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Orlando,
Thomas M.
Orlando,
Thomas M.
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ItemCharacterization of H2O vapor transport through Lunar Mare and Lunar Highland simulants at low pressures for in-situ resource utilization - Data Files(Georgia Institute of Technology, 2023) Farr, Tyler P. ; Jones, Brant M. ; Orlando, Thomas M. ; Loutzenhiser, Peter G.H2O(v) transport through packed beds of Lunar Mare and Lunar Highland simulants was examined for relevant in-situ resource utilization conditions to inform volatile H2O extraction from the lunar surface. Experiments were conducted with different packed beds at average bed pressures of 105 and 3,960 Pa at ~350K for different flow regimes in the range of 0.47 < < 20.7. A piecewise model was used to describe the transition between the advective flow regime to the Knudsen flow regime. Non-linear regression was used to determine a tortuosity shape factor of 2.6175 ± 0.0092 and 0.0937 ± 0.0008, a transition Knudsen number of 1.5984 and 4.0995, and a viscous flow permeability of 0.8238 ± 0.0010 × 10-12 m2 and 5.4805 ± 0.0061 × 10-12 m2 for the Lunar Mare simulant and Lunar Highland simulant, respectively. The resulting Knudsen diffusivities are 6.6530 ± 0.0018 cm2·s-1 and 18.9008 ± 0.0100 cm2·s-1, respectively. These results are necessary for informing the development of in-situ resource utilization technologies for the thermal extraction of H2O.
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ItemCaCO3 Polymorphs as Mineral Catalysts for Prebiotic Phosphorylation of Uridine(Georgia Institute of Technology, 2022-12) Schaible, Micah J. ; Castañeda, Alma D. ; Menor-Salvan, Cesar ; Pasek, Matthew A. ; Burcar, Bradley T. ; Orlando, Thomas M.Establishing plausible routes for the abiotic formation of nucleotides is a challenging problem because the phosphorylation of organic molecules is thermodynamically unfavorable in water, and because common phosphorous-containing minerals such as apatite are highly insoluble. Reactions of reduced phases such as the meteoritic mineral schreibersite with ammonia containing solutions can form stable amino-derivatives of phosphates/phosphite, and carbonate-rich lakes have been suggested as environments where phosphate species and organic molecules could accumulate in significant abundances, thus promoting an ideal environment for abiotic phosphorylation. This work reports the catalytic properties of three CaCO3 polymorphs – calcite, aragonite, and vaterite – on diamidophosphate (DAP)-induced phosphorylation of the uridine nucleoside during a 24-hour dry-down reaction. It is shown that the phosphorylation reaction is accelerated in solutions containing CaCO3 compared to those with no mineral present. For un-buffered solutions with no mineral present, the primary products formed are uridine monophosphates (UMP), with yields making up 22.3 ± 3.9% of the total detected species, while solutions containing calcite and aragonite formed primarily UMP dimers (yields of 15.3 ± 1.1% and 14.8 ± 1.3%, respectively). Vaterite showed a strong preference for forming cyclic UMP (cUMP) (26.3 ± 0.3% yield), and no higher order polymers were observed using any carbonate mineral. Reactions containing CaSO4∙2H2O (gypsum) showed a preference for forming cUMP, though not as strong as vaterite, while those containing CaCl2 (calcium chloride) and CaWO4 (scheelite) did not yield any phosphorylated products other than UMPs. These results suggest that CaCO3 minerals could have played an important role in facilitating prebiotic phosphorylation in aqueous environments that undergo drying cycles.
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ItemTemperature Programmed Desorption Comparison of Lunar Regolith to Lunar Regolith Simulants LMS-1 and LHS-1 - Data Files(Georgia Institute of Technology, 2022) Clendenen, Ashley Rebekah ; Aleksandrov, Aleksandr ; Jones, Brant M. ; Loutzenhiser, Peter G. ; Britt, Daniel T. ; Orlando, Thomas M.Water and molecular hydrogen evolution from Apollo sample 14163 and lunar regolith simulants LMS-1 and LHS-1 were examined using Temperature Programmed Desorption (TPD) in ultra-high vacuum. LMS-1, LHS-1, and Apollo 14163 released water upon heating, whereas only the Apollo sample directly released measurable quantities of molecular hydrogen. The resulting H2O and H2 TPD curves were fit using a model which considers desorption at the vacuum grain interface, transport in the void space between grain-grain boundaries, molecule formation via recombination reactions and sub-surface diffusion. The model yielded a most probable H2O formation and desorption effective activation energy of ~150 kJ mol-1 for all samples. The probability distribution widths were ~100 - 400, ~100 - 350, and ~100 - 300 kJ mol-1 for LMS-1, LHS-1, and Apollo 14163, respectively. In addition to having the narrowest energy distribution width, the Apollo sample released the least amount to water (103 ppm) relative to LMS-1 (176 ppm) and LHS-1 (195 ppm). Since essentially no molecular hydrogen was observed from the simulants, the results indicate that LMS-1 and LHS-1 display water surface binding and transport interactions similar to actual regolith but not the desorption chemistry associated with the implanted hydrogen from the solar wind. Overall, these terrestrial surrogates are useful for understanding the surface and interface interactions of lunar regolith grains, which are largely dominated by the terminal hydroxyl sites under both solar wind bombardment and terrestrial preparation conditions.
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ItemCharacterization of H2O Transport Through Johnson Space Center Number 1A Lunar Regolith Simulant at Low Pressure for In-situ Resource Utilization - Data File(Georgia Institute of Technology, 2021-02-04) Schieber, Garrett L. ; Jones, Brant M. ; Orlando, Thomas M. ; Loutzenhiser, Peter G.H2O transport through a packed bed of Johnson Space Center number 1A (JSC-1A) lunar regolith simulant was examined at relevant temperatures and pressures for in-situ resource utilization (ISRU) on the Moon. Experimentation was conducted over a range of pressures from 50 to 2,065 Pa at ~350 K, corresponding to Knudsen numbers of 0.3 < Kn < 11 and relevant towards ISRU technologies. A piecewise function was used to evaluate transition and Knudsen regime flows. The piecewise model utilized a Knudsen number that predicted the transition point between advective and Knudsen flows. A transition Knudsen number of 1.66 ± 0.61 and a tortuosity shape parameter of 0.736 ± 0.13 were determined from non-linear regression, and Knudsen diffusivities of 10.62 cm2·s-1, 10.40 cm2·s-1 and 9.04 cm2·s-1 for packed beds of JSC-1A with porosities of 0.388, 0.385, and 0.365, respectively. The experimental measurements, methodology, and modeling provide useful information for ISRU technologies involving the transport of volatiles (e.g., thermal extraction of H2O).
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ItemThermal Evolution of Water and Hydrogen from Apollo Lunar Regolith - Data Files(Georgia Institute of Technology, 2021) Jones, Brant M. ; Aleksandrov, Aleksandr ; Hibbitts, Charles ; Orlando, Thomas M.The evolution of water and molecular hydrogen from Apollo lunar sample 15221, a mature mare soil, was examined by temperature program desorption (TPD) experiments conducted under ultra-high vacuum conditions. Desorption at the grain/vacuum interface with re-adsorption as water transports though the void space of the grains and activated sub-surface diffusion were found to reproduce the experimental TPD signal. Signal from the grain/vacuum interface yielded the second order desorption activation energies and site probability distributions. Water from sample 15221 exhibited a broad distribution of activation energies peaking at 130 kJ mol-1 extending up to 350 kJ mol-1 at zero coverage limit with an onset of 110 kJ mol-1 at full coverage. Our results suggest that water and hydrogen originating from lunar regolith contributes a minor amount to the observed mass in the LCROSS impact event. The abnormal amount of molecular hydrogen observed in the ejecta plume of the LCROSS impact may indicate that the radiolytic production of H2 from electron and galatic cosmic rays of physisorbed water is a contributor to the vast quantity of molecular hydrogen detected.
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ItemPhoton Stimulated Desorption of MgS as a Potential Source of Sulfur in Mercury’s Exosphere - Data Files(Georgia Institute of Technology, 2020-06-14) Schaible, Micah J. ; Sarantos, Menelaos ; Anzures, Brendan A. ; Parman, Stephen W. ; Orlando, Thomas M.Mercury has a relatively high sulfur content on its surface, and a signal consistent with S+ was observed by the fast ion plasma spectrometer (FIPS) instrument on the MESSENGER spacecraft. To help confirm this assignment and to better constrain the sources of exospheric sulfur at Mercury, 193 nm photon stimulated desorption (PSD) of neutral sulfur atoms (S0) from MgS substrates was studied using resonance enhanced multiphoton ionization (REMPI) and time-of-flight (TOF) mass spectrometry. Though the PSD process is inherently non-thermal, the measured velocity distributions were fit using flux weighted Maxwellian distributions with translation energies ˂E> expressed as translational “temperatures” Tt = ˂E>/µkB. A bi-modal distribution consisting of both thermal (Tt = 300 K) and supra-thermal (Tt >1000 K) components in roughly a 2:1 ratio was found to best fit the data. The experimental PSD cross-section, ~4×10-22 cm2, and integrated velocity distributions were used to calculate the PSD source rate of S0 into the exosphere of Mercury. Exosphere simulations using the calculated rates demonstrate that PSD is likely a primary source to S0 in Mercury’s exosphere at low (<1000 km) altitudes.
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ItemLow-Energy Electron Interactions with Complex Biomolecules and Carcinogenesis(Georgia Institute of Technology, 2020-01-14) Orlando, Thomas M.
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ItemA New In Situ Quasi-continuous Solar-wind Source of Molecular Water on Mercury - Data Files(Georgia Institute of Technology, 2020) Jones, Brant M. ; Sarantos, Menelaos ; Orlando, Thomas M.Radar observations of Mercury and the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) spacecraft data indicate the probable existence of water ice in the permanently shadowed polar regions. Generally, water is accepted to be of exogenous origin through delivery via comets and meteoritic impact. However, a continuous water formation process that involves thermal transformation of chemically stable mineral-bound hydroxyl groups produced by implanted solar wind protons is readily available on the surface of Mercury. At typical temperatures prevailing on Mercury’s dayside surface, H2O can be produced from reactions involving OH groups on or within the H-saturated regolith grain interfaces. Similar reactions will also occur due to micrometeorite impact events on both the day and nightside. Once produced, H2O is released into the exosphere and then transported and processed via Jeans escape, photodissociation, dissociative adsorption, or condensation. Water reaching cold traps will be bound over geological periods. This simple water cycle will produce a highly chemically reduced surface and can contribute significant amounts of H2O over geological time periods. The overall process is an important but hitherto unnoticed source term that will contribute to the accumulation of water in the permanently shadowed regions of Mercury.
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ItemEfficient Intermolecular Energy Exchange and Soft Ionization of Water at Nanoplatelet Interfaces - Data Files(Georgia Institute of Technology, 2020) Jones, Brant M. ; Hu, Hang ; Alexsandrov, Alexandr ; Smith, William ; Clark, Aurora E. ; Li, Xiaosong ; Orlando, Thomas M.X-ray, energetic photon and electron irradiation can ionize and electronically excite target atoms and molecules. These excitations undergo complicated relaxation and energy transfer processes that ultimately determine the manifold of system responses to the deposited excess energy. In weakly bound gas- and solution-phase samples, intermolecular Coulomb decay (ICD) and electron-transfer mediated decay (ETMD) can occur with neighboring atoms or molecules leading to efficient transfer of the excess energy to the surroundings. In ionic solids such as metal-oxides, intra- and inter-atomic Auger decay produces localized final states that lead to lattice damage and typically removal of cations from the substrate. The relative importance of Auger stimulated damage (ASD) versus ICD and ETMD in micro-solvated nanoparticle interfaces is not known. Though ASD is generally expected, essentially no lattice damage resulting from ionization and electronic excitation of micro-solvated boehmite (AlOOH) nanoplatelets has been observed. Efficient energy transfer and soft ionization of interfacial molecules is likely a general phenomenon at gas-oxyhydroxide nanoparticle interfaces where the density of states of the ionized chemisorbed species significantly overlap the core hole states of the solid.
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ItemAdvection Diffusion Model for Gas Transport Within a Packed Bed of JSC-1A Regolith Simulant - Data File(Georgia Institute of Technology, 2020) Schieber, Garrett L. ; Jones, Brant M. ; Orlando, Thomas M. ; Loutzenhiser, Peter G.The advection diffusion model was evaluated for gas transport within a packed bed of lunar JSC-1A regolith simulant at low to medium total pressures over three flow regimes: (1) the slip flow regime (2) the transition regime and (3) the Knudsen regime. These regimes are pertinent to the design of H2O extraction devices for in-situ resource utilization, sampling missions, and surface science. Experimentation was conducted over a range of average pressures of 100 to 25,000 Pa, corresponding to Knudsen numbers between 0.01 and 100 at ambient temperature with Ar and N2. Non-condensing, gases with ideal behavior were evaluated to isolate key flow properties as first step towards evaluating more complex H2O flows. Experimental results were coupled to physical models, and key properties were evaluated to assess the model fit. The experimental results in the transition regime followed the expected behavior based on similar works for microchannel flow and showed that advection is not negligible for transition regime flows. The advection diffusion model in the transition regime fit the results for Knudsen numbers less than unity, and showed the need to further develop gas slip models for Knudsen numbers greater than unity. Key parameters necessary to define were the porosity, tortuosity, pore diameter of the regolith medium, and the gas slip parameter was key in determining the gas-specific transport rate.