Friday 20 June 2014

Martian Survival Classes

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.

2 comments:

  1. They could build their first base next to the polar ice cap and use all that ice to make oxygen.

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  2. The 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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