Watch: How did Mars lose its atmosphere?

(CBS News) Mars wasn't always the Red Planet. Eons ago, it is possible that Mars was as lush as Earth is today. So, what happened? NASA is on the case with this enlightening video of how Mars may have lost its atmosphere.

The idea behind the atmospheric "sputtering" Mars may have experienced is fairly simple to understand. But, of course, NASA is not sure this is what happened, which is why this educational video doubles as an announcement of the space agency's newest mission: the Mars Atmosphere And Volatile EvolutioN (MAVEN) mission, which will launch sometime around December 2013. A NASA statement explains: "MAVEN will be the first mission devoted to understanding the Martian upper atmosphere. The goal of MAVEN is to determine the role that loss of atmospheric gas to space played in changing the Martian climate through time."