From: Jet Propulsion Laboratory
Posted: Friday, November 4, 2011
As we approach the anniversary of the EPOXI flyby of Hartley 2, it is time to look at what we have learned about comets from this mission. In the first week of October, a special session of the annual DPS meeting http://meetings.copernicus.org/epsc-dps2011/, jointly held with the European Planetary Science Congress, highlighted recent mission results in an all-day session http://meetingorganizer.copernicus.org/EPSC-DPS2011/session/8405. Key results from EPOXI included:
* new evidence that the two lobes of Hartley 2 are different in composition,
* separation of the icy grains from the refractory grains quantitatively improved statistics on the motion of the large chunks in the coma,
* the correlation of surface ice with topography on the nucleus,
* an analysis of spectra showing that the thermal inertia of the nucleus is very small (highest surface temperature at noon rather than in the afternoon).
The results for the abundances of carbon monoxide (CO) and carbon dioxide (CO_2 ) relative to water mesh nicely with results from the Akari satellite on these abundances in other comets and the results on deuterium in Hartley 2 suggest that the origin of comets needs to be rethought.
Meanwhile, NASA has decided that there will be a senior review of all operating planetary exploration missions. That will likely include a review of the status of the Deep Impact Flyby spacecraft to determine whether an additional extended mission should be approved. Decisions will not occur until early 2012.
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