Wired: In The Knowledge, you incorporate ideas and methods from many different branches of science. How does this kind of interconnectedness show up in your own work?
Dartnell: Drawing from lots of different sources is what I do in my own research in astrobiology, and not just knowledge, but the methods and techniques you could use. It’s not just biology, but engineering, and robotics and instruments as well as physics and planetary science, and you’re constantly outside of your comfort zone having to learn new things. It keeps you on your toes, but that’s what I enjoy about astrobiology.
Wired: What is your role with the ExoMars mission?
Dartnell: The exciting thing about ExoMars is that, not only will it for the first time have a drill so it can get properly underground on Mars and find stuff that has been protected from the surface environment, but it’s also going to use experiments like Raman spectroscopy, which is the one that I’m directly involved in at the University of Leicester. The reason Raman’s exciting is that it’s very sensitive and very competent and capable of picking up organic molecules or bio signatures of life, and we want to try this new technique on Mars.
Wired: What are your expectations for ExoMars?
Dartnell: We don’t know, and that’s the point of exploration; you don’t always know what you’re going to try and find. You know what you’re hoping for, and what might be realistic to expect. So what we hope to find on Mars are organic molecules – the basic Lego pieces or building blocks or chemistry kit for life; amino acids and sugars that should exist on Mars but we have yet to discover. Hopefully either NASA’s Curiosity or ESA’s ExoMars will discover those, and maybe beyond that they’ll find not just the building blocks for life but signs of life itself – biosignatures.
Wired: What kinds of biosignatures would be convincing as a sign of past life?
Dartnell: A biosignature is any sign or any evidence of life, and this might be something like a fossilised shape that looks a bit like a cell, it might be things as complex as DNA. It might be more subtle things like isotopic ratios in rocks, which on Earth are used to show early cases of life. Or if we do find things like amino acids, we can tell if they are made by life or through non-living processes like pre-biotic chemistry by their molecular handedness. So there are various quirks or various signs of organic molecules we can look for that would point to biology, rather than geochemical processes.
Wired: What is the likelihood that you will find biosignatures on Mars?
Dartnell: Unfortunately, you basically can’t answer that question. It’s somewhere between 0 and 1, but we don’t know because whenever you’re trying to do something in science you’re trying to do something new that you don’t already know the answer to,
However, for all we know about life on Earth, it seems to have arisen pretty rapidly. It seems like it might be a probable thing to happen, if you’ve got the right kind of environment. So the big question is whether Mars ever have the right kind of environment, and if so, did that basic pre-biotic chemistry ever get far enough down the line to produce cells? And if that happened, what might be the best way of looking for that life and trying to detect these biosignatures? Which biosignatures would still remain after all this time? This is the kind of thing we’re trying to do with ExoMars.