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Hypervelocity Impact Effect of Molecules from Enceladus’ Plume and Titan’s Upper Atmosphere on NASA’s Cassini Spectrometer from Reactive Dynamics Simulation

Jaramillo-Botero, Andres and An, Qi and Cheng, Mu-Jeng and Goddard, William A., III and Beegle, Luther W. and Hodyss, Robert (2012) Hypervelocity Impact Effect of Molecules from Enceladus’ Plume and Titan’s Upper Atmosphere on NASA’s Cassini Spectrometer from Reactive Dynamics Simulation. Physical Review Letters, 109 (21). Art. No. 213201. ISSN 0031-9007. doi:10.1103/PhysRevLett.109.213201.

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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.

Item Type:Article
Related URLs:
URLURL TypeDescription DOIArticle
Jaramillo-Botero, Andres0000-0003-2844-0756
An, Qi0000-0003-4838-6232
Cheng, Mu-Jeng0000-0002-8121-0485
Goddard, William A., III0000-0003-0097-5716
Beegle, Luther W.0000-0002-4944-4353
Hodyss, Robert0000-0002-6523-3660
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).
Funding AgencyGrant Number
Department of Energy (DOE) National Nuclear Security AdministrationDE-FC52-08NA28613
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Issue or Number:21
Classification Code:PACS: 95.30.Ft, 34.50.Lf, 82.20.Wt, 96.30.N-
Record Number:CaltechAUTHORS:20130103-093549050
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:36139
Deposited By: Tony Diaz
Deposited On:09 Jan 2013 19:27
Last Modified:09 Nov 2021 23:20

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