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M.S. Hanner (JPL/Caltech), T.L. Hayward (Gemini Observatory)
Comet 81P/Wild 2 was observed in the thermal infrared over 6 months during its 1997 perihelion passage. The comet was most active in late February, about 3 months pre-perihelion; dust production declined by a factor of 3 between February and August. For the GIOTTO Halley dust size distribution, maximum dust production rate was ~ 2 x 103 kg/s. The comet displayed a 10 micron silicate feature about 25% above the continuum, similar to several other short-period comets, but much lower than that seen in a number of Oort Cloud comets.
NASA's Stardust sample return mission will encounter P/Wild 2 98 days postperihelion in January 2004. Based on our observations at a similar point in the orbit and the Halley size distribution, we predict that the mass fluence on the spacecraft for a 150 km miss distance will be about 8 x 10-5 kg/m2 for particles up to 1 cm in radius. The corresponding areal coverage will be about 10-4.
This research was conducted in part at JPL under contract with NASA (Planetary Astronomy Program).