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 Atlantis operated as the primary research vessel for the Woods Hole Oceanographic Institution from 1930 to 1966. Space Shuttle "Atlantis" lifted off on its maiden voyage on 3 October 1985, on mission STS-51-J, the second dedicated Department of Defense flight. It flew one other mission, STS-61-B, the second night launch in the shuttle program, before the Space Shuttle "Challenger" disaster temporarily grounded the Shuttle fleet in 1986. Among the five Space Shuttles flown into space, "Atlantis" conducted a subsequent mission in the shortest time after the previous mission (turnaround time) when it launched in November 1985 on STS-61-B, only 50 days