Lar DeSouza, Twitter handle @lartist, a cartoonist, sketches during the STS-135 Tweetup, Thursday, July 7, 2011, at Kennedy Space Center in Cape Canaveral, Fla. About 150 NASA Twitter followers attended the event. The STS-135 mission will be NASA's last space shuttle launch. Photo Credit: (NASA/Paul E. Alers)