Thirty Meter Telescope

The Thirty Meter Telescope (TMT) will be a ground-based astronomical observatory with a 30 metre (98 foot) diameter segmented mirror capable of observations from the near-ultraviolet to the mid-infrared (0.31 to 28 micrometres). An adaptive optics system will correct for image blur caused by the atmosphere of the Earth. At wavelengths longer than 0.8 micrometres, this correction will enable observations with ten times the spatial resolution of the Hubble Space Telescope. TMT will 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 will be the first of the new generation of Extremely Large Telescopes.

Science case

A "Detailed Science Case" [http://www.tmt.org/foundation-docs] for TMT is available.

TMT will be a general purpose observatory capable of investigating abroad range of astrophysical problems including:

* Dark energy, dark matter and tests of the Standard Model of particle physics

* Characterization of the first stars and galaxies in the Universe
* Characterization of the epoch of reionization
* Galaxy assembly and evolution over the past 13 billion years
* Connections between supermassive black holes and galaxies
* Star-by-star dissection of galaxies out to 10 million parsecs
* Physics of planet and star formation
* Exoplanet discovery and characterization
* Kuiper belt object surface chemistry
* Solar system planetary atmosphere chemistry and meteorology
* The search of life on planets outside the Solar System

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

Observatory design

A complete description of the TMT Observatory design can be found in the"TMT Construction Proposal (2007)" [http://www.tmt.org/foundation-docs] .

Telescope

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 hexagonalmirrors. 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-azimuthmount. This mount will be capable of repositioning the telescopebetween any two points of the sky in less than 5 minutes, with aprecision of 2.0 arcseconds or better. Once the celestial object isacquired, the telescope will track its motion with a precision of a few
milliarcseconds.

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

This design descends from the successful W. M. KeckObservatory.

Adaptive optics

Integral to the observatory is a multi-conjugate adaptive optics system. This MCAO system will measure atmospheric turbulence by observing a combination of natural (real) 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.

cientific instrumentation

Early-light capabilities

When TMT science operations begin, three instruments will be available for scientific observations.

The Wide Field Optical Spectrometer (WFOS) will provide 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 will enable long-slit observationsof single objects as well as short-slit observations of hundreds of objects simultaneously. WFOS will use natural (uncorrected) seeing images.

The Infrared Imaging Spectrometer (IRIS) will be mounted on the observatory MCAO system and be capable of diffraction-limited imaging and integral-field spectroscopy at near-infrared wavelengths (0.8 – 2.5 μm).

The Infrared Multi-object Spectrometer (IRMS) will allow 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).

Additional first-decade capabilities

For planning purposes, TMT has developed concepts for an additional sixinstruments to be deployed during the first decade of scienceoperations. These plans will be reviewed and updated on a roughlybi-annual basis starting in 2010.

In no order of preference, planned additional scientific capabilitiesinclude:

* 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 (0.0005 arcsecond) astrometric imaging 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)

Location

In cooperation with
AURA, the TMT project has recently completed a multi-yearsite evaluation program.

The sites included in this program were:
* Cerro Armazones, Antofagasta Region, Republic of Chile

* Cerro Tolanchar, Antofagasta Region, Republic of Chile

* Cerro Tolar, Antofagasta Region, Republic of Chile

* Mauna Kea, Hawaiokinai, United States

* San Pedro Martir, Baja California, Mexico

The final TMT site selection decision will be based on a combination ofscientific, financial, and political criteria. Local culturalsensitivities will also be an important part of any TMT site decision.

Partnership

The TMT Observatory Corporation is a partnership between:

* Association of Canadian Universities for Research in Astronomy (ACURA) [http://universityastronomy.ca]

* California Institute of Technology (Caltech)
* University of California (UC)

The current US$ 80 million, five year design and development program isplanned for completion in 2009. Construction is expected to commenceimmediately thereafter, leading to initial science operations in thesecond half of the next decade. The Gordon and Betty Moore Foundation has committed US$ 200 million for construction. Caltech and
University of California have committed an additional US$ 50 millioneach. TMT is actively seeking additional major partners for theconstruction and operations phase.

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

* Gordon and Betty Moore Foundation
* Canada Foundation for Innovation
* Ontario Ministry of Research and Innovation
* National Research Council of Canada
* Natural Sciences and Engineering Research Council of Canada
* British Columbia Knowledge Development Fund
* Association of Universities for Research in Astronomy (AURA)
* National Science Foundation (NSF)

ee also

* Extremely Large Telescopes
* Giant Magellan Telescope
* European Extremely Large Telescope

References

# http://www.tmt.org/foundation-docs/TMT-DSC-2007-R1.pdf
# http://www.tmt.org/news/TMT-Construction%20Proposal-Public.pdf
# http://www.astro.utoronto.ca/acura/en/index.html

External links

* Project web site: http://www.tmt.org
* TMT foundation documents: http://www.tmt.org/foundation-docs/index.html
** Construction Proposal (2007)
** Detailed Science Case (2007)
** Observatory Requirements Document
** Observatory Architecture Document
** Operations Concept Document