The hopes of turning Mars into a more Earth-like planet have just taken a hit.
Science-fiction writers have long dreamed of terraforming Mars—changing the frigid Red Planet’s climate to make it more suitable for human colonization. One potential way to do this involves freeing lots of heat-trapping carbon dioxide from the Martian crust back into the atmosphere.
And it had been reasonable to speculate that Martian rocks might contain lots of this greenhouse gas. After all, the Red Planet lost the vast majority of its CO2-dominated atmosphere billions of years ago, and the air had to go somewhere.
“If that’s where all the CO2 had gone from an early thick atmosphere, that [terraforming] might be possible,” said Bruce Jakosky, principal investigator of NASA’s MAVEN mission, which has been studying the Martian atmosphere from orbit since November 2014.
But MAVEN results announced that the planet’s CO2 went up rather than down: Shortly after Mars’ global magnetic field shut down about 4.2 billion years ago, the solar wind and powerful sun explosions stripped away most of the planet’s atmosphere, sending it off into space.
That’s bad news for terraforming advocates, according to Jakosky, who’s based at the University of Colorado Boulder’s Laboratory for Atmospheric and Space Physics.