It has been nearly 40 years since the Viking life detection experiments on Mars—the only such experiments ever conducted on another planet. The results of these experiments remain controversial today, and the reluctant scientific consensus is that the Viking landers were launched too early, at a time when we did not understand the Martian environment sufficiently to interpret the obtained experimental data.
Based on this sobering state of affairs, I recently organized and moderated a roundtable discussion with five leading experts in the field, to address whether it is time to launch a new life detection effort to another planet, and if so, how best to proceed in doing so. The discussion was hosted by the journal Astrobiology and appears in the June 2015 issue.
The experts participating in the discussion were John Rummel (East Carolina University and former NASA planetary protection officer), Gilbert Levin (Arizona State University and former principal investigator of Viking’s Labelled Release Experiment), Steve Benner (Foundation for Applied Molecular Evolution, Gainesville, Florida), Victor Parro (Center of Astrobiology, Spain, and principal investigator for the Signs of Life Detector (SOLID) instrument for the proposed Icebreaker Mission) and Sam Kounaves (Tufts University, Massachusetts, and Imperial College, London, UK).
The group agreed that the scientific community has made great strides in understanding the environment of Mars, but differed over whether we are ready to send a new life detection mission now. While Levin and Parro thought yes, Kounaves felt that we first need to have a better idea of the suite of organic compounds present on Mars. There was general consensus that if we launch a new life detection mission, the lander or rover should carry several instruments dedicated only to finding life—rather than sending a single instrument piggybacked on a mission with broader scientific aims. The goal should be to both look for life that might once have existed on Mars, as well as life that may exist today and is still metabolically active. The group emphasized that we should send instruments that complement each other and take different approaches to detecting life, in order to obtain solid proof for a possible detection.
Another topic discussed was whether the mission should rely on “in-situ” instruments to search for life while still on the Martian surface, or whether it would be better to have a sample-return mission bring back rocks and soil for analysis on Earth. The group leaned toward the in-situ approach, at least for now, with Kounaves arguing that the best approach of all would be a human-tended laboratory on Mars. The group also discussed how such a mission could be backed politically and approved by NASA or ESA, given the current budget climate. Other planetary bodies like Europa and Enceladus were also mentioned as possible targets. But of all these places, we know Mars the best, which will likely keep it at the top of the list for a new life detection mission.