NASA has approved a new unmanned mission to Mars, one aimed at explaining exactly how the Red Planet lost most of its atmosphere. A spacecraft is scheduled to launch in late 2013 and begin orbiting around Mars about 10 months later for a yearlong study. Scientists suspect that the sun has been stealing off Martian air for eons, and they expect the new probe to put that theory to the test. NASA has given the $438 million project, which was first proposed in 2008, a heady name: the Mars Atmosphere and Volatile Evolution mission. Scientists are calling it "Maven" for short. "Maven will examine all known ways the sun is currently swiping the Martian atmosphere, and may discover new ones as well," said Joseph Grebowsky, the mission's project scientist at NASA's Goddard Space Flight Center in Greenbelt, Md., in a statement.