OTD…Aug. 18 and STS-68 abort

#OTD in 1988…Discovery returned Americans to space after the Challenger accident

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.

American and Soviet crews were launched today in 1975 for the first handshakes in space between the two superpowers as part of the Apollo-Soyuz Test Project.