If scientists or rovers ever do find evidence of life on Mars, it might be more convenient if it’s dead, joked NASA planetary scientist Chris McKay today at the annual American Association for the Advancement of Science conference in San Francisco. McKay’s reasoning? Well, there’s the risk that we’ll contaminate it (or vice versa). We’d also be responsible for keeping it alive, which could be quite tricky if it’s discovered in ice a half mile below the planet’s surface. And there’s also the philisophical dilemma of setting the code of ethics of the proper ways to treat alien life.

But even if we do find some perfectly dead, well-preserved Martian critters, things won’t be all peaches and cream, McKay said. There are two theories for how life might have originated on Mars. One says that it follows the same blueprint as life on Earth, the result of microbe-spreading asteroids pinballing between the two planets. The other possibility is that there was a “Second Genesis” on Mars, which scientists are crossing their fingers for because it increases the chance that it wasn’t a one-time deal here on Earth and that the universe is sprinkled with life.

Scientists could run into trouble with “Second Genesis,” though. Martian life might look so foreign that we’d skip right by it. And if we do spot it we might have trouble figuring out how it works. “If you always played with Legos, and someone gave you Lincoln Logs, could you make sense of it?” McKay asked. You can build a house with both toys, but the pieces and means for doing so are completely different. “Unfortunately, science doesn’t know how Spock’s tricorder works,” McKay joked, referring to the Star Trek character’s tool used to scan and identify alien life-forms and their composition. “Even worse, science fiction doesn’t know how it works!”

Because of the current limitations of robotic explorers (their drills, for instance, can’t reach the several-hundred-foot depths needed to do a thorough search for life or its remnants), it wil probably take a human mission to settle the Red Planet’s greatest mystery. Before sending humans, McKay said, we should first determine whether Mars can sustain a human presence. A robotic vegetable-planting mission would be one good way to accomplish that, McKay said, because, like Valentine’s Day, “if you can’t be there in person, send flowers.” – Bjorn Carey