P003-0004
Detection of Organic Molecules and D-H Ratios in Laboratory Mass-Spectra of Hypervelocity Dust Impacts Into Ice
Monday, 7 December 2020
Poster
Zach Ulibarri1, Tobin Munsat1, Bernd Abel2, Richard Dee1, Mihaly Horanyi3, David James4, Sascha Kempf5, Zoltan Kupihar6 and Zoltan Sternovsky7, (1)University of Colorado, Boulder, CO, United States, (2)University of Leipzig, Leipzig, Germany, (3)University of Colorado, Physics Department, Boulder, CO, United States, (4)Laboratory for Atmospheric and Space Physics, Boulder, CO, United States, (5)LASP/University of Colorado, Boulder, CO, United States, (6)University of Colorado at Boulder, Boulder, United States, (7)University of Colorado, Smead Aerospace Engineering Sciences Department, Boulder, CO, United States
Abstract:
Analysis from the Cassini spacecraft’s impact ionization time of flight (TOF) mass spectrometer indicates that the environment around Enceladus is rich with dust from both the ice surface and the subsurface ocean. While some laboratory work has been performed to match CDA flight spectra, these studies have laser ablated flowing liquid sources rather than impacting actual dust into ice surfaces. However, the University of Colorado dust accelerator at the Institute for Modeling Plasma, Atmospheres, and Cosmic Dust (IMPACT), paired with a cryogenic target capable of creating H2O ice mixtures, allows for unique, tightly controlled experiments to study hypervelocity dust impacts into ice under realistic conditions. Such experiments will answer significant questions about the chemical evolution of icy bodies under dust bombardment as well as the survivability and detectability of complex organic chemistry and the Deuterium-to-Hydrogen (D-H) ratios in icy dust grains studied by impact ionization TOF instruments on flyby spacecraft.
Water ice was doped with various amino acids and bombarded with dust. TOF chemical analysis of the impact plume shows that amino acids and even the more fragile di-peptide dual amino acid chain lysine-glycine survive the impact process and can be measured directly. Furthermore, spectra from impacts into water ice doped with the amino acid histidine show that fragmentation products are related but not identical to those found in the NIST electron impact ionization mass spectra of histidine. This indicates that even in the event of breakup, it may be possible to use the breakup products as a means to identify the parent molecule.
Similar experiments were performed with ice created with a known D-H ratio. Co-added TOF spectra from the impact plume indicates that the D-H ratio can be measured correctly with this method. This means that impact ionization mass spectrometers on future fly-by spacecraft will be able to measure the D-H ratio of icy ocean worlds such as Enceladus. While the D-H ratio of Enceladus plumes were measured by INMS and the surface by IR spectroscopy, this will provide an independent measurement of the icy dust grains.
