Routes into space science

OK. So hello, we’re delighted to have Professor Sanjeev Gupta of Imperial College London, who is a planetary scientist who has been studying Mars for some time now. So Sanjeev, thank you very much for being here. Thanks. Great to be here. So why observe Mars in the first place? What makes it interesting, particularly for you? So I’m actually an interloper. So I’m actually an Earth geologist, and most of my career has been actually working on modern environments on Earth. So I’m interested in surface processes, what shapes the landscape. I got interested in Mars accidentally really. And what’s fantastic about Mars is we have a really, really rich record of sedimentary rocks on Mars.

In fact, we have an abundance of sedimentary rocks from really the earliest time of planet formation on Mars. Way more than on Earth, because on Earth, the oldest rocks have been destroyed by plate tectonic processes. So they’re really deformed and horrible to look at really, where they are pristine on Mars. And what’s really exciting about those rocks is that they likely record a time that Mars was really warm, and very wet, and so potentially habitable for life. So that’s a really interesting thing. But in some ways, early Mars was somewhat similar to early Earth, is that right? That’s right. So the oldest evidence for life that we can be sure about is 3 and 1/2 billion years ago.

And we have these things that are called stromatolites.

They were sticky mats created by microbes which sediment got trapped in, and you can see these beautiful layers and domes et cetera. And we can be certain that those are almost certainly formed by early life. But we have rocks on Mars of that age, and to me it seems surprising that life only arose on Earth and didn’t arise on Mars. And so we can look for that evidence in those rocks on Mars. So you’ve been involved sometime in the NASA Curiosity rover.

How have you been using that mission to try to understand Mars? So I have two roles on the mission. Firstly, I’m a scientist on the mission, I’m part of the Mastcam camera team. And my role is, as a sedimentologist and geologist, is to basically pick targets for imaging the landscape and rock outcrops on Mars where Curiosity is. And basically selecting targets and actually thinking about where we’re going to drive et cetera. And then interpreting those images in terms of what processes form those rocks, what was a palaeoenvironment, and was habitable for life basically. And then to lead to all these other questions. Should we drill there et cetera to look for chemical signatures of life et cetera?

Secondly, I have a major operations role, so I’m one of 10 what we call long-term planners. And this is a strategic role where we work directly with project management in guiding the science team to achieve its objectives. Keeping them on the road basically. And then I work with the engineers when I’m on shift which might be three or four days a month. Maybe longer sometimes, a week, where we lay out the plans for what the rover’s going to do in the next few days to a week ahead. So most of the team basically work tactically, they turn up for shift on a particular day, and just planning what the rover will do that day, what experiments we will do.

But often those experiments have been strategically planned. And so that’s my role, along with the other long-term planners, is thinking carefully about how we will achieve these goals. And so obviously, for most of the history of astronomy, observing Mars has only been able to be done with a telescope from afar. What does Curiosity, what do rovers and landers get us, that telescopes simply can’t? Well, we can take pictures that we can see images of rocks. If you look at the palm of my hand, you can see the lines on the palm of my hand. We can see things at that scale on Mars, and it’s completely changed the game of understanding the evolution of Mars.

Very early in the mission, we were able to see images of pebbles encased in rock. And actually that was interesting was we took a picture of a patch of light-coloured rock with a navigation camera image, and we couldn’t see the pebbles, and then we drove away. We imaged the patch of rock with the Mastcam cameras and then we drove away. When we got those images down, we could see these pebbles. Actually when you walk around Greenwich here, you can actually find pebbles in the sediments here. The rounded pebbles were formed by rivers transporting gravels basically, and they’re too large to be moved by the wind.

And so they were the smoking gun evidence, if you like, of water flow on Mars. There’s the old joke that NASA’s always discovering evidence for water on Mars. [LAUGHTER] And we’ve been able to see channels on Mars et cetera for a long time with orbital images. But there’s no other - with these rover images, there’s no other way. And so many of our findings tell us completely new things about Mars. There are a number of other missions on their way to Mars at the moment. One in which you’re directly involved in, which is the Perseverance rover. What will that be able to do that Curiosity couldn’t, or perhaps do differently? OK. So Curiosity can do detailed chemical analysis.

But scientists and geologists, like myself, really want samples to come back to Earth where we can really analyse them in detail in Earth laboratories, and look for chemical traces of life, and biosignatures, and all of these other things. And so actually, Perseverance is the first step in this very exciting mission concept which is called Mars sample return. And what Perseverance will do, it’s going to a crater called Jezero where we can see clear signatures of an ancient lake and a delta. And it will collect core, and collect samples, and cache them for future return to Earth.

And then in probably around about 2026, 2027, there’ll be another mission that lands on Mars, sends a fetch rover which collects these samples, takes them back to the lander, and there’s a Mars ascent vehicle that puts them into Mars orbit. And then a subsequent mission, maybe in 2030, will collect them from Mars orbit and bring them back to Earth. And then we have another mission that the UK is playing a huge part in, which is the ExoMars Rosalind Franklin rover that was supposed to go again this year, but it’s been delayed for the launch date of 2022. Both Curiosity and Perseverance only drill to about 5 centimetres into the Mars surface.

This is within the radiation damage zone and the idea is that maybe organics that are present will get destroyed. Potentially signs of life - Yeah. - that sort of thing. So what ExoMars, the Rosalind Franklin rover will do is actually drill up to 2 metres into the rocks in the Martian surface, and collect samples from below the radiation damage zone, and will analyse them. So that’s not sample return, but we’ll analyse the chemistry of these samples on the rover itself. One last thing then. So there’s been a lot of talk recently about the possibility of getting humans to Mars. How game changing would that be when it comes to analysing the geology of Mars compared to rovers? Yeah.

It would completely change the game. I think what we might do in a week with the rover, we could probably do in a couple of hours with an astronaut geologist basically. And actually we can do many, many more things. So the trouble is, obviously with a rover, you’re commanding it, there’s latency, it takes time for us to analyse the data, et cetera. But also a rover can’t get everywhere, whereas obviously a human is much more dexterous, but also can make cognitive decisions. You can make decisions. Oh look, this looks interesting. I’ll go here. Oh maybe that’s not as interesting as what looks over there.

And can make very, very rapid decisions and can map the terrain, and move around the terrains. And then if we do discover things, we’ll actually want to discover more. It’s not the end of the game. We don’t say, oh we’ve found life, that’s it, we’ll move on to other things. No, no. We’ll be absolutely sending lots of humans, astronauts to go and explore and discover. And the other important thing is that it’s not just the life question. It’s really that Mars has this very, very rich record of the early history of terrestrial planets that we don’t have preserved on Earth. So actually by going to Mars, we actually learn something about ourselves.

And that’s to me actually almost the most important reason. Absolutely. Professor Sanjeev Gupta, thank you very much for joining us. Thank you very much indeed.