Editing Chandra X-ray Observatory (section)

==History==
In 1976, the Chandra X-ray Observatory (called AXAF at the time) was proposed to NASA by [[Riccardo Giacconi]] and Harvey Tananbaum. Preliminary work began the following year at [[Marshall Space Flight Center]] (MSFC) and the [[Smithsonian Astrophysical Observatory]] (SAO), where the telescope is now operated for NASA<ref>{{cite web |title=Chandra X-ray Center |url=https://cxc.cfa.harvard.edu/ |website=CXC.CFA.Harvard.edu |access-date=February 21, 2022 }}</ref> at the Chandra X-ray Center in the [[Harvard-Smithsonian Center for Astrophysics|Center for Astrophysics {{!}} Harvard & Smithsonian]]. In the meantime, in 1978, NASA launched the first imaging X-ray telescope, [[Einstein Observatory|Einstein]] (HEAO-2), into orbit. Work continued on the AXAF project throughout the 1980s and 1990s. In 1992, to reduce costs, the spacecraft was redesigned. Four of the twelve planned mirrors were eliminated, as were two of the six scientific instruments. AXAF's planned orbit was changed to an elliptical one, reaching one third of the way to the Moon's at its farthest point. This eliminated the possibility of improvement or repair by the [[Space Shuttle program|Space Shuttle]] but put the observatory above the Earth's [[Van Allen radiation belt|radiation belts]] for most of its orbit. AXAF was assembled and tested by [[TRW Inc.|TRW]] (now [[Northrop Grumman]] Aerospace Systems) in [[Redondo Beach, California|Redondo Beach]], [[California]].

[[File:STS-93 launch.jpg|thumb|left|[[Space Shuttle Columbia|Space Shuttle ''Columbia'']], [[STS-93]] launches in 1999]]

AXAF was renamed Chandra as part of a contest held by NASA in 1998, which drew more than 6,000 submissions worldwide.<ref name="harvard20131031">{{cite web |url=http://chandra.harvard.edu/chronicle/0413/name/ |title=Tyrel Johnson & Jatila van der Veen - Winners of the Chandra-Naming Contest - Where Are They Now? |publisher=Center for Astrophysics {{!}} Harvard & Smithsonian |first=Wallace |last=Tucker |date=October 31, 2013 |access-date=January 12, 2014 }}</ref> The contest winners, Jatila van der Veen and Tyrel Johnson (then a high school teacher and high school student, respectively), suggested the name in honor of Nobel Prize–winning [[Indian-American]] [[astrophysicist]] [[Subrahmanyan Chandrasekhar]]. He is known for his work in determining the [[Chandrasekhar limit|maximum mass]] of [[white dwarf]] stars, leading to greater understanding of high energy astronomical phenomena such as [[neutron star]]s and [[black hole]]s.<ref name="cowinners1998">{{cite web |url=http://chandra.harvard.edu/contest/co_winners.html |title=And the Co-Winners Are... |publisher=Center for Astrophysics {{!}} Harvard & Smithsonian |date=1998 |archive-date=January 12, 2014 |archive-url=https://web.archive.org/web/20140112205117/http://chandra.harvard.edu/contest/co_winners.html }}</ref> Fittingly, the name Chandra means "moon" in [[Sanskrit]].<ref>{{cite web |url=https://www.behindthename.com/name/chandra |title=Meaning, origin and history of the name Chandra |website=Behind the Name |access-date=June 19, 2024 }}</ref>

Originally scheduled to be launched in December 1998,<ref name="harvard20131031" /> the spacecraft was delayed several months, eventually being launched on July 23, 1999, at 04:31&nbsp;UTC by {{OV|Columbia}} during [[STS-93]]. Chandra was deployed by [[Catherine Coleman|Cady Coleman]]<ref>{{cite web |publisher=NASA |title=Image: July 23, 1999, Chandra X-ray Observatory Awaits Deployment |url=https://chandra.harvard.edu/press/bios/coleman_bio.html |website=Phys.org |access-date=February 21, 2022 }}</ref> from ''Columbia'' at 11:47&nbsp;UTC. The Inertial Upper Stage's first stage motor ignited at 12:48&nbsp;UTC, and after burning for 125 seconds and separating, the second stage ignited at 12:51&nbsp;UTC and burned for 117 seconds.<ref>{{cite web |url=http://www1.msfc.nasa.gov:80/NEWSROOM/news/status/chandrastatus/chandrastatus27.html |title=Chandra X-ray Observatory Status Report: July 23, 1999 6:00 p.m. EDT |series=Marshall Space Flight Center Status Reports |publisher=NASA |first=Dave |last=Drachlis |date=July 23, 1999 |archive-url=https://web.archive.org/web/20000226004401/http://www1.msfc.nasa.gov/NEWSROOM/news/status/chandrastatus/chandrastatus27.html |archive-date=February 26, 2000 }}</ref> At {{convert|22753|kg|lb}},<ref name="chandra-quick-facts" /> it was the heaviest payload ever launched by the shuttle, a consequence of the two-stage [[Inertial Upper Stage]] booster rocket system needed to transport the spacecraft to its high orbit.

Chandra has been returning data since the month after it launched. It is operated by the SAO at the Chandra X-ray Center in [[Cambridge, Massachusetts]], with assistance from [[MIT]] and [[Northrop Grumman]] Space Technology. The ACIS CCDs suffered particle damage during early radiation belt passages. To prevent further damage, the instrument is now removed from the telescope's focal plane during passages.

Although Chandra was initially given an expected lifetime of 5 years, on September 4, 2001, NASA extended its lifetime to 10 years "based on the observatory's outstanding results."<ref>{{cite web |url=http://chandra.harvard.edu/chronicle/0301/extended_mission.html |title=Chandra's Mission Extended to 2009 |publisher=Center for Astrophysics {{!}} Harvard & Smithsonian |date=September 28, 2001}}</ref> Physically Chandra could last much longer. A 2004 study performed at the Chandra X-ray Center indicated that the observatory could last at least 15 years.<ref>{{cite journal |title=The Development and Scientific Impact of the Chandra X-Ray Observatory |journal=International Journal of Modern Physics D |first=Daniel A. |last=Schwartz |volume=13 |issue=7 |pages=1239–1248 |date=August 2004 |doi=10.1142/S0218271804005377 |arxiv=astro-ph/0402275 |bibcode=2004IJMPD..13.1239S|s2cid=858689 }}</ref> It is active as of 2024 and has an upcoming schedule of observations published by the Chandra X-ray Center.<ref>{{cite web |title=CXO Long-term Schedule |url=https://cxc.harvard.edu/target_lists/longsched.html |website=CXC.Harvard.edu |access-date=February 21, 2022 }}</ref>

In July 2008, the [[International X-ray Observatory]], a joint project between [[ESA]], [[NASA]] and [[JAXA]], was proposed as the next major X-ray observatory but was later canceled.<ref>{{cite web |url=http://constellation.gsfc.nasa.gov/ |title=International X-ray Observatory |publisher=NASA |archive-url=https://web.archive.org/web/20080303062108/http://constellation.gsfc.nasa.gov/ |archive-date=March 3, 2008 }}</ref> ESA later resurrected a downsized version of the project as the [[Advanced Telescope for High Energy Astrophysics]] (ATHENA), with a proposed launch in 2028.<ref name="space20131101">{{cite news |url=http://www.space.com/23440-athena-xray-space-telescope-2028.html |title=X-ray Space Telescope of the Future Could Launch in 2028 |work=Space.com |first=Elizabeth |last=Howell |date=November 1, 2013 |access-date=January 1, 2014 }}</ref>

On October 10, 2018, Chandra entered safe mode operations, due to a gyroscope glitch. NASA reported that all science instruments were safe.<ref name="cnet20181012">{{cite news |url=https://www.cnet.com/news/another-nasa-space-telescope-chandra-x-ray-observatory-just-went-into-safe-mode/ |title=Another NASA space telescope just went into safe mode |work=CNET |first=Amanda |last=Kooser |date=October 12, 2018 |access-date=October 14, 2018 }}</ref><ref>{{cite web |url=https://www.nasa.gov/feature/chandra-enters-safe-mode-investigation-underway |title=Chandra Enters Safe Mode; Investigation Underway |publisher=NASA |editor-first=Brian |editor-last=Dunbar |date=October 12, 2018 |access-date=October 14, 2018 |archive-date=November 11, 2022 |archive-url=https://web.archive.org/web/20221111213927/https://www.nasa.gov/feature/chandra-enters-safe-mode-investigation-underway/ }}</ref> Within days, the 3-second error in data from one gyro was understood, and plans were made to return Chandra to full service. The gyroscope that experienced the glitch was placed in reserve and is otherwise healthy.<ref>{{cite web |url=http://chandra.si.edu/press/18_releases/press_101518.html |title=Chandra Operations Resume after Cause of Safe Mode Identified |publisher=NASA/[[Smithsonian]] |first1=Felicia |last1=Chou |first2=Molly |last2=Porter |first3=Megan |last3=Watzke |date=October 24, 2018 |access-date=June 19, 2024 }}</ref>

In March 2024, Congress decided to reduce funding for NASA and its missions.
This may lead to the premature end of this mission.<ref>{{cite news |url=https://www.space.com/chandra-x-ray-observatory-nasa-fy2025-budget |title=The Chandra X-ray spacecraft may soon go dark, threatening a great deal of astronomy |work=Space.com |first=Monisha |last=Ravisetti |date=March 23, 2024 |access-date=June 13, 2023 }}</ref>
In June 2024, Senators urged NASA to reconsider the cuts to Chandra, which was accepted.<ref>{{cite news|url=https://spacenews.com/congressional-letter-asks-nasa-to-rescind-chandra-cuts/ |title=Congressional letter asks NASA to rescind Chandra cuts |work=Spacenews.com |first=Jeff |last=Foust |date=June 13, 2024 |access-date=June 13, 2024 }}</ref>