OTD…Oct. 20 and STS-73

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

#OTD in 1991…The launch of Columbia on Spacelab Life Sciences 1 mission

Today in 2011, shuttle Discovery made a graceful landing at Kennedy Space Center, returning from her final voyage after a remarkable three-decade life of service.