Astronauts operate and work aboard spacecraft and the space station.

In July 2011, NASA ended its Space Shuttle program with the landing of the shuttle Atlantis. It is still possible to become an astronaut and work on the International Space Station or in the private sector. Other countries still send astronauts to the space station as well.

Before astronauts go to space, they spend years in training. They use machines and mockups that simulate spacecraft and the International Space Station. For example, one machine simulates the vibrations, noises, and views of a launch and landing.

While in space, astronauts work aboard spacecraft and the space station. They run experiments, repair the International Space Station, and maintain spacecraft. Crews also release, capture, or repair satellites. Astronauts spend six to nine months on the space station.

Space station crews conduct research, conduct medical experiments, and maintain the station. Station crews research bioastronautics, spaceflight, physical and Earth sciences, space biology, and space product development.

Astronauts also conduct experiments on themselves while in space. They monitor the stresses of extended microgravity and its effects on their bodies. These experiments help predict and prevent negative, long-term effects that might harm future crews on deep space missions, such as to Mars.

The astronauts' mission continues after they return to Earth. Typically, the crew spends several days in medical testing and debriefing. They share their experiences to assist in future training and to add to space flight knowledge. They also meet with the media to discuss the flight.