Tomorrow, all being well, the multipurpose NASA lander Perseverance will touch down and begin its programme of exploration. With China and the UAE putting probes into orbit, poor old Mars must be feeling quite invaded. And Perseverance is at last designed to answer the one question that everyone including David Bowie has been asking for centuries-Is there Life on Mars?
Except some of us have strange feelings of deja-vu. Readers who recall the long hot summer of 1976 will recall the touch down of two then state of the art probes, Vikings 1 and 2, thousands of kilometeres apart on the surface. Each carried four carefully designed and controlled experiments, mini-laboratories if you will, designed to answer Bowie’s question. On each Viking, three out of four results came back negative. And one on each came back positive.
The positive test was designed by a man called Gilbert Levin. It was called the Labelled Release (LR) and he had been using it for years to look for micro-organisms in sewage samples on Earth. It took a sample of Martian soil, added a little aqueous nutrient spiked with 14C and waited. If anything were alive in the soil , its metabolism would release CO2, which being labelled with 14C, meant you couldn’t miss it. Surprise, surprise, the LP results were overwhelming for both Vikings. For a brief period of about 12 hours the headlines LIFE ON MARS! screamed around planet Earth in the creaky media of the day. And then NASA killed it.
We won’t go into all the ins and outs of the controversies of the next few days, months and decades. Look, we’ve listed a few places to read below. It was held then, as it basically is now, that the weight of the other three experiments was enough to negate the LR ones. That was the story, and they’re sticking to it. We are the last to gainsay NASA and scientific caution. But we wondered then, as we do now-why go to all that trouble to set up an experiment then think of every reason you can to prove it was wrong all along? How can the negative interpretation be sustained in the light of the last forty years, with the discovery of things like methane, water and organic molecules on the Red Planet? Could something like perchlorates, now known to exist on Mars, have vitiated some Viking results?
We await the Perseverance results with interest. When it comes to science, a default conservatism can be justas misleading as a default sense of wonder.
Michael Brooks 13 Things that Don’t Make Sense Profile 2009 (still gives the human story of the Viking controversy)
#mars #astrobiology #perseverance #viking #microbiallife #extraterrestrial #NASA