Mars Life: Hope Against Hope
Good news: the Viking landers (1976) may have been unable to detect life on Mars if it were present. Bad news: the dust devils on Mars probably would kill anything alive on the surface. These contrasting stories recently tugged in opposite directions on hopes to find life on the red planet. A report on PNAS1 questioned the ability of the Viking experiments to detect organic molecules on Mars. The team, including Martian-meteorite promoter David McKay (08/06/2006), found organics in Antarctica and the Atacama and Libyan deserts that would have been below the detection limit of the Viking instruments.
Mars, however, is continually swept by the mini-tornados known as dust devils. The Science News2 Oct. 28 cover shows a picture of a terrestrial “satanic wind” lofting dust high into the air. On Mars, Sid Perkins writes, the thinner atmosphere allows these vortices to rise much higher and gain enough energy to strip molecules of their electrons. The reactions blanket the surface with highly-oxidizing compounds, like hydrogen peroxide, that would sterilize microorganisms on the surface, let alone bleach their hair. Hopes for Martian life are thus reduced significantly:
Highly reactive peroxide would scour organic chemicals from Martian soil, says [Gregory T.] Delory [UC Berkeley]. That process would make the surface of the Red Planet hostile to life. Furthermore, because the planet lacks an ozone layer, large quantities of ultraviolet radiation reach Mars’ surface. Deep in the soil, where neither ultraviolet radiation nor peroxide infiltrates, however, life might survive.
The 10-man research team that published these results in Astrobiology last June3 believes the peroxide molecules could survive up to four years in the soil. Martian dust devils, which are ubiquitous on the red planet, also generate high amounts of static electricity that could pose risks to future human explorers. See also the 08/02/2006 entry on this topic.
1Navarro-Gonzalez et al, “The limitations on organic detection in Mars-like soils by thermal volatilization-gas chromatography-MS and their implications for the Viking results,” Proceedings of the National Academy of Sciences USA, 10.1073/pnas.0604210103, published online before print October 23, 2006.
2Sid Perkins, “Satanic winds: Looking at dust devils on Earth and Mars,” Science News, Week of Oct. 28, 2006; Vol. 170, No. 18, p. 282.
3Atreya et al, “Oxidant Enhancement in Martian Dust Devils and Storms: Implications for Life and Habitability,” Astrobiology, Jun 2006, Vol. 6, No. 3: 439-450.
Delory left intact a tiny bit of hope by saying, “The jury’s still out as to whether there is life on Mars.” The answer, my friend, is blowin’ in the wind.