In a space shuttle, a crew member who assists the commander to operate and control the vehicle. A pilot-astronaut may also serve as commander of a mission and is able to use the Canadarm to help deploy and retrieve satellites. The first 15 shuttle pilots were selected in 1978. Pilot-astronaut candidates must be between 162.5 and 193 cm tall and be able to pass NASA's Class 1 space medical, having at least 20/50 vision uncorrected (20/20 corrected). Candidates must have a minimum of a Bachelor of Science degree (in engineering, biological science, physical science, or mathematics) and have flown at least 1 000 hours as an air force jet pilot, with aircraft test-pilot experience desirable.