An introduction to Astrobiology

Sunday , 11, September 2016

For 10 days this summer I attended the summer course “Volcanism, Plate Tectonics, Hydrothermal Vents and Life” on Terceira island, the Azores, Portugal. I myself research the interplay between tectonics and volcanism on Mars, so the summer course looked quite promising. The course however turned out to have a big emphasis on the latter subject, life. But that was no problem, as there were still enough people attending who were involved in tectonics and volcanism. I made some great contacts and shared ideas which will definitely benefit my PhD.

But what about life? Well… wow, life is cool! We did some awesome stuff during the summer school. We went into a lava cave to find out it was teeming with microbes. We did some tests in the laboratory to find out more about them. Nowadays you can extract DNA and compare it with a database of known microbes to see out if you maybe found something new. We went out on other excursions to see the volcanic geology of the island, which is also affected by tectonics. And we learned that living things can be found inside all the nooks and crannies of mother Earth. It has adapted to what we humans would find pretty extreme conditions (the so called extremophiles). This made me realize that the existence of life on Mars, possibly hiding somewhere deep below the surface, is not so unlikely as I once thought. Had I been geo-brainwashed during my former studies to love rocks over life? Mars superficially may look like a dead planet (although climatologists and geomorphologists probably disagree as Mars still has dust storms and active dune formation), microbial life may be present in deep warm layers or in brine water near the surface. Or it has been laying dormant and frozen, waiting for a localized heat pulse caused by an asteroid or cometary impact, or by volcanism.

One question that interests me is how in the future we will deal with two things which are seemingly in contradiction: the prospect of finding Martian life and the prospect of spreading terrestrial life to Mars. If we don’t find life after many thousands of drilling expeditions will we officially declare Mars devoid of life? Or, oeps, did the drilling unknowingly spread microbes to the Martian depths? Will we keep on searching for life indefinitely, all the time keeping the planetary protection protocol in place? Or will we maybe stumble upon life, abandon large-scale terraforming and turn Mars into a protected park? Or will we be under so much pressure to create a second Earth that whether or not we find Martian life, we will start terraforming Mars anyway? If so, then the microbes which are being studied in Martian analogue locations – such as the lava caves on the Azores – might be a good starting point. Through genetic engineering we could create life which can survive in Martian lava caves, in the proposed Martian brine water conditions or even on the cold and low pressure surface of Mars itself. And in the long run we might be able to alter the Martian atmosphere just as fast as we are currently changing our own.

Weirdly enough, the ethics behind planetary protection is becoming a reality faster than I could have imagined when I used ‘in the future’ in the previous paragraph. The NASA Curiosity rover which may still contain terrestrial microbes is expected to pass close to a possible brine water flow site. If Curiosity comes too close it might ‘infect’ these brines with terrestrial microbes. But staying away from them is 1) difficult engineering wise and 2) a missed opportunity for science. Philosophically speaking we’re always changing what we observe. With satellite geology this ‘change’ is of course insignificant. But with landers… And we can completely forget about the planetary protection protocol when we send humans to Mars, with their extensive gut microbial ecosystems. Although this would add another complication: can these humans ever go back, possibly affecting Earth with Martian critters?

So with respect to Curiosity I guess we have to ask the question, how likely is it to contaminate this possible brine water source, and will the contamination spread? We might already have spread microbial life to Mars with earlier missions. And Mars is definitely not a closed system. Pieces of rock from Earth have impacted Mars for billions of years. So what are the chances of microbial life surviving a trip on a meteorite from Earth to Mars? And how does this natural occurrence compare with our missions? With all this in mind my hope is that we will be not too strict with the planetary protection protocol. Life is about taking risks anyway, don’t you think?