OTD…April 29 and STS-51B

#OTD…Launch of a 1993 environmental mission on Discovery and Atlantis’ ISS flight in 2002

#OTD in 1989…Columbia launched with a classified communications satellite for the Defense Department

#OTD in 1990…Columbia launched to retrieve NASA’s Long duration Exposure Facility (LDEF) on the longest Shuttle flight to date.