Searching for Life on Mars Is Really Hard

The ExoMars rover will head up to the Red Planet in 2019 to look for signs of life.

by Robert McCallum
Feb 2 2015, 12:50pm

​ExoMars rover. Image: ​ESA

​Scientists have been trying to find life on Mars for centuries. But leaps in technology mean now, more than ever, they're edging closer to the day they find evidence of life on the Red Planet.

Back in December, the UK Space Agency piled an ​additional £200 million into Europe's space programme. This gave the country leadership of the ExoMars mission, and UK researchers access to the International Space Station (ISS). This not only means that a UK rover will be the first non-US rover on Mars, but also that the Union Jack will fly in space, as the UK becomes a full partner of the ISS for the first time.

I got in touch with Andrew C​oates, a lead scientist on the development of the ExoMars rover and head of planetary science at UCL's Mullard Space Science Laboratory, to ask him how exactly they plan to look for life on Mars.

Andrew Coates with the PanCam. Image: UCL/MSSL - M. de la Nougerede, 2015

MOTHERBOARD: So you're a lead scientist on the ExoMars rover project. What does your job actually entail?
Andrew Coates: I'm the leading investigator for the PanC​am camera on the mission, which will be going to the surface of Mars in 2019. ExoMars is a collaboration between the European Space Agency and the Russian Space Agency. The key thing about it is that it is going to be able to drill underneath the surface of Mars to look for signs of past, or possibly even present, life.

What kind of scientist are you?
I'm a plasma scientist, so a professor of physics, but I've been working on space missions for many years. One particular thing that interests me is how the wind interacts with different objects in the Solar System. About a million tonnes of material comes away from the Sun per second. PanCam uses filters to look between the sun and the location where the rover is, measuring the amount of water vapour in the atmosphere.

And how did you get into the field of space technology?
I thought that plasma physics could be the answer to mankind's energy problems. But back in the 1980s it seemed to be about 30 years away in terms of the technology. It's still about the same now actually! So I think I made the right decision to go into space plasma physics. It is a real dream to be leading the PanCam team. We did a trial​ with a test rover in the Atacama Desert in 2013. We had an operation centre in Harwell, and used the PanCam emulator along with WI​SDOM [Water Ice and Subsurface Deposit Observation on Mars], which is the subsurface sounding radar, and the close-up imager, which is a bit like a hand lens.

With the ExoMars rover, we're going to be able to drill up to two metres underneath the surface

So how does the PanCam that you are developing work?
It consists of two wide-angle cameras, 50 cm apart, in an optical bench. Imagine a vertical boom about the height of a human above the surface with the optical bench at the top of it. Each eye has 11 filters on it, which are designed to look at different colours of light being reflected off the rocks to give you the composition. It gives a much better stereo reconstruction than we can with our eyes.

It can look for signs of hydrated minerals, things like clays, and do a better determination of those than has been done on any previous camera on the surface. There is also a high-resolution camera, which adds texture to that three-dimensional picture. PanCam is one of a combination of instruments that is looking at context and then the drill gets samples from underneath the surface for the onboard chemical laboratory, which is the thing that is looking for signs of life.

So ExoMars is going to be the first non-US lander on Mars?
Yes. There is a European lander going in 2016, the Trace G​as Orbiter (TGO). That is another part of the ExoMars mission, where we are trying to map methane out in the atmosphere of Mars. The Curiosity mission publis​hed data just before Christmas about the presence of methane. Leading on from this discovery, it is a really important thing to do. All the previous landers have been American apart from Russia, who actually had the first successful soft landing with M​ars 3 in 1971. Though it landed at the time of a large dust storm and only lasted 15 seconds.

The TGO. Image: ​ESA​

You said that the rover will be able to dig under the surface of Mars. Is that new technology?
The Curiosity rover that is on Mars at the moment can drill 5 cm underneath the surface of the rock. With the ExoMars rover, we're going to be able to drill up to two metres underneath the surface. Mars has an oxidising environment, but there is also high radiation on the surface, because it has a very thin atmosphere, about one percent of the Earth's atmospheric pressure; so the best chance for finding past or present life is to drill underneath the surface.

How do you test the samples once you have drilled for them?
In the sample drawer there is an infrared instrument, an ultraviolet spectrometer, and then a third one that heats parts of the sample in an oven and looks at the mass of the sample, looking for carbonates. The Mars Organics Mol​ecule Analyser (MOMA) is also looking for something called chira​lity; so right or left "handed" organic molecules. Chirality allows you to look at whether life is involved in producing the elements that we already know are there.

So what are the chances of finding life on Mars?
There was a time, 3.8 billion year ago, when Mars was much more like the Earth is today. It had a thick atmosphere, a magnetic field and volcanism; quite different to the way Mars is now. There is a possibility that life started on Mars then because there is a very similar combination of chemicals.

What is the hardest thing about the ExoMars mission?
Daytime on Mars will be around 0°C, then at night it goes down to a possible -120°C. That is the engineering challenge for building anything for the surface of Mars. So we've got thermal chambers, which have been able to do testing and show that this design has survived. We deliver the structural model in March. We're very, very excited about beginning to deliver hardware.

It becomes a series of missions to Mars, which may end up with a human landing

How long is the rover planned to be on Mars for if its going through such vast temperature changes?
The design lifetime is about 218 days on Mars, which are called sols. But we hope that, like some of the other rovers, the engineering will be good enough to survive longer than that. It is years since the Curiosity landed on Mars. It's amazing that it is still working after all that time.

How close are we to landing people on Mars?
NASA would like to do this in the 2030s. I went to a talk that Ellen Stofan, chief scientist at NASA, did at the Science Museum in November. Their plan is to focus on trying to get people to Mars. It is a much, much more difficult endeavour. It would have to be a much heavier landing because of the equipment and fuel to get them off the surface again. There are ideas about splitting water on the surface to provide fuel. It is going to be tried on the 2020 NASA mission. Because we have lead PanCam, we have been invited to be on that rover. So it becomes a series of missions to Mars, which may end up with a human landing.

How will that work differ from the 2019 mission?
The main reason for that mission is to gather samples together to bring back to Earth. There is only a certain amount you can do on the surface with the instruments that we are taking on ExoMars. Ultimately we would like to get a sample back to Earth laboratories, which are much more sensitive. We may answer it with ExoMars, but I think it is more likely bringing a sample back to Earth can finally answer the question: Was there life on Mars?