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Old March 5th 21, 10:22 PM posted to sci.space.policy
David Spain
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Default Mars colonization

On 3/3/2021 3:39 PM, Alain Fournier wrote:
On Mar/3/2021 at 09:19, David Spain wrote :
IMHO one of the biggest blows to the concept was went it was
discovered that the chemical composition of Martian soil sampled at
one of the lander sites (I forget which) showed that the soil contains
poisonous compounds that would either prevent plant growth or cause
grown plants to become inedible. Therefore either soils will have to
be transported from Earth or food grown hydroponically. I suppose one
could hold up hope that with an extensive surface exploration program,
maybe one might find a spot on Mars that is otherwise. Seems unlikely
from where we stand today.


I'm not sure what you're talking about up there with the chemical
composition of Martian soil. I've heard that the soil is too salty. If
you have a cite for some information I don't have please provide it.
Soil that is too salty isn't a show stopper, just a hassle.


OK, you made me look it up. But you could have too. Chemical composition
of Martian contains a high degree of percholrate compounds that contain
cholrine. Including calcium perchlorate. In addition the most common
silicates in Martian dust are olivine, pyroexene and feldspar.

https://en.wikipedia.org/wiki/Martian_soil


This is not the pattern of chemistry used on Earth where soils are
typically infused with Nitrogen and Potassium in bacteria laden loam to
increase plant yields.

So I guess it depends largely on your definition of 'salts', but we're
not talking Sodium Chloride here.

Maybe you can grow a crop of water hyacinths to filter the percholrates
out of the Martian soil (see link above). But it isn't as simple a
process as adding dried human dung as laid out in the book and movie The
Martian. Andy Weir has written and admitted as much.

I'll discount the killer UV radiation that floods the planet surface,
since that can and will be filtered out in the habitat. Either via the
dome material or an underground cave.

When you can start growing food crops in perchlorate laden soils, why
not send a link to your results here. I'd be very interested.

Dave