The Cassini-Huygens mission detected large negative ions in Titan's ionosphere at pressures as low as 10-6 Torr. These ions ultimately polymerize to form Titan's complex organic haze particles, which are observed throughout the atmosphere and potentially on the surface. Laboratory analogs of these hazes, known as tholins, have been used to study Titan's aerosols; however, most are produced at much higher pressures. The influence of formation pressures on key physical properties-such as particle size, density, surface energy, and mechanical strength-remains poorly constrained. These properties govern the haze's aggregation efficiency, radiative behavior, and surface-atmosphere interactions, shaping Titan's climate and surface. To investigate the effects of formation pressure, we generate tholins using a newly developed cold plasma discharge system. A 95% nitrogen and 5% methane gas mixture is exposed to plasma at two pressures, 1 Torr and 0.125 Torr. For both samples, we measure the production rate, particle size, morphology, density, surface free energy, Young's modulus, and nanoindentation hardness. While particle size, morphology, surface energy, and Young's modulus are similar across both pressures, tholins produced at lower pressure exhibited a threefold lower production rate, but a higher density and nanoindentation hardness. These variations likely reflect pressure-dependent changes in chemical structure, porosity, and mechanical strength. Because Titan's hazes form at much lower pressures than investigated here, actual haze particles are potentially even denser and mechanically stronger than our analogs, with implications for aerosol aggregation, aeolian and fluvial transport, and surface modification on Titan.

This paper presents developments in stationary phase coatings for microelectromechanical system gas chromatography (MEMS GC). Specifically, we present the coating of MEMS GC separation columns with a chiral stationary phase for the separation of amino acid enantiomers. Three commercial columns coated with chiral stationary phases from Restek were tested: Rt-βDEXm, Rt-βDEXsm, and Rt-βDEXsa. Four amino acid enantiomers (d- and l-) were tested with the 3 commercial columns: alanine (Ala), valine (Val), leucine (Leu), and aspartic acid (Asp). The Rt-βDEXsm column provided the best experimental performance with separation of d- and l-Ala and partial separation of d- and l-Asp. The resolution, Rs, values were 4.65 for the Ala enantiomers and 0.98 for the Asp enantiomers, respectively. The Rt-βDEXsm chiral stationary phase was dynamically coated on three 10-m-long microcolumns connected in series to investigate amino acid enantiomer separation. Successful separation of d- and l-Ala and partial separation of d- and l-Asp were observed with the microcolumns. The Rs values from the chiral-stationary-phase-coated microcolumns were 1.21 and 0.553 for the Ala and Asp enantiomers, respectively. The chromatographically separated amino acid enantiomers were detected by the MAss Spectrometer for Planetary EXploration (MASPEX), a spaceflight mass spectrometer. Future work is required for improving the MEMS GC separation column performance consisting of testing static versus dynamic coating methods and more rigorous investigation of the stationary phase coating thickness. A discussion is provided on future work for the development of an MEMS GC suite targeting broad analyte selectivity for future space science missions.

This paper presents developments in stationary phase coatings for microelectromechanical system gas chromatography (MEMS GC). Specifically, we present the coating of MEMS GC separation columns with a chiral stationary phase for the separation of amino acid enantiomers. Three commercial columns coated with chiral stationary phases from Restek were tested: Rt-beta DEXm, Rt-beta DEXsm, and Rt-beta DEXsa. Four amino acid enantiomers (d- and l-) were tested with the 3 commercial columns: alanine (Ala), valine (Val), leucine (Leu), and aspartic acid (Asp). The Rt-beta DEXsm column provided the best experimental performance with separation of d- and l-Ala and partial separation of d- and l-Asp. The resolution, Rs, values were 4.65 for the Ala enantiomers and 0.98 for the Asp enantiomers, respectively. The Rt-beta DEXsm chiral stationary phase was dynamically coated on three 10-m-long microcolumns connected in series to investigate amino acid enantiomer separation. Successful separation of d- and l-Ala and partial separation of d- and l-Asp were observed with the microcolumns. The Rs values from the chiral-stationary-phase-coated microcolumns were 1.21 and 0.553 for the Ala and Asp enantiomers, respectively. The chromatographically separated amino acid enantiomers were detected by the MAss Spectrometer for Planetary EXploration (MASPEX), a spaceflight mass spectrometer. Future work is required for improving the MEMS GC separation column performance consisting of testing static versus dynamic coating methods and more rigorous investigation of the stationary phase coating thickness. A discussion is provided on future work for the development of an MEMS GC suite targeting broad analyte selectivity for future space science missions.

We present an overview of the radiation environment monitoring program planned for the Europa Clipper mission. The harsh radiation environment of Jupiter will be measured by a dedicated Radiation Monitor (RadMon) subsystem, yielding mission accumulative Total Ionizing Dose (TID) and instantaneous electron flux measurements with a 1-Hz cadence. The radiation monitoring subsystem is comprised of a stand alone sensor assembly along with distributed TID assemblies at various locations on the spacecraft. The sensor assembly itself is made of a TID sensor stack using the Metal-Oxide Semiconducting Field-Effect Transistor (MOSFET) and a Charge Rate Monitor (CRM) that uses a stack of bulk charge collection plates. The TID measurements will provide the critical information about the overall radiation levels relevant to the degradation of electronics over time, and the electron flux data can serve as a proxy for the Internal ElectroStatic Discharge (IESD) environment by measuring the >∼1 MeV electron environment. In addition, the radiation monitoring subsystem data will be augmented by serendipitous radiation data from science instruments onboard. This will be enabled by careful modeling and analysis of opportunistic background data from potentially the following instruments: Europa Imaging System (EIS), Europa-Ultraviolet Spectrograph (Europa-UVS), Mapping Imaging Spectrometer for Europa (MISE), MAss Spectrometer for Planetary EXploration (MASPEX), Plasma Instrument for Magnetic Sounding (PIMS), and SUrface Dust Analyzer (SUDA). Based on the current analysis, these instruments will be most sensitive to >1 MeV electrons. As such, the high-energy electron data obtained by the radiation monitoring subsystem will be qualitatively and quantitatively enhanced by the high-energy electron data acquired by the instruments. The holistic radiation monitoring program for the mission will be an extensive collaboration among many teams across the flight and payload systems. Although the radiation monitoring subsystem itself is an engineering resource for the mission, the collective data from the mission can also be used to improve the scientific understanding of the Jovian magnetosphere and the high-energy electron environment near Europa, where the motion of charged particles is perturbed by the local electromagnetic environment. The data could also help in the understanding of the radiation modification of Europa surface compounds, which could subsequently help guide lab experiments to aid in understanding the origin and evolution of surface materials and in constraining the interpretation of observational data. To this end, the radiation monitoring subsystem is a useful resource for helping address the Europa Clipper mission’s primary goal of assessing the habitability of Europa.

We present a novel, innovative approach to gas chromatography-mass spectrometry (GC-MS) based on micro-electro-mechanical systems (MEMS) columns that improve the current, state-of-the-art by dramatically reducing the size, mass, and power resources for deploying GC for future landed missions. The outlet of the MEMS GC column was coupled to a prototype of the MAss Spectrometer for Planetary EXploration (MASPEX) through a heated transfer line into the ion source. MEMS GC-MS experiments were performed to demonstrate linearity of response and establish limit of detection (LOD) to alkanes (organics), fatty acid methyl esters (FAMEs) and chemically derivatized amino acids (biological molecules). Linearity of response to each chemical family was demonstrated over two orders of magnitude dynamic range and limit of detection (LOD) values were single to tens (4–43) of picomoles per 1 μl injection volume. MEMS GC column analytical performance was also demonstrated for a “Mega Mix” of chemical analytes including organics and biological molecules. Chromatographic resolution exceeded 200, retention time reproducibility was << 1% RSD (majority ≤ 0.3%), and peak capacity values calculated to be 124 ± 2 over a 435 s retention time window. The 5.5 m MEMS column was also shown to be a suitable alternative to traditional commercial columns for use in comprehensive two-dimensional gas chromatography (GC × GC). Mass spectra collected from MASPEX showed close consistency with National Institute of Technology (NIST) reference mass spectra and were used for high confidence identification of all eluting analytes.

3D3) Measurement of simple molecules with multiple rare ("clumped") isotopes

The mass spectrometer for planetary exploration (MASPEX) is a versatile mass spectrometer with unprecedented mass resolution designed for spaceflight. However, the current version of MASPEX is designed for continuous sampling during flybys of planetary bodies and does not include gas chromatography, which can improve the analysis of complex mixtures of organic compounds in space environments. Here, micro-electro-mechanical system (MEMS) gas chromatography (GC) linearity, reproducibility, and column analytical performance were first demonstrated prior to the coupling to MASPEX for MEMS GC-mass spectrometer (MS) analyses. Linearity of response was demonstrated for n-hexane over 2 orders of magnitude of on-column mass (concentration). Retention time reproducibility in the MEMS GC was <= 2% relative standard deviation (RSD). MEMS GC column analytical performance calculations showed the average number of theoretical plates, N, and the height equivalent to a theoretical plate, HETP, to be 16 239 (1623 plates per meter) and 0.062 cm, respectively. N defines a chromatographic centroid peak apex divided by the peak width at half height, similar to mass resolution. When coupled to MASPEX, the retention time reproducibility was in a similar range of 1-2% relative standard deviation with a slightly larger deviation seen from the mass spectrometer detector due to start trigger variations with a manual start trigger in the FastFlight software compared to the LabView code used for the MEMS GC-MS testing. The collected mass spectra showed close consistency with National Institute of Standards and Technology (NIST) reference mass spectra providing confidence in chemical compound identification. We present the first data generated from the coupling of these devices.

The future Europa Clipper NASA mission to Europa will carry the MAss Spectrometer for Planetary EXploration (MASPEX), which will analyze the compounds making up Europa's exosphere, and plumes, if present. Europa's exosphere is likely to feature abundant atomic oxygen, a product of sputtering of Europa's surface by energetic particles from Jupiter's radiation belts, or photolysis of oxygen-bearing molecules in the exosphere. Due to its very high reactivity, this atomic oxygen could induce chemical processes within MASPEX. These processes could involve materials composing the instrument, or other compounds from Europa's exosphere. In both cases, the possible effect on the instrument's measurements is a concern. In this work we first review previous relevant experiments on the effect of atomic oxygen on several candidate metals and conclude that stainless steel with a gold coating is the most satisfactory choice for MASPEX's antechamber walls, and alumina for the impact plate. We then perform simulations of adsorption/desorption processes within the instrument's antechamber to bound the effect of atomic oxygen on other compounds from Europa's exosphere. We find that the accumulation of atomic oxygen during a flyby would lead to a reduction of the apparent abundance of water by as much as 0.125% (Delta[H2O]/[H2O] = -1.25 x 10(-3)). Evaluating the exact extent of this effect during data post-processing would require constraining the atomic oxygen abundance, which would have to be achieved with other instruments, such as the ultraviolet spectrometer.

OF ICY WORLDS (ERSO) CONCEPT. C. M. Phillips-Lander1, T. Z. Moore1, U. Raut1, P. M. Molyneux1, M. A. Miller1, K. Nowicki3, R. C. Blase1, M. W. Davis1, T. J. Veach1, G. J. Dirks1, K. B. Persson1, Y. D. Tyler1, R. A. Klar1, P. L. Karnes1, M. A. Freeman1, C. J. A. Howett3, A. Soto3, K. Mandt4, L. Roth5, B. Schmidt6, E. Spiers, A. Templeton7, J. D. Mason8, E. S. Fry8, K. Retherford1, 1Southwest Research Institute, San Antonio, TX (clander@swri.edu), 2University of Texas at San Antonio, San Antonio, TX, 3Southwest Research Institute, Boulder, CO, 4Johns Hopkins University, Applied Physics Laboratory, Laurel, MD, 5Department of Space and Plasma Physics, KTH, Stockholm, Sweden,6Earth and Atmospheric Sciences, Georgia Tech, Atlanta, GA, 7Geological Sciences, University of Colorado, Boulder, CO, 8Texas A&M University, College Station, TX.

One of the most fundamental measurements that an atmospheric probe can make is the noble gas composition of the well-mixed atmosphere. The relatively inert chemical nature of noble gases makes them excellent tracers of the original reservoirs of material that formed the planet. Three types of measurements are important in this context: 1) abundance relative to the background H2 atmosphere; 2) relative abundances of He, Ne, Ar, Kr, and Xe; and 3) isotopic abundance patterns within individual noble gases. In the latter context, comparison of the Xe isotopic abundances with those from comet 67P by ROSINA/Rosetta provides constraints on the origin of Earth’s volatiles (Marty et al., 2017). The Galileo Probe mass spectrometer made measurements of the noble gases at Jupiter that indicated a factor of 2-3 increase relative to protosolar values. Likewise the noble gas enrichment system, a subsystem of the Galileo Probe mass spectrometer that is based on a SAES-171 getter, provided measurements of He, Ne, and Ar, but did not provide adequate signal-to-noise measurements for Kr and Xe. This task fell to the hydrocarbon enrichment system that used a carbon sieve trapping system (Mahaffy et al., 2000). The criticality of these measurements to the atmospheric probe mission makes it imperative to understand potential issues involved in the Galileo Probe measurements, and indicates the need to use this information to design a more robust gas enrichment system for future probes. Another relevant point concerns the recent observations of ammonia from Juno (Bolton et al., 2017), which suggest that the phase transitions of condensable volatiles as a function of pressure are highly complex at Jupiter and latitude-dependent as a result of dynamical effects. Therefore, of equal importance when considering the sampling systems for the probe mass spectrometer is the need to measure both gaseous and aerosol phases of important condensable compounds such as CH4, NH3, H2S, NH4SH, and H2O that will allow an adequate characterization of the bulk elemental abundances as a function of pressure/altitude. The effects of condensation will be magnified at Saturn and the ice giants owing to greater volatile enrichments and lower atmospheric temperatures. Based on the preceding considerations, the measurement types listed above should have increasing robustness against possible observational artifacts.

Southwest Research Institute investigated the response of a microchannel plate (MCP) detector to isotropic radioactive source emissions at photon energies of 0.662 and approximately 1.25 million electronvolts (MeV) and to a beam of monoenergetic photons (gamma rays) at 2.5, 5, 7, 10, 13, and 20 MeV in the Free Electron Laser Laboratory at Duke University. These measurements were performed to quantify anticipated noise levels of a mass spectrometer instrument for space exploration in a harsh radiation environment and included various incident angles of radiation on the MCP. Measured photon detection efficiencies at 0 degrees incident angle to 0.662 and 1.25 MeV were approximately 0.3%-0.4% and are bracketed by previously published data. In the 2.5- to 20-MeV energy range for which comparable published data are not available, measured detection efficiencies were on the order of 0.02%-0.2%. Radiation transport simulations were compared to the experimental results and showed decent agreement. The measured detection efficiency increased as the incident photon angle was changed from being normal to the MCP surface (0 degrees) to being aligned with the MCP edge (90 degrees). At greater off-axis angles, photons were incident on the side of the detector cartridge and generated secondary radiation from photon interactions in the cartridge materials that subsequently registered MCP counts.

In this paper, we examine the history of detection efficiency measurements of photons (soft to hard X-rays and beyond) with microchannel plates (MCPs). We investigate the detection efficiency as a function of photon energy over a wide energy range, from a few hundred eVs up to 20 MeV. We also investigate detection efficiency as a function of incident angle onto the MCP. We interpreted the published efficiency data measured with a variety of MCPs and the use of MCP coatings for enhancement of X-ray quantum detection efficiency, and discuss theoretical expectations based on the main photon interactions with matter: the photoelectric effect, Compton scattering, and pair production. Contributing to the published literature at the highest end of the energy range, we also discuss our photon detection efficiency experiments from 2.5 to 20 MeV and theoretical implications.

An unshielded microchannel plate (MCP) detector with an ultrafine pore diameter of 2 μm was irradiated by an electron beam to determine the detection efficiency of electrons for creating detector signals, or counts. Tested electron energies spanned a range of 3 kiloelectron volts (keV) to 28 keV. Higher detection efficiencies were measured at the lower end of this energy range, 0.376 counts per incident electron at 3 keV down to 0.155 at 15 keV with an increase to 0.217 at 18 keV and then another decrease down to 0.15 counts per incident electron at 28 keV. The increase at 18 keV is attributed to primary electron interaction with the L shell electrons of lead (Pb), leading to an increase in secondary electron and X-ray generation within the MCP and thus an increase in detection efficiency. For the electron beam directed normal to the MCP surface, the lowest efficiency of 0.15 counts per incident electron was observed at 28 keV. Detection efficiency was also tested as a function of incident angle with angular steps of 5°. Detection efficiency was more sensitive to the angle of incidence as the incident electron energy decreased. The detection efficiency at 3 keV decreased from 0.376 counts per electron at the zero degree angle (normal incidence to MCP surface) to 0.027 counts per electron at an incident angle of 50° (average in both orientations). At 28 keV, the decrease in detection efficiency as a function of increasing angle was less pronounced, ranging from 0.15 counts per electron at zero degrees to 0.08 counts per electron at 50° (average in both orientations). Experimental data showed lower detection efficiencies compared with previously published data.

The Jovian system is the focus of multiple current and future NASA and ESA missions, but dangerously high radiation levels surrounding the planet make operations of instruments sensitive to high energy electrons or gamma rays problematic. Microchannel plate (MCP) detectors have been the detectors of choice in planetary ultraviolet spectrographs for decades. However, the same properties that give these detectors high response to vacuum ultraviolet photons also make them sensitive to high energy electrons and gamma rays. The success of ultraviolet investigations in the Jovian system depends on effectively shielding these MCP detectors to protect them as much as possible from this withering radiation. The design of such shielding hinges on our understanding of the response of MCP detectors to the high energy electrons and gamma rays found there. To this end, Southwest Research Institute and Massachusetts Institute of Technology collaborated in 2012-13 to measure the response of a flight-spare microchannel plate detector to a beam of high energy electrons. The detector response was measured at multiple beam energies ranging from 0.5-2.5 MeV and multiple currents. This response was then checked with MCNP6, a radiation transport simulation tool, to determine the secondary gamma rays produced by the primary electrons striking the detector window. We report on the measurement approach and the inferred electron and gamma sensitivities.

A compact E × B mass spectrometer is presented. The mass spectrometer presented is termed a "perfect focus" mass spectrometer as the resolution of the device is independent of both the initial direction and energy of the ions (spatial and energy independent). The mass spectrometer is small in size (∼10.7 in.(3)) and weight (∼2 kg), making it an attractive candidate for portability when using small, permanent magnets. A multi-collector Faraday cup design allows for the detection of multiple ion beams in discrete collectors simultaneously; providing the opportunity for isotope ratio monitoring. The mass resolution of the device is around 400 through narrow collector slits and the sensitivity of the device follows expected theoretical calculations of the ion current produced in the electron impact ion source. Example mass spectra obtained from the cycloidal focusing mass spectrometer are presented as well as information on mass discrimination based on instrumental parameters and isotope ratio monitoring of certain ion signals in separate Faraday cups.