Goddard Space Flight Center, Greenbelt, Maryland 20771 

ENGINEERING COLLOQUIUM 

Monday, February 14, 2000 / 3:30 PM, Building 3 Auditorium 

Roger Angel

ABSTRACT -- The Hubble Space Telescope is essentially the 1917 Mt Wilson telescope transported to space.  Mt Wilson was designed for the ground based environment, a compact optical system in a passive OTA rigid enough to hold its alignment when turned in a gravity field, and in the presence of wind.  Future space telescopes will respect the completely different space environment.  The NGST will take steps toward much lighter mirrors with active figure control, such as the MARS technology developed at the University of Arizona.  Beyond NGST, we envisage widely spaced constellations of free-flying, ultra-lightweight optical components and solar shields, with flat or nearly flat membranes as their primary elements, and complete integration of active controls to maintain diffraction limited images.  Ground based telescopes of ~ 30 m diameter are being planned.  These will actively control aberrations caused by atmospheric turbulence and wind-induced mirror distortion.  Arizona is working on concepts with adaptive primary mirrors, essentially an f/0.5  radio dish faced with glass panels 1 cm thick with thousands of fast-acting actuators to recover diffraction limited images.

SPEAKER -- Roger Angel is the founder and director of the Steward Observatory Mirror Laboratory at The University of Arizona, where he is also Regents Professor.  Over the past 20 years he has led a technological renaissance in mirror making.  His lab is making giant "honeycomb" mirrors of lightweight glass for several telescopes, including the international Large Binocular Telescope being built in eastern Arizona with twin 8.4 m mirrors, the largest ever.  Angel has pioneered ways to find and study Earth-like planets of other stars to determine whether there is life on them, by spectroscopic analysis with new space telescopes also being developed at the Mirror Lab.  Angel received his bachelor's and doctoral degrees in physics from Oxford University, England.  He taught physics at Columbia University before joining The University of Arizona in 1974.  He is a Fellow of the Royal Society, a member of the American Academy of Arts and Sciences, an Honorary Fellow of St. Peter's College, Oxford, and a MacArthur Fellow.