The Next Generation Space Telescope (NGST) is under study by NASA as a successor to the Hubble Space Telescope (HST), and the infrared missions SIRTF (Space Infrared Telescope Facility), SOFIA (Stratospheric Observatory for Infrared Astronomy), and ISO (Infrared Space Observatory). It would have an aperture > 4 m, optimized for 1–5 μm, with a goal of 8 m and 0.5 – 20 µm. It would be radiatively cooled and would be launched on an Atlas HAS to the Lagrange Point L2 around 2006. At wavelengths longer than a few µm, it offers a speed advantage of the order of 106 over a large ground based telescope.
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