The Experts below are selected from a list of 360 Experts worldwide ranked by ideXlab platform

Joel Martinez-frias - One of the best experts on this subject based on the ideXlab platform.

Oded Aharonson - One of the best experts on this subject based on the ideXlab platform.

  • diffusion barriers at Mars Surface conditions salt crusts particle size mixtures and dust
    Journal of Geophysical Research, 2008
    Co-Authors: T L Hudson, Oded Aharonson
    Abstract:

    The diffusion coefficient of water vapor through porous media at Mars-like Surface conditions is measured for a variety of complex particle size distributions and soil compositions. Micron-sized dust simulants, mixtures of sand- and dust- sized particles, and salt- encrusted sand are examined. We find that while the value of the diffusion coefficient, D, can be reduced by up to a factor of 10 for heavily salt- encrusted soils (minimum observed D = 0.4 ± 0.04 cm^2 s^-1), moderate amounts of salt only produce minor reductions in D. Mechanical packing of pure dust can lower D by a similar amount, while mixtures of dust with sand- sized particles produce at most a factor of ~4 reduction. We conclude that present- day processes of aeolian redistribution, moderate levels of salt encrustation, and volatile loss from dirty ice would be inefficient at producing soil deposits and lags on Mars that pose significant barriers to diffusion. Therefore, subSurface ice deposits that are thermally unstable would not be protected against sublimative loss by such materials.

G. M. Muñoz Caro - One of the best experts on this subject based on the ideXlab platform.

Tijs Karman - One of the best experts on this subject based on the ideXlab platform.

  • measurements and semi empirical calculations of co2 ch4 and co2 h2 collision induced absorption across a wide range of wavelengths and temperatures application for the prediction of early Mars Surface temperature
    Icarus, 2020
    Co-Authors: Martin Turbet, C Boulet, Tijs Karman
    Abstract:

    Abstract Reducing atmospheres have recently emerged as a promising scenario to warm the Surface of early Mars enough to drive the formation of valley networks and other ancient aqueous features that have been detected so far on the Surface of Mars. Here we present a series of experiments and calculations to better constrain CO2 + CH4 and CO2 + H2 collision-induced absorptions (CIAs) as well as their effect on the prediction of early Mars Surface temperature. First, we carried out a new set of experimental measurements (using the AILES line of the SOLEIL synchrotron) of both CO2 + CH4 and CO2 + H2 CIAs. These measurements confirm the previous results of Turbet et al. (2019), Icarus vol. 321, while significantly reducing the experimental uncertainties. Secondly, we fitted a semi-empirical model to these CIAs measurements, allowing us to compute the CO2 + CH4 and CO2 + H2 CIAs across a broad spectral domain (0–1500 cm−1) and for a wide range of temperatures (100–600 K). Last, we performed 1-D numerical radiative-convective climate calculations (using the LMD Generic Model) to compute the Surface temperature expected on the Surface of early Mars for several CO2, CH4 and H2 atmospheric contents, taking into account the radiative effect of these revised CIAs. These calculations demonstrate that thick CO2 + H2-dominated atmospheres remain a viable solution for warming the Surface of Mars above the melting point of water, but not CO2 + CH4-dominated atmospheres. Our calculated CO2 + CH4 and CO2 + H2 CIA spectra and predicted early Mars Surface temperatures are provided to the community for future uses.

Mason, Lee S. - One of the best experts on this subject based on the ideXlab platform.

  • Comparison of Energy Conversion Technologies for Space Nuclear Power Systems
    2019
    Co-Authors: Mason, Lee S.
    Abstract:

    A key element of space nuclear power systems is the energy conversion subsystem that converts the nuclear heat into electrical power. Nuclear systems provide a favorable option for missions that require long-duration power in hostile space environments where sunlight for solar power is absent or limited. There are two primary nuclear power technology options: (1) radioisotope power systems (RPSs) utilize the natural decay heat from 238Pu to generate electric power levels up to about 1 kW and (2) fission power systems (FPSs) rely on a sustained fission reaction of 235U and offer the potential to supply electric power from kilowatts to megawatts. Example missions utilizing nuclear power include Mars science rovers (e.g., Curiosity, Mars 2020), lunar and Mars Surface landers, crewed Surface outposts, deep space planetary orbiters, Ocean World science landers, and robotic space probes that utilize nuclear electric propulsion. This report examines the energy conversion technology options that can be used with RPSs and FPSs, and provides an assessment of their relative performance

  • A Comparison of Energy Conversion Technologies for Space Nuclear Power Systems
    2018
    Co-Authors: Mason, Lee S.
    Abstract:

    A key element of space nuclear power systems is the energy conversion subsystem that converts the nuclear heat into electrical power. Nuclear systems provide a favorable option for missions that require long-duration power in hostile space environments where sunlight for solar power is absent or limited. There are two primary nuclear power technology options. Radioisotope Power System (RPS) utilize the natural decay heat from Pu238 to generate electric power levels up to about one kilowatt. Fission Power System (FPS) rely on a sustained fission reaction of U235 and offer the potential to supply electric power from kilowatts to megawatts. Example missions for nuclear power include Mars science rovers (e.g. Curiosity, Mars 2020), lunar and Mars Surface landers ? including crewed missions, deep space planetary orbiters, Ocean World science landers, and robotic space probes that utilize nuclear electric propulsion. This paper examines the energy conversion technology options that can be used with RPS and FPS, and provides an assessment of their relative performance and technology readiness