NASA has lost one of its own. 

The space agency shared a tweet Saturday that said legendary astronaut John Young has died.  He was 87.

"We're saddened by the loss of astronaut John Young, who was 87," NASA tweeted. 

Young walked on the moon and also commanded the first space shuttle flight.

He went to space six times in the Gemini, Apollo, and Space shuttle programs. 

Young retired from NASA in 2004 after a 42-year career with the agency, making him the longest serving astronaut.