Showing papers by "Mark C. Price published in 2020"
TL;DR: A systematic study, accelerating organic ice‐particle simulants into soft inert metal targets at velocities ranging 0.5–3.0 km s−1, to explore the efficacy of a plume capture instrument and found organic chemical compounds remained chemically intact in particles captured at speeds up to ~2 km s‐1.
Abstract: The presence and accessibility of a sub-ice-surface saline ocean at Enceladus, together with geothermal activity and a rocky core, make it a compelling location to conduct further, in-depth, astrobiological investigations to probe for organic molecules indicative of extraterrestrial life. Cryovolcanic plumes in the south polar region of Enceladus enable the use of remote in situ sampling and analysis techniques. However, efficient plume sampling and the transportation of captured organic materials to an organic analyzer present unique challenges for an Enceladus mission. A systematic study, accelerating organic ice-particle simulants into soft inert metal targets at velocities ranging 0.5-3.0 km s-1, was carried out using a light gas gun to explore the efficacy of a plume capture instrument. Capture efficiency varied for different metal targets as a function of impact velocity and particle size. Importantly, organic chemical compounds remained chemically intact in particles captured at speeds up to ~2 km s-1. Calibration plots relating the velocity, crater, and particle diameter were established to facilitate future ice-particle impact experiments where the size of individual ice particles is unknown.
16 citations
TL;DR: In this article, the authors report the production of a weak simulant material, analogue to carbonaceous meteorites with a CM-like composition, following the preliminary compositional results for Bennu and Ryugu.
16 citations
TL;DR: In this article, an organic fluorescent tracer dye, Pacific Blue™, was dissolved in borate buffer and frozen into saline ice projectiles, which were then frozen into micron-sized particles that impacted the target.
Abstract: Enceladus is a compelling destination for astrobiological analyses due to the presence of simple and complex organic constituents in cryovolcanic plumes that jet from its subsurface ocean. Enceladus plume capture during a flyby or orbiter mission is an appealing method for obtaining pristine ocean samples for scientific studies of this organic content because of the high science return, reduced planetary protection challenges, and lower risk and expense compared to a landed mission. However, this mission profile requires sufficient amounts of plume material for sensitive analysis. To explore the feasibility and optimization of the required capture systems, light gas gun experiments were carried out to study organic ice particle impacts on indium surfaces. An organic fluorescent tracer dye, Pacific Blue™, was dissolved in borate buffer and frozen into saline ice projectiles. During acceleration, the ice projectile breaks up in flight into micron‐sized particles that impact the target. Quantitative fluorescence microscopic analysis of the targets demonstrated that under certain impact conditions, 10–50% of the entrained organic molecules were captured in over 25% of the particle impacts. Optimal organic capture was observed for small particles (d ~ 5–15 µm) with velocities ranging from 1 to 2 km s\(^{−1}\). Our results reveal how organic capture efficiency depends on impact velocity and particle size; capture increases as particles get smaller and as velocity is reduced. These results demonstrate the feasibility of collecting unmodified organic molecules from the Enceladus ice plume for sensitive analysis with modern in situ instrumentation such as microfluidic capillary electrophoresis (CE) analysis with ppb organic sensitivity.
11 citations
TL;DR: In this paper, the authors consider how the presence of an internal ocean modifies the energy density needed to disrupt an icy body with internal ocean and find that the energy required to cause an impact on a decimetre-scale body is 16.25 ± 1.35
3 citations
TL;DR: The wavelength dependence and temporal evolution of the hypervelocity impact self-luminous plume (or flash) from CO2 ice, water ice and frozen Martian and lunar regolith-simulant targets have been investigated using the Kent two-stage light-gas gun as mentioned in this paper.
Abstract: The wavelength dependence and temporal evolution of the hypervelocity impact self-luminous plume (or ‘flash’) from CO2 ice, water ice and frozen Martian and lunar regolith-simulant targets have been investigated using the Kent two-stage light-gas gun. An array of ten band-pass filtered photodiodes and a digital camera monitored changes in the impact flash intensity during the different phases of the emitting ejecta. Early-time emission spectra were also recorded to examine short-lived chemical species within the ejecta. Analyses of the impact flash from the varied frozen targets show considerable differences in temporal behaviour, with a strong wavelength dependence observed within monitored near-UV to near-IR spectral regions. Emission spectra showed molecular bands across the full spectral range observed, primarily due to AlO from the projectile, and with little or no contribution from vapourised metal oxides originating from frozen regolith-simulant targets. Additional features within the impact flash decay profiles and emission spectra indicate an inhomogeneity in the impact ejecta composition. A strong correlation between the density of water ice-containing targets and the impact flash rate-of-decay was shown for profiles uninfluenced by significant atomic/molecular emission, although the applicability to other target materials is currently unknown. Changes in impact speed resulted in considerable differences in the temporal evolution of the impact flash, with additional variations observed between recorded spectral regions. A strong correlation between the impact speed and the emission decay rate was also shown for CO2 ice targets. These results may have important implications for future analyses of impact flashes both on the lunar/Martian surface and on other frozen bodies within the Solar System.