Space plants for Martian greenhouses

[CaptainPanic]

Good morning!

 

Over coffee, I came up with the following.

 

I believe that Mars is quite a nice place for plants. The atmosphere is nearly pure CO2, which must sound like heaven for a plant if it had ears.

 

The pressure is 750 Pa (7.5 mbar). That means that the CO2 pressure is a lot higher than on earth (where we have merely 35 Pa CO2 pressure).

 

How difficult would it be to grow plants in the Martian atmosphere?

 

I know that the temperature is too low. Water, if available at all, is solid. But those two points can be solved with a simple solution: a greenhouse.

 

The point I'm trying to make is: a greenhouse could be really simple and low-tech. Just a plastic foil to create an insulation and raise the temperature to a little above zero Celsius.

 

Also, the additional vapor pressure from water would be no problem (at 5 deg C, we are talking about 6.5 mmHg (or, 8.5 mbar). That overpressure is perfect for keeping the greenhouse inflated.

 

The only high-tech piece of equipment you could need is a way to remove oxygen from the "air" inside the greenhouse. Venting it to the outside atmosphere would also cause the greenhouse to lose water.

 

Any thoughts?

[Gilded]

Here's a NASA article on the subject:

 

http://science.nasa.gov/headlines/y2004/25feb_greenhouses.htm

 

That's over four years old, but I'm pretty sure there's still lot of research to be done regarding how to make plants adapt to low pressure. And even then the 8.5mbar you mentioned is far too low.

 

Anyway, while the atmospheric conditions aren't that hostile I wouldn't say that Mars per se is a nice place for plants as the soil is basically barren.

[YT2095]

as for the soil, chlorates have been found in it, AKA weedkiller.

so it`s probably not the Best idea to use the native soil anyway

[CaptainPanic]

First of all - thanks for the article. It's really interesting. I've enjoyed reading it. It probably contains more parameters for growing plants on Mars than we could come up with in this thread.

 

That's over four years old, but I'm pretty sure there's still lot of research to be done regarding how to make plants adapt to low pressure. And even then the 8.5mbar you mentioned is far too low.

 

Why would that be too low?

 

760 mmHg = 1 bar

6.5 mmHg = 0.0085 bar = 8.5 mbar. That is the vapor pressure of water at 5 deg C.

 

You probably meant to say that, of course, the soil needs to be watered. Plants cannot get the water from the air. Plants (most at least) prefer liquid water. I'm just talking about the added vapor pressure that can be used to inflate the greenhouse, because in greenhouses the air is almost completely saturated with water...

 

as for the soil, chlorates have been found in it, AKA weedkiller.

so it`s probably not the Best idea to use the native soil anyway

 

Hmm. Good point. We'd need a whole bunch of nutrients. We also need to remove a couple of other nutrients.

 

Would moss be an option? Some of the mosses grow on bare rock. For those, perhaps merely removing the toxic components is enough? It could limit the amount of fertilzer needed. And they also grow at low temperatures.

 

I would suggest that the ultimate goal of developing plants for Mars is that you can work in open greenhouses, like here on earth. Greenhouses that do have their own climate (temperature, humidity), but that are ventilated with outside CO2 (Martian air).

[Moontanman]

Good morning!

 

Over coffee, I came up with the following.

 

I believe that Mars is quite a nice place for plants. The atmosphere is nearly pure CO2, which must sound like heaven for a plant if it had ears.

 

The pressure is 750 Pa (7.5 mbar). That means that the CO2 pressure is a lot higher than on earth (where we have merely 35 Pa CO2 pressure).

 

How difficult would it be to grow plants in the Martian atmosphere?

 

I know that the temperature is too low. Water, if available at all, is solid. But those two points can be solved with a simple solution: a greenhouse.

 

The point I'm trying to make is: a greenhouse could be really simple and low-tech. Just a plastic foil to create an insulation and raise the temperature to a little above zero Celsius.

 

Also, the additional vapor pressure from water would be no problem (at 5 deg C, we are talking about 6.5 mmHg (or, 8.5 mbar). That overpressure is perfect for keeping the greenhouse inflated.

 

The only high-tech piece of equipment you could need is a way to remove oxygen from the "air" inside the greenhouse. Venting it to the outside atmosphere would also cause the greenhouse to lose water.

 

Any thoughts?

 

Actually the main problem would be that water cannot be a liquid at the atmospheric pressure of Mars. It sublimes like frozen CO2 does on the earth.

[CaptainPanic]

Actually the main problem would be that water cannot be a liquid at the atmospheric pressure of Mars. It sublimes like frozen CO2 does on the earth.

 

That is why I initially proposed an over-pressure (created by water vapor) inside the greenhouse. I showed what pressure would be required at 5 deg C to have a normal equilibrium between liquid water and the water vapor at 5 deg C.

 

But you're right that because of the really low pressure, it is not possible to have open systems like I proposed in the last line of my 2nd post in this thread.

 

Conclusion: Greenhouses on Mars must be like big transparent balloons!