Planning instrumentation for the Thirty Meter Telescope

Abstract

What is dark energy? And dark matter? How did galaxies and supermassive black holes form and evolve in the early universe? What is the origin of stars, planets, and life itself? Answers to these and related questions require new developments in spaceand groundbased astronomy coupled with advances in experimental and theoretical physics. It is becoming increasingly clear that wemust push tomuch fainter sources withmuch better data than currently possible to make significant progress on solving many of the key problems. We are designing the Thirty Meter Telescope (TMT) to rise to that challenge. It will work synergistically with other major observatories, including the James Webb Space Telescope (JWST) and the Atacama Large Millimeter Array. We are also mindful that, as history demonstrates, many discoveries cannot be foreseen. We must therefore design the most powerful and versatile facility that we can afford. The TMT project is rapidly moving toward construction of a telescope with a primary mirror diameter of 30m, offering 10 times more light-gathering power than the current largest telescopes. In addition, from the outset we are designing TMT to deliver perfect (diffraction-limited) images over much of its operating wavelength range. As a result, many science programs will realize a 100-fold gain in the detection and study of faint sources. Some key capabilities, like the detection of faint planets orbiting nearby stars, will increase by factors of up to 1000. A 30mmirror currently offers the optimum balance between science benefit, cost, technological readiness, and development schedule. The telescope will have an f/1 primary mirror composed of 492 1.4m hexagonal segments, building upon the experience gained with the 10m Keck telescopes. Perhaps the biggest engineering challenge is to ensure that all of the individual mirror segments operate as one mirror. In addition, the entire system must be capable of being pointed quickly anywhere in the sky and then precisely tracking celestial objects without disturFigure 1. The telescope is a wide-field Ritchey-Chretien design with a highly segmented 30m primary mirror. The tertiary mirror located at the center of the primary will direct the beam to any of the instruments located on the two large Nasmyth platforms. The laser-launch telescope is located at the very top of the structure, behind the secondary mirror. The elevation axis will be 23m above the observatory floor.