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Thermal stability of a 4 meter primary reflector for the scanning microwave limb sounder

Show simple item record Cofield, Richard E. Kasl, Eldon P. 2013-10-07T16:26:41Z 2013-10-07T16:26:41Z 2011-08-24
dc.identifier.citation SPIE Optics + Photonics 2011, San Diego, California, August 20-25, 2011. en_US
dc.identifier.clearanceno 11-2856
dc.description.abstract The Scanning Microwave Limb Sounder (SMLS) is a space-borne heterodyne radiometer which will measure pressure, temperature and atmospheric constituents from thermal emission in [180,680] GHz. SMLS, planned for the NRC Decadal Survey’s Global Atmospheric Composition Mission, uses a novel toric Cassegrain antenna to perform both elevation and azimuth scanning. This provides better horizontal and temporal resolution and coverage than were possible with elevation-only scanning in the two previous MLS satellite instruments. SMLS is diffraction-limited in the vertical plane but highly astigmatic in the horizontal (beam aspect ratio 1:20). Nadir symmetry ensures that beam shape is nearly invariant over ±65 azimuth. A low-noise receiver FOV is swept over the reflector system by a small azimuth-scanning mirror. We describe the fabrication and thermalstability test of a composite demonstration primary reflector, having full 4m height and 1/3 the width planned for flight. Using finite-element models of reflectors and structure, we evaluate thermal deformations and optical performance for 4 orbital environments and isothermal soak. We compare deformations with photogrammetric measurements made during soak tests in a chamber. The test temperature range exceeds predicted orbital ranges by large factors, implying in-orbit thermal stability of 0.21 micron rms/ C, which meets SMLS requirements. en_US
dc.description.sponsorship NASA/JPL en_US
dc.language.iso en_US en_US
dc.publisher Pasadena, CA : Jet Propulsion Laboratory, National Aeronautics and Space Administration, 2011. en_US
dc.subject microwave limg sounding en_US
dc.subject composite reflectors en_US
dc.subject toroidal en_US
dc.subject thermal distortion en_US
dc.subject physcial optics en_US
dc.title Thermal stability of a 4 meter primary reflector for the scanning microwave limb sounder en_US
dc.type Preprint en_US

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