Word: soho
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Dates: during 1990-1999
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...million miles away, cost $1 billion, and for more than two years has surveyed the sun with spectacular results. This cosmic overachiever--about the size of a Volkswagen beetle--is the Solar and Heliospheric Observatory, otherwise known as SOHO. Since April 1996 it has beamed back hundreds of thousands of remarkable images of solar eruptions and made dozens of scientific discoveries. It has also enhanced the ability of astronomers to predict and spot the powerful solar storms that produce auroras and cause power disruptions on Earth--as well as endanger satellites and astronauts in space...
Then, in late June, SOHO inexplicably fell silent, seemingly lost in space. "It was devastating," says John Credland, science project chief at the European Space Agency (ESA). "It was a show stopper...
...looks as if the show may go on. With a clever bit of detective work, technical ingenuity and the aid of giant radio telescopes, scientists at ESA and NASA (co-sponsors of SOHO) have located the wayward spacecraft and started nursing it back to health; they hope to regain control of it this week. If all goes well, SOHO could be fully back in business this fall in plenty of time to monitor the sun as it approaches the peak of its 11-year cycle of activity, around...
Earlier there seemed little hope of saving SOHO after the spacecraft stopped responding to controllers at NASA's Goddard Space Flight Center. At the time SOHO scientist Arthur Poland lamented, "There is a real fear we won't get it back...
...failure occurred during an unusually complex maintenance procedure and was caused by a combination of two computer-software glitches and a bad judgment call. Those glitches resulted in the shutdown of one essential SOHO attitude-sensing gyroscope, a failure by a computer to recognize that the gyroscope was not operating, the unnecessary firing of SOHO's hydrazine-powered thrusters, and a mistake by controllers in switching off a gyroscope that was working properly. "Thrusters kept firing to null out a roll that was not happening," explains NASA's Michael Greenfield, co-chair of the investigation group...