NASA is bringing rocks back from Mars, but what if those samples contain alien life?

NASA is planning its first-ever mission to bring dirt and rocks from Mars back to Earth — but before that momentous event happens, the space agency needs to figure out exactly how to protect our home planet from any alien microbes that might hitch a ride.

This week, the agency is holding public meetings and looking for feedback on its plan to land a spacecraft carrying Martian specimens at a U.S. Air Force testing range in Utah in the early 2030s.

“Maybe this is the most important environmental assessment that humans have ever done,” says Peter Doran, a geologist at Louisiana State University who studies life in extreme environments.

“I think that it’s a very low probability that there’s anything living at the surface of Mars,” says Doran, who also serves on an international committee devoted to planetary protection. “But there is a possibility.”

Having a rock sample from Mars here on Earth would let scientists run exhaustive lab tests to look for evidence of whether this cold, harsh, rocky world was once habitable and maybe even inhabited. Read more »