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Sun orbiter ends 18-year mission
Source: Agencies |
July 2, 2009, Thursday
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THE interplanetary space probe Ulysses has officially ceased operations after an 18-year voyage of roughly 8.85 billion kilometers and nearly three complete orbits around the sun, NASA said.
The Volkswagen-sized spacecraft's transmitter was switched off on Tuesday, but NASA project manager Ed Massey said Ulysses will continue its wide, elliptical orbit around the sun indefinitely.
He said there was a chance the probe might eventually swing close enough to one of Jupiter's moons to alter its course to out of solar system.
Ulysses, a joint project of NASA and the European Space Agency, was launched from the space shuttle Discovery in 1990 and became the first probe to fly around the sun's poles.
Named for the hero of "The Odyssey," Ulysses was designed to help scientists study solar radiation and was originally expected to last for just five years.
By staying active for the better part of two 11-year solar cycles, Ulysses collected a wealth of information that formed the basis of over 1,000 scientific articles and two books.
Among its discoveries was a finding that the solar wind, a steady stream of charged sub-atomic particles blown out from the sun at about 1.6 million kilometers per hour, has dwindled to its lowest level in at least 50 years.
The solar wind inflates a massive protective bubble, called the heliosphere, around the solar system. As the solar wind weakens, the heliosphere is expected to contract in size and strength as well, allowing more cosmic radiation - super high-energy electrons and protons zipping through interstellar space - to reach the inner solar system.
The Earth remains shielded from these potentially harmful cosmic rays by virtue of a magnetic field that surrounds our planet. But the diminished solar wind and corresponding rise in cosmic rays are a concern for astronauts and spacecraft that venture beyond Earth's orbit.
The Volkswagen-sized spacecraft's transmitter was switched off on Tuesday, but NASA project manager Ed Massey said Ulysses will continue its wide, elliptical orbit around the sun indefinitely.
He said there was a chance the probe might eventually swing close enough to one of Jupiter's moons to alter its course to out of solar system.
Ulysses, a joint project of NASA and the European Space Agency, was launched from the space shuttle Discovery in 1990 and became the first probe to fly around the sun's poles.
Named for the hero of "The Odyssey," Ulysses was designed to help scientists study solar radiation and was originally expected to last for just five years.
By staying active for the better part of two 11-year solar cycles, Ulysses collected a wealth of information that formed the basis of over 1,000 scientific articles and two books.
Among its discoveries was a finding that the solar wind, a steady stream of charged sub-atomic particles blown out from the sun at about 1.6 million kilometers per hour, has dwindled to its lowest level in at least 50 years.
The solar wind inflates a massive protective bubble, called the heliosphere, around the solar system. As the solar wind weakens, the heliosphere is expected to contract in size and strength as well, allowing more cosmic radiation - super high-energy electrons and protons zipping through interstellar space - to reach the inner solar system.
The Earth remains shielded from these potentially harmful cosmic rays by virtue of a magnetic field that surrounds our planet. But the diminished solar wind and corresponding rise in cosmic rays are a concern for astronauts and spacecraft that venture beyond Earth's orbit.
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