It doesn't take much research
into the human and technical elements of colonising Mars to realise that huge
numbers of people across the world are keen to see it happen. Many of them are
using online forums to pool very practical ideas.
What are the basic technologies that
will keep colonists alive?
First of all is oxygen. The very
thin atmosphere of Mars is mostly carbon dioxide. Water can be electrolysed
into oxygen and hydrogen. So how will they find enough water?
- By digging it up! The loose Martian
dirt, or regolith, contains a varying amount of water ice. Heat the regolith and
collect the water vapour.
- By reacting the carbon dioxide
in the Martian atmosphere with hydrogen to make water and methane. The latter
is useful as fuel for rockets and generators. But the need for a stock of
hydrogen may make this impractical for long-term use.
- By 'adsorbtion' into a special
kind of rock called zeolite. Zeolite is a range of minerals known to be good
'molecular sieves'. One of these has a certain atomic structure which allows
water molecules to enter, but keeps out the larger carbon dioxide molecules. So
it just sits there and soaks up water from the atmosphere.
How efficient is zeolite? According
to a NASA fact sheet the atmosphere is 210 parts per million of water by volume.
So to squeeze one litre of water vapour from the air, you'd have to pump about
5 cubic metres of Martian air through the zeolite. And when that water vapour
condenses into liquid, it only makes about 1ml of water! (It's actually a lot
less, because the density of water vapour would be very low at Mars's very low
atmospheric pressure.) So you'd need a lot more than 5,000 cubic metres of air
to make a liquid litre. Then again, that tiny amount of water vapour in the
atmosphere will vary by season and location. A zeolite unit with an air pump
may become standard survival gear aboard crewed Mars rovers.
All this is like continually
planning a vacation that never comes. It will be intriguing to see how the
first Mars pioneers solve their problems.
They could build their first base next to the polar ice cap and use all that ice to make oxygen.
ReplyDeleteThe main difficulties with the polar approach are 1) much lower incidence of sunlight, so solar power is less efficient, and 2) the climate is even colder than mid-latitudes. Oh and there's 3) it takes more delta-V (more burning of fuel) to land that far from the equator. So it would be possible but impractical for an early colony site.
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