Between 1986 and 1992 - that is, from the time Challenger was destroyed to the time NASA first launched its replacement, the Orbiter Endeavour - NASA's Shuttle fleet numbered just three Orbiters. Perhaps not too surprisingly, the U.S. civilian space agency didn't normally highlight this fact.
Over the years I've been to many a space facility in the U.S. and elsewhere. When the opportunity arises, I generally collect whatever freebies are on offer. Lately I've been sorting through and refiling my collection. Today I found the NASA Public Affairs fact sheet at the top of this post. It dates from 1988, just before Discovery's Return To Flight mission (STS-26, 29 September-3 October 1988). What struck me about it is that it lists only three Orbiters. I think that it's the only NASA handout I have that highlights the 1986-1992 three-Orbiter fleet.
This made me wonder just how many years out of Space Shuttle's 30-year career NASA's fleet included four spaceflight-capable Orbiters. To simplify matters, I ignored those periods when individual Orbiters were grounded for upgrades or other reasons.
Columbia flew alone from April 1981 until April 1983, when Challenger first reached orbit. Discovery joined the fleet in August 1984, then NASA launched Atlantis for the first time in October 1985, bringing the fleet to four spaceworthy Orbiters for the first time. That first four-orbiter era was, however, short-lived; Challenger was lost on 28 January 1986, a little less than four months after Atlantis's first flight.
Endeavour first flew in May 1992. About 11 years later (1 February 2003), the venerable Orbiter Columbia was lost. This makes for a simple calculation: it means that NASA operated a four-Orbiter fleet for a little more than 11 years, or for only about a third of the Shuttle's 30-year career.
This surprised me. For some reason I had supposed that the fleet spent more time at full strength than not. I suspect that this new (to me, at least) realization will affect my future thinking about the Shuttle's career.
Related Beyond Apollo Posts
Challenger and the Diminishment of the NASA Space Program
A Stronger, Safer, Better Space Shuttle (1982)
