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
James Webb Space Telescope commissioning phase. An L2 orbit is only meta-stable so it requires orbital station-keeping or an object will drift away from this orbital configuration. The desire for a large infrared space telescope traces back decades; in the United States the "Shuttle Infrared Telescope Facility" was planned while the Space Shuttle was in development and the potential for infrared astronomy was acknowledged at that time. Compared to ground telescopes, space observatories were free from atmospheric absorption of infrared light; this would be a whole "new sky" for astronomers. However, infrared telescopes have a disadvantagethey need to stay extremely cold and the longer