re: Contamination
Bacillus safensis Venkateswaran, 2004 This bacillus has evolved to survive on spacecraft surfaces in JPL's Spacecraft Assembly Facility (whence its name). It is highly resistant to gamma and UV radiation and presumably draws energy from ions of trace metals like aluminum and titanium. It is almost certainly living aboard the Mars rovers and may survive as spores for millions of years.
http://home.earthlink.net/~misaak/taxonomy/taxEtym.html