OTD…July 29 and STS-51F

#OTD in 1995, Endeavour launched on the ASTRO-2 astronomy mission:

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.

NASA’s Kepler planet-finder began its mission to discover Earth-like worlds orbiting other stars in the galaxy today in 2009, successfully launching aboard a Delta 2 rocket from Cape Canaveral.