Becoming an astronaut is a fantasy for millions of people, a reality for very few. Astronaut careers can loosely be grouped as pilots and mission specialists. They divide up astronaut responsibilities: a pilot gets to fly the space shuttle and commercial ships into space while a mission specialist handles the countless other tasks life in space requires. Most of the crew on the International Space Station are specialists. Both pilots and specialists have to meet NASA's astronaut qualifications.

What Is Their Mission?

A decade or three from now, a mission specialist may need the skills to walk the red surface on Mars. At time of writing, mission specialists works on space shuttles and work on the ISS. NASA trains pilots to fly shuttles and trains mission specialists to handle other technical astronaut responsibilities.

• Fixing plumbing and heating. It's mundane work, but it's necessary, even in space.
  
• Space station construction.
  
• Making spacewalks.
• Satellite repair.
  
• Working in space via a robot arm.
  
• Planning missions, including the activity of the crew and the management of food and drink supplies.
• If the shuttle carries complex scientific equipment, a mission specialist may oversee the experiment.
  

In between space flights, a mission specialist may provide training and support to other shuttle crews and help assemble and test equipment. They may also apply for a tour of duty aboard the the International Space Station. Duties aboard the station include spacewalks, repair work, medical research, scientific experiments and docking with arriving spacecraft.

Shuttle missions can last anywhere from two to 18 days. If a mission specialist goes to work on the ISS, they'll probably be up there for six months.

Becoming a Mission Specialist

NASA receives thousands of online applications for astronaut training, but there aren't anywhere near that many job. Competition is tough. To have any chance at all you have to meet NASA's astronaut requirements. Physically, NASA wants you between 4 feet 10 inches and 6 feet 3 inches so that you'll fit into space vehicles and space suits. This is an improvement on the early years, when anyone over 5 foot 11 couldn't fit into the Mercury rocket capsule. You have to be in good enough condition to pass a physical and a swimming test. The swimming matters because NASA uses SCUBA diving to train mission specialists for extravehicular activity in weightless space.

Skill-wise, you need a bachelor's degree in engineering, biological or physical science, computers or math. On top of your B.S. you need three years of post-graduate professional experience or 1,000 hours as a pilot in command of a jet aircraft.

NASA astronauts have to be U.S. citizens. While some of them come from the military, it isn't mandatory.

Once NASA screens your application, they may ask for additional information if you look promising, or start contacting your references. If you make the initial cut, you'll undergo a week-long process of personal interviews, medical screenings and astronaut orientations. If NASA decides you're worth hiring, you'll also undergo a background check.

If you pass every test and check, you begin your two-year mission specialist training at NASA's Houston space center. This doesn't mean you're on your way to the stars; acceptance depends on completing your training.

• Becoming SCUBA qualified.
  
• International Space Station systems training.
  
• Extravehicular Activity skills training.
  
• Robotics skills training.
  
• Russian language training.
  
• Aircraft flight readiness training. 
  

Even if you fail, NASA may decide you're a good fit for an earthbound position in the agency.

Mission Specialist Pay

If you're a civilian, becoming an astronaut candidate makes you a federal employee. In the federal government's pay scale, your status ranges from GS-11 through GS-14, depending on your experience and academic achievements. That translates into a salary of anywhere from $53,000 to $116,000 a year at time of writing, with raises following standard federal rules.

Military astronaut candidates remain with the armed forces, but transferred to NASA duty. They'll receive the appropriate pay and benefits for their rank.