OTD…Sept. 30 and STS-68

Today marks the 40th anniversary — July 20, 1976 — of the first U.S. robotic landing on another planet by the Viking 1 spacecraft on Mars.

#OTD in 1985…Challenger suffered an engine shutdown on her way to orbit for a Spacelab mission

#OTD in 1989…Columbia launched with a classified communications satellite for the Defense Department