Sculpting Mars

Chris - So we've heard how stars and planets first form from clouds of gas and dust in the atmosphere, and there are lots of other different processes that go on once these planets are formed though. And that means weather and volcanic activity, meteorites coming in, movement of ice or ocean swells, they all contribute to shaping the surfaces of planets, and it's often hard to work out exactly what's been happening when you try and wind the clock back. But one planet we do know quite a bit about is Mars, and Dr. Matt Balme is a researcher at the Open University, and he actually been looking at the various changes that have helped to scope the Martian surface. And he's with us now. Hello, Matt.

马特-嗨。你过得如何?

Chris - Very well, thank you. So tell us a bit about your research on Mars.

Matt - Well, I look at surface processes on Mars, and these are generally, at themoment, things do with either wind, water or ice. And I think Mars is a majorly interesting planet to look at because it has an atmosphere. It has ice. It has water, or had water. And you know, so in many ways, it's very like the Earth, and all the same processes, all the same physics happens on Mars as happens on the Earth. And it's also got a little extra added piquancy which is, there may or may not have been life on Mars at some point. So that's really why we aim to look at these processes, it's all really tied into the search for habitats, and the search for evidence, possibly, of life on Mars.

Chris - It's interesting you mention the biological role of shaping surface in Mars, because we've had an email from Blaine who says, "Were the red sands of Mars caused by biological activities because when the levels of oxygen rose on Earth billions of years ago, large quantities of iron rusted out of the atmosphere, and that left iron oxide deposits in rocks. So could the same thing have happened to Mars?" he asks.

Matt - Well, possibly. I think it's probably not the correct reasoning. The reason sands on Mars are red is really just due to a magnetite composition or ferrous iron mineral composition. You know, Mars may or may not have had an ocean. If it did have an ocean, it probably didn't exist for a very long period of time, relatively speaking, not like the Earth, which has been around for billions of years. So you know, we're loathed to rule anything out until we actually go there. I mean, that's one of the, you know, one of the wonders of planetary science. There's an alternative answer to almost everything. So...

Chris - People have found quite good evidence for a lot of water on Mars in the past, and correct me if I'm wrong, an ancient tide line a sort of, an edge of where that ocean would've been, but I think that the ocean, being long gone, that tide line has been reshaped by the geological processes. So it's all higgledy piggledy. But is there, nonetheless?

马特——好吧,这是有争议的。有相当few groups of scientists who think that when you actually look at the more recent data that we have from Mars, which have a much higher resolution in terms of, you know, how many meters each pixel in the image actually represents on the ground, they haven't found any good evidence for these shorelines. So the shorelines are still heavily under debate, and again, Mars planetary science as a whole, it's a science influx. There's a lot we don't know. And as each hypothesis gets built and then torn down again, eventually, we are closer and closer to the truth. That's, I guess, why it's so exciting.

Chris - So what are you actually looking at directly yourself?

马特-目前,我很多我们要做的事rk on what are called periglacial terrains. And they are terrains that have a lot of ice in the surface, but also some degree of thaw. And if you've ever been to, let's think, Siberia or Northern Canada, you might have seen these amazing patterned grounds, sorted stone circles, and stripes. And they almost look like human beings have made them but actually they are a class of self-organizing landform, which means that, as you have a cycle of freeze and thaw, rocks get moved by frost heave, so ice has a different density to water. You get differential movements of rocks. It actually saw some amazing circles and patterns, and we have been seeing very similar sort of things on Mars. And obviously this is quite controversial and quite interesting because you can only get this if you have some elements of thaw of ice. So up until this point, a lot of people have said, "Well we know there's ice on Mars, and we know there was water years ago, but we don't think there's actually been any melting of the ice or not significantly for maybe hundreds of millions of years." But what we're looking at are sorted stone circles, and sorted stripes, and all sorts of other periglacial landforms that looked just like the sort of landforms you see in Siberia, or Alaska, or Canada. So the conclusion is, there's been some thaw in the very recent past on Mars.

Chris - And what are the implications of that, Matt?

Matt - Well, I think the implications are that the climate was perhaps warmer than we previously had thought, you know, just in the last few millions years. Or that maybe there's some other unknown process that allows this ice to thaw, so maybe there's an awful lot of salts dissolved in it. And that's, you know, anyone who has thrown salt onto the drive to, you know, help clear the ice knows, that you have salt in your water that depresses the freezing point. So, you know, all these things are interesting because they hint a possibility of a more habitable Mars than we previously thought.

Chris - Which of course, might have implications for not so much life once, but the existence perhaps of life today?

Matt - Well, yeah. I have to say I'm generally a bit of a non-believer in terms of life on Mars. I tend to think that if life ever got going it would be so obvious that we'd be able to see it from Earth very easily. But, you know, it does imply that if Mars was more recently wetter than we thought, it has a much higher chance there being current life or dormant life. Maybe if it was a million years ago there was habitability, obviously even if that stopped half a million years ago, and everything that was alive there is now dormant, we wouldn't be able to see it unless we actually got in there with a shovel and started digging.

Chris - What can we learn by studying these sorts of things on Mars about other planets, maybe not even in this solar system?

Matt - Well, Mars is a counter-example to the Earth. Everything we know really about geology and planetary geoscience in general, we basically we know from the Earth. Studying Mars gives a point, counterpoint sort of ideas about how planets evolve. In terms of outside the solar system, it can give us hints about sort of things we might be seeing, but of course, it's going to be impossible for us to ever, or I say ever but, in our lifetimes ever have our hypothesis tested. You know, you may think, "Oh perhaps this exoplanet has sand dunes, or glaciers, or rivers" but we'll never know. You know, at least not in our lifetime.