Hypervelocity impact effect of molecules from enceladus' plume and titan's upper atmosphere on NASA's cassini spectrometer from reactive dynamics simulation

Andres Jaramillo-Botero, Qi An, Mu Jeng Cheng, William A. Goddard, Luther W. Beegle, Robert Hodyss

Research output: Contribution to journalArticlepeer-review

15 Citations (Scopus)

Abstract

The NASA/ESA Cassini probe of Saturn analyzed the molecular composition of plumes emanating from one of its moons, Enceladus, and the upper atmosphere of another, Titan. However, interpretation of this data is complicated by the hypervelocity (HV) flybys of up to ∼18km/sec that cause substantial molecular fragmentation. To interpret this data we use quantum mechanical based reactive force fields to simulate the HV impact of various molecular species and ice clathrates on oxidized titanium surfaces mimicking those in Cassini's neutral and ion mass spectrometer (INMS). The predicted velocity dependent fragmentation patterns and composition mixing ratios agree with INMS data providing the means for identifying the molecules in the plume. We used our simulations to predict the surface damage from the HV impacts on the INMS interior walls, which we suggest acts as a titanium sublimation pump that could alter the instrument's readings. These results show how the theory can identify chemical events from hypervelocity impacts in space plumes and atmospheres, providing in turn clues to the internal structure of the corresponding sources (e.g., Enceladus). This may be valuable in steering modifications in future missions.

Original languageEnglish
Article number213201
JournalPhysical review letters
Volume109
Issue number21
DOIs
Publication statusPublished - 2012 Nov 21

All Science Journal Classification (ASJC) codes

  • Physics and Astronomy(all)

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