OTD…June 20 and STS-78 and NROL-38

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 2001…Discovery launched on an International Space Station crew exchange mission

VIDEO: The winged spaceship Columbia returned to Earth with a pinpoint landing at Edwards Air Force Base on this day 35 years ago, concluding the maiden flight of the space shuttle.