Making Mars Habitable For Plants Could Be Surprisingly Easy for Partial Terraforming

Around 50 K of surface warming is required on Mars to raise annual average low- to mid-latitude temperatures to above the melting point of liquid water. Mars’s current atmosphere is too thin to significantly attenuate ultraviolet (UV) or to provide greenhouse warming of more than a few kelvins. However, observations of dark spots on Mars’s polar carbon dioxide ice caps suggest that they are transiently warmed by a greater amount via a planetary phenomenon known as the solid-state greenhouse effect, which arises when sunlight becomes absorbed in the interior of translucent snow or ice layers. The solid-state greenhouse effect is strongest in materials that are partially transparent to visible radiation but have low thermal conductivity and low infrared transmissivity. Although carbon dioxide and water ices are common on Mars, they are much too volatile to make robust solid-state greenhouse shields for life. Silica has more favorable in properties in that it is chemically stable and refractory at Martian surface temperatures. Solid silica is transparent to visible radiation, but opaque to UV at wavelengths shorter than 200–400 nm and to infrared at wavelengths longer than ~2 μm.

Via the solid-state greenhouse effect, regions on the surface of Mars could be modified in the future to allow life to survive there with much less infrastructure or maintenance than via other approaches. The creation of permanently warm regions would have many benefits for future human activity on Mars, as well as being of fundamental interest for astrobiological experiments and as a potential means to facilitate life-detection efforts. The solid-state greenhouse warming concept also has applications for research in hostile environments on Earth today, such as Antarctica and Chile’s Atacama Desert.

It will be important to investigate the ease with which traditional silica aerogel manufacturing techniques can be adapted to conditions on Mars. However, given the ability of life on Earth to modify its environment, it is also interesting to consider the extent to which organisms could eventually contribute to sustaining Martian habitable conditions themselves. On Earth, multiple organisms already exist that utilize silica as a building material, including hexactinellid sponges and diatom phytoplankton. Diatoms in particular can grow up to several millimetres in length, produce frustules from ~1–10 nm-diameter amorphous silica particles (smaller than the mean pore diameter in silica aerogel networks) and are already known to have high potential for bionanotechnology applications in other areas. It could therefore be interesting in the future to investigate whether high-visible-transmissivity, low-thermal-conductivity silica layers could be produced directly via a synthetic-biology approach. If this is possible, in combination with the results described here, it could eventually allow the development of a self-sustaining biosphere on Mars.

There is the potential for Mars to be made habitable to photosynthetic life in the near to medium term, important ethical and philosophical questions must be considered. Most obviously, if Mars still possesses extant life today, its survival or detection might be hampered by the presence of Earth-based microorganisms. However, no mission has yet detected life on Mars, so if it does exist, it is likely to be confined to very specific regions in the subsurface. The approach studied here would not result in the survival of Earth-based life outside solid-state greenhouse regions, so it should be unlikely to pose a greater risk to the search for Martian life than the presence of humans on the surface. Nonetheless, the planetary protection concerns surrounding the transfer of Earth-based life to Mars are important, so the astrobiological risks associated with this approach to enabling Martian habitability will need to be weighed carefully against the benefits to Mars science and human exploration in future.

Nature – Enabling Martian habitability with silica aerogel via the solid-state greenhouse effect

The low temperatures and high ultraviolet radiation levels at the surface of Mars today currently preclude the survival of life anywhere except perhaps in limited subsurface niches4. Several ideas for making the Martian surface more habitable have been put forward but they all involve massive environmental modification that will be well beyond human capability for the foreseeable future9. Here, we present a new approach to this problem. We show that widespread regions of the surface of Mars could be made habitable to photosynthetic life in the future via a solid-state analogue to Earth’s atmospheric greenhouse effect. Specifically, we demonstrate via experiments and modelling that under Martian environmental conditions, a 2–3 cm-thick layer of silica aerogel will simultaneously transmit sufficient visible light for photosynthesis, block hazardous ultraviolet radiation and raise temperatures underneath it permanently to above the melting point of water, without the need for any internal heat source. Placing silica aerogel shields over sufficiently ice-rich regions of the Martian surface could therefore allow photosynthetic life to survive there with minimal subsequent intervention. This regional approach to making Mars habitable is much more achievable than global atmospheric modification. In addition, it can be developed systematically, starting from minimal resources, and can be further tested in extreme environments on Earth today.

SOURCES – Nature
Written By Brian Wang, Nextbigfuture.com

59 thoughts on “Making Mars Habitable For Plants Could Be Surprisingly Easy for Partial Terraforming”

  1. Based on discussions with chemists, the same chemicals have strong chemical interactions as have strong light/radiation interactions. Because both sorts of interactions involve the outer electron shells having electrons ready to absorb and give off energy.

    Which is why brightly coloured vegetables and spices have more vitamins and antioxidants.

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  2. Life would survive as soon as UV radiation is decreased. To make it safe long term for humans additional measures can be taken and there are many options.

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  3. Pretty condescending for a guy who misses the obvious, aren’t you? Sticking two stations on a tether and changing the distance is a mechanical solution, subject to wear and tear, like I already said. As is using a hull as a radiation shield. Planets have neither issue.

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  4. Yes, buckling is a failure mode that makes compression structures much, much heavier than the equivalent tensile structures once they reach any sort of size.

    Which is why you should try to make your structures tensile if you can.

    (Unless you are making them out of rock or concrete, which is strong in compression but rubbish in tension.)

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  5. Actually, I *do* question whether greenhouses would work. Mars has, in living memory, had wide-area duststorms that lasted months. Counting on sunlight isn’t practical.

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  6. I did a very basic calculation once and if you use Venusian imports (getting it off the ground with a battery of current tech railguns at a large order discount of 1Million /gun) and shipping it out with solar sails, you would arrive at 40 trillion USD. Which is only 40 ‘Apples’. Sure we’ll invent a better and cheaper approach, but even that price is not inconceivable (if spent over a century or more by an international body). The economic return would pay for it (agricultural colony with roughly the same available area as the land mass on Earth)

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  7. You severely overestimate the dosage of both forms or radiation on the surface of Mars even without any form of protection.

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  8. You severely overestimate the dosage of both forms of radiation even when standing completely naked on the surface (which no one will do).

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  9. They come in pairs to cancel precession. The whole pair rotates slowly, to make the connections tensile. They temporarily let out the lines to let the ‘roid pass. Clusters of large stations, where the individual structures required supplies the radiation shield. An obvious size to pick. My point is that thinking can be fun! Try it.

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  10. Nor can massive stations, what’s your point? Unless you’re talking about clusters of smaller stations, which are a waste of resources and won’t hold as many people.

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  11. Har! Planets are tiny and awkward. See G. K. O’Neill for details. They cannot move out of the way of asteroids.
    See Janov for a true visionary!

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  12. Planets are neither tiny nor awkward. They don’t tend to burst when a small asteroid hits them, either. The atmosphere being on the outside is a massive advantage, acting as a shield that never depletes. They are stable over much longer time periods than manmade objects that rely on machines to sustain them. O’Neill cylinders are nice to have, but only planets are necessary for the long term goal of seeding life thoughout the stars.

    Also, my comment wasn’t an attempt at sarcasm, it was sarcasm. You’re not a visionary, you’re some bloke on some web site’s comments section. Get over yourself.

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  13. Or, better yet, to the much larger, by millions of times, O’Neill Space of our local solar system. Planets are so tiny, and awkward to live on, we should leave them to Nature, as far as possible. Especially where *advanced* Nature already exists. Sometimes attempts at sarcasm reveal truth to the attemptor! I’ve seen it many times, esp with Janov’s discovery.

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  14. You’d never use NF3. But there are plenty of far less reactive compounds available. Basically all of them ARE fluorine compounds, though, for some reason.

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  15. Pretty much, it would be a flat balloon with internal stays, unroll it, inflate it, and then fill the bottom with dirt. It wouldn’t be self inflating, because it would have to be air tight, there’s no room for the dirt until after you inflate it.

    You’d need about 300 grams of structure per cubic meter of interior, conservatively estimating. The air would actually have 4 times that mass!

    For greenhouse use you would set it on the surface, and cover it with the aerogel tiles after inflating. For living purposes, you’d bury it with enough dirt to counter most of the air pressure, for radiation and meteor protection.

    In fact, you’d probably stack them, living space on the bottom, a few meters of dirt, then greenhouse on top.

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  16. You’re confusing the difference between tension and compression. Holding IN air requires tensile strength, which tends to have the advantage of being deployed in a stable manner, so you can efficiently use almost all the available strength.

    Holding air out require strength in compression, which is subject to buckling.

    Vacuum airships require holding air out, are subject to buckling, and thus require a LOT more material than the simple numbers of PSI air vs KPSI material suggest.

    Fortunately on Mars we’d be holding air in, so the structural mass is quite low.

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  17. My other comment seems to have disappeared… NF3 is also an incredibly powerful etchant, and will eat through the silica domes like a fat kid through cake.

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  18. Oh such visionaries, bow to them! If restoring Earth to prime habitat should be the goal for Earth, spreading prime habitat to other planets is a logical extension of said goal.

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  19. Might as well use something heavier, like boron-doped glass, and have the internal air pressure support a portion of the weight.

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  20. To be fair, most humans already live in environments that require continuous maintenance.

    eg. As Tolstoy observed in his novel War and Peace, 1812 Moscow was a large city, made of wood, straw and tar, in which every room was heated by fire, lit by fire and all cooking was done by fire. It required continuous effort on the part of tens of thousands of people to stop the place burning down. As soon as the inhabitants fled ahead of the marauding French hordes, and were partially replaced by Frenchmen who neither knew nor cared that much about the firefighting requirements, it was inevitable that the place would burn to the ground. Which it did.

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  21. As I point out above, since Mars gravity is lower than Earth, and a normal atmosphere achieves its pressure by the weight of the gasses, Mars requires about 2.6 times as much gas per square meter as does Earth to maintain a given pressure.

    The advantage there is that it gives you 2.6 times as much radiation shielding, which could be very useful if you aren’t getting shielded by a planetary magnetic field.

    But yes, you need to get that atmosphere from somewhere. Venus seems to have too much…

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  22. NF3 is considered hazardous to breathe at levels above 1000 ppm. I’m not sure that’s what you want to be pumping into your atmosphere.

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  23. Worst of all, the article conveniently ignores the fact that the silica gel does nothing to block either cosmic or solar ionic radiation, which is much more deadly than UV. Life wouldn’t survive under the silica gel any better than without it.

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  24. Sounds good but the article conveniently ignores the fact that the silica gel does nothing to block either cosmic or solar ionic radiation, which is much more deadly than the UV. No life would survive under the silica gel any better than without it.

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  25. Establish the human colony on Mars first.  Allow to grow to at least 10-50K more or less.  Have the colonists setup on Mars factories at various locations to manufacture NF3 (Nitrogen Trifluoride); “..because NF3 has a 100-year global warming potential of 17,200, meaning that it is 17,200 times more powerful than carbon dioxide in trapping atmospheric heat over a 100-year time span – much higher than most other GHGs.”
    https://www.wri.org/blog/2013/05/nitrogen-trifluoride-now-required-ghg-protocol-greenhouse-gas-emissions-inventories

    In a time frame measured in likely decades (not centuries/millennia) this super-greenhouse gas will cause the Martian CO2 to outgas and the water melt; warming the planet & making the atmospheric pressure considerably higher, maybe above the Armstrong limit.

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  26. Indeed! If one can make that sort of lightweight rigid material that can handle 0 to 1 bar pressure difference, we’d already have vaccum airships –> stratosphere floating islands (with railguns on top for massive scale launch of inert materials), so way faster space colonization.

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  27. Surely magnetic field producing satellites could mitigate this problem?

    Obviously the field doesn’t need to be strong so much as wide, though perhaps the distance from Mars per satellite could reduce the necessary size of the field, given an equidistant network of them to cover the whole planet – or would the field only need to protect from the solar wind, and not cosmic radiation too?

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  28. If people had listened to me for the last 40 years as I “belly ached” about Mars Direct/First/Only, we would have started lunar development 40 years ago. Listening too me now will prevent further delay. THAT benefit! (edit: please tell Musk!, unless you are not trying to help him.)

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  29. Habitable for whom? I can easily see tardigrades living in these nano jungles. It would give earth life a chance to evolve into mars life. Then we can bioengineering ourselves.

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  30. Once they are there. The shifting of the context to the accomplished future does not answer the big, O’Neill question. How do we best get to that future? The answer is clear, but most of the people have not even heard the question!

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  31. “Rather”? I do celebrate Musk! Your continuing point that we can do everything masks the fact that we need to something ASAP. Almost looks like some sort of denial, to be honest. Once we get anything O’Neill like started, all else will be easy. Even Mars, if desired. Waiting for Mars will NOT.

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  32. Sounds like complete BS to me… mars is only habitable using nuclear energy to generate electricity for heater, grow lights to provide light without lethal radiation, and to run air rebreathers…. all else is bullcrap…

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  33. The Martians will trade with the Orbitals and Belters for things they lack and the others have. Trade is what makes the world work.

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  34. The pressure difference between sea-level Earth and ambient Mars gravity and pressure amounts to a lifting force of 27 tons/square meter. This is equivalent to 10 meters of solid rock or glass.

    So the easy way to make your habitat dome is to make it heavy and thick to counteract the internal pressure. This will also provide radiation shielding and thermal control. Most of the weight can be unprocessed local rocks and dirt.

    Assuming you want to grow things under the dome, Mars gets less light than Earth. So the way to handle that is heliostats (steerable mirrors) to direct sunlight through side-facing windows. The heliostats would be arranged around ground outside the dome to collect additional light. Since they are controllable, you can get whatever day/night and seasonal lighting the plants need.

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  35. Rather, you should celebrate that we’ve got Musk AND Bezos, Mars and Moon. Rather than putting all our extraterrestrial eggs in one basket.

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  36. Spectra is an oriented ultra high molecular weight polyethylene, easily manufactured from Martian resources. It is strong enough that a 10mm cord per every square meter would be sufficient to restrain full Earth atmospheric pressure. It’s also chemically resistant, and largely unaffected by UV radiation.

    You’d likely have infrequent but thick ropes anchored in the soil, which once they got above the area you wanted unobstructed would split fractally until they were supporting a membrane at close intervals. This membrane would restrain the air pressure, and then you’d stack the aerogel tiles over it for protection.

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  37. I am having great difficulty even understanding how this is different than setting up a green house on Mars which is exactly how it has always been talked about. Scaling this up to larger areas is called paraterraforming https://en.wikipedia.org/wiki/Terraforming#Paraterraforming . Silica is just glass, as in standard greenhouse. Silica aerogel just adds some insulation to the green house, great, but not revolutionary. But just adding some moisture from melting martian ice is not going to make the enclosed area too habitable for any sort of life. Way too much CO2 for animal life. Would need some serious structure for holding in the required pressure.

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  38. Elon needs to get off that Mars train. It is the wrong train. He has already decided to be unable to refuel with lunar water derived H and O. He needs CO2 from Mars, or launched. But every decision is/has been colored by Mars considerations. He only recently mentioned Moon as a destination, but still seems unimportant to him. Too bad!

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  39. “There is the potential for Mars to be made habitable to photosynthetic life in the near to medium term, important ethical and philosophical questions must be considered.”
    Such as “Is the surface of a planet the right place for an expanding technological civilization?” -G. K. O’Neill
    Get the wrong answer here, and such things as Mars are thought of instead!

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  40. Normal terraforming on Mars has several problems. Not just atmospheric stripping, which would even be slower than you suggest, especially if an artificial magnetosphere were produced.

    As I point out above, since Mars gravity is lower than Earth, and a normal atmosphere achieves its pressure by the weight of the gasses, Mars requires about 2.6 times as much gas per square meter as does Earth to maintain a given pressure. That’s a LOT of gas to import!

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  41. I don’t think building greenhouses, literally building greenhouses, is what most people mean by “terraforming”. Though it would unquestionably work, and could eventually be extended to enclose the entire planet in a bubble of atmosphere deep enough for local weather, but still requiring far less mass of gasses than a normal atmosphere would. (Given the lower gravity on Mars, maintaining Earth standard pressure requires about 2.6 times as much air per square meter as is needed on Earth.)

    It would be helpful to incorporate solettas, too, to compensate for the reduces sunlight. Thankfully, given Mars’ lower gravity, synchronous orbit is quite a bit lower.

    It’s a workable plan, though continuous maintenance would be required, given constant damage by meteors.

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  42. To clarify what this mean..  All you need to do is put in a greenhouse like structure made of multilayer tiles including a layer of silica aerogel and the temperature within the structure will automatically go up by 50-60 degree, the ice will melt, the frozen CO2 will evaporate and the pressure inside the structure will also increase due to gassing out of CO2 and other frozen gasses from the frozen soil.  All you need to do is bring in plants and some nitrogen fertilizer and let it grow for a few years. Photosynthesis will do its thing and turn the atmosphere into Oxygen rich and breathable.  Yes, the structure and the tiles will need to be robust but you would want that anyways.  Also, I think you could include a lead infused acrylic layer to block the radiation.  Will get nice and warm on the inside.  Considering people, equipment, animal all produce heat it will get almost tropical in there.  The great thing about it this can be started small, say a km2 and added to in new sections eventually covering large areas of multiple km2.

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  43. The linked article mentions strengthening the aerogel with some sort of embedded layer to maintain some level of pressure. Doesn’t give much detail, so they may not have thought that angle through yet.

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  44. Does the author realize that the pressure on Mars is equivalent to a very good vacuum on earth? The ‘simple solution’ becomes complex when the insides must be pressurized to 14.7psi, and the structure must withstand that 1bar differential to the outside, with likely a 3x to 4x safety factor. Aerogel won’t withstand very much pressure differential.

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  45. this is a great idea! the area could be small at first and grow with time. the incloused area will be pressurized and have additional radiation reducing layer, like leaded glass. the plants will make O2 and consume our CO2. It is called paraterraforming.

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  46. Total BS. You would need to make millions of sq. miles of this aerogel which would completely mess up the whole planet. You could not walk around on the surface as the air would be as thin as it is today and you would also still have the UV problem. Run a few la
    rge comets into mars and the atmosphere thickness problem is solved. You could do that with a nuclear powered ion rocket engine on the comet which you remove once the comet is on the correct path, You than put the engine on another comet.

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