Most were probably killed en route to the Red Planet. But, “given that some survive, what is likely to happen from that point on?” asks Andrew Schuerger, a University of Florida biologist who gets funding from Conley.
Schuerger tests how well Earth microbes survive in Martian conditions. The single-celled organism Serratia liquifaciens turns out to be spectacularly hardy, surviving in the harshest of environments. Weirdly, it’s also very common: It’s been spotted in ponds, on plants, even everyday cheese. It could be in your mouth right now, and — dead or alive — it has certainly hitched rides to Mars. If it made the trip, all it needs to survive is some water and some form of protection from the harsh ultraviolet sunlight — “an umbrella and a cold drink,” as Conley puts it. It’s harmless for us, but S. liquifaciens could be bad news for any native species.
Still, exploration is about pushing the limits, right? Someday, humans will go to Mars, and “you can’t sterilize a human,” Fairen argues. We’re so intertwined with microbes that biology writer Ed Yong describes himself as “trillions of microbes in a human-shaped sack.” But even so, Conley says, we can take precautions.
For now, she does a lot of traveling here on Earth, visiting other NASA labs or one of her international counterparts. When she tells her plane seatmates what she does, some understand. Some express interest or approval. Others worry that regulations might get in the way of doing science. And the rest? “About 10 percent of people are gung ho manifest destiny,” she says. We’re supposed to be able to go wherever we want, without caution, and to heck with the native species.
To Conley, that’s as unnerving as any multi-eyed CGI alien Hollywood could dream up: We explore other planets not just to add pins to a map, but to understand what else nature is capable of. What’s the point of searching out alien life if you bring your own?
[This article originally appeared in print as "Alien Protection Plan."]