As reported by DIXI meeting coordinator Don Hampton:
The Deep Impact EXtended Investigation science team met at the Geophysical Institute from June 21 through June 26 to discuss the results of the flyby of comet Hartley 2 on Nov. 8, 2010. The comet flyby was accomplished using the repurposed Deep Impact spacecraft that was originally used to observe a spacecraft impact with comet Tempel 1 in 2005.
While Hartley 2 is the smallest of the five comets observed by spacecraft it is in many ways the most exciting due to its activity level and unprecedented resolutions of the on-board cameras. Water and carbon dioxide ices inside comet nuclei begin to evaporate and the gases pull dust with them sometimes creating the beautiful displays seen from the earth.
The DIXI science team had speculated before that there should also be larger particles that get pulled off the surface, but in previous missions there was no evidence of anything larger than dust a few micrometers across (smaller than the thickness of a human hair). From Hartley 2, however, there is evidence of particles as large as a few inches across being dragged from the surface by the highly active gas jets.
These large particles and many other aspects of the comet were discussed and debated among DIXI team members from the University of Maryland, the NASA Jet Propulsion Laboratory, Brown University, Cornell University and the University of Hawaii. The team’s findings will be presented at upcoming meetings and in a series of scientific papers.