Editing Hubble Space Telescope (section)

== Future ==
=== Orbital decay and controlled reentry ===
[[File:Soft Capture Mechanism installed on Hubble (illustration).jpg|thumb|Illustration of the Soft Capture Mechanism (SCM) installed on Hubble]]

Hubble orbits the Earth in the extremely tenuous upper [[Earth's atmosphere|atmosphere]], and over time its orbit [[orbital decay|decays]] due to [[drag (physics)|drag]]. If not [[reboost]]ed, it will re-enter the Earth's atmosphere within some decades, with the exact date depending on how active the Sun is and its impact on the upper atmosphere. If Hubble were to descend in a completely uncontrolled re-entry, parts of the main mirror and its support structure would probably survive, leaving the potential for damage or even human fatalities.<ref>{{cite news |url=http://news.bbc.co.uk/2/hi/science/nature/3406079.stm |title=Why Hubble is being dropped |work=BBC News |first=David |last=Whitehouse |date=January 17, 2004 |access-date=January 10, 2007 |archive-date=June 14, 2017 |archive-url=https://web.archive.org/web/20170614030822/http://news.bbc.co.uk/2/hi/science/nature/3406079.stm |url-status=live }}</ref> In 2013, deputy project manager James Jeletic projected that Hubble could survive into the 2020s.<ref name="cbsnews20130530">{{cite web |url=http://www.cbsnews.com/network/news/space/home/spacenews/files/1ae7cac0d167055e41e1f0da7b0ac6a3-588.html |title=Four years after final service call, Hubble Space Telescope going strong |work=CBS News |first=William |last=Harwood |date=May 30, 2013 |access-date=June 3, 2013 |archive-date=October 30, 2019 |archive-url=https://web.archive.org/web/20191030221153/http://www.cbsnews.com/network/news/space/home/spacenews/files/1ae7cac0d167055e41e1f0da7b0ac6a3-588.html |url-status=live }}</ref> Based on solar activity and atmospheric drag, or lack thereof, a natural atmospheric reentry for Hubble will occur between 2028 and 2040.<ref name="cbsnews20130530" /><ref>{{cite news |url=http://www.space.com/29206-how-will-hubble-space-telescope-die.html |title=How Will the Hubble Space Telescope Die? |work=Space.com |first=Mike |last=Wall |date=April 24, 2015 |access-date=May 16, 2017 |archive-date=May 5, 2017 |archive-url=https://web.archive.org/web/20170505052811/http://www.space.com/29206-how-will-hubble-space-telescope-die.html |url-status=live }}</ref> In June 2016, NASA extended the service contract for Hubble until June 2021.<ref>{{Cite press release |url=http://www.nasa.gov/press-release/nasa-extends-hubble-space-telescope-science-operations-contract |title=NASA Extends Hubble Space Telescope Science Operations Contract |publisher=NASA |last=Northon |first=Karen |date=June 23, 2016 |access-date=June 26, 2016 |archive-date=June 26, 2016 |archive-url=https://web.archive.org/web/20160626065803/http://www.nasa.gov/press-release/nasa-extends-hubble-space-telescope-science-operations-contract/ |url-status=live }}</ref> In November 2021, NASA extended the service contract for Hubble until June 2026.<ref>{{Cite press release |url=https://www.nasa.gov/feature/nasa-extends-hubble-operations-contract-provides-mission-update |title=NASA Extends Hubble Operations Contract, Provides Mission Update |publisher=NASA |last=Adkins |first=Jamie |date=November 16, 2021 |access-date=June 19, 2022 |archive-date=March 17, 2022 |archive-url=https://web.archive.org/web/20220317212639/https://www.nasa.gov/feature/nasa-extends-hubble-operations-contract-provides-mission-update/ |url-status=live }}</ref>

NASA's original plan for safely de-orbiting Hubble was to [[STS-144|retrieve it using a Space Shuttle]]. Hubble would then have most likely been displayed in the [[Smithsonian Institution]]. This is no longer possible since the [[Space Shuttle retirement|Space Shuttle fleet has been retired]], and would have been unlikely in any case due to the cost of the mission and risk to the crew. Instead, NASA considered adding an external propulsion module to allow controlled re-entry.<ref>{{cite news |url=http://www.spaceref.com/news/viewnews.html?id=1050 |first=Keith |last=Cowing |title=NASA Considering Deletion of Hubble Deorbit Module |date=July 22, 2005 |access-date=January 10, 2007 |publisher=SpaceRef |archive-date=May 30, 2012 |archive-url=https://archive.today/20120530063700/http://www.spaceref.com/news/viewnews.html?id=1050 |url-status=live }}</ref> Ultimately, in 2009, as part of Servicing Mission 4, the last servicing mission by the Space Shuttle, NASA installed the Soft Capture Mechanism (SCM), to enable deorbit by either a crewed or robotic mission. The SCM, together with the Relative Navigation System (RNS), mounted on the Shuttle to collect data to "enable NASA to pursue numerous options for the safe de-orbit of Hubble", constitute the Soft Capture and Rendezvous System (SCRS).<ref name="Soft Capture" /><ref>{{cite web |title=Servicing Missions |url=https://hubblesite.org/mission-and-telescope/servicing-missions |access-date=April 7, 2022 |website=HubbleSite.org |publisher=[[Space Telescope Science Institute]] |archive-date=April 9, 2022 |archive-url=https://web.archive.org/web/20220409085742/https://hubblesite.org/mission-and-telescope/servicing-missions |url-status=live }}</ref>

=== Possible service missions ===
{{As of|2017}}, the [[First presidency of Donald Trump|Trump Administration]] was considering a proposal by the [[Sierra Nevada Corporation]] to use a crewed version of its [[Dream Chaser]] spacecraft to service ''Hubble'' some time in the 2020s as a continuation of its scientific capabilities and as insurance against any malfunctions in the James Webb Space Telescope.<ref name="Popular Mechanics-2017-02-03">{{cite news |url=http://www.popularmechanics.com/space/telescopes/a25211/mission-to-service-hubble-space-telescope/ |title=A New Spaceship Could Fly Astronauts to the Hubble Space Telescope for Repairs |work=[[Popular Mechanics]] |first=Jay |last=Bennett |date=February 14, 2017 |access-date=February 15, 2017 |archive-date=February 14, 2017 |archive-url=https://web.archive.org/web/20170214211431/http://www.popularmechanics.com/space/telescopes/a25211/mission-to-service-hubble-space-telescope/ |url-status=live }}</ref> In 2020, [[John Grunsfeld]] said that [[SpaceX Crew Dragon]] or [[Orion (spacecraft)|Orion]] could perform another repair mission within ten years. While robotic technology is not yet sophisticated enough, he said, with another crewed visit "We could keep Hubble going for another few decades" with new gyros and instruments.<ref name="foust20200615">{{Cite web |last=Foust |first=Jeff |date=June 15, 2020 |title=Hugging Hubble longer |url=https://www.thespacereview.com/article/3965/1 |access-date=June 16, 2020 |website=The Space Review |archive-date=June 16, 2020 |archive-url=https://web.archive.org/web/20200616040203/https://www.thespacereview.com/article/3965/1 |url-status=live }}</ref>

Billionaire [[Commercial astronaut|private astronaut]] [[Jared Isaacman]] proposed to fund a servicing mission using SpaceX spacecraft. Though it might save NASA much money, SpaceX and NASA differed on the mission's risk.<ref>{{cite web |last1=Greenfieldboyce |first1=Nell |title=Private mission to save the Hubble Space Telescope raises concerns, NASA emails show |work=NPR |url=https://www.npr.org/2024/05/16/1250250249/spacex-repair-hubble-space-telescope-nasa-foia |access-date=22 May 2024}}</ref> In September 2022, NASA and SpaceX signed a Space Act Agreement to investigate the possibility of launching a Crew Dragon mission to service and boost Hubble to a higher orbit, possibly extending its lifespan by another 20 years.<ref>{{Cite web |last=Garner |first=Rob |date=September 29, 2022 |title=NASA, SpaceX to Study Hubble Telescope Reboost Possibility |url=https://www.nasa.gov/feature/goddard/2022/nasa-spacex-to-study-hubble-telescope-reboost-possibility/ |access-date=November 6, 2022 |website=nasa.gov |language=en-US |archive-date=November 3, 2022 |archive-url=https://web.archive.org/web/20221103143905/https://www.nasa.gov/feature/goddard/2022/nasa-spacex-to-study-hubble-telescope-reboost-possibility/ |url-status=live }}</ref> This mission could have been the second of the [[Polaris Program]], but by June 2024 NASA had rejected a private servicing mission because of potential damage to the observatory.<ref>{{cite web | url=https://www.nytimes.com/2022/09/29/science/nasa-hubble-spacex-polaris.html | title=NASA May Let Billionaire Astronaut and SpaceX Lift Hubble Telescope (Published 2022) | website=[[The New York Times]] | date=September 30, 2022 }}</ref><ref>{{cite web | url=https://www.nasa.gov/missions/hubble/nasa-spacex-to-study-hubble-telescope-reboost-possibility/ | title=NASA, SpaceX to Study Hubble Telescope Reboost Possibility - NASA | date=December 22, 2022 }}</ref><ref>{{cite web |last=Foust |first=Jeff |url=https://spacenews.com/crew-dragon-splashes-down-to-conclude-polaris-dawn-mission/ |title=Crew Dragon splashes down to conclude Polaris Dawn mission |work=[[SpaceNews]] |date=September 15, 2024 |access-date=November 24, 2024}}</ref>

=== Successors ===
{{further|James Webb Space Telescope}}
{{see also|List of proposed space observatories}}
{| class="wikitable" style="text-align:center; float:right; margin:10px"
| colspan="2" style="text-align:center;"|'''&nbsp;[[Visible spectrum]] range&nbsp;'''
|-
![[Color]]
|[[Wavelength]]
|-
| style="background:#ccb0f4;"|'''[[violet (color)|violet]]'''
|380–450&nbsp;nm
|-
| style="background:#b0b0f4;"|'''[[blue]]'''
|450–475&nbsp;nm
|-
| style="background:#b0f4f4;"|'''[[cyan]]'''
|476–495&nbsp;nm
|-
| style="background:#b0f4b0;"|'''[[green]]'''
|495–570&nbsp;nm
|-
| style="background:#f4f4b0;"|'''[[yellow]]'''
|570–590&nbsp;nm
|-
| style="background:#f4ccb0;"|'''[[orange (color)|orange]]'''
|590–620&nbsp;nm
|-
| style="background:#f4b0b0;"|'''[[red]]'''
|620–750&nbsp;nm
|}

[[File:Primary Mirror Size Comparison Between Webb and Hubble.webm|thumb|upright=1.0|right|Design, size, and mirror comparison between the James Webb Space Telescope and Hubble]]
There is no direct replacement to Hubble as an ultraviolet and visible light space telescope, because near-term space telescopes do not duplicate Hubble's wavelength coverage (near-ultraviolet to near-infrared wavelengths), instead concentrating on the further infrared bands. These bands are preferred for studying high redshift and low-temperature objects, objects generally older and farther away in the universe. These wavelengths are also difficult or impossible to study from the ground, justifying the expense of a space-based telescope. Large ground-based telescopes can image some of the same wavelengths as Hubble, sometimes challenge HST in terms of resolution by using [[adaptive optics]] (AO), have much larger light-gathering power, and can be upgraded more easily, but cannot yet match Hubble's excellent resolution over a wide field of view with the very dark background of space.<ref name=":3" /><ref name=":4" />

Plans for a Hubble successor materialized as the Next Generation Space Telescope project, which culminated in plans for the James Webb Space Telescope (JWST), the formal successor of Hubble.<ref name="SAOverview">{{cite web |url=http://www.scientificamerican.com/article.cfm?id=hubble-servicing-mission-shuttle |title=Last Dance with the Shuttle: What's in Store for the Final Hubble Servicing Mission |first=John |last=Matson |date=May 8, 2009 |work=Scientific American |access-date=May 18, 2009 |archive-date=December 26, 2010 |archive-url=https://web.archive.org/web/20101226170143/http://www.scientificamerican.com/article.cfm?id=hubble-servicing-mission-shuttle |url-status=live }}</ref> Very different from a scaled-up Hubble, it is designed to operate colder and farther away from the Earth at the L2 [[Lagrangian point]], where thermal and optical interference from the Earth and Moon are lessened. It is not engineered to be fully serviceable (such as replaceable instruments), but the design includes a docking ring to enable visits from other spacecraft.<ref>{{cite web |url=http://www.space.com/3833-nasa-adds-docking-capability-space-observatory.html |first=Brian |last=Berger |title=NASA Adds Docking Capability For Next Space Observatory |publisher=Space.com |date=May 23, 2007 |access-date=June 4, 2012 |archive-date=February 4, 2019 |archive-url=https://web.archive.org/web/20190204010427/https://www.space.com/3833-nasa-adds-docking-capability-space-observatory.html |url-status=live }}</ref> A main scientific goal of JWST is to observe the most distant objects in the universe, beyond the reach of existing instruments. It is expected to detect stars in the [[Timeline of the Big Bang|early Universe]] approximately 280&nbsp;million years older than stars HST now detects.<ref>{{cite press release |url=http://www.nasa.gov/mission_pages/hubble/science/farthest-galaxy.html |title=NASA's Hubble Finds Most Distant Galaxy Candidate Ever Seen in Universe |publisher=NASA |date=January 26, 2011 |access-date=June 4, 2012 |archive-date=May 2, 2017 |archive-url=https://web.archive.org/web/20170502061732/https://www.nasa.gov/mission_pages/hubble/science/farthest-galaxy.html |url-status=live }} [http://www.nasa.gov/images/content/512584main_i1105bw.jpg Visual representation] {{Webarchive|url=https://web.archive.org/web/20190605120204/https://www.nasa.gov/mission_pages/hubble/science/farthest-galaxy.html |date=June 5, 2019 }}.</ref> The telescope is an international collaboration between NASA, the European Space Agency, and the [[Canadian Space Agency]] since 1996,<ref>{{cite web |url=http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33148 |archive-url=https://web.archive.org/web/20030821120829/http://sci.esa.int/science-e/www/object/index.cfm?fobjectid=33148 |url-status=dead |archive-date=August 21, 2003 |title=ESA JWST Timeline |publisher=Sci.esa.int |date=June 30, 2003 |access-date=June 4, 2012}}</ref> and was launched on December 25, 2021, on an [[Ariane 5]] rocket.<ref>{{cite web |url=http://www.jwst.nasa.gov/launch.html |title=About Webb's Launch |publisher=NASA |access-date=November 4, 2006 |archive-date=June 16, 2019 |archive-url=https://web.archive.org/web/20190616111938/https://jwst.nasa.gov/launch.html |url-status=live }}</ref> Although JWST is primarily an infrared instrument, its coverage extends down to 600&nbsp;nm wavelength light, or roughly orange in the visible spectrum. A typical human eye can see to about 750&nbsp;nm wavelength light, so there is some overlap with the longest visible wavelength bands, including orange and red light.<ref>{{Cite web |title=FAQ |url=https://jwst.nasa.gov/content/about/faqs/faq.html |access-date=April 6, 2022 |website=jwst.nasa.gov |language=en |archive-date=July 23, 2019 |archive-url=https://web.archive.org/web/20190723142004/https://jwst.nasa.gov/content/about/faqs/faq.html |url-status=live }}</ref>

[[File:JWST-HST-primary-mirrors.svg|left|thumb|Hubble and JWST mirrors (4.0 m<sup>2</sup> and 25&nbsp;m<sup>2</sup> respectively)]]
A complementary telescope, looking at even longer wavelengths than Hubble or JWST, was the European Space Agency's [[Herschel Space Observatory]], launched on May 14, 2009. Like JWST, Herschel was not designed to be serviced after launch, and had a mirror substantially larger than Hubble's, but observed only in the [[far infrared]] and [[submillimeter astronomy|submillimeter]]. It needed helium coolant, of which it ran out on April 29, 2013.<ref name=bbc>{{cite web |url=https://www.bbc.co.uk/news/science-environment-21934520 |title=Herschel space telescope finishes mission |work=BBC News |first=Jonathan |last=Amos |date=April 29, 2013 |access-date=April 29, 2013 |archive-date=February 21, 2019 |archive-url=https://web.archive.org/web/20190221174104/https://www.bbc.co.uk/news/science-environment-21934520 |url-status=live }}</ref>

{| class=wikitable style="text-align:center; margin:10px"
|-
| colspan="8" style="text-align:center;"|'''Selected space telescopes and instruments'''<ref>{{cite web |url=http://herschel.jpl.nasa.gov/relatedMissions.shtml |title=JPL: Herschel Space Observatory: Related Missions |publisher=Herschel.jpl.nasa.gov |access-date=June 4, 2012 |archive-date=December 3, 2016 |archive-url=https://web.archive.org/web/20161203091854/https://herschel.jpl.nasa.gov/relatedMissions.shtml |url-status=live }}</ref>
|-
! Name !! Year || Wavelength || Aperture
|-
| Human eye || — || 0.39–0.75 μm || 0.005 m
|-
| [[Spitzer Space Telescope|Spitzer]] || 2003 || 3–180 μm || 0.85 m
|-
| Hubble STIS || 1997 || 0.115–1.03 μm || 2.4 m
|-
| Hubble WFC3 || 2009 || 0.2–1.7 μm || 2.4 m
|-
| [[Herschel Space Observatory|Herschel]] || 2009 || 55–672 μm || 3.5 m
|-
| [[James Webb Space Telescope|JWST]] || 2021 || 0.6–28.5 μm || 6.5 m
|}

Further concepts for advanced 21st-century space telescopes include the [[Large Ultraviolet Optical Infrared Surveyor]] (LUVOIR),<ref>"What Will Astronomy Be Like in 35 Years?". ''Astronomy''. August 2008.</ref> a conceptualized {{convert|8|to|16.8|m|in |abbr=off|sp=us}} optical space telescope that if realized could be a more direct successor to HST, with the ability to observe and photograph astronomical objects in the visible, ultraviolet, and infrared wavelengths, with substantially better resolution than Hubble or the Spitzer Space Telescope. The final planning report, prepared for the 2020 [[Astronomy and Astrophysics Decadal Survey]], suggested a launch date of 2039.<ref name=":1">{{cite web |date=August 26, 2019 |title=LUVOIR Mission Concept Study Final Report |url=https://www.luvoirtelescope.org/copy-of-design |access-date=May 24, 2021 |work=luvoirtelescope.org |publisher=[[NASA]] |archive-date=May 24, 2021 |archive-url=https://web.archive.org/web/20210524221618/https://www.luvoirtelescope.org/copy-of-design |url-status=live }}</ref> The Decadal Survey eventually recommended that ideas for LUVOIR be combined with the [[Habitable Exoplanet Imaging Mission|Habitable Exoplanet Observer]] proposal to devise a new, 6-meter flagship telescope that could launch in the 2040s.<ref name="NA-20211104">{{cite news |author=Staff |date=November 4, 2021 |title=New Report Charts Path for Next Decade of Astronomy and Astrophysics; Recommends Future Ground and Space – Telescopes, Scientific Priorities, Investments in Scientific Community |work=[[National Academies of Sciences, Engineering, and Medicine]] |url=https://www.nationalacademies.org/news/2021/11/new-report-charts-path-for-next-decade-of-astronomy-and-astrophysics-recommends-future-ground-and-space-telescopes-scientific-priorities-investments-in-scientific-community |url-status=live |accessdate=November 5, 2021 |archive-url=https://web.archive.org/web/20211105002202/https://www.nationalacademies.org/news/2021/11/new-report-charts-path-for-next-decade-of-astronomy-and-astrophysics-recommends-future-ground-and-space-telescopes-scientific-priorities-investments-in-scientific-community |archive-date=November 5, 2021}}</ref>

Existing ground-based telescopes, and various proposed [[Extremely Large Telescopes]], can exceed the HST in terms of sheer light-gathering power and diffraction limit due to larger mirrors, but other factors affect telescopes. In some cases, they may be able to match or exceed Hubble in resolution by using adaptive optics (AO). However, AO on large ground-based reflectors will not make Hubble and other space telescopes obsolete. Most AO systems sharpen the view over a very narrow field—[[Lucky imaging|Lucky Cam]], for example, produces crisp images just 10 to 20 arcseconds wide, whereas Hubble's cameras produce crisp images across a 150 arcsecond (2½ arcminutes) field. Furthermore, space telescopes can study the universe across the entire electromagnetic spectrum, most of which is blocked by Earth's atmosphere. Finally, the background sky is darker in space than on the ground, because air absorbs solar energy during the day and then releases it at night, producing a faint—but nevertheless discernible—[[airglow]] that washes out low-contrast astronomical objects.<ref name="Fienberg">{{cite news |last=Fienberg |first=Richard Tresch |date=September 14, 2007 |title=Sharpening the 200-Inch |work=Sky & Telescope |url=http://www.skyandtelescope.com/astronomy-news/sharpening-the-200-inch/ |url-status=live |access-date=July 1, 2008 |archive-url=https://web.archive.org/web/20180828035625/https://www.skyandtelescope.com/astronomy-news/sharpening-the-200-inch/ |archive-date=August 28, 2018}}</ref>

{{multiple images |total_width=550 |direction=horizontal |align=center |header=Left: image taken by Hubble (2017) vs Right: the image taken by Webb (2022)<ref name="NBC-20220712">{{cite news |last1=Chow |first1=Denise |last2=Wu |first2=Jiachuan |title=Photos: How pictures from the Webb telescope compare to Hubble's - NASA's $10 billion telescope peers deeper into space than ever, revealing previously undetectable details in the cosmos. |url=https://www.nbcnews.com/data-graphics/compare-photos-nasas-james-webb-space-telescope-hubble-space-telescope-rcna37875 |date=July 12, 2022 |work=[[NBC News]] |accessdate=July 23, 2022 |archive-date=July 15, 2022 |archive-url=https://web.archive.org/web/20220715193545/https://www.nbcnews.com/data-graphics/compare-photos-nasas-james-webb-space-telescope-hubble-space-telescope-rcna37875 |url-status=live }}</ref>
 |image1=NASA-HubbleSpaceTelescope-DeepField-2017.jpg |image2=Webb's First Deep Field (adjusted).jpg
 |footer=[[Webb's First Deep Field|Deep Field]] – [[Galaxy cluster]] [[SMACS J0723.3-7327]].<ref name="NASA-20220711">{{cite news |last=Garner |first=Rob |title=NASA's Webb Delivers Deepest Infrared Image of Universe Yet |url=https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet |date=July 11, 2022 |work=[[NASA]] |accessdate=July 23, 2022 |archive-date=July 12, 2022 |archive-url=https://web.archive.org/web/20220712000119/https://www.nasa.gov/image-feature/goddard/2022/nasa-s-webb-delivers-deepest-infrared-image-of-universe-yet/ |url-status=live }}</ref><ref name="NYT-20220711">{{cite news |last1=Overbye |first1=Dennis |last2=Chang |first2=Kenneth |last3=Tankersley |first3=Jim |title=Biden and NASA Share First Webb Space Telescope Image – From the White House on Monday, humanity got its first glimpse of what the observatory in space has been seeing: a cluster of early galaxies. |url=https://www.nytimes.com/2022/07/11/science/nasa-webb-telescope-images-livestream.html |date=July 11, 2022 |work=[[The New York Times]] |accessdate=July 23, 2022 |archive-date=July 12, 2022 |archive-url=https://web.archive.org/web/20220712005736/https://www.nytimes.com/2022/07/11/science/nasa-webb-telescope-images-livestream.html |url-status=live }}</ref><ref name="SA-202207">{{cite news |last=Pacucci |first=Fabio |title=How Taking Pictures of 'Nothing' Changed Astronomy - Deep-field images of "empty" regions of the sky from Webb and other space telescopes are revealing more of the universe than we ever thought possible |url=https://www.scientificamerican.com/article/how-taking-pictures-of-nothing-changed-astronomy1/ |date=July 15, 2022 |work=[[Scientific American]] |accessdate=July 23, 2022 |archive-date=July 16, 2022 |archive-url=https://web.archive.org/web/20220716023339/https://www.scientificamerican.com/article/how-taking-pictures-of-nothing-changed-astronomy1/ |url-status=live }}</ref>}}