Presentation #511.01 in the session “Comet Surfaces”.
Comet 103P/Hartley 2 is a hyperactive comet which has relatively high production rates of H2O and CO2 gases. The comet was also visited by the Deep Impact spacecraft during the extended EPOXI mission on Nov 4, 2010. The closest approach to the comet was 694 km when the comet was about 1.06 AU from the sun. Images and spectra were taken by the MRI and HRI onboard. The infrared measurements taken close to the comet revealed the H2O vapor was mostly released from the waist of the nucleus, and CO2 and ice chunks/grains were emitted from the small end of the bi-lobe shaped nucleus. Besides being monitored by spacecraft, the coma was also measured by SOHO/SWAN and ground-based telescopes. Interesting discrepancies existed in the H2O production rate measurement. The measurement with a bigger aperture has a larger production rate, which leads to the explanation that a significant amount of H2O is produced by the extended sources of icy grains or chunks in the coma. In this work, we feed the HRI images, which were taken within 8 hours before and after the closest approach, into our inversion model to determine the potential H2O and CO2 source regions on the surface of the comet. The obtained potential source regions, combined with the solar illumination condition, will yield the total H2O and CO2 gas fluxes from the surface. The production rates from the nucleus will be compared with other measurements.
Support for this work comes from grant 80NSSC17K0212 from the NASA Discovery Data Analysis Program.