Matching Items (4)
- All Subjects: Mars
- Creators: School of Earth and Space Exploration
- Member of: Barrett, The Honors College Thesis/Creative Project Collection
A wide range of types of activity in mid-latitude Martian gullies has been observed over the last decade (Malin et al., 2006; Harrison et al., 2009, 2015; Diniega et al., 2010; Dundas et al., 2010, 2012, 2015, 2017) with some activity constrained temporally to occur in the coldest times of year (winter and spring; Harrison et al., 2009; Diniega et al., 2010; Dundas et al., 2010, 2012, 2015, 2017), suggesting that surficial frosts that form seasonally and diurnally might play a key role in this present-day activity. Frost formation is highly dependent on two key factors: (1) surface temperature and (2) the atmospheric partial pressure of the condensable gas (Kieffer, 1968). The Martian atmosphere is primarily composed of CO2and CO2 frost formation is not diffusion-limited (unlike H2O). Hence, for temperatures less than the local frost point of CO2, (~ 148 K at a surface pressure of 610 Pa) frost is always present (Piqueux et al., 2016). Typically, these frosts are dominated volumetrically by CO2, although small amounts of H2O frosts are also present, and typically precede CO2 frost deposition (due to water’s higher condensation temperature (Schorghofer and Edgett, 2006)). Here we use the Thermal Emission Imaging System (THEMIS) and the Thermal Emission Spectrometer (TES) onboard Mars Odyssey and Mars Global Surveyor, respectively, to explore the global spatial and temporal variation of temperatures conducive to CO2 and H2O frost formation on Mars, and assess their distribution with gully landforms. CO2 frost temperatures are observed at all latitudes and are strongly correlated with dusty, low thermal inertia regions near the equator. Modeling results suggest that frost formation is restricted to the surface due to near-surface radiative effects. About 49 % of all gullies lie within THEMIS frost framelets. In terms of active gullies, 54 % of active gullies lie within THEMIS framelets, with 14.3% in the north and 54% in the south.
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.
This paper addresses many of the problems that will be encountered when travelling to Mars and discusses the possibility of different solutions. Protection from radiation, oxygen production, and water sources are some of the major problems and the solution to these problems are vital for the success of future space travel. By utilizing technology that has already been used in space travel and implementing the use of technology that is successful on Earth, humans will be able to live on Mars successfully.
Characterizing Diurnal Density and Temperature Variations in the Martian Atmosphere Using Data/Model Comparisons
This project focuses on using Neutral Gas and Ion Mass Spectrometer (NGIMS) density data for carbon dioxide, oxygen, carbon monoxide, and nitrogen during deep dip campaigns 5, 6, and 8. Density profiles obtained from NGIMS were plotted against simulated density profiles from the Mars Global Ionosphere-Thermosphere Model (MGITM). Averaged temperature profiles were also plotted for the three deep dip campaigns, using NGIMS data and MGITM output. MGITM was also used as a tool to uncover potential heat balance terms needed to reproduce the mean density and temperature profiles measured by NGIMS.
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.
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.