dipper@utastro.UUCP (Debbie Byrd) (02/13/86)
A spacecraft will fly within 300 miles of the heart of Halley's Comet. More -- when we come back. February 13 Giotto Next month on this date the Giotto spacecraft will dive into the giant cloud of dust particles and gases surrounding Comet Halley. This immense cloud is called the comet's coma. It extends for thousands of miles into space -- and hides the exact location of Halley's small icy nucleus, or core. The coma is debris ejected from the nucleus. The particles -- tiny as they are -- are traveling at tremendous speeds -- and will batter the Giotto spacecraft as it passes near the nucleus of Comet Halley. The goal of the European Space Agency -- which launched Giotto last July -- is to aim the spacecraft to within three hundred miles of Halley's nucleus. The nucleus itself is only three miles across. It is the most audacious trajectory for any of spacecraft from Earth due to visit Halley next month. It's possible that Giotto will not survive its plunge into the coma. Like other planned missions to Halley, Giotto will cross between the comet and the sun. Halley revolves around the sun in a direction opposite to Earth's orbit -- and to the direction that Giotto is traveling. The relative speed of the comet to the spacecraft at the time of the encounter will be about l65 thousand miles per hour. Halley will whiz by in one direction -- the spacecraft in the other. Total time of Giotto's encounter with Halley is expected to last only a few hours. An onboard computer will keep Giotto's camera pointed toward the tiny nucleus. Possibly the camera's eye will pierce the dusty coma to reveal what lies at the heart of Comet Halley. Script by Diana Hadley. (c) Copyright 1985, 1986 McDonald Observatory, University of Texas at Austin