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Understanding Hypervelocity Sampling of Biosignatures in Space Missions

Jaramillo-Botero, Andres and Cable, Morgan L. and Hofmann, Amy E. and Malaska, Michael and Hodyss, Robert and Lunine, Jonathan (2021) Understanding Hypervelocity Sampling of Biosignatures in Space Missions. Astrobiology, 21 (4). pp. 421-442. ISSN 1531-1074. PMCID PMC7994429. doi:10.1089/ast.2020.2301.

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The atomic-scale fragmentation processes involved in molecules undergoing hypervelocity impacts (HVIs; defined as >3 km/s) are challenging to investigate via experiments and still not well understood. This is particularly relevant for the consistency of biosignals from small-molecular-weight neutral organic molecules obtained during solar system robotic missions sampling atmospheres and plumes at hypervelocities. Experimental measurements to replicate HVI effects on neutral molecules are challenging, both in terms of accelerating uncharged species and isolating the multiple transition states over very rapid timescales (<1 ps). Nonequilibrium first-principles-based simulations extend the range of what is possible with experiments. We report on high-fidelity simulations of the fragmentation of small organic biosignature molecules over the range v = 1−12 km/s, and demonstrate that the fragmentation fraction is a sensitive function of velocity, impact angle, molecular structure, impact surface material, and the presence of surrounding ice shells. Furthermore, we generate interpretable fragmentation pathways and spectra for velocity values above the fragmentation thresholds and reveal how organic molecules encased in ice grains, as would likely be the case for those in “ocean worlds,” are preserved at even higher velocities than bare molecules. Our results place ideal spacecraft encounter velocities between 3 and 5 km/s for bare amino and fatty acids and within 4–6 km/s for the same species encased in ice grains and predict the onset of organic fragmentation in ice grains at >5 km/s, both consistent with recent experiments exploring HVI effects using impact-induced ionization and analysis via mass spectrometry and from the analysis of Enceladus organics in Cassini Data. From nanometer-sized ice Ih clusters, we establish that HVI energy is dissipated by ice casings through thermal resistance to the impact shock wave and that an upper fragmentation velocity limit exists at which ultimately any organic contents will be cleaved by the surrounding ice—this provides a fundamental path to characterize micrometer-sized ice grains. Altogether, these results provide quantifiable insights to bracket future instrument design and mission parameters.

Item Type:Article
Related URLs:
URLURL TypeDescription CentralArticle
Jaramillo-Botero, Andres0000-0003-2844-0756
Cable, Morgan L.0000-0002-3680-302X
Hofmann, Amy E.0000-0001-6869-5118
Malaska, Michael0000-0003-0064-5258
Hodyss, Robert0000-0002-6523-3660
Lunine, Jonathan0000-0003-2279-4131
Additional Information:© 2021 Andres Jaramillo-Botero et al. Published by Mary Ann Liebert, Inc. This Open Access article is distributed under the terms of the Creative Commons Attribution Noncommercial License [CC-BY-NC] ( which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and the source are credited. Submitted 21 May 2020; Accepted 9 November 2020; Online Ahead of Print: March 19, 2021. This work was performed at the California Institute of Technology and the Jet Propulsion Laboratory (JPL), California Institute of Technology, under contract with the National Aeronautics and Space Administration - NASA (80NM0018D0004). Government sponsorship acknowledged. J.L. was the David Baltimore Distinguished Visiting Scientist during the preparation of this work. The authors thank Frank Postberg for the helpful suggestions regarding hypervelocity impact experiments with electrostatic dust accelerators, Adri van Duin for fruitful discussions and for sharing the organics ReaxFF parameter set, and Juan Marmolejo for helping with some of the Configuration Interaction calculations in the Supplementary Data, and Jeroen Koopman and Stefan Grimme for sharing the QCEIMS code. Funding Information: Jet Propulsion Laboratory Research and Technology Development Program. No competing financial interests exist.
Funding AgencyGrant Number
JPL Research and Technology Development FundUNSPECIFIED
Subject Keywords:Enceladus; Titan; Hypervelocity sampling; Space biosignatures; Amino and fatty acids fragmentation; Reactive molecular dynamics
Issue or Number:4
PubMed Central ID:PMC7994429
Record Number:CaltechAUTHORS:20210330-140753214
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Official Citation:Understanding Hypervelocity Sampling of Biosignatures in Space Missions. Andres Jaramillo-Botero, Morgan L. Cable, Amy E. Hofmann, Michael Malaska, Robert Hodyss, and Jonathan Lunine. Astrobiology. Apr 2021.421-442.
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:108585
Deposited By: Tony Diaz
Deposited On:30 Mar 2021 22:17
Last Modified:30 Mar 2021 22:17

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