Arianespace has agreed to do everything possible to ensure that the launch will take place within a three-week launch window in the January 2003 time frame. Furthermore, an upper stage of the booster is being assigned the extra duty of an extended coast phase. Remaining in a highly elliptical coast orbit around Earth for just under two hours, the stage and its Rosetta cargo will then rocket onto an Earth escape trajectory, headed towards Mars.
Meet an iceberg
Over the next eight years, Rosetta will swing by Mars once and Earth twice. Thanks to the gravity assists at each flyby, Rosetta then strikes out for a rendezvous with Comet 46P/Wirtanen in November 2011. En route to its ultimate target, the ESA comet chaser is set to zip by asteroids Siwa and Otawara.
Once at the comet, Rosetta -- consisting of an orbiter craft and a small lander -- starts an extensive survey of the icy world. Science instruments carried by the Rosetta Orbiter can view the space iceberg at various ranges, down to less than a mile away (1 kilometer).
Rosetta's reconnaissance of the comet is scheduled to last nearly two years. During that time, scientists expect to view changes in the comet as the Sun's warming rays begin to vaporize its nucleus.
Nose down on a nucleus
While giving the comet a lengthy look-see, the Rosetta Orbiter also ejects a small lander that drops atop the surface of the cosmic wanderer. That Lander is outfitted to make on-the-spot observations of the solid nucleus. The nucleus is a mix of water ice, other frozen gases such as carbon monoxide and carbon dioxide, and solid particles.
Observations made of Comet Halley by ESA's Giotto spacecraft in 1986 found that nucleus rife with plumes of gas and dust blasting up from the surface like geysers.
The Rosetta Lander totes along its own set of instruments, including a camera and sensors that can study individual grains of the nucleus down to the microscopic level.
Next page: Data chats
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