P003-0012
Understanding hypervelocity sampling of ice-borne biosignatures in space missions
Monday, 7 December 2020
Poster
Andres Jaramillo-Botero1, Amy Hofmann2, Michael Malaska3, Robert P Hodyss4, Jonathan I Lunine5, Sarah E. Waller6, Morgan E.C. Miller7, Sally Burke8, Robert Continetti7, Bernd Abel9, Frank Postberg10 and Morgan L Cable11, (1)California Institute of Technology, Pasadena, CA, United States, (2)NASA Jet Propulsion Laboratory, Pasadena, CA, United States, (3)Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States, (4)Jet Propulsion Laboratory, Pasadena, CA, United States, (5)Cornell University, Department of Astronomy, Ithaca, NY, United States, (6)JPL/NASA/Caltech, Pasadena, CA, United States, (7)University of California San Diego, La Jolla, United States, (8)University of California San Diego, La Jolla, CA, United States, (9)University of Leipzig, Leipzig, Germany, (10)Freie UniversitÓ“t Berlin, Berlin, Germany, (11)NASA Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, United States
Abstract:
In space missions meant to study the potential for life on other planetary bodies, current sampling strategies include analysis of planetary atmospheres and plumes during hypervelocity flyby encounters at different altitudes. This is conventionally done through the use of mass spectrometers and other instruments capable of measuring the composition of gases, ices, and organic compounds. During collection, fragmentation of these materials can occur following their initial impact, prior to actual measurement, or from radiolytic processes on the surface, prior to or during surface sputtering. Although this can be mitigated by reducing the flyby speed of the spacecraft relative to the atmosphere, this compromises sampling signal intensities, collisional ionization strategies for analyzing dust, and may not be practical for certain missions.
We will present results to address some of the unknowns of hypervelocity impacts on the mass spectra of single impacting molecules, specifically for neutral molecules, in order to determine if existing space mission data obtained at hypervelocity from mass spectrometers and other instruments are compromised by impact-induced fragmentation. The results provide key insights into the design criteria for the optimization of spacecraft instruments meant to measure low concentrations of neutrals in low-density atmospheres during hypervelocity flybys, and enable establishing parameter bounds for future hypervelocity sampling missions, considering the trade-off between potential induced ionization and high encounter velocities to increase the effective mass flow and accuracy in signal resolution.
We will show: 1) fragmentation fraction is a sensitive function of impact angle for some amino and fatty acid species and not others, 2) minimal fragmentation occurs for velocities below 3km/s for bare molecules, and 3) encasing organic molecules in ice grains, as would be the case for samples in 'ocean world' plumes and atmospheres, preserves molecules at higher velocities, by as much as 2 km/s for ice-shells of 12.8nm in thickness[1]. These results are consistent with a recent experiments recommending plume encounter velocities of 4-6 km/s to sample amino fatty acids using laser-induced ionization that simulates the impact ionization and analysis via mass spectrometry[2]
