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 Surveillance Telescope Space Surveillance Telescope The Space Surveillance Telescope is a telescope for detecting and tracking orbital debris. It has a 3.5 meter (138″) aperture mirror and came online in 2011. Two noted design features include Mersenne-Schmidt type optics and a curved CCD. In 2010s the telescope, which was in New Mexico, United States, was transferred to United States Air Force Space Command and moved to Australia. The discovery and tracking of space debris is noted as a growing problem in the 21st century. One problem is that among the 20-30 thousand large objects in orbit that are tracked, and an estimated