OTD…April 26 and STS-55

#OTD in 1990…Columbia launched to retrieve NASA’s Long duration Exposure Facility (LDEF) on the longest Shuttle flight to date.

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 1997…Discovery launched to deploy and later retrieve the CRISTA-SPAS atmospheric research satellite