The race is on to land human explorers on Mars, possibly as early as the 2030s. NASA, the European Space Agency and the China National Space Administration all have plans, however vague, to put people on the Red Planet.
But the race to land on Mars risks sidelining—and potentially canceling out—a separate effort to find evidence of life on Mars, be it living microbes or the remains of long-dead ones. When Earth explorers arrive on the Red Planet, there’s a good chance they’ll bring Earth microbes with them.
That could contaminate Mars’ environment, and make it difficult or even impossible to distinguish Martian organisms from Earth organisms. In our rush to colonize another planet, we might thwart our best chance of finding life on that same planet.