Active regions are typically 10 km2 in area. About 6 m depth of material is lost from an active region per orbit around the Sun. The observed topography indicates structural strength of the surface. Three major jets were evident. The maximum emission of dust was not directly towards the Sun but towards a direction 30 deg south of the comet-Sun line.
Dust is swept around from the dayside to the nightside by the expanding gas flow.
Large particles dominate the mass loss from the nucleus. Dust to gas ratios of around 2 are consistent with observations. The dust was slightly redder than the nucleus itself. HMC's fate 9 seconds before closest approach, HMC stopped functioning. Subsequent analysis showed that the microprocessors in the instrument electronics had experienced a power glitch.