Planetary scientists sometimes joke that we know more about Mars than we do about the moon. NASA first landed a spacecraft on the surface of the fourth planet during the U.S. Bicentennial, five years before the first space shuttle ever lifted off. And we’ve learned plenty in the intervening 35 years: Viking 1 and 2 analyzed Mars rocks, Spirit and Opportunity found evidence of ancient water, and Phoenix saw the Martian snow. Yet the biggest question — whether Mars could ever be home to life — still eludes us.
NASA’s newest rover, Curiosity, sets off this week in search of answers. It’s the most complex interplanetary explorer ever, earning a PopSci 2011 Best of What's New award. If everything goes to plan — from Saturday’s thundering Atlas V launch to the rover’s self-piloted atmospheric entry and hovercraft airdrop — it just might become the type of once-in-a-generation explorer that raises even more questions than it answers.