Thirty Meter Telescope

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Thirty Metre Telescope (Proposed)
TmtSummitComposite.jpg
Rendering of the Thirty Metre Telescope design as of late 2007
Location Mauna Kea Observatory 13 North[1][2]
Coordinates 19°49′58″N 155°28′54″W / 19.8327°N 155.4816°W / 19.8327; -155.4816Coordinates: 19°49′58″N 155°28′54″W / 19.8327°N 155.4816°W / 19.8327; -155.4816[3]
Altitude 4,050 m[2]
Wavelength Mid-IR to visible (0.31–28 μm)
Built planned (est. completion 2018)
Telescope style Segmented Ritchey-Chrétien telescope
Diameter 30 metres (98 feet)
Collecting area 655 m²[2]
Focal length f/15 (450 m)[2]:52
Mounting Altitude/azimuth
Dome Spherical calotte[disambiguation needed ]
Website http://www.tmt.org/

The Thirty Metre Telescope (TMT) is a proposed ground-based large segmented mirror reflecting telescope to be built on Mauna Kea in Hawaii. The telescope is designed for observations from the near-ultraviolet to the mid-infrared (0.31 to 28 μm). An adaptive optics system would correct for image blur caused by the atmosphere of the Earth. At wavelengths longer than 0.8 μm, this correction would enable observations with ten times the spatial resolution of the Hubble Space Telescope. TMT would be more sensitive than existing ground-based telescopes by factors of 10 (natural seeing mode) to 100 (adaptive optics mode). If completed on schedule, TMT would be the first of the new generation of Extremely Large Telescopes.

The telescope cost was estimated in 2009 to be $970 million[4] to $1.2 billion;[5] the funding had not been completely raised by mid-2011, although $100 million had already been spent on design, engineering and site-assessment work.

Contents

[edit] Science case

A Detailed Science Case [1] for TMT is available. TMT would be a general purpose observatory capable of investigating a broad range of astrophysical problems including:

By design, TMT complements the scientific capabilities of the James Webb Space Telescope and Atacama Large Millimeter Array.

[edit] Observatory design

The TMT began in the 1990s as the California Extremely Large Telescope, and due to a positive response continued to be developed. [6] The project changed its name to Thirty Metre Telescope in 2003-4 as the scope of development partners evolved, including a merger with the Canadian VLOT project and the GSMT.

A description of the TMT Observatory design can be found in the TMT Construction Proposal (2007) [2].

[edit] Telescope

Thirty Meter Telescope design (late 2007)

The centerpiece of the TMT Observatory will be a Ritchey-Chrétien telescope with a 30 metre diameter primary mirror. This mirror will be segmented and consist of 492 smaller (1.4 m), individual hexagonal mirrors. The shape of each segment, as well as its position relative to neighboring segments, will be controlled actively.

A 3 m secondary mirror produces an unobstructed field-of-view of 20 arcminutes in diameter with a focal ratio of 15. A flat tertiary mirror will direct the light path to science instruments mounted on large Nasmyth platforms. The shape of each mirror will be controlled actively.

The telescope will have an altitude-azimuth mount. This mount will be capable of repositioning the telescope between any two points of the sky in less than 5 minutes, with a precision of 2.0 arcseconds or better. Once the celestial object is acquired, the telescope will track its motion with a precision of a few milliarcseconds.

The TMT moving mass (including instruments) is almost 2000 tonnes.

This design descends from the successful W. M. Keck Observatory.

[edit] Adaptive optics

Integral to the observatory is a Multi-Conjugate Adaptive Optics (MCAO) system. This MCAO system will measure atmospheric turbulence by observing a combination of natural (real) stars and artificial laser guide stars. Based on these measurements, a pair of deformable mirrors will be adjusted many times per second to correct optical wavefront distortions caused by the intervening turbulence.

This system will produce diffraction-limited images over a 30 arcsecond diameter field-of-view. For example, the core of the point spread function will have a size of 0.015 arcsecond at a wavelength of 2.2 micrometres, almost 10 times better than the Hubble Space Telescope.

[edit] Scientific instrumentation

[edit] Early-light capabilities

Three instruments are planned to be available for scientific observations:

  • Wide Field Optical Spectrometer (WFOS) providing near-ultraviolet and optical (0.3–1.0 μm wavelength) imaging and spectroscopy over a more than 40 square arcminute field-of-view. Using precision cut focal plane masks, WFOS would enable long-slit observations of single objects as well as short-slit observations of hundreds of objects simultaneously. WFOS would use natural (uncorrected) seeing images.
  • Infrared Imaging Spectrometer (IRIS) mounted on the observatory MCAO system, capable of diffraction-limited imaging and integral-field spectroscopy at near-infrared wavelengths (0.8–2.5 μm).
  • Infrared Multi-object Spectrometer (IRMS) allowing close to diffraction-limited imaging and slit spectroscopy over a 2 arcminute diameter field-of-view at near-infrared wavelengths (0.8–2.5 μm).

[edit] Additional first-decade capabilities

For planning purposes, TMT has developed concepts for an additional six instruments, which it proposes to be deployed during the first decade of science operations. These plans have been reviewed and updated on a roughly bi-annual basis starting in 2010.

In no order of preference, planned additional scientific capabilities include:

  • Extremely high contrast (1 part in 108 @ 1.65 μm) exoplanet imaging and spectroscopy at near-infrared wavelengths
  • Diffraction-limited echelle spectroscopy (resolving power ~ 25 000) at near-infrared wavelengths (1.0–2.5 μm)
  • Diffraction-limited imaging and echelle spectroscopy (resolving power ~ 50,000) at mid-infrared wavelengths (8–28 μm)
  • High precision (~0.01 arcsecond) astrometric imaging and (<<0.001 arcsecond) astrometry at near-infrared wavelengths (1.0–2.5 μm)
  • Multiple integral-field unit spectrometers deployable over a 5 arcminute diameter field-of-view, each with individual adaptive optics correction, at near-infrared wavelengths (1.0–2.5 μm)

[edit] Location

In cooperation with AURA, the TMT project completed a multi-year evaluation of five sites:

The TMT Observatory Corporation board of directors narrowed the list to two sites, one in each hemisphere, for further consideration: Cerro Armazones in Chile's Atacama Desert, and Mauna Kea on Hawai'i Island. On July 21, 2009 the TMT Board selected Mauna Kea as the preferred site.[5][7] The final TMT site selection decision was based on a combination of scientific, financial, and political criteria; ESO is also building a very large telescope E-ELT, and was very likely to be doing so in Chile, and if both next-generation telescopes were in the same hemisphere, there would be many astronomical objects that neither could observe.

[edit] Controversy

The State of Hawaii Board of Land and Natural Resources conditionally approved the Mauna Kea site for the TMR on Friday, February 26, 2011, even though some of the local residents objected to the project because of adverse effects to native Hawaiian cultural practices, desecration of a site held sacred in Hawaiian religion, and altering of view planes of the northern slope of Mauna Kea.

[edit] Partnership

The TMT Observatory Corporation is a partnership between:

  • Association of Canadian Universities for Research in Astronomy (ACURA) [3]

The current US$80 million, five year design and development program is planned for completion in 2012.[8] Construction is expected to commence immediately thereafter, leading to initial science operations in 2018.[8] The Gordon and Betty Moore Foundation has committed US$200 million for construction. Caltech and University of California have committed an additional US$50 million each. TMT is actively seeking additional major partners for the construction and operations phase.

  • In 2008, the National Astronomical Observatory of Japan (NAOJ) joined TMT as a Collaborating Institution.[9]
  • In 2009, the National Astronomical Observatories of the Chinese Academy of Sciences (NAOC) joined TMT as an Observer.[10][11]
  • In 2010, a consortium of Indian Astronomy Research Institutes (IIAp, IUCAA and ARIES) joined TMT project as an observer. The observer status is the first step in becoming a full partner in TMT and participating in the engineering development and scientific use of the observatory (Subject to approval of funding from Indian Government). [12]

TMT has received design and development funding from the following public and private organizations:

[edit] See also

[edit] References

[edit] General

  1. http://www.tmt.org/foundation-docs/TMT-DSC-2007-R1.pdf
  2. http://www.astro.utoronto.ca/acura/en/index.html

[edit] Specific

  1. ^ Thirty Meter Telescope Selects Mauna Kea, TMT Observatory Corporation, 2009-07-21, http://www.tmt.org/news/site-selection.htm, retrieved 2009-07-24 
  2. ^ a b c d Thirty Metre Telescope Construction Proposal, TMT Observatory Corporation, 2007-09-12, p. 29, http://www.tmt.org/news/TMT-Construction%20Proposal-Public.pdf, retrieved 2009-07-24 
  3. ^ Sanders, Gary H (2005-01-11), [79.03] The Thirty Metre Telescope (TMT) Project, p. 17, http://www.tmt.org/whats-new/G-Sanders-Jan05-AAS.pdf 
  4. ^ Adam Mann, "Titanic Thirty Meter Telescope Will See Deep Space More Clearly", Wired November 16, 2009 (accessed 18 October 2010)
  5. ^ a b Klaus Schmidt , "Hawaii chosen to host world's largest telescope, Space Fellowship July 22, 2009 (accessed 18 October 2010)
  6. ^ http://press.ucsc.edu/archive/00-01/09-00/celt.htm
  7. ^ McAvoy, Audrey (July 21, 2009), "World's largest telescope to be built in Hawaii" ([dead link]), Washington Post, http://www.washingtonpost.com/wp-dyn/content/article/2009/07/21/AR2009072102367.html 
  8. ^ a b Thirty Meter Telescope operations page, TMT Observatory Project, http://www.tmt.org/observatory/operations, retrieved 2010-10-12 
  9. ^ http://www.tmt.org/facts-scientists/TMT-History.htm
  10. ^ http://www.tmt.org/news/NAOC-Join-TMT.htm
  11. ^ "China, India to jump forward with Hawaii telescope". Associated Press. http://news.yahoo.com/china-india-jump-forward-hawaii-telescope-023243908.html. Retrieved January 12, 2012. 
  12. ^ http://www.tmt.org/news-center/india-joins-thirty-meter-telescope-project

[edit] External links

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