Instead of illuminating the end of the bar, however, the laser in fact was reflected from a worn spot on a black-anodized metal cap placed over the end of the bar to isolate its center visible through a hole in the cap | "What Will Astronomy Be Like in 35 Years? Transits of Venus: New Views of the Solar System and Galaxy |
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Wilford, John April 9, 1990 | "In-orbit performance of the COSTAR-corrected Faint Object Camera" |
They believed the other two null correctors were less accurate than the reflective null corrector and so could not verify its reliability | "A Hubble Space Telescope Study of Posteclipse Brightening and Albedo Changes on Io" |
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Power to Explore: History of Marshall Space Flight Center 1960—1990 | Gebhardt, K; Bender, R; Bower, G; Dressler, A; et al |