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I'm wondering if the following is possible:

  • Find a sunny spot on Mars
  • Fix up the soil so it's not poisonous
  • Put heaters in the soil
  • Put a loose transparent tent over it to help hold in the heat
  • Add "water" - I'm guessing the water would actually be water vapor, due to low pressure.

So: could anything edible grow there? Maybe fungus?

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    $\begingroup$ fungi are consumers not producers, they need plant life to feed on. $\endgroup$ – John Oct 25 '20 at 16:36
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Someone tried this:

They planted crops in simulated Martian soil and subjected them to simulated Martian lighting.

... kale, sweet potatoes, certain lettuces, and, surprisingly, hops grew very easily, tasting no different than their terrestrial counterparts. Other foods, including regular russet potatoes—the famous staple of the stranded astronaut in the 2015 film The Martian—required special soil or light treatments.

The only thing missing from your question and what they did was they added pressure. The student doing the study added Earth-like air pressure for the experiment.

Lichen can grow at Mars atmospheric pressure, so can some Algae, but for anything else you'll need to increase the pressure to at least 0.47atm. So, until terraforming gets pretty far, you're growing plants indoors on Mars. That "loose transparent tent" is an airtight dome.

Note that the highest human settlement (La Rinconada) has an air pressure of about 0.5atm, and humans can survive as low as 0.06atm (with supplemental oxygen), so there's a decent chance humans will be outside on mars without pressure suits before plants can grow.

Algae has potential to be a good food source - so with a bit of genetic engineering / selective breeding the answer to your question is a reserved yes. But growing typical crops at mars air pressure - no.

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  • $\begingroup$ "humans can survive as low as 0.06atm" - do you have a source for this? $\endgroup$ – void_ptr Oct 25 '20 at 15:44
  • $\begingroup$ en.wikipedia.org/wiki/Armstrong_limit $\endgroup$ – Ash Oct 25 '20 at 16:01
  • $\begingroup$ @void_ptr You are correct I should clarify that's pressure minimum. Hypoxia can kill even if the pressure is sufficient. $\endgroup$ – Ash Oct 25 '20 at 16:03
  • $\begingroup$ Wow, the student added Earth-like air pressure? Elaborate system of pressure vessels? Pressurized old airplane fuselage? ;) $\endgroup$ – Harper - Reinstate Monica Oct 25 '20 at 19:03
  • $\begingroup$ If you rely on the martian atmopshere, You couldn't grow legumes and other plants that fix their own nitrogen - martian atmosphere is too low in N. IIRC nitrogen was a major plot point in the red mars trilogy and had to be imported from somewhere else. $\endgroup$ – mart Oct 26 '20 at 7:56
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In actual natural Mars Atmosphere, this is impossible.

The air pressure is too low. It varies a lot, but never exceeds about 1.2% of Earth sealevel, and is usually below half of that.

At such low pressure, there is no such thing as wet water! All of your water will be either ice, or water vapor. (or a brine so strong it is almost a sludge, and completely toxic to all life)

The composition of Martian air is not a big problem. Very rich in CO2, very poor in buffer gases and O2, but many plants could handle it if only the pressure was increased 50 fold.

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  • $\begingroup$ It has apparently been tried successfully, though I've never been able to track down details of the experimental setup. The cell walls of the plants can provide enough pressure to keep water liquid, though they would transpire it ridiculously quickly and would require constant irrigation...you would not grow plants this way except as a stunt. More reasonable would be to make a sealed greenhouse and allow the water vapor to pressurize it, which only adds 0.03 atm or so of pressure (depends on temperature). $\endgroup$ – Christopher James Huff Oct 26 '20 at 0:19

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