Hypervelocity Impact Effect of Molecules from Enceladus' Plume and Titan's Upper Atmosphere on NASA's Cassini Spectrometer from Reactive Dynamics Simulation
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 ∼18 km/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.
Additional Information
© 2012 American Physical Society. Received 21 February 2012; revised manuscript received 30 April 2012; published 21 November 2012. Thanks to Adri van Duin and colleagues for providing the basic TiO_2-H_2O ReaxFF force field, Patrick L. Theofanis for his suggestions on the manuscript, and Chi Feng (SURF Fellow at Caltech) for his contributions to hexane simulations. This work was performed at Caltech and JPL under a contract with the National Aeronautics and Space Administration (NASA). Partial support was provided by the Department of Energy National Nuclear Security Administration under Contract No. DE-FC52-08NA28613 (Caltech PSAAP).Attached Files
Published - PhysRevLett.109.213201.pdf
Supplemental Material - README.TXT
Supplemental Material - SM_Jaramillo-Botero_et_al.pdf
Supplemental Material - ffield.pdf
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Additional details
- Eprint ID
- 36139
- Resolver ID
- CaltechAUTHORS:20130103-093549050
- Department of Energy (DOE) National Nuclear Security Administration
- DE-FC52-08NA28613
- Created
-
2013-01-09Created from EPrint's datestamp field
- Updated
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2021-11-09Created from EPrint's last_modified field
- Other Numbering System Name
- WAG
- Other Numbering System Identifier
- 1004