Editing Space Shuttle Discovery (section)

== Features and upgrades ==
[[File:STS-41-D_Crew_Enjoying_Space_-_GPN-2004-00024.jpg|thumb|On the maiden voyage of ''Discovery'': [[Judith Resnik]], [[Henry Hartsfield]], [[Michael L. Coats]], [[Steven A. Hawley]], [[Charles D. Walker]], and [[Richard M. Mullane]]]]
[[File:SRBsepfromDiscovery07042006.png|thumb|''Discovery'' after booster separation]]
[[File:STS-121 Discovery posing for inspection photos edit1.jpg|thumb|''Discovery'' approaching the [[International Space Station|ISS]] on [[STS-121]], its 'teardrop' feature clearly visible|alt=Discovery is approaching the International Space Station during STS-121. The payload in the shuttle's cargo compartment would be attached to the ISS later in the mission. The spaceship's unique 'teardrop' feature, consisting of several black tiles near the cockpit, is clearly visible.]]
[[File:Deployment of the Hubble Space Telescope (28248653761).jpg|thumb|''Discovery'' sends the [[Hubble Space Telescope]] into orbit on April 25, 1990]]
During its construction, ''Discovery'' was fitted with several black tiles near the middle starboard window where there should have been white tiles. It is unknown if this was the result of a harmless manufacturing mishap or done intentionally to give a distinctive look to the shuttle. This feature has been called 'teardrop' and allowed ''Discovery'' to be told apart from the rest of the fleet without looking at its name, although often unnoticed by the uninitiated.<ref>{{Cite web |title=Tire marks and teardrop tiles: Smithsonian curator on shuttle Discovery at 30 years {{!}} collectSPACE |url=http://www.collectspace.com/news/news-082914a-shuttle-discovery-30th-anniversary.html |access-date=August 4, 2022 |website=collectSPACE.com |archive-date=November 7, 2022 |archive-url=https://web.archive.org/web/20221107194024/http://www.collectspace.com/news/news-082914a-shuttle-discovery-30th-anniversary.html |url-status=live }}</ref>

The spacecraft weighed roughly {{cvt|6870|lb|kg}} less than ''Columbia'' when it was brought into service due to optimalizations determined during the construction and testing of ''Enterprise'', ''Columbia'' and ''Challenger''.<ref name="over">{{cite web|title=Space Shuttle Overview: Discovery (OV-103)|url=http://www.nasa.gov/centers/kennedy/shuttleoperations/orbiters/discovery-info.html|publisher=NASA|access-date=March 10, 2011|archive-date=November 7, 2007|archive-url=https://web.archive.org/web/20071107032526/http://www.nasa.gov/centers/kennedy/shuttleoperations/orbiters/discovery-info.html|url-status=live}}</ref> ''Discovery'' weighs {{convert|6|lb}} heavier than ''[[Space Shuttle Atlantis|Atlantis]]'' and {{convert|363|lb}} heavier than ''[[Space Shuttle Endeavour|Endeavour]]'' after further weight-saving adjustments were made.<ref name="FT facts">{{cite news|title=Space Shuttle Discovery Facts|url=http://www.floridatoday.com/article/20110408/NEWS0208/110408015/Space-Shuttle-Discovery-facts|newspaper=Florida Today|date=April 10, 2011|access-date=May 1, 2011|archive-date=August 16, 2016|archive-url=https://web.archive.org/web/20160816221633/http://www.floridatoday.com/errors/404/|url-status=live}}</ref>

Part of the ''Discovery'' weight optimizations included the greater use of quilted [[Space Shuttle thermal protection system#Flexible Insulation Blankets/Advanced Flexible Reusable Insulation (FIB/AFRSI)|AFRSI]] blankets rather than the white [[Space Shuttle thermal protection system#Low-temperature reusable surface insulation (LRSI)|LRSI]] tiles on the fuselage, and the use of [[graphite epoxy]] instead of aluminum for the payload bay doors and some of the wing spars and beams.<ref>{{cite web|title=STS-41D Press Kit|url=http://www.jsc.nasa.gov/history/shuttle_pk/pk/Flight_012_STS-41D_Press_Kit.pdf|publisher=NASA|access-date=July 12, 2013|page=13|date=August 1984|quote=Graphite epoxy has replaced some internal aluminum spars and beams in the wings and in the payload bay doors.|archive-url=https://web.archive.org/web/20130315170409/http://www.jsc.nasa.gov/history/shuttle_pk/pk/Flight_012_STS-41D_Press_Kit.pdf|archive-date=March 15, 2013|url-status=dead}}</ref>

Upon its delivery to the Kennedy Space Center in 1983, ''Discovery'' was modified alongside ''Challenger'' to accommodate the liquid-fueled [[Centaur-G]] booster, which had been planned for use beginning in 1986 but was cancelled in the wake of the ''Challenger'' disaster.<ref>{{cite book|last=Lardas|first=Mark|title=Space Shuttle Launch System: 1972–2004|year=2012|publisher=Osprey Publishing|page=37}}</ref>

Beginning in late 1995, the orbiter underwent a nine-month [[Orbiter Maintenance Down Period]] (OMDP) in [[Palmdale, California]]. This included outfitting the vehicle with a fifth set of cryogenic tanks and an external airlock to support missions to the [[International Space Station]]. As with all the orbiters, it could be attached to the top of specialized aircraft and did so in June 1996 when it returned to the Kennedy Space Center, and later in April 2012 when sent to the Udvar-Hazy Center, riding [[piggy-back (transportation)|piggy-back]] on a [[Shuttle Carrier Aircraft|modified Boeing 747]].<ref name=over/>

After [[STS-105]], ''Discovery'' became the first of the orbiter fleet to undergo Orbiter Major Modification (OMM) period at the Kennedy Space Center. Work began in September 2002 to prepare the vehicle for Return to Flight. The work included scheduled upgrades and additional safety modifications.<ref name=over/>