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The large adaptive reflector: a 200-m diameter wideband centimeter- to meter-wave radio telescope

2000; SPIE; Volume: 4015; Linguagem: Inglês

10.1117/12.390431

1996-756X

Brent Carlson, Luc Bauwens, Leonid Belostotski, Elizabeth Cannon, Ya-Ying Chang, Xiaohui Deng, P. E. Dewdney, Joeleff Fitzsimmons, David Halliday, Kai Kuerschner, G. Lachapelle, David Lo, Pedram Mousavi, Meyer Nahon, Lot Shafai, Sigfried F. Stiemer, R. Taylor, B. Veidt,

Structural Analysis and Optimization

The Large Adaptive Reflector (LAR) is a concept for a low- cost, large aperture, wideband, radio telescope, designed to operate over the wavelength range from 2 m to 1.4 cm. It consists of a 200-m diameter actuated-surface parabolic reflector with a focal length of 500 m, mounted flat on the ground. The feed is held in place by a tension-structure, consisting of three or more tethers tensioned by the lift of a large, helium-filled aerostat -- a stiff structure that effectively resists wind forces. The telescope is steered by simultaneously changing the lengths of the tethers with winches (thus the position of the feed) and by modifying the shape of the reflector. At all times the reflector configuration is that of an offset parabolic antenna, with the capability to point anywhere in the sky above approximately 15 degree Elevation Angle. At mid-range wavelengths, the feed is a multi-beam prime-focus phased array, about 5 m diameter; at meter wavelengths, it is a single-beam phased array of up to 10 m diameter. Simulations have shown that in operating wind conditions (10 m/s average speed with 2.5 m/s gusts), the position of the feed platform can be stabilized to within a few cm over time scales of approximately 20 s. Research indicates that the telescope concept is feasible and that an order of magnitude improvement in cost per m 2 of collecting area over traditional designs of large parabolic antennas can be achieved.