OTD…Oct. 6 and STS-41

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…Launch of Discovery in 1990 with the Hubble Space Telescope, our window on the universe!

Shuttle Endeavour launched for the 25th and final time on this date in 2011.