Centimeter by centimeter, Curiosity is hunting for evidence that Gale, a desiccated ding in the planet's surface with a central peak towering 18,000 feet above the crater floor, may have harbored conditions that permitted primitive life to exist early in Mars' history. But that's just one spot on the planet – akin to trying to figure out the biological history of Earth by landing solely in rural Chile (which scientists often use as a stand-in for Mars).
Over the next eight years other missions will help fill in elements of the planet's profile. In December, NASA will send aloft MAVEN (Mars Atmosphere and Volatile Evolution Mission), an orbiter intended to tease out the story of how Mars' atmosphere has changed over its history. The launch follows a Mars-orbiter mission India is planning for November. In 2016, the United States will send a lander, InSight (Interior Exploration using Seismic Investigations, Geodesy and Heat Transport), to probe the Martian interior. NASA will also play a supporting role in ExoMars, a joint project between the European Space Agency and Russia's Roscosmos that aims to launch spacecraft to orbit and land on the red planet in 2016 and 2018.
Finally, in 2020, NASA will attempt to put another Curiosity-size rover on Mars. It is widely expected to begin a campaign to achieve one of the holy grails of space science: eventually return a rock or soil sample from Mars. It's an objective that just a few months ago had been axed from NASA's budget.
"It's huge," says Dr. Hubbard of the recent announcement of the 2020 mission.