When composing a checklist for future space explorers, it's a good idea to first consult the folks who spent more than 50 years defining "the right stuff." NASA no longer uses the shuttle-era roles described below, but many of the basic requirements and skill sets remain unchanged for missions aboard the International Space Station (ISS). It makes sense. After all, the space shuttles, once launched, essentially acted as temporary space stations [source: Ross].
In the early days of the space program, NASA chose rocketeers according to their guts, quick wits and piloting skills. The agency also required them to have bachelor's degrees in math, engineering or science. In the later Apollo missions, NASA folks expanded their selection criteria to include non-test pilots with advanced degrees [source: Ross]. Harrison Schmitt of Apollo 17, a civilian with a doctorate in geology from Harvard University, logged more than 301 hours of spaceflight and 22 hours of extravehicular activities (EVAs) [source: NASA].
With the advent of the shuttle program, space travel became more about return trips, construction and experimentation, which made room for a wider range of abilities and demanded a broader array of skills. As of 2004, NASA had three kinds of astronauts -- commander/pilot, mission specialist and payload specialist -- each with different requirements. With the space shuttle retired, these designations could change to match the space agency's evolving mission.
Traditionally, pilots and commanders controlled their vehicles, helped deploy or retrieve satellites and aided in payload operations. The job required a bachelor's degree in engineering, biological science, physical science or mathematics, and 1,000 hours of pilot-in-command time in jets. It also required 20/100 vision (correctable to 20/20), blood pressure of 140/90 and a height of 62-75 inches (157.5-190.5 centimeters) [source: NASA]. Killer moves on the dance floor? Sadly, not a requirement.
Mission specialists coordinated systems, crew activities, consumables, experiments and payload. They also performed EVAs and operated remote manipulators. Applicants needed a bachelor's degree as above, as well as three years of related professional experience, depending on their degree level. Their physical standards were more relaxed, however: 20/200 vision (correctable to 20/20), blood pressure of 140/90 and a height of 58.5-76 inches (149-193 centimeters) [source: NASA].
Payload specialists were not NASA astronauts per se; for example, they might be a teacher, a senator or a foreign dignitary. They had to receive a nomination from NASA, a foreign sponsor, or whoever sponsored the payload in question, and needed to possess appropriate education and training, meet certain physical requirements and pass NASA's space physical [source: NASA].
In 2012, America's space program sends similar personnel to the ISS but aboard Soyuz rockets with different physical requirements.
Just as NASA's requirements for its space travelers changed as its missions evolved, the ideal candidate for long-term explorer or colonist might require reimagining the ideal astronaut. The one thing that won't change? The necessity that candidates possess physical toughness and mental mettle equal to the task.