AirSpaceMag.com

A few observations about the STS-135 shuttle astronauts, the last people to fly the 30-year-old spaceplane into orbit.

By accident or design, the crew comes from a mixed military background, with one each from the Navy (commander Chris Ferguson), Marines (pilot Doug Hurley), and Air Force (mission specialist Rex Walheim). The other MS, Sandy Magnus, was a materials scientist before she became an astronaut.

None of them were out of school at the time of the first shuttle launch in 1981. Ferguson, the oldest at 49, was still three years away from graduating college. And only two of the STS-135 astronauts, Magnus and Walheim, had flown in space at the time of the 2003 Columbia accident.

Flying this last mission with no second shuttle standing by for a rescue required some complicated planning as to how to get the crew home if Atlantis can’t return to Earth for some reason. When the STS-135 astronauts dock with the space station on Sunday, ten people will be in orbit. If the shuttle is out of commission, they’d have to wait their turn to ride back in three-person Soyuz capsules.

Here’s a profile of the final four shuttle astronauts, the last of 355 people to ride NASA’s spaceplane.