Space Shuttle Columbia that remained fitted to the avionics suite, and an internal airlock that, originally fitted into the other orbiters, was later removed in favor of an external airlock to facilitate Shuttle/Mir and Shuttle/International Space Station dockings. Due to its weight, "Columbia" could not have used the planned Centaur-G booster (cancelled after the loss of "Challenger"). The retention of the internal airlock allowed NASA to use "Columbia" for the STS-109 Hubble Space Telescope servicing mission, along with the Spacehab double module used on STS-107. Due to "Columbia's" heavier weight, it was less ideal for NASA to use it for missions to the
Space Shuttle Challenger Space Shuttle Challenger Space Shuttle "Challenger" (Orbiter Vehicle Designation: OV-099) was the second orbiter of NASA's space shuttle program to be put into service, after "Columbia". "Challenger" was built by Rockwell International's Space Transportation Systems Division, in Downey, California. Its maiden flight, STS-6, began on April 4, 1983. The orbiter was launched and landed nine times before breaking apart 73 seconds into its tenth mission, STS-51-L, on January 28, 1986, resulting in the death of all seven crew members, including a civilian school teacher. It was the first of two shuttles to be destroyed in flight, the other being "Columbia",