OTD…April 4 launches of STS-6 and 83

#OTD…Gamma Ray Observatory launched in 1991 on Atlantis and Discovery’s 2010 ISS flight

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

#OTD in 1985…Challenger suffered an engine shutdown on her way to orbit for a Spacelab mission