Jul 9 1979
From The Space Library
NASA announced that MSFC had appointed a board to investigate the automatic cutoff of a test firing July 2 at NSTL of the Space Shuttle main engine test article (three main engines mounted in an orbiter aft section and attached to an external tank). A liquid-hydrogen leak from a main fuel valve caused the cutoff after 18.5 seconds; no explosion occurred, and the gaseous nitrogen and water tire-control systems put out an external fire resulting from hydrogen accumulation around the test article's aft area. Inspection revealed damage to the aft heat shield and charring of external-tank insulation, but the engines appeared generally in good condition. (NASA Release 79-92)
July 9-13: NASAs Voyager 2 passed within 404,000 miles of Jupiter July 9, making its closest approach at 6:29 p.m. EDT and sending from more than 570 million miles a flood of scientific data and "stunning photographs of the planet and some of its moons," as the New York Times described them. Scientists at the JPL, control center for the mission, said that the flight was continuing to provide them with "new surprises." They had modified observing sequences on Voyager 2 to benefit from discoveries by Voyager 1 on its encounter in March. Changes included more dark side images of the planet to measure lightning and aurora; images of Jupiter's ring, taken away from the equatorial plane; and about nine hours of continuous imaging of Io for volcanic activity. Voyager 2's inward track past three of the four "Galilean" satellites had let it see regions not viewed by Voyager 1; its path was "more conservative," as it passed 10 Jupiter radii above the visible clouds compared to Voyager 1's 4.9 radii, for "complementary observations." Voyager 2 studies began April 25 and would continue for a seven month look compared to Voyager 1's three month look. Voyager 2 had been launched August 20, 1977; Voyager 1, launched September 5, 1977, on a faster and shorter course, had overtaken its sister ship before the end of the year.
Scientists found that Jupiter and its moons did not resemble planets or satellites nearer the Sun, nor one another. Surprises in the findings were due, they said, to real differences between the outer and inner solar system and lack of previous knowledge, a result of the distance separating Earth from Jupiter. Before Voyager 1, "we thought we had some idea of what planets were like," said Laurence A. Soderblom of the U.S. Geological Survey after seeing Europa images from Voyager 2. Instead of a sphere heavily pocked such as Earth's moon and Mars from meteor impacts, Voyager 2 images showed Europa "as smooth as a billiard ball," with hardly any craters on a surface covered by a mantle of slushy snow and ice up to 60 miles deep, with far reaching shallow marks like cracks in an eggshell. The spacecraft passed Callisto and Ganymede on its way toward Europa and, after its encounter with Jupiter, had begun a 10-hour watch for Io, where it photographed six volcanoes erupting. On its approach to Jupiter, Voyager 2 had encountered radiation so intense that JPL had turned off a sensitive ultraviolet (UV) detector six hours earlier than planned; however, project director Ray Heacock declared "no problems and no failures in any of our instruments." (JPL Release 901; NASA MOR S-802-77-01/02, June 26/79; NY Times, July 10/79, C-1; W Post, July 10/79, A-10; W Star, July 11/79, A-4; July 13/79, A-10)
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