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Pioneer 10  von Professor aus der Kategorie Freier Text - Wissenschaft, Technik |
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Pioneer 10 -------------------------------------------------------------------------------- Launched on March 2, 1972, the first spacecraft to cross the Main Asteroid Belt and to fly close by Jupiter (December 3, 1973). It is now on an exit trajectory from the solar system, together with three other probes, Pioneer 11, Voyager 1, and Voyager 2. Of this interstellar quartet, only Pioneer 10 is heading in the opposite direction to the Sun's motion through the Galaxy. It continues to be tracked in an effort to learn more about the interaction between the heliosphere and the local interstellar medium. Pioneer 10 is heading for interstellar space at a speed of 12.23 km/sec. (7.60 miles/sec). At this rate it would take about 105,000 years to reach what is currently the nearest star to the Sun, Proxima Centauri. However, Pioneer 10's course is taking it generally toward Aldebaran (65 light-years away) in the constellation of Taurus, and a (very!) remote encounter about 2 million years from now. The closest that it will come to another star system within the next 100,000 years is 3.27 light-years (1.00 parsec) from the red dwarf Ross 248 in about the year 32,608 A.D. Even then, this distant passage will owe more to the relative motions of the stars themselves than the probe's own efforts. It so happens that Ross 248 is approaching the Sun at about 80 km/sec. (50 miles/sec.) so that by the year 34,923 A.D the gap between the Sun and the red dwarf will have narrowed from its present value of 10.3 light-years (3.2 parsecs) to just 2.9 light-years (0.9 parsec). Uncertainties in the movements of stars over long periods are one of the main reasons that mission specialists cannot be absolutely sure when and at what range future stellar flybys of escaping probes will take place. On December 15, 2002, Pioneer 10 was 81.86 astronomical units (12.28 billion km, 7.63 billion miles) from the Sun, equivalent to a round-trip light travel time of 22 hours 25 minutes. The probe continues to function. It was superseded as the most distant human-made object by Voyager 1 in mid-1998.1 | ||||||||||
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