On Nov. 18, 2013, NASA launched the MAVEN spacecraft to Mars.
The name MAVEN stands for Mars Atmosphere and Volatile Evolution. The spacecraft is an orbiter designed to help scientists figure out what happened to Mars' water and its atmosphere. Mars is dry today, but data from several Mars missions suggest that it was a much wetter environment a long time ago. MAVEN is tracking the rate of atmospheric loss from Mars.
The planet has a super thin atmosphere that has been leaking into space for a few billion years. Scientists think that when Mars lost its atmosphere, water dried up on the surface as a result. Solar storms that blast radiation into the solar system appear to have blasted away some of the atmosphere. Carbon dioxide in the atmosphere once kept Mars warm enough to sustain water, and losing that greenhouse gas turned Mars into a cold and dry place.
MAVEN's science mission ended in 2016, but the spacecraft is still used to relay communications with other missions on Mars.
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