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Space Telescope Science Institute
The Next Generation Space Telescope (NGST)

John Mather
NASA Goddard Space Flight Center, Code 685
Greenbelt, MD

The Next Generation Space Telescope study has been initiated, led by Goddard Space Flight Center and the Space Telescope Science Institute, with participation from Marshall, JPL, Langley, and two industrial consortia led by Lockheed-Martin and TRW. Following the recommendation of the Dressler HST and Beyond committee, the study addressed the feasibility of a telescope much larger and colder than HST, and showed that it is feasible to obtain an aperture of 8 m, cooled to 30 K, for operation from 0.5 to 20 microns, with a cost cap of $0.5 billion for the construction phase. It would be deployed after launch on an Atlas IIAS to the Lagrange Point L2, 1.5 million km from Earth and in line with the Sun and Earth. Following deployment it would be adjusted to proper figure, so the optical requirements are quite different from traditional telescopes. Deployable thermal shields would allow a purely radiative cooling for the telescope. InSb detectors would cover the 0.5 to 5 micron range, and HgCdTe or Si:As IBC detectors could reach longer IR wavelengths. The NGST will enable detailed study of infant galaxies and of star forming regions and is a central part of NASA's Origins Program. It would be capable of detailed study of protoplanetary and debris disks around many stars. It could be launched as early as 2005, and would be the world's premier telescope.