First consideration for additional crew members is given to qualified NASA mission specialists. When payload specialists are required they are nominated by NASA, the foreign sponsor, or the designated payload sponsor. Although payload specialists are not part of the Astronaut Candidate Program, they must have the appropriate education and training related to the payload or experiment. All applicants must meet certain physical requirements and must pass NASA space physical examinations with varying standards depending on classification. Astronaut Candidate Training Astronaut candidates receive training at JSC near Houston, Texas.
Candidates also receive training in land and sea survival training, scuba diving, and space suits.
Consequently, all Astronaut Candidates will be required to pass a swimming test during their first month of training. They must swim 3 lengths of a 25M pool in a flight suit and tennis shoes. The strokes allowed are freestyle, breast, and sidestroke. There is no time limit. They must also tread water continuously for 10 minutes.