A Search for Deep Impact's Large Particle Ejecta
  The Deep Impact encounter with the nucleus of 9P/Tempel ejected small grains (a <~ 10 micron) into the comet's coma, evidenced by thermal emission from small dust grains at mid-infrared wavelengths (~10 micron) and dynamical simulations of optical images. Meteor-sized particles (a >~ 100 micron) ejected by the impact will likely have the lowest ejection velocities and will weakly interact with solar radiation pressure. Therefore, large particles may remain near the nucleus for weeks or months after ejection by Deep Impact. We present initial highlights of our Spitzer Space Telescope/MIPS 24 micron camera program to image comet 9P/Tempel at 30, 80, 420, and 560 days after the Deep Impact encounter. The MIPS data, combined with our dynamics model, enable detection of large dust grains potentially ejected by Deep Impact. 
Michael S. Kelley (1), William T. Reach (2), Charles E. Woodward (1)   ((1) Department of Astronomy, University of Minnesota...