Editing Space Shuttle Columbia (section)

==First operational orbiter==

===Weight===
As the second orbiter to be constructed and the first able to fly into space, ''Columbia'' was roughly {{convert|8000|lb|abbr=on}} heavier than subsequent orbiters such as [[Space Shuttle Endeavour|''Endeavour'']] when she was first constructed, which had benefited from advances in materials technology.<ref>{{cite web|url=http://spaceflightnow.com/shuttle/features/000414overhaul/weightloss.html |title=Orbiter Overhaul: The Columbia weight loss plan |publisher=Spaceflight Now |date=April 14, 2000 |access-date=July 17, 2009}}</ref> In part, this was due to heavier wing and fuselage spars, the weight of early test instrumentation 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.<ref>{{cite web|url=http://spaceflightnow.com/shuttle/features/000414overhaul/future.html |title=Orbiter Overhaul: Flying into the future |publisher=Spaceflight Now |date=April 14, 2000 |access-date=July 17, 2009}}</ref>.''Columbia'' was not modified for the planned [[Centaur (rocket stage)|Centaur-G]] booster (canceled after the loss of ''Challenger'').<ref>{{cite book|last=Lardas|first=Mark|title=Space Shuttle Launch System: 1972-2004|year=2012|publisher=Osprey Publishing|pages=35}}</ref> The retention of the internal airlock allowed NASA to use ''Columbia'' for the [[STS-109]] [[Hubble Space Telescope]] servicing mission, along with the [[Astrotech Corporation|Spacehab]] double module used on [[STS-107]].{{Citation needed|date=December 2017|reason=An external airlock would have fit fine on Columbia's last two missions, but there was no need. Columbia would have carried Endeavour's external airlock on its next mission (to ISS) if they had made it home safely from STS-107.}} Due to ''Columbia's'' higher weight, it was less ideal for NASA to use it for missions to the International Space Station due the performance decreases needed to carry the heavy payloads to the high inclination orbit, though modifications were made to the Shuttle during its last refit in case the spacecraft was needed for such tasks.

===Thermal protection system===
[[File:STS-3 infrared on reentry.jpg|right|thumb|upright=1.2|alt=The underside of the orbiter shows a temperature gradient from relatively cool at the edges of the wing to hottest in the middle of each wing and towards the back.|The [[Space Shuttle thermal protection system]] in the underside of ''Columbia'' as seen in a visible (left side) and infrared (right side) image which was taken by the [[Kuiper Airborne Observatory]] on [[STS-3]]]]

Externally, ''Columbia'' was the first orbiter in the fleet whose surface was mostly covered with High & Low Temperature Reusable Surface Insulation (HRSI/LRSI) tiles as its main [[Space Shuttle thermal protection system|thermal protection system]] (TPS), with white silicone rubber-painted [[Nomex]] – known as Felt Reusable Surface Insulation (FRSI) blankets – in some areas on the wings, fuselage, and payload bay doors. FRSI once covered almost 25% of the orbiter; the first upgrade resulted in its removal from many areas, and in later flights, it was only used on the upper section of the payload bay doors and inboard sections of the upper wing surfaces.<ref name="OTPS">{{cite web |url=http://www-pao.ksc.nasa.gov/kscpao/nasafact/pdf/TPS-06rev.pdf |title=Orbiter Thermal Protection System (PDF) |publisher=NASA's [[Kennedy Space Center]] Public Affairs Office |year=2006 |access-date=June 7, 2011 |url-status=dead |archive-url=https://web.archive.org/web/20110610021002/http://www-pao.ksc.nasa.gov/kscpao/nasafact/pdf/TPS-06rev.pdf |archive-date=June 10, 2011 }}</ref> The upgrade also involved replacing many of the white LRSI tiles on the upper surfaces with Advanced Flexible Reusable Surface Insulation (AFRSI) blankets (also known as Fibrous Insulation Blankets, or FIBs) that had been used on ''Discovery'' and ''Atlantis''.<ref>{{cite web|url=http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/tps/blankets.html |archive-url=https://web.archive.org/web/20010210011912/http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/tps/blankets.html |url-status=dead |archive-date=February 10, 2001 |title=Advanced Flexible Reusable Surface Insulation Blankets |publisher=NASA |date=April 7, 2002 |access-date=June 7, 2011}}</ref>

[[File:STS-4 landing.jpg|thumb|right|''Columbia'' landing on July 4, 1982, concluding [[STS-4]], accompanied by a [[Northrop T-38 Talon|T-38 Talon]] flying in formation.]]

Originally, ''Columbia'' had 32,000 tiles – the upgrade reduced this to 24,300. The AFRSI blankets consisted of layers of pure silica felt sandwiched between a layer of silica fabric on the outside and S-Glass fabric on the inside, stitched together using pure silica thread in a 1-inch grid, then coated with a high-purity silica coating. The blankets were semi-rigid and could be made as large as 30" by 30". Each blanket replaced as many as 25 tiles and was bonded directly to the orbiter.<ref name="OTPS" /> The direct application of the blankets to the orbiter resulted in weight reduction, improved durability, reduced fabrication, and installation cost, and reduced installation schedule time.<ref>{{cite web|url=http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/tps/blankets.html |archive-url=https://web.archive.org/web/20010210011912/http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/tps/blankets.html |url-status=dead |archive-date=February 10, 2001 |title=Advanced Flexible Reusable Surface Insulation Blankets |publisher=NASA |date=April 7, 2002 |access-date=June 7, 2011}}</ref> All of this work was performed during ''Columbia's'' first retrofitting and the post-''Challenger'' stand-down.

Though the orbiter's thermal protection system and other enhancements had been refined, ''Columbia'' would never weigh as little unloaded as the other orbiters in the fleet. The next-oldest shuttle, [[Space Shuttle Challenger|''Challenger'']], was also relatively heavy, although {{convert|2200|lb|abbr=on}} lighter than ''Columbia''.

===Markings and insignia===
{{multiple image
| align             = right
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| image1            = B747 with Space Shuttle on it from above.jpg
| width1            = 250
| image2            = Endeavour after STS-126 on SCA over Mojave from above.jpg
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| caption2          = Overhead views of ''Columbia'' (top) and ''[[Space Shuttle Endeavour|Endeavour]]'' (bottom)
}}

''Columbia'' was the only operational orbiter with black [[Chine (aeronautics)|chines]]. These were added because at first, shuttle designers did not know how reentry heating would affect the craft's upper wing surfaces.{{citation needed|date=March 2014}} The chines allowed ''Columbia'' to be easily recognized at a distance, unlike the subsequent orbiters. The black chines were a late modification and were a high temperature paint over the white FRSI. The chines were modified on ''Columbia'' shortly before rollover to the Vehicle Assembly Building in late 1980 for STS-1. The only other orbiter with black chines was ''[[Space Shuttle Pathfinder|Pathfinder]]'',<ref>{{Cite web |last= |first= |title=Stock Photo - Space Shuttle Pathfinder |url=https://www.alamy.com/space-shuttle-pathfinder-image255442853.html |website=Alamy}}</ref> but it was a cosmetic [[test article (aerospace)|test article]] and only gained it when was refurbished.

Additionally, until its last refit, ''Columbia'' was the only operational orbiter with wing markings consisting of an [[Flag of the United States|American flag]] on the port (left) wing and the letters "USA" on the starboard (right) wing. ''[[Space Shuttle Challenger|Challenger]]'', ''[[Space Shuttle Discovery|Discovery]]'', ''[[Space Shuttle Atlantis|Atlantis]]'', and ''[[Space Shuttle Endeavour|Endeavour]]'' all, until 1998, bore markings consisting of the letters "USA" above an American flag on the left-wing, and the pre-1998 [[NASA insignia#NASA "worm" logotype|NASA "worm" logotype]] afore the respective orbiter's name on the right-wing. ''[[Space Shuttle Enterprise|Enterprise]]'', the test vehicle which was the prototype for ''Columbia'', originally had the same wing markings as ''Columbia'' but with white chines and the "USA" letters on the right-wing spaced closer together. ''Enterprise'''s markings were modified to match ''Challenger'' in 1983. The name of the orbiter was originally placed on the payload bay doors much like ''Enterprise'' but was placed on the crew cabin after the ''Challenger'' disaster so that the orbiter could be easily identified while in orbit.

From its last refit following the conclusion of STS-93 to its destruction, ''Columbia'' bore markings identical to those of its operational sister orbiters–the [[NASA insignia#NASA "meatball" insignia|NASA "meatball" insignia]] on the left-wing and the American flag afore the orbiter's name on the right-wing. ''Columbia'' only flew twice with these markings, STS-109 and STS-107.

===SILTS pod===
Another unique external feature, termed the "SILTS" pod (Shuttle Infrared Leeside Temperature Sensing),<ref>{{Cite web |author=Dismukes |first=Kim |date=October 27, 2000 |title=Shuttle Infrared Leeside Temperature Sensing |url=http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/comm/inst/silts.html |url-status=unfit |archive-url=https://web.archive.org/web/20010116125600/http://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/comm/inst/silts.html |archive-date=January 16, 2001 |access-date=February 8, 2023 |series=Shuttle Reference Manual}}</ref> was located on the top of ''Columbia's'' vertical stabilizer, and was installed after [[STS-9]] to acquire infrared and other thermal data. Though the pod's equipment was removed after initial tests, NASA decided to leave it in place, mainly to save costs, along with the agency's plans to use it for future experiments. The vertical stabilizer was later modified to incorporate the drag chute first used on [[Space Shuttle Endeavour|''Endeavour'']] in 1992.

===OEX/MADS "black box"===
One unique feature that permanently stayed on ''Columbia'' from [[STS-1]] to [[STS-107]] was the OEX (Orbiter Experiments) box or MADS (Modular Auxiliary Data System) recorder. On March 19, 2003, this "black box" was found slightly damaged but fully intact by the [[U.S. Forest Service]] in [[San Augustine County]] in [[Texas]] after weeks of search and recovery efforts after the [[Space Shuttle Columbia disaster]]. The OEX/MADS was not designed to survive a catastrophic loss like an airplane [[Flight recorder|black box]].<ref>{{Cite web|url=https://bringingcolumbiahome.wordpress.com/2017/03/20/columbias-black-box/|title=Columbia's "Black Box"|first=Jonathan|last=Ward|date=March 20, 2017}}</ref><ref>{{Cite web|url=https://spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/comm/inst/mads.html|archive-url=https://web.archive.org/web/19991217123830/http://www.spaceflight.nasa.gov/shuttle/reference/shutref/orbiter/comm/inst/mads.html|url-status=dead|archive-date=December 17, 1999|title=HSF - The Shuttle|website=spaceflight.nasa.gov}}</ref>

===Other upgrades===
[[File:Space Shuttle Columbia lands following STS-62 on 18 March 1994..jpg|right|thumb|''Columbia'' landing at the [[Shuttle Landing Facility|SLF Runway&nbsp;33]] ([[STS-62]] mission)]]
''Columbia'' was originally fitted with [[Lockheed Corporation|Lockheed]]-built ejection seats identical to those found on the [[SR-71 Blackbird]]. These were active for the four orbital test flights, but deactivated after [[STS-4]], and removed entirely after [[STS-9]].  ''Columbia'' was the only spaceworthy orbiter not delivered with [[head-up display]]s for the Commander and Pilot, although these were incorporated after STS-9. Like its sister ships, ''Columbia'' was eventually retrofitted with the new MEDS "[[glass cockpit]]" display and lightweight seats.

===Planned future===
[[File:STS-109 launch.jpg|thumb|Space Shuttle ''Columbia'' STS-109(HST-3B) launch, its final successful mission]]

Had ''Columbia'' not been destroyed, it would have been fitted with the [[Androgynous Peripheral Attach System#APAS-95|external airlock/docking adapter]] for [[STS-118]], an [[International Space Station]] assembly mission, originally planned for November 2003. ''Columbia'' was scheduled for this mission due to ''Discovery'' being out of service for its Orbital Major Modification, and because the ISS assembly schedule could not be adhered to with only ''Endeavour'' and ''Atlantis''.

''Columbia'''s career would have started to wind down after [[STS-118]]. It was to service the [[Hubble Space Telescope]] two more times between 2004 and 2005. Following the ''Columbia'' accident, NASA flew the [[STS-125]] mission using ''[[Space Shuttle Atlantis|Atlantis]]'', combining the planned fourth and fifth servicing missions into one final mission to Hubble. Because of the retirement of the Space Shuttle fleet, the batteries and gyroscopes that keep the telescope pointed will eventually fail, which would result in its reentry and breakup in Earth's atmosphere.  A "Soft Capture Docking Mechanism", based on the docking adapter that was to be used on the [[Orion (Constellation program)|Orion spacecraft]], was installed during the last servicing mission in anticipation of this event.