I'm a scientist working on the next mission to Mars (MAVEN) which launches on Monday. It'll investigate the missing Martian atmosphere. AMA!
Something catastrophic had to have happened to have changed the ancient warm and wet Mars into the modern cold and dry Mars. MAVEN will investigate our leading hypothesis which is that the Solar Wind eroded away the atmosphere over billions of years. The MAVEN mission launches on Nov. 18 and will go into orbit around Mars in Sept. 2014. Video summary: http://www.youtube.com/watch?v=etL2ZhqGNCs
Proof: https://twitter.com/NASAGoddard/status/401050345591144448 http://lasp.colorado.edu/home/maven/files/2013/11/Espley_Reddit.jpg https://twitter.com/JaredEspley/status/401047297288441856 https://twitter.com/MAVEN2Mars/status/401047573948952576
Answering questions today on the maven2Mars account is Jared Espley, space scientist at NASA's Goddard Space Flight Center in Greenbelt, MD and a member of the MAVEN science team. He's happy to answer questions about MAVEN, Mars, and NASA. Espley twitter account is @JaredEspley, MAVEN's Twitter account is @MAVEN2Mars, and NASA Goddard is @NASAGoddard
Edit: 3pm ET Ok, Jared here signing off.
Edit2: 8:45pm ET Ok, Jared back here for a bit to answer a few more questions and fix some typos.
Edit3: 10pm ET Signing off again! Thanks for all the questions. Sorry to those I didn't get to. If I get a chance I'll come by through the weekend to answer any straggler questions if my colleagues don't catch them. Go Mars!