The Giant Segmented Mirror Telescope (GSMT)
The Giant Segmented Mirror Telescope (GSMT), a ground- based telescope with a mirror approximately 30 meters in diameter, will provide a major advance in ground-based astronomy over the world's largest optical telescopes. The GSMT will have 10 times the light-collecting area of each of the twin Keck Telescopes in Hawaii, which now rank as the world's largest, and more than 20 times the collecting area of the NGST. With its much greater mirror size, the GSMT will play the same role with respect to the NGST that the Keck Telescopes do for the Hubble Space Telescope. The GSMT will investigate in greater detail the cosmic sources of radiation that the space-borne telescope discovers.
Because the GSMT will remain on Earth, it can profit from ongoing improvements in its complement of instruments, including marvelously precise spectrographs that will measure the amounts of radiation at different wavelengths. While it observes the cosmos in visible light and infrared radiation,the GSMT will employ an advanced system of adaptive optics. This system will continuously monitor the atmospheric fluctuations that would blur the telescope's vision, and it will then readjust the mirror surface many times per second in order to compensate for these ripples in the air. With this approach, and with a much larger mirror, the GSMT can obtain deep images in the short-wavelength portion of the infrared domain that are even crisper and deeper than those obtained by the NGST. Although it cannot observe galaxies as early in their history as the NGST can, the GSMT will have the infrared observing capability to follow the evolution of galaxies through all eras after the formation stage. It will be able to trace galactic history back to 10 billion years ago or earlier. In addition to galaxies, the GSMT will observe the closest planetary systems and star-forming regions within our Milky Way Galaxy.
The GSMT's great primary mirror will consist of individual segments, each as large as a good-sized astronomical telescope. The pioneering development of the Keck Telescopes' 10--meter mirrors, each of which consists of 36 individual segments, has led to the construction of other segmented-mirror instruments within a now highly developed technological framework. Technological progress should enable production of a 30-meter mirror capable of adaptive-optics readjustments at a reasonable cost.
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