IT’S getting busier on Mars. The European Space Agency’s ExoMars orbiter is sniffing the Red Planet’s air for signs of methane. And NASA’s InSight lander is en route to expand knowledge of our neighbour’s geophysics.
But all that activity, along with that of rovers already there, won’t offer solid answers to the big question: is there life, extinct or extant?
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Which is why it is so welcome to hear ESA and NASA’s recent joint announcement of intent to “explore concepts” for retrieving Martian soil for testing on Earth. Given how this could dramatically increase the chance of answering that question, both agencies are right to push it. Even more so, given the shrinking prospects of boots on Mars in the 2030s as the US refocuses on moon landings.
Bringing a sample back will be hard. It would need at least three missions. First, NASA’s Mars 2020 rover would collect samples. The second mission would put them into Mars orbit, and the third would bring them to Earth.
It would require lots of money, and lots of time. A recent call to bolster sample return protocols says planning for handling facilities on Earth should start now, for example.
So far, insights about Mars have mainly come from meteorites, which provide limited knowledge, are lacking geologic context and are not representative samples of the Martian crust. Attempts to answer the life question in situ by remote control have proven futile. The 1970s saw the Viking landers analyse Martian soil. It was highly reactive and tested positively for the products of metabolism, but molecular analysis didn’t detect organic material. This contradiction raised important questions: what in the soil is metabolising if no life exists on Mars? Are we confident in the accuracy of those results? The Viking experiments remain hotly debated.
Even if scientists don’t find evidence of living organisms in a returned sample, they could use powerful equipment that can’t be put on a rover – for example to measure isotope ratios, which can indicate past life. And returned soil can be a gift that keeps on giving. Lunar samples have been yielding new information for decades, thanks to long-term experiments and the advent of new analytical techniques.
Beyond the invaluable science, a sample return mission would help sustain wider enthusiasm for possible human exploration of Mars at a time when it is waning. The buzz from announcements invariably fades, as even the most optimistic timelines eye the mid-2020s and NASA’s extend beyond the 2030s – distant enough to lose lustre, if not confidence.
If we can’t take our geologists to the rocks any time soon, let’s bring the rocks to them.
This article appeared in print under the headline “Rocks off the Red Planet”
