Comet spacecraft encounters

Images of comet nuclei taken during various spacecraft encounters illustrate both similarities and differences. Figure 12.2 compares images of comets Borrelly (taken by Deep Space 1 in 2001), Wild2 (taken by Stardust in 2004), and Tempel 1 (taken by Deep Impact in... 

NASA s most recent comet missions are Deep Impact and Rosetta. Deep Impact was launched on January 12, 2005, with Comet Tempel 1 as its target. The spacecraft encountered Tempel 1 on July 3, 2005, at which time it released a 770-pound (350 kg) copper projectile at the comet. Cameras and spectrometers on the spacecraft photographed and collected samples of materials ejected from the comet nucleus and relayed that information to scientists on Earth. Rosetta was launched on March 2, 2004, with Comet 67P/Churyumov-Gerasimenko as its target. The spacecraft will orbit the comet and make observations for about two years as the comet approaches the Sun. It will also release a small package of instruments that make the first-ever landing on the surface of a comet. 

At the time of encounter, Wild2 was at 1.86 AU, and thus was very active. Comets release thousands of tons of dust during cometary activity - the dust is there for the taking, the trick is to snatch it without destroying it or the spacecraft. Two technological achievements by scientists at the Jet Propulsion Laboratory made the collection of comet dust possible the clever design of a trajectory that allowed the spacecraft to encounter the comet coma at a relatively modest speed (6.1 kms ), and the development of a capture medium that slowed and trapped the particles without destroying them. 

The Stardust spacecraft was launched successfully in February of 1999 from Kennedy Space Center on a Delta launch vehicle. During the cruise phase prior to the comet encounter. 

The Central On-Board Computer of the Philae Lander in the Context of the Rosetta Space Mission. Andras Baldzs, from the Wigner Research Centre for Physics in Budapest, Hungary, presented an overview of the major hardware and software design aspects of the central on-board computer of the Philae lander, which traveled over 10 years as the precious payload of the Rosetta spacecraft that recently made the historical encounter with the comet 67P/Churyumov-Gerasimenko. 

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