Extremely large telescope

{{for|the specific observatory by this name|Extremely Large Telescope}}

{{comparison optical telescope primary mirrors.svg|upright{{=}}2|the above extremely large telescopes and}}

An extremely large telescope (ELT) is an astronomical observatory featuring an optical telescope with an aperture for its primary mirror from 20 metres up to 100 metres across,As [http://www.astro-opticon.org/fp5/skelcase.html A Skeleton Science Case For Extremely Large (20m–100m) Ground-based Telescopes (ELTs)] and first section of [https://www.science.org.au/sites/default/files/user-content/resources/file/eltroadmap040917.pdf ELT Roadmap] {{webarchive|url=https://web.archive.org/web/20150518234711/https://www.science.org.au/sites/default/files/user-content/resources/file/eltroadmap040917.pdf |date=2015-05-18 }}, PDF{{cite news |last=Overbye |first=Dennis |authorlink=Dennis Overbye |title=Good News and Bad News for Astronomers’ Biggest Dream - The National Science Foundation takes a step (just one) toward an “extremely large telescope.” |url=https://www.nytimes.com/2024/03/08/science/astronomy-extremely-large-telescope.html |date=8 March 2024 |work=The New York Times |url-status=live |archiveurl=https://archive.today/20240308112703/https://www.nytimes.com/2024/03/08/science/astronomy-extremely-large-telescope.html |archivedate=8 March 2024 |accessdate=8 March 2024 }} when discussing reflecting telescopes of optical wavelengths including ultraviolet (UV), visible, and near infrared wavelengths. Among many planned capabilities, extremely large telescopes are planned to increase the chance of finding Earth-like planets around other stars.{{Cite news |url=https://www.theguardian.com/science/2006/aug/05/spaceexploration.universe |title=Extremely Large Telescope could reveal secrets of life, the universe and everything |work=The Guardian |first=Alok |last=Jha |date=5 August 2006}} Telescopes for radio wavelengths can be much bigger physically, such as the {{convert|300|m|yd|abbr=off}} aperture fixed focus radio telescope of the Arecibo Observatory (now defunct). Freely steerable radio telescopes with diameters up to {{convert|100|m|yd|abbr=off}} have been in operation since the 1970s.

These telescopes have a number of features in common, in particular the use of a segmented primary mirror (similar to the existing Keck telescopes), and the use of high-order adaptive optics systems.{{Cite journal |url=http://www.tmt.org/news/TMT-Construction%20Proposal-Public.pdf |publisher=TMT Observatory Corporation |page=29 |title=Thirty Meter Telescope Construction Proposal |date=2007-09-12 |access-date=2009-07-24 |journal= |archive-date=2016-03-24 |archive-url=https://web.archive.org/web/20160324230243/http://tmt.org/news/TMT-Construction%20Proposal-Public.pdf |url-status=dead }}{{Cite book |title=GMT Conceptual Design Report |chapter=Chapter 6: Optics |url=http://www.gmto.org/CoDRpublic |chapter-url=http://www.gmto.org/codrfolder/GMT-ID-01467-Chapter_6_Optics.pdf |pages=6–3 |access-date=2008-04-02 |publisher=GMT Consortium}}

Although extremely large telescope designs are large, they can have smaller apertures than the aperture synthesis on many large optical interferometers. However, they may collect much more light, along with other advantages.

List of telescopes

class="wikitable sortable" style="text-align: center; font-size:100%;" ! # ! class="unsortable" \| Image ! Name ! data-sort-type="number" \| Aperture (m) ! Area (m²) ! Primary mirror ! Altitude (m) ! First light ! class="unsortable" \| Notes ! class="unsortable" \| Refs
1 \| align=left nowrap \| 100px \| Extremely Large Telescope (ELT) \| 39.3 \| 978 \| 798 × 1.45 m hexagonal {{f/}}1 \| 3060 \| 2029 \| Under construction at Cerro Armazones Obs., Chile \|{{cite web \|url=http://www.eso.org/public/news/eso1419/ \|title=Groundbreaking for the E-ELT \|date=19 June 2014}}{{cite news \|url=https://www.science.org/content/article/europe-downscales-monster-telescope-save-money \|first=Govert \|last=Schilling \|title=Europe Downscales Monster Telescope to Save Money \|date=14 June 2011 \|work=Science Insider}}{{Cite web \|url=http://www.eso.org/public/astronomy/teles-instr/e-elt_num.html \|title=The E-ELT in numbers \|access-date=2009-08-11 \|archive-url=https://web.archive.org/web/20090821225427/http://www.eso.org/public/astronomy/teles-instr/e-elt_num.html \|archive-date=2009-08-21 \|url-status=dead }}
2 \| align=left nowrap \| 100px \|Thirty Meter Telescope (TMT) \| 30.0 \| 655 \| 492 × 1.45 m hexagonal {{f/}}1 \| 4050 \| 2030s (?) \| Construction approved at Mauna Kea Obs. in Hawaii, USA, halted as of September 2019 due to protests \|{{Citation \|url=http://www.tmt.org/observatory/timeline \|title=Thirty Meter Telescope timeline page \|publisher=TMT Observatory Project \|access-date=2010-10-12 \|archive-date=2010-09-25 \|archive-url=https://web.archive.org/web/20100925013506/http://www.tmt.org/observatory/timeline \|url-status=dead }}[https://www.tmt.org/page/timeline?category=Observatory+Construction TMT Timeline], accessed February 11, 2018{{cite news \|url=https://www.bbc.com/news/world-us-canada-46046864 \|title=Hawaii top court approves controversial Thirty Meter Telescope \|date=31 October 2018 \|work=BBC News}}
3 \| align=left nowrap \| 100px \|Giant Magellan Telescope (GMT) \| 24.5 \| 368 \| 7 × 8.4 m circular {{f/}}0.71 \| 2516 \| 2030s \| Under construction at Las Campanas Obs., Chile; 6/7 mirrors cast \|{{cite news \|first=Elizabeth \|last=Howell \|url=http://sen.com/news/giant-telescope-gets-20m-funding-boost-as-design-takes-shape \|title=Giant telescope gets $20m funding boost as design takes shape \|date=29 December 2014 \|work=Sen \|access-date=8 January 2015 \|archive-date=17 July 2021 \|archive-url=https://web.archive.org/web/20210717164947/https://sen.com/news/giant-telescope-gets-20m-funding-boost-as-design-takes-shape \|url-status=dead }}{{Cite web \|date=12 March 2021 \|title=Giant Magellan Telescope – 6th mirror cast \|url=https://www.universetoday.com/150506/the-giant-magellan-telescopes-6th-mirror-has-just-been-cast-one-more-to-go/ \|access-date=11 July 2023}}
style="background: #FFFFE0;" \| 4 \| align=left nowrap \| 100px \| Large Binocular Telescope (LBT) \| 11.8 (equiv. area) 22.8 (equiv. detail limit) \| 111 \| 2 × 8.4 m circular \| 3221 \| 2008 \| Largest non-segmented mirrors. Located on Mount Graham, Arizona, USA \|{{cite press release \|title=Large Binocular Telescope Achieves First Binocular Light \|url=http://medusa.as.arizona.edu/lbto/firstbinocularlight_press_release.htm \|date=2008-02-28 \|publisher=Large Binocular Telescope Corporation \|url-status=dead \|archive-url=https://web.archive.org/web/20080310010642/http://medusa.as.arizona.edu/lbto/firstbinocularlight_press_release.htm \|archive-date=2008-03-10}}
colspan=10 style="font-size: 0.9em; font-weight: normal; text-align: left; padding: 4px 2px 6px 4px;" \|Note: Aperture of LBT: the baseline is obtained via aperture synthesis.

class="wikitable sortable" style="text-align: center; font-size:100%;"

! #

! class="unsortable" | Image

! Name

! data-sort-type="number" | Aperture (m)

! Area (m²)

! Primary mirror

! Altitude (m)

! First
light

! class="unsortable" | Notes

! class="unsortable" | Refs

| align=left nowrap | 100px

| Extremely Large Telescope
(ELT)

| 39.3

| 978

| 798 × 1.45 m
hexagonal {{f/}}1

| 3060

| 2029

| Under construction at Cerro Armazones Obs., Chile

|{{cite web |url=http://www.eso.org/public/news/eso1419/ |title=Groundbreaking for the E-ELT |date=19 June 2014}}{{cite news |url=https://www.science.org/content/article/europe-downscales-monster-telescope-save-money |first=Govert |last=Schilling |title=Europe Downscales Monster Telescope to Save Money |date=14 June 2011 |work=Science Insider}}{{Cite web |url=http://www.eso.org/public/astronomy/teles-instr/e-elt_num.html |title=The E-ELT in numbers |access-date=2009-08-11 |archive-url=https://web.archive.org/web/20090821225427/http://www.eso.org/public/astronomy/teles-instr/e-elt_num.html |archive-date=2009-08-21 |url-status=dead }}

| align=left nowrap | 100px

|Thirty Meter Telescope
(TMT)

| 30.0

| 655

| 492 × 1.45 m
hexagonal {{f/}}1

| 4050

| 2030s (?)

| Construction approved at Mauna Kea Obs. in Hawaii, USA, halted as of September 2019 due to protests

|{{Citation |url=http://www.tmt.org/observatory/timeline |title=Thirty Meter Telescope timeline page |publisher=TMT Observatory Project |access-date=2010-10-12 |archive-date=2010-09-25 |archive-url=https://web.archive.org/web/20100925013506/http://www.tmt.org/observatory/timeline |url-status=dead }}[https://www.tmt.org/page/timeline?category=Observatory+Construction TMT Timeline], accessed February 11, 2018{{cite news |url=https://www.bbc.com/news/world-us-canada-46046864 |title=Hawaii top court approves controversial Thirty Meter Telescope |date=31 October 2018 |work=BBC News}}

| align=left nowrap | 100px

|Giant Magellan Telescope
(GMT)

| 24.5

| 368

| 7 × 8.4 m
circular {{f/}}0.71

| 2516

| 2030s

| Under construction at Las Campanas Obs., Chile;
6/7 mirrors cast

|{{cite news |first=Elizabeth |last=Howell |url=http://sen.com/news/giant-telescope-gets-20m-funding-boost-as-design-takes-shape |title=Giant telescope gets $20m funding boost as design takes shape |date=29 December 2014 |work=Sen |access-date=8 January 2015 |archive-date=17 July 2021 |archive-url=https://web.archive.org/web/20210717164947/https://sen.com/news/giant-telescope-gets-20m-funding-boost-as-design-takes-shape |url-status=dead }}{{Cite web |date=12 March 2021 |title=Giant Magellan Telescope – 6th mirror cast |url=https://www.universetoday.com/150506/the-giant-magellan-telescopes-6th-mirror-has-just-been-cast-one-more-to-go/ |access-date=11 July 2023}}

style="background: #FFFFE0;"

| 4

| align=left nowrap | 100px

| Large Binocular Telescope
(LBT)

| 11.8
(equiv. area)
22.8
(equiv. detail limit)

| 111

| 2 × 8.4 m
circular

| 3221

| 2008

| Largest non-segmented mirrors.
Located on Mount Graham, Arizona, USA

|{{cite press release |title=Large Binocular Telescope Achieves First Binocular Light |url=http://medusa.as.arizona.edu/lbto/firstbinocularlight_press_release.htm |date=2008-02-28 |publisher=Large Binocular Telescope Corporation |url-status=dead |archive-url=https://web.archive.org/web/20080310010642/http://medusa.as.arizona.edu/lbto/firstbinocularlight_press_release.htm |archive-date=2008-03-10}}

colspan=10 style="font-size: 0.9em; font-weight: normal; text-align: left; padding: 4px 2px 6px 4px;" |Note: Aperture of LBT: the baseline is obtained via aperture synthesis.

File:Size comparison between the E-ELT and other telescope domes.jpg|The domes of the ELT, the TMT and the GMT compared to other well-known telescopes

Budget

Possible budget figures, which are estimates and can vary over time. For construction costs, it is recommended to estimate the cost of a giant telescope with the relation {{Math|cost ∝ D^2.7}}.{{Cite web|url=http://www.gsmt.noao.edu/documentation/SPIE_Papers/Stepp.pdf|title=Estimating the costs of extremely large telescopes |first1=Larry |last1=Stepp |first2=Larry |last2=Daggert |first3=Paul |last3=Gillett |website=National Optical Astronomy Observatory}}

class="wikitable sortable" style="text-align:left;font-size:100%;"

! Name

! Cost
(est. USD)

! Alternate

Extremely Large Telescope (ELT)

| $1590 million

| €1300 million{{Cite web |title=Funding boost for ESO’s Extremely Large Telescope |url=https://www.eso.org/public/announcements/ann20034/ |access-date=29 August 2024 |website=The European Southern Observatory (ESO)}}

Thirty Meter Telescope (TMT)

| $1400 million

| $3600 million{{Cite web |title=NSF board approves funding for just one of two proposed giant telescopes |url=https://www.science.org/content/article/nsf-board-approves-funding-just-one-two-proposed-giant-telescopes |access-date=29 August 2024 |website=Science (Science.org)}}

Giant Magellan Telescope (GMT)

| $1000 million

|$2540 million

style="background: #FFFFE0;"

| Large Binocular Telescope (LBT)

| $120 million

Projects

class="infobox" style="width: 300px"

style="white-space: nowrap; background-color: #444;" |

{| cellpadding=0 cellspacing=0

colspan=2 |File:Latest Rendering of the E-ELT.jpg File:Top view of tmt complex.jpg

rowspan=2 |File:Giant Magellan Telescope - artist's concept.jpg

| File:LargeBinoTelescope NASA.jpg File:KeckTelescopes-hi.png

File:Paranal opendome.jpg File:Grantelescopio.jpg

|Extremely large telescopes:

Compared to the LBT, Keck, VLT, and GTC

There were several telescopes in various stages in the 1990s and early 2000s, and some developed into construction projects.

;Under construction

ELT:{{Cite web|url=http://www.eso.org/public/teles-instr/elt/|title=Elt | Eso}} Extremely Large Telescope
GMT:{{Cite web|url=https://gmto.org/|title=Giant Magellan Telescope|website=Giant Magellan Telescope}} Giant Magellan Telescope

;Funded construction

TMT:{{Cite web|url=https://www.tmt.org/|title=TMT International Observatory|website=TIO}} Thirty Meter Telescope

;Projects

Some of these projects have been cancelled, or merged into ongoing extremely large telescopes.

GSMT:{{Cite web|url=http://www.aura-nio.noao.edu/|title=AURA NIO: Home|date=October 19, 2006|archive-url=https://web.archive.org/web/20061019105956/http://www.aura-nio.noao.edu/|archive-date=2006-10-19}} Giant Segmented Mirror Telescope, merged into TMT
OWL:{{Cite web|url=https://www.eso.org/sci/facilities/eelt/owl/|title=The ESO 100-m OWL optical telescope concept|website=www.eso.org}} Overwhelmingly Large Telescope, passed over in favor of ELT
VLOT:{{Cite web|url=http://www.hia-iha.nrc-cnrc.gc.ca/VLOT/|title=VLOT {{)}} The Very Large Optical Telescope for CI am Canada|date=May 2, 2009|archive-url=https://web.archive.org/web/20090502050342/http://www.hia-iha.nrc-cnrc.gc.ca/VLOT/|archive-date=2009-05-02}} Very Large Optical Telescope, merged into TMT
LAT:{{Cite web |url=http://astrosun.tn.cornell.edu/atacama |title=Atacama |access-date=2006-12-13 |archive-date=2003-12-02 |archive-url=https://web.archive.org/web/20031202212639/http://astrosun.tn.cornell.edu/atacama |url-status=dead }} Large Atacama Telescope
EURO50:{{Cite web|url=http://www.astro.lu.se/~torben/euro50/|title=Euro50|date=December 14, 2006|archive-url=https://web.archive.org/web/20061214083436/http://www.astro.lu.se/~torben/euro50/|archive-date=2006-12-14}} European 50-metre Telescope, merged into ELT
LPT:{{Cite web|url=http://serweb.oamp.fr/denis/elt/ngcfht_may01.html|title=LPT {{!}} Large Petal Telescope|date=November 23, 2006|archive-url=https://web.archive.org/web/20061123185947/http://serweb.oamp.fr/denis/elt/ngcfht_may01.html|archive-date=2006-11-23}} Large Petal Telescope
Magellan 20: merged into GMT
HDRT:https://home.ifa.hawaii.edu/users/kuhn/tmp.html%25|title= 22 March 2002. High Dynamic Range Telescope
JELT:http://optik2.mtk.nao.ac.jp/futureplan/eltproje.htm{{Dead link|date=December 2022 |bot=InternetArchiveBot |fix-attempted=yes }} Japanese ELT Project; Japan joined the TMT project in 2008
CELT:{{Cite web|url=http://celt.ucolick.org/|title=index.html|date=June 5, 2002|archive-url=https://web.archive.org/web/20020605200532/http://celt.ucolick.org/|archive-date=2002-06-05}} California Extremely Large Telescope, became/merged into TMT
MAXAT:{{cite web |title=MAXAT – the Maximum Aperture Telescope |url=http://www.gemini.edu/science/maxat/ |archive-url=https://web.archive.org/web/20070706082910/http://www.gemini.edu/science/maxat/ |archive-date=6 July 2007}} Maximum Aperture Telescope

References

External links

{{commons category-inline}}
[https://web.archive.org/web/20060825102344/http://www.aao.gov.au/instrum/ELT/Workshop/ Australian National Workshop on Extremely Large Telescopes (ELTs)]
[http://www.astro-opticon.org/fp5/ELT.html The OPTICON ELT Working Group] a Europe-wide research project
[https://web.archive.org/web/20120213001211/http://www.roe.ac.uk/ukatc/projects/elt/ The science case for Extremely Large Telescopes (ELTs)] from the Royal Observatory, Edinburgh
[https://web.archive.org/web/20200602141340/http://the-colossus.com/ Colossus Telescope]

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Category:Reflecting telescopes

Extremely large telescope

List of telescopes

Budget

Projects

See also

References

External links