Dec 22 1983
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(New page: The International Sun-Earth Explorer (ISEE), a spacecraft in-tended to be the first man-made machine to encounter a comet, came within 72 miles of the Moon's surface in a maneuver designed...)
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The International Sun-Earth Explorer (ISEE), a spacecraft in-tended to be the first man-made machine to encounter a comet, came within 72 miles of the Moon's surface in a maneuver designed to carry it through the tail of the comet Giacobini-Zinner in September 1984. Engineers at GSFC stored the five-year-old spacecraft on a horseshoe-shaped path behind the Moon, then down over the Sea of Smyth on the visible side of the Moon, where it picked up speed and sped out toward deep space. Goddard's worldwide tracking network lost contact with the spacecraft when it flew behind the Moon, then regained contact when it flew across the Moon in a flyby as close as any unmanned spacecraft had ever made to another heavenly body without going into orbit around it. The close approach to the Moon was intended to provide a slingshot effect from the brush with lunar gravity that accelerated the spacecraft from 2,900 to 5,145 males per hour.
The flight through the comet's tail was to take place on September 11, 1985, when Giacobini-Zinner was 44 million miles from Earth. It was planned that the spacecraft would fly through the comet's tail for about 30 minutes at a distance of about 12,000 miles from its head.
On passing the Moon, the ISEE-3 spacecraft was renamed the International Cometary Explorer to emphasize its new mission. (NASA Dly Acts Rept, Dec 28/83; W Post, Dec 23/83, A-4)
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