Mars may not be as inhospitable to some forms of terrestrial life as previously thought, according to US scientists, writes Natasha Gilbert.
Evidence suggests that life forms similar to those found on Earth could grow on Mars. However, any search for them on the surface of the planet may be contaminated by earthly microbes that hitch a lift on the spacecraft.
Ronald Crawford and his team at the Environmental Research Institute, University of Idaho, have found that dried spores of the bacteria Bacillus subtilis survive in soil enriched with the biocide potassium ferrate, believed to be like Martian soil, and in environmental conditions found on Mars - extreme desiccation, cold and an atmosphere dominated by carbon dioxide. The spores also subsisted under high levels of ultraviolet radiation at a depth of 5mm under the soil.
Dr Crawford said: "If Mars were self-sterilising, it would be easier to explore without concern about contamination. However, at this point we cannot make that assumption."
Dr Crawford said there is a need to develop better methods of cleaning spacecraft without damaging sensitive instruments.
The research team's work appears in the online journal BMC Microbiology.