What is Astrobiology and why do I study it?

When asked what I research, the response “astrobiology” normally raises an eyebrow or two. It is then invariably followed by the question as to what exactly is astrobiology? Normally I’d wheel out the description employed by NASA that it’s the study of the origin, evolution and distribution of life in the universe and we would move on from there. However, I always feel like that description is one made from necessity for writing grants and other administrative literature. It fails to find what is truly exciting and interesting in what is an utterly wonderful field of research to be in. To give you my perspective, I will try and elaborate on why I find Astrobiology so interesting and what questions I seek to answer in my research. To achieve this, it is easiest to explain what I study and then hopefully convince you that it is interesting.

The question that I spend most of my time thinking about is, if life exists on Mars, what might it look like biochemically? As a biochemist, my interests are naturally biased towards such a question. What I find fascinating about Mars is that it harbours environments unlike any seen here on Earth. Therefore, it asks questions of biology which make no sense to ask if we were to solely focus on terrestrial life. Fortuitously for me, as it makes no sense to ask these questions, it means nobody has answered them, which produces a perfect little niche to fill with my PhD thesis.

So what environments am I talking about and what do they look like? The environments that I mainly focus on are concentrated perchlorate brines which are aqueous environments with high concentrations of perchlorate salts. Perchlorates salts are strong oxidising agents and are particularly lethal to life (unless you happen to be the subset of life that can eat small quantities of perchlorate). These environments have been hypothesised to exist deep underground in the Martian groundwater or even as a subglacial lake under the Martian south pole due o their extremely low freezing points (roughly -70 °C). So in addition to being rich in perchlorate salts, these environments have two other factors to keep in mind, namely the high pressures and the extremely low temperatures. This interplay between perchlorate concentration, pressure and temperature is something that we just fundamentally do not see here on Earth.

Recently, I have been studying how the perchlorate and pressure interplay affects a model enzyme. From this work (which will hopefully soon find its way past peer review) and the work of others, I have been able to develop a hypothesis about the biochemical nature of potential Martian life. This is the part of astrobiology that I find amazing. From the results of simple benchtop experiments, the application of biophysics and a sprinkling of evolutionary theory we are then able to derive scientifically valid conclusions about what might be happening deep underground on a rocky red planet millions of kilometres away. What is more amazing is that I can then go on and test this hypothesis and I thoroughly plan to do so. So whilst life on Mars may be totally novel in its biochemical ways (although I doubt it’s anything too novel), the fact that we are at a place in time where these questions can escape from the prison of thought experiment and have life breathed into them through experiment is utterly astounding to me. If and when the results get published, I can then go into them in greater length, so for now you’ll have to bear with me.

Therefore astrobiology is, to me, a scientific mindset from which we can explore questions about biology which we would never have asked, had we not looked out into the night sky. Along this line of enquiry we are bound to find weird and wonderful facets of biology and biochemistry not previously thought possible. It would be even more interesting though to find that the answers should not have been as unexpected all along.