Science Interviews


Mon, 19th Oct 2015

Welcome to Mars

Professor David Rothery, The Open University

Listen Now    Download as mp3 from the show Could we ever Colonise Mars?

If we managed to make the seven month journey to Mars, what would be Marswaiting for us when we got there? What technical challenges do we need to solve to survive: how would we get food, water, shelter? David Rothery is Professor of Planetary Geosciences at the Open University, and he took Georgia Mills on a virtual tour of the red planet...

David - Well because Mars is a planet, so to say what mars is actually like is rather similar to saying, what Earth is actually like because there are many different settings on Mars. But the big difference with the Earth is that there's not much atmosphere. I mean, the pressure exerted by the atmosphere at the surface is less than a hundredth of what you'll experience on the Earth and itís not breathable air anyway.

Georgia - Say, you and I have solved the challenges of interplanetary travel, weíve just hopped over to mars and we very foolishly stepped out of our spaceship, what would happen? What would kill us first?

David - Well, I hope weíre not going to step outside the spaceship without wearing a spacesuit, pretty much the same kind of spacesuit as you need to wear in total vacuum because Marsí atmosphere is very, very tenuous. The atmospheric pressure is less than a hundredth for what we got on the Earth. So, even if the air on Mars was breathable, which isn't because it doesnít have oxygen in it, it would not be nearly dense enough to breath. So, you need to protect yourself in a spacesuit.

You also need to keep warm. By day, it can be well above zero centigrade - a nice warm 10 degrees or something, but in the winter, itís a lot colder and certainly at night, it gets extremely cold. So, the cold would kill you if you didnít have a way to keep warm.

If you're going to stay on Mars a long time, youíve got to worry about cosmic rays, solar wind particles. Mars has no magnetic field to deflect these, so you would get a radiation dose by wandering around on the surface of Mars. You would have a worse radiation dose on your journey from or to Mars because you'd be out in space. You wouldnít have a planet hiding half the sky. So radiation is an issue, but not the biggest issue on the surface.

Georgia - I guess first things first, we need to set up a base. What kind of things we need to take into account when weíre deciding where to put it?

David - If we want to survive, we go somewhere thatís warm and cosy, and has resources. If you want to go somewhere warm, thatís rather incompatible with finding somewhere where there's accessible ice if you want water. So, I guess we can keep ourselves warm with some solar panels to make electricity, so, Iíd say go somewhere where we can get a some water.

So you go to the polar caps but thatís very, very cold. Maybe go to a lower latitude where you think there's some ice a few centimetres or a few metres below the ground, and you can dig for the ice. But the trouble is, if you want to drink that ice, youíve got to purify it because itís probably pretty salty and I just donít mean table salt sodium chloride, I mean perchlorate. They're quite nasty alkaline salt. So, youíve got to be prepared to purify it.

Georgia - You mentioned using solar power. Is this the most feasible way to generate energy while you're on Mars?

David - Itís almost never cloudy on mars. Sometimes thereís a dust storm which blocks out the sun, but by day, youíve got clear skies. The intensity of the sunlight, because you are further from the sun is a half or less than what it is on the Earth but thatís plenty! Solar panels can generate lots of electricity for you. I mean, there's no point setting up a windmill. I mean, the winds do blow and they blow quite fast, but the atmosphere is so tenuous. There's not much power in that. So, forget wind power, solar power is the way to generate energy on Mars.

Georgia - What about oxygen? You mentioned the atmosphere is pretty rubbish really for breathing. Would we have to take all of our own?

David - Well, the atmosphere is mostly carbon dioxide and carbon dioxide is 2/3 oxygen. So, you can with the use of electricity split that apart and get some oxygen out of it. Or you can get oxygen from water. There is oxygen in the rocks! The rocks are silicates which is silicon dioxide and various metals. In fact, the Martian surface rocks are extremely oxidised - Mars is rust - thatís why it looks so red.

Now, thatís oxygen thatís there but if you can use a bit of electricity or any kind of power or chemical process to get that oxygen out of the rocks and get oxygen atoms to bond together to form O2, the oxygen molecule then youíve got something you can breathe.

So there's plenty there. It will cost you effort to get at it though and turn it into breathable form.

Georgia - Now thinking long term, how would we provide ourselves with food? Could you ever grow food on Mars?

David - I think you would be taking quite a gamble if you were the first person to arrive on Mars and were relying growing your food because plants require all kinds of trace elements which may or may not be there in the soil. The stuff at the surface of Mars isn't really a soil as we know on Earth. Of course, there's no organic content, or very little organic content and itís mostly very fine grained, very oxidizing fragments. But plants have been grown in Martian regulated simulants on Earth. So, there's a fair chance you can grow things on Mars. Weíre not sure how they'd cope with the weaker gravity - the Martian gravity is 1/3 what it is on the Earth. Thatís probably strong enough to give plants a good sense of what's up and what's down, which they need. There's enough sunlight. If youíve got water from the ground or from melting ice, itís certainly viable to grow plants on Mars.

Georgia - Just a bit tricky.

David - Just a bit tricky. Probably, more than a bit tricky but itís a problem that somebody will overcome one day.


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