Viking First Encounter of Phobos: Preliminary Results

• DOI: 10.1126/science.199.4324.61
• Publication Date: 2006-10-05T16:35:25Z
• Authors: R. H. Tolson; T. C. Duxbury; G. H. Born; E. J. Christensen; R. E. Diehl; D. Farless; C. E. Hildebrand; R. T. Mitchell; P. M. Molko; L. A. Morabito; F. D. Palluconi; R. J. Reichert; H. Taraji; J. Veverka; G. Neugebauer; J. T. Findlay
• Keywords: Orbiter; Albedo (alchemy)

During the last 2 weeks of February 1977, an intensive scientific investigation martian satellite Phobos was conducted by Viking Orbiter-1 (VO-1) spacecraft. More than 125 television pictures were obtained during this period and infrared observations made. About 80 percent illuminated hemisphere imaged at a resolution about 30 meters. Higher images limited areas also obtained. Flyby distances within kilometers surface achieved. An estimate mass (GM) observing effect Phobos's gravity on orbit VO-1 as sensed Earth-based radiometric tracking. Preliminary results indicate value GM 0.00066 +/- 0.00012 cubic kilometer per second squared (standard deviation 3) mean density 1.9 0.6 gram centimeter 3). This low density, together with albedo recently determined spectral reflectance, suggest that is compositionally similar to type I carbonaceous chondrites. Thus, either object formed in outer part asteroid belt or Lewis's theory such material cannot condense 1.5 astronomical units incorrect. The data first encounter are comparable quantity all Mars returned Mariner flights 4, 6, 7.