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- All Subjects: astrobiology
- All Subjects: Mars
- Creators: School of Earth and Space Exploration
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
Relatively small amounts of H2O frost (~ 10–100 μm) are also likely to form diurnally and seasonally. The global H2O frost point distribution follows water vapor column abundance closely, with a weak correlation with local surface pressure. There is a strong hemispherical dependence on the frost point temperature—with the northern hemisphere having a higher frost point (in general) than the southern hemisphere—likely due to elevation differences. Unlike the distribution of CO2 frost temperatures, there is little to no correlation with surface thermophysical properties (thermal inertia, albedo, etc.). Modeling suggests H2O frosts can briefly attain melting point temperatures for a few hours if present under thin layers of dust, and can perhaps play a role in present-day equatorial mass-wasting events (eg. McEwen et al., 2018).
Based on seasonal constraints on gully activity timing, preliminary field studies, frost presence from visible imagery, spectral data and thermal data (this work), it is likely that most present-day activity can be explained by frosts (primarily CO2, and possibly H2O). We predict that the conditions necessary for significant present-day activity include formation of sufficient amounts of frost (> ~20 cm/year) within loose, unconsolidated sediments (I < ~ 350) on available slopes. However, whether or not present-day gully activity is representative of gully formation as a whole is still open to debate, and the details on CO2 frost-induced gully formation mechanisms remain unresolved.
The Star Planet Activity Research CubeSat (SPARCS) will be a 6U CubeSat devoted to photometric monitoring of M dwarfs in the far-ultraviolet (FUV) and near-ultraviolet (NUV) (160 and 280 nm respectively), measuring the time-dependent spectral slope, intensity and evolution of M dwarf stellar UV radiation. The delta-doped detectors baselined for SPARCS have demonstrated more than five times the in-band quantum efficiency of the detectors of GALEX. Given that red:UV photon emission from cool, low-mass stars can be million:one, UV observation of thes stars are susceptible to red light contamination. In addition to the high efficiency delta-doped detectors, SPARCS will include red-rejection filters to help minimize red leak. Even so, careful red-rejection and photometric calibration is needed. As was done for GALEX, white dwarfs are used for photometric calibration in the UV. We find that the use of white dwarfs to calibrate the observations of red stars leads to significant errors in the reported flux, due to the differences in white dwarf and red dwarf spectra. Here we discuss the planned SPARCS calibration model and the color correction, and demonstrate the importance of this correction when recording UV measurements of M stars taken by SPARCS.
Assembly theory as a way of defining the biotic/abiotic boundary has been established for molecules, but not yet for crystal structures. This is an assembly algorithm that calculates the complexity of biotic and abiotic minerals in order to constrain the quantitative fundamentals of "life". The calculation utilizes the Hermann-Mauguin space group symmetry and Wyckoff sites of mineral unit cells to calculate the path-building complexity of a crystal structure. 5,644 minerals from the American Mineralogist COD database were run through the algorithm. The five structures with the highest information complexity were a mix of biotic and abiotic minerals, indicating that further calculations on larger datasets would be pertinent. Furthermore, an expansion of the definition of mineral to include biotically synthesized solids would further research efforts aimed at using minerals as possible biomarkers.
During the Dawn mission, bright spots were discovered on the surface of the dwarf planet Ceres, which were determined to be evaporite deposits of sodium carbonate, ammonium carbonate, and hydrohalite. These deposits are significant because they indicate the presence of subsurface water and potential geologic activity on Ceres. These evaporites form from the brine-water mixture in the deep Ceres reservoir, which likely possesses the conditions ideal for forming complex organics. Here, we report the results of a suite of laboratory techniques (CHN Elemental Analyzer, Secondary Ion Mass Spectrometry, Fourier-Transform Infrared Spectroscopy, Gas Chromatography, and Brunauer-Emmett-Teller Analysis) for quantifying the likelihood of primordial carbon survival and distribution in analog materials found on Ceres, particularly in salt evaporates. We are specifically looking at if the amino acid glycine can be preserved in sodium chloride crystals. Our results conclude that if the Ceres brine reservoir is saturated with organics, and with the lower limits that we have for our instrumentation thus far, these techniques should be more than sufficient to measure glycine content should we ever receive samples from Ceres.
This method of using NGIMS data as a validation tool for MGITM simulations has been tested previously using dayside data from deep dip campaigns 2 and 8. In those cases, MGITM was able to accurately reproduce the measured density and temperature profiles; however, in the deep dip 5 and 6 campaigns, the results are not quite the same, due to the highly variable nature of the nightside thermosphere. MGITM was able to fairly accurately reproduce the density and temperature profiles for deep dip 5, but the deep dip 6 model output showed unexpected significant variation. The deep dip 6 results reveal possible changes to be made to MGITM to more accurately reflect the observed structure of the nighttime thermosphere. In particular, upgrading the model to incorporate a suitable gravity wave parameterization should better capture the role of global winds in maintaining the nighttime thermospheric structure.
This project reveals that there still exist many unknowns about the structure and dynamics of the night side of the Martian atmosphere, as well as significant diurnal variations in density. Further study is needed to uncover these unknowns and their role in atmospheric mass loss.