The Minor Planet Center, the world clearinghouse for information about newly discovered asteroids, raised the alarm last week. In an email to professional observatories, they announced that a previously unknown asteroid would miss the Earth by just 5,600 kilometers.
The newly discovered space rock was given an official label by the MPC, which is run by the Smithsonian Astrophysical Observatory, Massachusetts, for the International Astronomical Union. Observations for 2007 VN84 were collected from astronomers around the world, to track the threatening celestial body. This would be one of the closest approaches ever by a sizable asteroid - less than half the diameter of the Earth.
Then Denis Denisenko, of Moscow's Space Research Institute (IKI), made an interesting discovery. He noticed that the incoming asteroid's track matched that of the European space probe Rosetta on a scheduled flyby of Earth.
The Rosetta craft was launched from Europe's Guiana Space Center in early March of 2004; the purpose of the space probe is to place itself in low orbit around the comet Churyumov-Gerasimenko at a distance of 675 million kilometers from the sun. To get there, the billion-dollar craft will spend ten years boosting its velocity (using the gravity assist technique) with no fewer than three flybys of Earth and one of Mars.
Apparently there is no central directory of artificial satellite trajectories.
This incident, along with previous NEOCP postings of the WMAP spacecraft, highlights the deplorable state of availability of positional information on distant artificial objects (whether in earth orbit or in solar orbit). The Distant Artificial Satellites Observations (DASO) page lists a number of such objects, but has to be updated on a fairly regular basis from five different sources and data is not always available for the timespans needed. A single source for information on all distant artificial objects would be very desirable.
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