Q. What is an astronaut’s salary?
A. Salaries for civilian Astronaut Candidates are based on the Federal Government’s General Schedule pay scale for grades GS-12 through GS-13. Each person’s grade is determined according to his/her academic achievements and experience. Currently, a GS-12 starts at $65,140 per year and a GS-13 can earn up to $100,701 per year.

Military Astronaut Candidates are assigned to the Johnson Space Center and remain in an active duty status for pay, benefits, leave, and other similar military matters.

Source : http://www.nasa.gov/centers/kennedy/about/information/astronaut_faq.html#5

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