The Thirty Meter Telescope

Artist's Impression of TMT from NASA.

Artist's Impression of the Thirty Meter Telescope from NASA.

The Thirty Meter Telescope (TMT) is a collaboration between the Association of Canadian Universities for Research in Astronomy, the California Institute of Technology, the University of California, the National Astronomical Observatory of Japan, the National Astronomical Observatories of the Chinese Academy of Sciences, and the Department of Science and Technology of India. According to the TMT Timeline, First Light should occur in October 2017 and the first science should be conducted in June 2018.

The Telescope

The thirty meter primary mirror of TMT will be segmented into 492 1.44m hexagonal segments as shown in the image below. After hitting the primary mirror, the light will be reflected onto a tiltable 3.1m secondary mirror and then onto a 3.5m x 2.5m elliptical tertiary mirror that will send the light into the instruments on the Nasmyth platforms. TMT will have two Nasmyth platforms with space for eight instruments total.

TMT Primary Mirror (TMT Collaboration)

An artist's conception of the segmented primary mirror of TMT. The 1.44m hexagonal segments will be placed only 2.5mm apart. The elliptical tertiary mirror is shown at the center of the primary mirror. Note the tiny person in the upper left for scale. (TMT Collaboration)

The Site

TMT design operations are based in Pasadena, CA, but the selected telescope site is within the 36-acre “Area E” on the summit of Mauna Kea in Hawaii as shown on the map below. Mauna Kea is a well-established site for observatories due to the high-quality seeing, dry conditions, and typical lack of cloud cover. Once constructed, the TMT complex would consist of a dome 56m in height and 66m wide, 5 acres of roads, and 1.44 acres of buildings.

Proposed Site for TMT (UH and USGS)

Proposed Site for TMT in Area E on the summit of Mauna Kea. For reference, the locations of existing telescopes are indicated by the numbered yellow circles. Map produced by UH and USGS.


In addition to the Narrow Field Infrared Adaptive Optics System (NFIRAOS), TMT will have three first light instruments:

  1. Wide Field Optical Spectrometer (WFOS): Spectroscopy and imaging without AO at near-ultraviolet and optical wavelengths (0.3-1.0 microns) over a >40 square arcminute FOV.
  2. InfraRed Imaging Spectrometer (IRIS): Integral-field spectroscopy and diffraction-limited imagaing at near-infrared wavelengths (0.8-2.5 microns).
  3. InfraRed Multi-object Spectrometer (IRMS): Slit spectroscopy and diffraction-limited imaging at near-infrared wavelengths (0.8-2.5 microns) over a 2′ diameter FOV.

Science Goals

As explained in the TMT Science Case, the science goals for TMT are:

  • Spectroscopy of the first galaxies
  • Observations of the formation of large-scale structure
  • Detection and investigation of central black holes
  • Observations of star and planet formation
  • Characterization of exoplanet atmospheres
  • Direct detection of exoplanets

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