Commander of the second-to-last shuttle mission, Kelly is best known as the husband of former congresswoman Gabrielle Giffords, who was shot in Arizona in January 2011. Kelly left NASA to help Giffords with her recovery, and while he's no longer an astronaut, he has joined a safety advisory panel for SpaceX and has written a children's book about mouse astronauts, which will be published this fall.

Chief of the astronaut office before being selected to command the third-to-last shuttle flight, Lindsey left NASA last summer while the Atlantis was still in orbit. Like Kelly, he has gone into the private sector, directing flight operations for Sierra Nevada's Dream Chaser, which is currently competing for a major NASA contract with Boeing, SpaceX, and other new space-exploration companies.

Hobaugh rose through the military as a test pilot and a Marine Corps combat flier, and was chosen to become an astronaut in 1996. After flying three shuttle missions – and commanding one in 2009 – he resigned from NASA. He has decided to keep flying, however, as a cargo pilot for Federal Express.

The son of Mexican-immigrant farm¬hands, Hernandez entered the astronaut corps in 2004. He flew only one shuttle mission before stepping down to work for an engineering firm in Houston. He is now running for Congress in central California, where he faces an uphill battle against an incumbent Tea Party Republican.