The Viking lander experiments
In the mid-1970s, NASA sent two Viking landers to the surface of Mars equipped with instruments that conducted the only life detection experiments ever conducted on another planet. The results of those tests were very confusing at the time and remain so today. While some of them — particularly the labelled release experiment (which tested for microbial metabolism) and the pyrolytic release experiments (which tested for organic synthesis) — were initially positive for life, the gas exchange experiment was not.
Death by water
At the time of those landings, scientists had very little understanding of the Martian environment. Since Earth is a water planet, it seemed reasonable that adding water might coax life to show itself in the extremely dry Martian environment. In hindsight, it is possible that approach was too much of a good thing. What I and other researchers have learned in extremely dry places on Earth, such as Chile’s Atacama Desert, is that there is a gradual progression of life forms as the habitat gets more arid.
Hope from hydrogen peroxide
More than 15 years ago, my colleague Joop Houtkooper and I upped the level of scientific speculation on this topic by taking a different perspective on the puzzling Viking results. We suggested that microbial life on Mars might have hydrogen peroxide in their cells — an evolutionary adaptation that would allow them to draw water directly from the atmosphere. The mixture would have other advantages, too, such as keeping water liquid at freezing Martian temperatures, preventing the formation of ice crystals that would rupture the cells.
R&I-Rawr
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Article URL : https://bigthink.com/hard-science/accidentally-killed-life-mars/