Going to Mars Could Mess Up the Hunt for Alien Life
Elon Musk wants to send humans to the red planet. But even our robotic presence there risks contaminating Mars with invasive microbes.
Twenty years ago, America celebrated its Independence Day by landing several thousand invaders on the surface of Mars.
On July 4, 1997, the Pathfinder spacecraft touched down in a northern lowland called Chryse Planitia carrying a small rover named Sojourner—as well as a large amount of stowaways in the form of earthly microbes.
Did any of these microbes survive and reproduce, establishing themselves as Earth’s first colonists on a distant world? Highly unlikely, NASA assured us at the time, noting that scientists believed “it would be difficult to sustain and cultivate life on Mars.”
That remains true today. In the years since Pathfinder, scientists have cataloged more than a dozen factors—from radiation to soil toxins—that make the red planet a
