# Rings on Venus to shelter life?



## Brian G Turner (May 4, 2004)

The idea that microbes may be alive and well in Venus's clouds is controversial. But some scientists are becoming more convinced that microorganisms could survive, thanks to the shelter from ultraviolet radiation provided by molecular rings of sulphur.

 Venus might once have been warm and wet, and a potential breeding ground for life, but at some point a runaway greenhouse effect dried the planet out and heated its surface to more than 480 °C. 

 A few scientists have argued that if Venus's climate change was slow enough for life to adapt, microbes could survive there today, living in acidic clouds at altitudes of about 50 kilometres. The temperature there is only about 50 to 70 °C - conditions some terrestrial microbes can endure.

 Dirk Schulze-Makuch of the University of Texas at El Paso and his colleagues have argued that the chemistry of the atmosphere is hard to explain unless microbes are influencing its composition (*New Scientist* print edition, 28 September 2002). 

 But unlike Earth, Venus does not have a protective shield of ozone. How could bugs survive the intense UV light from the Sun, which should by rights fatally damage proteins and DNA? Now Schulze-Makuch and his team say they have found a solution.


*Double bond* 

 Patterns of absorption in the UV spectra of the planet suggest that the atmosphere may contain lots of "cycloocta-sulphur", rings of eight sulphur atoms.

 These have double bonds that readily absorb UV light, then re-radiate the energy at relatively harmless visible wavelengths. Schulze-Makuch says this could mean that the atmosphere provides a sunscreen for any Venusian bugs (_Astrobiology_, vol 4, p 11). 

 Critics of the idea say there is not enough free water on the planet for microbes to survive. But Schulze-Makuch says Venusian microbes could suck water from hydrated sulphur compounds in the clouds.

 Many probes visited the planet in the 1960s and 1970s, but there was no search for life. "At that time, we didn't know about terrestrial life in extreme environments, in hot springs or deep beneath the crust of the Earth," says Schulze-Makuch. "Now that we do, it's time to design missions to look for life in the clouds of Venus." 

 The researchers have suggested a plan to the European Space Agency. A ship orbiting Venus would release a canister to sample the atmosphere, recapture it and return it to Earth for analysis.



  From: http://www.newscientist.com/news/news.jsp?id=ns99994936


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