The rocky, desert-like surface of Venus
is too hot and parched for microbial life as we know it.
But airborne microbes could thrive, at least temporaily, in the cooler climes about 31 miles (50 kilometers) above Venus--earning the planet a score of 0.4 on the new Standard Microbial Habitability index, announced in October 2009.
The potential habitat for life in Venus's atmosphere is actually bigger than in Earth's atmosphere, said Mendez, of the University of Puerto Rico in Arecibo.
However the atmosphere of Venus is unstable, Mendez said. Air circulation would eventually force life to lower altitudes, where it would be sterilized by the higher temperatures.
Image courtesy Magellan Project, JPL, NASA