Comet Borrelly

Grigg-Skjellerup was visited by the Giotto spacecraft in 1989. NASA s demonstration spacecraft DS1 imaged the nucleus of Comet Borrelly in 2001. 

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... 

Figure 6 Stereo images of comet Borrelly taken by NASA s Deep Space 1 Mission.

Figure 5 Active jets observed from comet Borrelly. This directed emission from sunlit areas is responsible for the rocket effect that measurably perturbs many comet from normal Keplerian orbits purely determined by gravity. Image taken by NASA s Deep Space 1 Mission.

Figure 7 High-resolution image of comet Borrelly with topographic and albedo regions mapped (source Soderblom et al, 2002).

A second successful U.S. comet mission was Deep Space 1, launched from Cape Canaveral on October 24, 1998. Its principal goal was to test a variety of new space technologies. It completed this primary mission in Septemher 1999. The spacecraft s mission was then extended to include a flyby of Comet Borrelly, which it accomplished on Septemher 22, 2001. Deep Space 1 sent hack black and white photographs of the comet, infrared spectrometer readings, ion and electron data, and measurements of the magnetic held and plasma waves in the vicinity of the comet. 

Nucleus composed of rock, dust, ices, frozen gases often described as dirty snowballs, however the ices are covered by dark dust and rocks. The nuclei are irregularly shaped and the diameters range from several 100 m to some dozens of km. Up to now only the nuclei of the comets Halley (Fig. 5.3), Borrelly, Wild and Tempel 1 have been investigated by satellite missions and photographed directly. 

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