The space shuttle Atlantis landed Wednesday, May 26, leaving only two more planned flights for the shuttle program. Because the crews of the final two remaining flights are expected to include only repeat passengers, no one will ever again feel the excitement of riding the shuttle for the first time. This means that, after almost 30 years of ferrying astronauts into the final frontier, the number of space shuttle passengers should remain forever at 355, said Robert Pearlman, editor of collectSPACE.com, an online publication and community for space history and artifact enthusiasts, and a contributor to Life's Little Mysteries sister site SPACE.com.

Unlike the astronauts who piloted the Mercury, Apollo and Gemini capsules, space shuttle passengers came from diverse backgrounds, Pearlman said. In fact, only 332 of the 355 passengers on the space shuttle were United States astronauts. The rest included members of foreign space programs, employees of private companies ensuring that their satellite deployed correctly and even some teachers, Pearlman said.

There are certain requirements for becoming a space shuttle astronaut , so they all fall within a certain height range, a certain education range. But what the space shuttle did is open up space to a wide range of people, so you have a great diversity of people, Pearlman said. In many ways, the only thing uniting them is that they've all flown on the shuttle.

Not every flight featured a passenger heading to space for the first time, and many astronauts flew on three or more missions, according to NASA. Astronauts Jerry Ross and Franklin Chang-Diaz tie for the most number of trips, each having ridden in the shuttle seven times. Story Musgrave holds the record for having flown on the most different shuttles, ascending into space on every orbiter except Enterprise (which never went to space), Pearlman said.

The ages of the shuttle passengers also varies greatly.

The youngest member of a shuttle crew, Sultan Salman Abdelazize Al-Saud, of Saudi Arabia, was only 28yearsold when he flew aboard the space shuttle Discovery, Pearlman said. The youngest U.S. astronaut to fly the shuttle was Sally Ride, who was 32 when she became the first American woman in space. The oldest passenger was Senator John Glenn, a former astronaut himself who NASA let fly at the age of 77.