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Jay Reeves, Associated Press
Five-time shuttle astronaut Robert "Hoot" Gibson stands near a candle honoring fallen astronauts during a remembrance ceremony honoring astronauts killed in three accidents plus 40 others who were part of the astronaut corps and have died, Thursday, Jan. 29, 2015, at Marshall Space Flight Center in Huntsville, Ala.

HUNTSVILLE, Ala. — NASA is remembering 17 astronauts who were killed in the line of duty and dozens more who have died since the agency's beginning.

Dozens of people attended a remembrance ceremony Thursday at NASA's Marshall Space Flight Center in Huntsville.

The memorial honored astronauts killed in three accidents plus 40 others who were part of the astronaut corps and have died.

Five-time shuttle astronaut Robert "Hoot" Gibson lit a candle of remembrance. He was friends with all 14 astronauts killed aboard shuttles.

The memorial comes a day after the 29th anniversary of the explosion of the space shuttle Challenger, in which seven astronauts died in 1986.

Seven more astronauts were killed aboard the shuttle Columbia in February 2003, and three astronauts died during ground testing of Apollo 1 in January 1967.