OTD…May 4 and STS-30

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 2009, the final Hubble Space Telescope servicing mission launched

#OTD…Launch of a 1993 environmental mission on Discovery and Atlantis’ ISS flight in 2002