"It is not often apparent to microbiologists or members of the public that we know for certain that there has been life on Mars. Since the crash of the Soviet’s Mars 2 lander on the surface of the planet in 1971 (Fig. 1), a diversity of landed and crashed probes of various kinds, many of them not sterilized, have been delivered to the surface of Mars by the world’s space-faring nations. Only the Viking spacecraft (Fig. 2), which landed in 1976, were completely heat sterilized to kill spores. Many of these spacecraft have delivered an inventory of spores found in spacecraft assembly facilities, including Bacillus species. A fascinating scientific question is whether there is, on the surface of Mars today, a viable spore hidden and shielded from Mars’ intense UV radiation in one of these various contraptions. There seems to no reason why a spore, cooled to Mars’ average temperature of –60 °C should not have survived since the 1970s. So on the face of it the answer to the question I was asked to address is likely to be ‘yes’."Elsewhere in the same issue, Lewis Dartnell describes the microbial flora of spacecraft and discusses the idea of planetary protection.
A few years ago at a meeting on Astrobiology in Loughborough, I raised this claim with NASA astrobiologist Lynn Rothschild, who stated quite clearly that NASA no longer believed it. I was thus surprised to hear the claim repeated in a BBC Horizon programme broadcast a few years later, in November 2006. I contacted Lynn by e-mail, who put me in touch with NASA's Planetary Protection Officer, John Rummel, who had actually appeared in the show. He told me that he had discussed the claim with the producer of the show and made it clear that NASA no longer supported it:
If the BBC program (BBC Horizon?) stated that the microbe survived on the Moon, and didn’t also have me on saying that it was likely contamination, then I have a bone to pick with the producer!
I never did get to hear whether they picked over that bone, but I did discuss with John how one could squash such an urban myth. I hit on the idea of writing a Wikipedia article entitled The Myth of Streptococcus mitis on the Moon and linking to it from the Apollo 12 and Surveyor 3 pages.
I haven't look at the page lately, but it survives to this day, but to comply with the Wikipedia neutral point of view, it is now entitled Reports of Streptococcus mitis on the Moon. In fact, much of what I wrote has been stripped out but the Wikipedia lets you compare today's version with my original. Interesting to see how the Wikipedia's neutralism neuters an article (maybe Knols will prove more reliable, or maybe not). BUT worse still, someone has added in the counter-claim that NASA's official view is to accept the myth (will be e-mailing Lynn and John again on this one!)
Returning to Cockell's claim, one day humans will visit Mars and retrieve those probes, so we can see test Cockell's hypothesis and see how well terrestrial bacteria survive on Mars. But let us hope that next time, they take care not to contaminate them on the way home!