Mars in 3d
Chris - It's been an exciting week for Mars this week. Let's join Peter Muller, who's from the Mullard Space Laboratory at University College London. Hi Peter! Thank you for joining us. Part of your work is to try to get a three dimensional map of the surface of Mars, and I have to say having seen it, I'm gobsmacked.
Peter - Well it has been a revolution. Over the last few years we've received this stereo data from the European Space Agency's stereo camera, and with that and new computer technology we've been able to find out what the true 3D shape of Mars is. And what we've learnt from this, is that water is playing an important part. And what we heard over the last week was that in fact over the last 10 years, it appears that water has acted on the surface. So all of that has only been possible because of the increased resolution that we have from the stereo camera, and our understanding of how water flows on other surfaces.
Chris - Peter can you just explain to us a bit about what the stereo camera is and how it works?
Peter - Well we have nine different views that look at different angles. So there's a short time interval between each of those different views.
Chris - Where are they looking from though?
Peter - They're looking from orbit. From a space craft that swoops down to about 250km above the surface. And then when it gets down to the lowest point, it starts sweeping out a swab over the surface, looking first forwards and then underneath and then looking backwards. And by finding common points between those three in just the same way that we find common points in our brains between objects that we see in our eyes, we get perception of depth.
Chris - So why are you doing this? I mean it sounds nice, having seen the pictures it was staggering, it was literally like being in an aeroplane flying over the surface of Mars, but what sort of benefits will there be for us in having this sort of information?
Peter - Well currently the most important scientific investigations of Mars are concerned with looking at conditions which might in the past or possibly even at the present time, where there's life. Now, in order for life as we understand it, to exist on another planetary surface, we have to have water. Now in the case of Mars we don't see any standing bodies of water, we see ice sheets, but we do see examples of how water has carved out the landscape. Now just looking at pictures, and working out that yes this looks like a feature such as a feature on the earth is one thing. But in order to prove that it's actually water, and also to be able to calculate how much water, we need to be able to work out what the true feature shape is. That's really the significance of this work. Now for the first time we can determine whether or not water has flowed on the surface and how much water was required, and when this water flowed.
Chris - So apart from studying the hydrodynamics of Mars, are there any other tangible benefits, sort of like finding sites to put bases of the future. President Bush wants to go to Mars doesn't he.
Peter - Yes, I mean in 20 to 30 years time it's likely that we will have humans. Although the passage to Mars is still a bit challenging in terms of radiation from the Sun. But in terms of finding likely spots, where we can put robots and of course in future, humans, is very dependent on knowing what the 3D shape of the surface is. Not just because we don't want to land one of these spacecraft on a rock-strewn, boulder-strewn landscape that the space craft is likely to break up and collapse. But also from the point of view that we need to know how the surface interacts with the atmosphere, and in the case of Mars, that can happen for up to 20kms above the surface. And that makes a huge difference as to where the balloons and the parachutes will actually land our space craft.
Chris - I presume it will also give us a good clue as to where hot spots would be for life if we were going to go looking. It should give us an idea as to where we should focus our attention shouldn't it?
Peter - Yes. So far not just the 3D but other instruments on the European Mars Express space craft are now on the American Mars reconaissance, are pointing to those most likely locations. And it's a source of great debate, both transatlantic and within Europe and within the US, as to where we should go, what is the most likely place. Now, each of us has our own favourite place on Mars, my favourite place on Mars is a place that we believe there was a large frozen sea of pack ice, that we saw about 18 months ago. And it was reported in the literature. We want to go there because we know that water flowed in that area in the last few million years which is very young. But of course, we've seen the observations last week of gullies, where there appears to have been water in the last 10 years. And they may also be places we want to target on future space missions.