Life has not yet been found on Mars, and no one is sure whether it will be. But some researchers say it is not too early to consider the possibility that humans could do irreversible damage to indigenous Martian life.
A group of international experts will meet as early as this September to discuss whether it is time to revise policies that protect Mars from contamination.
At issue is the ethics of exploring the Red Planet – in particular whether hitchhiking Earth microbes could harm Martian habitats.
Past missions, including NASA’s twin rovers, have already ferried hundreds of thousands of bacterial cells to the Red Planet. Most of the microbes on the exterior of these craft were quickly destroyed by intense ultraviolet radiation, which passes easily through Mars’s thin atmosphere.
But dormant microbes might survive for tens of thousands of years on the interior of the crafts. And in the case of the Mars Polar Lander, which crashed into the planet’s south pole in 1999, its interior surfaces may have come in direct contact with soil rich in water ice, which could potentially provide a habitable environment for the hitchhikers.
“The option of not contaminating Mars is an option that’s no longer available to humanity,” says Christopher McKay, a planetary scientist at NASA’s Ames Research Center, who wrote a commentary about the need to protect any Martian life in the current issue of the journal Science. “Mars already has earthlings. We know that for a fact.”
He warns that Earth life could be reawakened if weather conditions on the planet change. This could happen as a result of periodic swings in the planet’s tilt, or if humans purposely alter the Martian environment, which, ironically, they might do to make conditions cosier for any Martian life they might discover. Microbes on subsurface drills in search of liquid water could also contaminate potential Martian habitats.