just above liquid air temps; the moat still catches air and you pump it (or just let it flow) back into the reservoir. Adiabatic compression will heat the surrounding air somewhat but it has a big shade or something to keep it cool.

Somewhat further afield I note that imperfectly conducting gas disks around stars rotating through a magnetic field create a toroidal field that pinches it. I wonder if that could be applied to a toroidal basin/moat setup to squash the scale height.
I'm pretty sure the problem is the sides of the air dam, where the armstrong-pressure breathing gas is trying to shear your anchor points off.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Greg Hullender on 07/04/2022 03:01 pm
Hi! I'm not sure if this is the right place to post this, but I just need some scientific points of view.
I'm going to start drawing/writing a mini webcomic series based around space exploration in the Solar System in 2270 (just for fun).
So, after three years, does anyone know if the webcomic ever got done?
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: rakaydos on 07/15/2022 09:15 pm
By changing the composition in this region to have a lower scale height, the top of this pillar of air can remain mars pressure while the bottom of the pillar of air can be... higher than it is currently.
High enough to be useful? I dont know enough to say.

Scale height is inversely proportional to molar mass of the gas. Hence, sulphur hexafluoride would have a scale-height 3.32x smaller than Mars' current 11.1km (so 3.34km.)

So picking a fairly arbitrary 10km between bottom of Hellas-deep and the membrane cap, that would give you 3 SH6 "scales", so 20 times (e^3) increase in pressure at the bottom compared to the top. Assuming Mars ambient pressure at the top (roughly 600pa), gives you around 12kpa at the bottom. So, 12% of Earth normal, around 1/8th SL. Equiv of 15km altitude. That's lower than the operating pressure of a pure-oxygen EVA suit, so you still need a pressure suit.

Sulphur hexafluoride is a potent (crazy potent) greenhouse gas, which might seem like a good idea, keeping temps above freezing and a much reduced day/night thermal cycle. But it might be too potent a GHG, making the basin too hot, even with the conductive/convective cooling through the membrane.

It's also an anaesthetic gas, so you can't just mix it with oxygen. But at that pressure, you'd still be living in pressurised habs and wearing pressure suits when outside, so it's not an issue.

However... Using Perfluorobutane as the fill gas, you nearly double the molar mass, which nearly halves the scale height again and increases bottom pressure (by e^6) to higher-that-Earth-SL. Which is starting to get interesting.

It's also still a stupidly potent greenhouse gas, but not as crazy as SF6, and given the high pressure, can be diluted with any arbitrary gas, like nitrogen, to lower the pressure, so might be more useful. It is, however, much harder to produce than SF6 AIUI. Same issue with SH6 in being an anaesthetic and nervous system depressant, so you still need a separate breather and good seals. However, being at high pressure means your habs can be unpressurised, and there's a greater risk of outside atmosphere flowing inwards through leaky seals, instead of outwards. It's still vastly safer than a pressure vessel in a near-vacuum, but now adds its own special risk. So you might aim to keep the outside pressure at 3/4 SL (via mix gases to dilute the perflurobutane) with the habs at a full 1atm, in order to ensure positive pressure. Likewise, when working outside, have your breathing mask or hood pressurised just slightly above that outside 3/4 SL, just enough positive pressure to give some protection against suffocation if your mask-seals are crappy. (No pre-breath required.)

Downside of all the fluorides is that when used around, say, arcing electrical equipment and high-temp industrial equipment, can break down into fluorine gas or hydrogen fluoride. Which is super unfun, yo. But I don't know how big a risk that is. Worst case, you put those systems in a nitrogen or CO2 bubble.

Concept: The Hellas Double-Dome.

A landing pad is established a safe distance from the rim of the hellas basin, and a train is set up to the basin. A (relatively) thin membrane is floated over the entire basin, using blown air to generate enough overpressure to suspend this outer membrane. A manufacturing site is established to manufacture [heavy gas mixture], which is pumped in under the dome. Overpressure at the top of the basin is filtered to extract [heavy gas mix] and release the Martian atmospheric gasses.

As the pressure from [heavy gas mixture] increases, Another dome is placed over the majority of the useful basin surface, pressurized with breathing gas to survivable levels, minimizing the effects of scale height on terrain WITHIN the inner dome. This inner dome is initially inflated to armstrong pressure, but pressure is allowed to increase to maintain a positive pressure differential with the bottom of the column of [heavy gas mixture] outside the inner dome, supplied by the train/tram through the uninhabitable intermediate layer.

The inner dome is then locally  para-terraformed at leisure.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Paul451 on 07/16/2022 11:59 pm
Just a reminder that Hellas has a diameter of 2300km (1400mi). This membrane could cover the most of western US, or western Europe.

The point of paraterraforming is to avoid megastructures. Each cell is supposed to be modest scale and immediately usable while you build the next...
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Slarty1080 on 07/21/2022 08:41 pm
I think that paraterraforming is far more likely to provide a realistic means of making Mars more habitable than trying to implement some planet wide traditional terraforming project. It would also be far more incremental and produce results in a much shorter time frame.

With paraterraforming the idea is to progressively inclose the surface with interconnected pressurised structures. I don't know what the optimum size of structure might be, but it doesn't matter for the argument and will probably evolve over time. But it should eventually be possible to enclose many square kilometers at a time andd have the space available within a few months or years. No comet bombardment, no mass transportation of materials from Venus and no waiting for decades or centuries for the outcome of some giant planetary experiment.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Robotbeat on 07/21/2022 08:46 pm
I think partial terraforming of mars to increase its surface pressure to Armstrong Limit is not ultimately that hard and would probably be easier than setting up a (largely) self-sustaining city of 1 million people. Thereís a lot of misinformation about this, and it doesnít require massive new technology or anything like that (massive solar sails launched on highly reusable rockets is good enough), although doubtless that will be developed. Wouldnít take centuries, either.

Now if youíre talking creating a breathable atmosphere on Mars, I agree. Paraterraforming is easier.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: mlorrey on 07/28/2022 12:03 am
Venus might be cooled with a combination of CO2 conversion and a huge, manufactured in space 'sunshield'. But the darn place rotates so terribly slowly this contributes to it's lackluster magnetic field - and who wants permanent daylight anyhow?! Mars is a better candidate for Terraforming. But I've always been very lukewarm for the idea. It would take a hell of a lot of money, energy and centuries of time to change it. Why bother? All the trillions spent on it and centuries to Terraform might instead be better used Terraforming Earth back to the 'ideal' state and building Starships to travel to other systems where Earth like planets had been discovered.

We already build gigantic sports stadiums and enclosed communities on Earth. Why not just use our Civil Engineering Super-know how to build pressurized Super-Domed cities on Mars? And if Mars does turn out to have a residual, albeit dying ecosystem left there - I don't think we have the ethical right to decimate it. Just my two cents worth of opinions...

Even with a 100% reflective sun shield it will take over a millennia for Venus to radiate all its stored heat, and that does nothing about getting rid of 91 of the 92 atmospheres of CO2 and SO2 that are the crux of the problem. You could make nanoballoon robots that replicate themselves from carbon and construct nanodiamonds they drop to the surface. This would take centuries still, and the surface would retain enough heat to cause the ignition of the many meters thick layer of nanodiamonds at some point (because by then you'll have raised the atmospheric levels of O2 to over 50% and you still have 92 atmospheres, now its mostly O2 rather than CO2 and SO2.
You really need a crapload of water on Venus so your robots can construct limestone bomblets, and thus build up a half mile thick layer of limestone sand, under a sea of water that absorbs the heat of the crust and radiates it to space via convection. This will still take millenia. Terraforming Mars is FAR simpler and faster.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Robotbeat on 07/28/2022 02:19 am
Venus might be cooled with a combination of CO2 conversion and a huge, manufactured in space 'sunshield'. But the darn place rotates so terribly slowly this contributes to it's lackluster magnetic field - and who wants permanent daylight anyhow?! Mars is a better candidate for Terraforming. But I've always been very lukewarm for the idea. It would take a hell of a lot of money, energy and centuries of time to change it. Why bother? All the trillions spent on it and centuries to Terraform might instead be better used Terraforming Earth back to the 'ideal' state and building Starships to travel to other systems where Earth like planets had been discovered.

We already build gigantic sports stadiums and enclosed communities on Earth. Why not just use our Civil Engineering Super-know how to build pressurized Super-Domed cities on Mars? And if Mars does turn out to have a residual, albeit dying ecosystem left there - I don't think we have the ethical right to decimate it. Just my two cents worth of opinions...
Of course itís easier to geoengineer Earth than terraform Mars! Thatís not an argument against terraforming Mars because the motivation has nothing to do with trashing Earth. (No matter how many times that strawman is repeated!!)

And terraforming Mars, in particular partial terraforming, is FAR easier than substantial crewed interstellar travel. Like you describe. Only someone who doesnít really understand how hard interstellar travel is would say otherwise.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Nomadd on 07/28/2022 03:31 am
And terraforming Mars, in particular partial terraforming, is FAR easier than substantial crewed interstellar travel. Like you describe. Only someone who doesnít really understand how hard interstellar travel is would say otherwise.

 I don't bookmark a lot of sites, but I really liked this one. It dos a great job of covering the details of various interstellar travel concepts.
 I know I'm not the first one to mention it here.

http://www.projectrho.com/public_html/rocket/slowerlight3.php#relcalc
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: KelvinZero on 08/26/2022 12:53 pm
You could make nanoballoon robots that replicate themselves from carbon and construct nanodiamonds they drop to the surface.
I had wondered about nano-balloon robots quite recently, or more specifically a " lighter than air liquid".

Im not sure if my logic is correct, but I think instead of having an atmosphere that gradually thins to nothing you could fill a crater or canyon with a lighter than air liquid and trap an atmosphere beneath it. The compressed air beneath is denser than the liquid but above could be pure vacuum.

..or maybe it would just form a whirlpool hole and the air would gush through it.

Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Paul451 on 08/26/2022 09:00 pm
You could make nanoballoon robots that replicate themselves from carbon and construct nanodiamonds they drop to the surface.
I had wondered about nano-balloon robots quite recently, or more specifically a " lighter than air liquid".
Im not sure if my logic is correct, but I think instead of having an atmosphere that gradually thins to nothing you could fill a crater or canyon with a lighter than air liquid and trap an atmosphere beneath it. The compressed air beneath is denser than the liquid but above could be pure vacuum.
..or maybe it would just form a whirlpool hole and the air would gush through it.

If the balloon-layer is "lighter than air", then it's not significantly compressing the atmosphere. So the air beneath would expand up and out (pushing up the "liquid") until it matches the density of the balloon-layer. At that point, the balloons and top-most air would mix freely, and the air would be able to disperse, further lowering the pressure of the air beneath; rinse and repeat until there's nothing left but the nano-balloons sitting on the ground.

The only way to prevent it would be if the nano-bots secured the balloons together into a coherent, air-tight layer. Which is just a membrane again.

So the question just becomes "could we use nanobots to make a membrane of arbitrarily large size?"
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Vultur on 08/27/2022 10:57 pm
Venus might be cooled with a combination of CO2 conversion and a huge, manufactured in space 'sunshield'. But the darn place rotates so terribly slowly this contributes to it's lackluster magnetic field - and who wants permanent daylight anyhow?! Mars is a better candidate for Terraforming. But I've always been very lukewarm for the idea. It would take a hell of a lot of money, energy and centuries of time to change it. Why bother? All the trillions spent on it and centuries to Terraform might instead be better used Terraforming Earth back to the 'ideal' state and building Starships to travel to other systems where Earth like planets had been discovered.

We already build gigantic sports stadiums and enclosed communities on Earth. Why not just use our Civil Engineering Super-know how to build pressurized Super-Domed cities on Mars? And if Mars does turn out to have a residual, albeit dying ecosystem left there - I don't think we have the ethical right to decimate it. Just my two cents worth of opinions...
Of course itís easier to geoengineer Earth than terraform Mars! Thatís not an argument against terraforming Mars because the motivation has nothing to do with trashing Earth. (No matter how many times that strawman is repeated!!)

And terraforming Mars, in particular partial terraforming, is FAR easier than substantial crewed interstellar travel. Like you describe. Only someone who doesnít really understand how hard interstellar travel is would say otherwise.

Yes... also, I doubt you'd find truly Earthlike (breathable) environments around nearby stars. "Earthlike" is a loose term... humans couldn't breathe Earth's atmosphere for most of its geological history. So you'll probably need terraforming technology anyway, if you want to live on off-Earth planetary surfaces.

(I personally think it would be easier to go from enclosed habitats on Mars to- once ISRU and asteroid mining is perfected - O'Neill style in-space habitats made from NEO or asteroid belt materials.)
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: su27k on 08/28/2022 06:05 am
How to terraform Mars for $10b in 10 years (https://caseyhandmer.wordpress.com/2022/07/12/how-to-terraform-mars-for-10b-in-10-years/)

Quote from: Casey Handmer
The pitch is to mass produce small scale solar sails in terrestrial cell phone factories, launch them into Low(ish) Earth Orbit (LEO), and have them fly themselves to Mars where, hanging out near Sun-Mars L2, they would reflect additional sunlight onto the night side of the planet. I first wrote about this four years ago.

<snip>

Marsí cross sectional area is about 36,000,000 km^2. 1000 sails add one additional square km to this tally. 150 million sails per year adds 150,000 km^2, which is an 0.4% increment in solar forcing. It is uncertain exactly how much extra heat is needed to heat Mars to the point where volatiles outgas from the regolith and trigger a positive feedback loop preventing radiative heat escape, but even if we brute force it, a decade of launches will increase the effective solar collection by 4% and, with 1.5 billion sails above Marsí night sky, the view would be spectacular. As a rough estimate, a 4% increase in energy input would require 4% higher thermal radiation to achieve equilibrium, which depending on some geometric factors of order unity, would result in a 1% temperature increase, from 210 K to 212 K. This is twice what weíve achieved with 250 years of industrial effort on Earth, burning a trillion tonnes of fossil fuels!

In fact, a solar sail placed near Sun-Mars L2 would have an apparent magnitude of about -0.75, similar to Polaris or Saturn, while billions of them filling a cloud with an angular extent of about 5 degrees would have thousands of sails per human eye pixel, creating a cloud of light like the Milky Way, only a substantially brighter echo of the reflected sun. While the surface brightness of this cloud would be only ~0.1% of the sun, the integrated brightness would be more than Earthís Moon when full.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: sghill on 08/28/2022 11:02 am
I've yet to read a single terraforming idea that is at the same time simpler, faster, cheaper, and more permanent than dropping large wet rocks onto the planet.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Twark_Main on 08/28/2022 11:10 pm
I've yet to read a single terraforming idea that is at the same time simpler, faster, cheaper, and more permanent than dropping large wet rocks onto the planet.

Water isn't the problem. Heat is the problem.

A large asteroid impact produces a lot of heat on a human scale, but it's tiny compared to solar radiation. Blanketing dry ice snow polar caps with dust also won't work, because the dry ice already sublimates away and switches poles twice a year.



Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Phil Stooke on 08/28/2022 11:43 pm
I'm surprised that you think finding large wet rocks, getting them to Mars and making them hit it will be simple, fast and cheap. 
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Vultur on 08/29/2022 12:34 am
A strong greenhouse effect could probably give Mars a reasonable temperature.

It's more a question of:

- hitting Mars with comets will mess up anything people are already doing on Mars

- if you can move comets on that scale, you can probably build space habitats, which would likely show results quicker than terraforming

I am not sure what the *point* is since you need large-scale asteroid-mining type tech/infrastructure anyway.

OTOH terraforming Mars may be a good vision to *sell* developing that infrastructure for someone like Elon Musk (like the big mural at SpaceX). But if that infrastructure ever actually exists, I don't think terraforming Mars is what it'll be used for -- at least not through

(IF it ever does happen, I'd expect something less disruptive like highly engineered microbes/nanobots [if there's even a difference] cracking atmosphere out of rock.)
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: Twark_Main on 08/29/2022 05:37 am
Hurling sulfur hexafluoride tanks at Mars is one possibility.

At 230 K and 6 bar the density of SF6 is 1.83 g/ml (https://www.researchgate.net/figure/P-v-diagram-of-Sulfur-Hexafluoride-i-ii-i-i-i-between-250-and-450-K-32_fig2_319028728). A 200 tonne spherical tank would be 6 meters in diameter.

That 200 tonne tank would have the equivalent greenhouse gas impact as 200 t x 23,900 x rEarth2/rMars2 = 17 million tonnes of CO2. So "only" 4,420 tanks per synod would need to be launched to match the current warming rate due to terrestrial CO2e emissions.

I presume the tanks would be designed to break up on reentry to release the SF6. Nice and simple. A small Starlink-derived cruise stage would ensure the tanks remain on course for Mars.

The tanks would be jettisoned after TMI by a "launcher" Starship, which would immediately retro-burn to remain in the Earth SOI. This way a single Starship can deliver multiple tanks per cycle.

If we assume that Earth is experiencing 1 degree of warming per century, then it would take "only" 884,000 tanks to achieve 2 K of warming.

This works out to about 118x as much mass as Casey Handmer's reflector proposal. But...

  • Sulfur hexafluoride has an atmospheric lifetime of 800-3,200 years (caveat: on Earth), vs optimistically a 30 year failure half-life for satellites

  • Sulfur hexafluoride is 80Ę/kg (https://exportv.ru/price-index/sulfur-hexafluoride), which compares favorably to $200/kg for satellites

  • There exists mixtures of greenhouse gases that offer roughly twice the specific warming (https://www.researchgate.net/publication/251438006_Radiative-convective_model_of_warming_Mars_with_artificial_greenhouse_gases) of pure SF6

  • In real life you would almost certainly simply make the sulfur hexafluoride in-situ on Mars and vent it, eliminating tank and launch costs.  :)



One of the first steps would be to better constrain the atmospheric lifetime of SF6 (and friends) on Mars.
Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: mike robel on 08/29/2022 06:20 pm
Does not contribute to the scientific discussion here, but a fun game to play for 1 to 5 players is https://boardgamegeek.com/boardgame/167791/terraforming-mars available from Sweden, various game stores, amazon, and even Target.  This is one of my favorite games to play and there are several expansions to include additional Mars maps, Venus, a prelude (to make games go faster), colonies, and Turmoil which adds trials and tribulations.

It can also be played in various digital forms.

There is also a card game version which I have not played.    https://www.fryxgames.se/produkt/terraforming-mars-ares-expedition/

Title: Re: Terraforming of Mars Ideas (and questions!)
Post by: KelvinZero on 09/01/2022 07:50 am
You could make nanoballoon robots that replicate themselves from carbon and construct nanodiamonds they drop to the surface.
I had wondered about nano-balloon robots quite recently, or more specifically a " lighter than air liquid".
Im not sure if my logic is correct, but I think instead of having an atmosphere that gradually thins to nothing you could fill a crater or canyon with a lighter than air liquid and trap an atmosphere beneath it. The compressed air beneath is denser than the liquid but above could be pure vacuum.
..or maybe it would just form a whirlpool hole and the air would gush through it.

If the balloon-layer is "lighter than air", then it's not significantly compressing the atmosphere. So the air beneath would expand up and out (pushing up the "liquid") until it matches the density of the balloon-layer. At that point, the balloons and top-most air would mix freely, and the air would be able to disperse, further lowering the pressure of the air beneath; rinse and repeat until there's nothing left but the nano-balloons sitting on the ground.

The only way to prevent it would be if the nano-bots secured the balloons together into a coherent, air-tight layer. Which is just a membrane again.

So the question just becomes "could we use nanobots to make a membrane of arbitrarily large size?"

Im not convinced of my own idea, but your intuition might not be strictly correct either. It may not do much to hold in pressure but it could reduce the height at which a wall in needed to hold the atmosphere in by hundreds of kilometers.

Just using the example of earth pressure where we have 10 tons of atmosphere sitting above every square meter. Maybe the first 9 tons fits into the first 20km or so (thats a guess) but then it just goes on and on. Your lighter than air liquid could still be lighter at that height. If this layer is thick enough to provide one ton of pressure its weight could equal what the hundreds of km of ever thinning atmosphere would have produced. I don't think there is any particular reason for the atmosphere to push through it, because it is lighter at the boundary and that is all that matters

(apart from all sorts of whether effects and whirlpools forming etc. Im only arguing at a spherical cow level)

edit: and sure, it could have some sort of surface-tension or other sort of clingyness. It has to be at least non-permeable to gasses, not with many gaps like a ball pit.