OK, so despite all the doom and gloom of my last but one post (here), I have now been working at Imperial College London for the last week. We have finally escaped Norfolk, breaking the ‘If you stay for 5 years, you stay forever’ rule.
I’m employed as a ‘Research Associate in Organic Matter and Minerals of Mars’, my job is to look for ways to improve our chances of detecting organic matter for future Mars lander missions. Put simply, I’m helping to LOOK FOR LIFE ON MARS (cue some Bowie)!
To sum up the problem I’ll be working on, as I understand it so far (remember, I’m not a chemist): Mars landers have not yet discovered conclusive evidence of organic matter (note: organic matter does not necessarily mean biological matter, they are compounds containing carbon and usually C-H and/or C-C bonds) but have found evidence of a group of minerals called perchlorates (ClO4) being pretty ubiquitous in Martian lake sediments (e.g. Glavin et al., 2013). These sediments are also the places we would expect to find evidence of organic matter, through its concentration by fluvial and lacustrine sedimentation processes. We know that there should be a measurable concentration of organics delivered to the Martian surface by meteorites and certain compounds could indicate evidence of past or current alien life, but nothing has been found so far. We believe that it is the presence of perchlorate that is currently blocking the positive identification of organic matter.
Analysis of Martian sediments for organics is carried out by pyrolysis gas chromatography mass spectrometry (Py-GC-MS). The sample is heated in the absence of oxygen to break down large molecules into smaller ones which can be separated by gas chromatography and detected by mass spectrometry, the products tell us what the big molecules originally were. The issue here is, perchlorate is strongly oxidising; it is a bleach. When it is heated in the pyrolysis unit as part of the sample, it breaks down releasing oxygen and chlorine. The presence of oxygen causes any organic matter present to combust, being lost as carbon dioxide, carbon monoxide and water. With everything breaking down and combusting, we do not detect either the organic matter or the perchlorate by this method – so it took a long time for anyone to even realise there was a problem.
Along with the rest of the research group, I now have to figure out a way to make this less of a problem, hopefully in time for ExoMars2020…
So far I’ve been reading up on the last 40 years of geochemical analysis on Mars trying to get my head around the problem and understand a bit of the chemistry, which is fun as I haven’t done any organic geochemistry since my Masters.
On Friday I got sent to an outreach event across the road at the Royal Albert Hall, showing kids some bits of actual Martian meteorite and talking about the various ages of Mars, using Earth analogue rocks to demonstrate the strata which were laid down during each period. However, the guy next to us who’d brought a replica space suit to try on proved more popular for some reason.
This was all part of a big school event which culminated in the Royal Philharmonic playing the planets, which was a pretty cool way to spend a Friday afternoon. It was good to hear that I am studying the planet with the best soundtrack.
Next week I’ll actually get to grips with the machine I’ll be mostly working on (the Py-GCMS) and will be thrown in at the deep end analysing irreplaceable Apollo 17 moon rocks, so let’s see how that goes…
I think this project is going to be a bit more interesting than the snails…