NASA astronaut Fernando Caldeiro died Oct. 3 following a two-and-a-half year battle with a brain tumor. He was 51.

Caldeiro was hired by NASA’s Kennedy Space Center in 1991 as a cryogenics and propulsion systems expert. He was accepted into the astronaut corps in 1996 and qualified for flight assignment as a mission specialist two years later but never flew to space.

His most recent assignment was to NASA’s Aircraft Operations Division in Houston where he directed the integration and operation of high-altitude atmospheric research experiments aboard the NASA WB-57 aircraft.

Caldeiro was born in Buenos Aires, Argentina, and attended high school and college in New York before earning a master’s degree in engineering management from the University of Central Florida in 1995.

He is survived by his wife Donna and two daughters.