A5051957688- Planetary Science and Exploration
- Astro and Planetary Science
- Space Exploration and Technology
- Geology and Paleoclimatology Research
- Methane Hydrates and Related Phenomena
- Spacecraft and Cryogenic Technologies
- Cryospheric studies and observations
- Isotope Analysis in Ecology
- Space Science and Extraterrestrial Life
- Scientific Research and Discoveries
- Stellar, planetary, and galactic studies
- Climate change and permafrost
- Climate variability and models
- Arctic and Antarctic ice dynamics
- Meteorological Phenomena and Simulations
- Spaceflight effects on biology
- Astronomy and Astrophysical Research
- Fluid Dynamics and Turbulent Flows
- Gas Dynamics and Kinetic Theory
- Karst Systems and Hydrogeology
- Hydrocarbon exploration and reservoir analysis
- Spacecraft Design and Technology
- Geological Modeling and Analysis
- Hydrology and Sediment Transport Processes
- Astrophysics and Star Formation Studies
Planetary Science Institute
2016-2024
University of Hawaiʻi at Mānoa
2014-2023
Monterey Institute for Research in Astronomy
2005-2019
University of Hawaii System
2009-2018
NASA Astrobiology Institute
2005-2016
California Institute of Technology
2002-2007
Massachusetts Institute of Technology
2000-2004
Chinese University of Hong Kong
2000-2001
University of Chicago
1995-2000
South University
1999
The surface elemental composition of dwarf planet Ceres constrains its regolith ice content, aqueous alteration processes, and interior evolution. Using nuclear spectroscopy data acquired by NASA's Dawn mission, we determined the concentrations hydrogen, iron, potassium on Ceres. show that materials were processed action water within interior. non-icy portion Ceres' carbon-bearing contains similar amounts hydrogen to those present in aqueously altered carbonaceous chondrites; however,...
We seek a better understanding of the distribution subsurface ice on Mars, based physical processes governing exchange vapor between atmosphere and subsurface. Ground is expected down to ∼49° latitude lower latitudes at poleward facing slopes. The diffusivity regolith also leads seasonal accumulation atmospherically derived frost ∼30°. burial depths zonally averaged boundaries observed from neutron emission are consistent with model predictions for ground in equilibrium abundance atmospheric...
We theoretically estimate the loss rate of buried ice from spherical bodies 2-3.3 AU Sun. The is explored as a function about dozen parameters. introduce concept "buried snow line," where sufficiently slow over age solar system. For dusty surface layer, can persist within top few meters billions years, if mean temperature less than 145 K. Variations in layer properties plausible range are unlikely to change this threshold by more 10 Longevity shallow subsurface asteroid 7968 Elst-Pizarro...
Abstract The Diviner Lunar Radiometer Experiment on the Reconnaissance Orbiter has been acquiring visible and infrared radiance measurements of Moon for nearly 10 years. These data have compiled into polar stereographic maps temperatures poleward 80° latitude at fixed local times subsolar longitudes to provide an overview diurnal regions. divided winter summer seasons, defined by year when is above or below equator, characterize variations in seasonal that result from 1.54° angle between...
Analysis of Dawn spacecraft Framing Camera image data allows evaluation the topography and geomorphology features on surface Ceres. The dwarf planet is dominated by numerous craters, but other are also common. Linear structures include both those associated with impact craters that do not appear to have any correlation an event. Abundant lobate flows identified, domical found at a range scales. Features suggestive near-surface ice, cryomagmatism, cryovolcanism been identified. Although...
High‐latitude ground ice on Mars discovered by the Gamma Ray Spectrometer suite is thought to be thermally stable owing presence of vapor in Martian atmosphere. However, local slopes can alter surface and subsurface temperatures substantially, hence allow persist at locations where it would otherwise unstable. Global statistics topography are computed, processed, extrapolated derive a description roughness spatial scales which should sensitive. This slope distribution convolved with new...
Permanently shaded areas near the poles of Moon and Mercury may harbor water ice. We develop a physical model for migration molecules in regolith discover two pathways that can lead to accumulation H 2 O subsurface. A small fraction delivered, either continuously or abruptly, permanently cold diffuses into remain there longer than on surface. Higher temperatures deeper burial. At constant temperature, this diffusive produces less one molecular layer volatile grains, because it is driven by...
The diffusion coefficient of water vapor in unconsolidated porous media is measured for various soil simulants at Mars‐like pressures and subzero temperatures. An experimental chamber which simultaneously reproduces a low‐pressure, low‐temperature, low‐humidity environment used to monitor flux from an ice source through barrier. Experiments are performed on four types simulants: 40–70 μ m glass beads, sintered filter disks, 1–3 dust (both loose packed), JSC Mars–1. A theoretical framework...
Abstract Ceres has only a small spin axis tilt (4°), and craters near its rotational poles can experience permanent shadow trap volatiles, as is the case on Mercury Earth's Moon. Topography derived from stereo imaging by Dawn spacecraft used to calculate direct solar irradiance that defines extent of permanently shadowed regions (PSRs). In northern polar region, PSRs cover ∼1800 km 2 or 0.13% hemisphere, most are cold enough water ice over geological time periods. Based modeling exosphere,...
The Mars Orbiter Camera (MOC) has imaged, sometimes repeatedly, mass movements known as slope streaks, which are abundant in the dust‐covered regions on Mars. They among few examples of contemporary surface changes. A survey 173 collocated image pairs indicates that these features currently forming at a high rate ∼7% per existing streak, Martian year. Either there is complete turnover within decades or streak population increasing rapidly. Large spatial, well possible temporal, variations...
Measurements acquired by the Mars Orbiter Laser Altimeter on board Global Surveyor indicate that large drainage systems have geomorphic characteristics inconsistent with prolonged erosion surface runoff. We find topography has not evolved to an expected equilibrium terrain form, even in areas where runoff incision been previously interpreted. By analogy terrestrial examples, groundwater sapping may played important role incision. Longitudinally flat floor segments provide a direct indication...
In a series of laboratory experiments, we measure thermal diffusivity, conductivity, and heat capacity icy regolith created by vapor deposition water below its triple point in low pressure atmosphere. We find that an ice‐regolith mixture prepared this manner, which may be common on Mars, potentially also present the Moon, Mercury, comets other bodies, has conductivity increases approximately linearly with ice content. This trend differs substantially from property models based preferential...
It has long been suggested that water ice can exist in extremely cold regions near the lunar poles, where sublimation loss is negligible. The geographic distribution of H-bearing regolith shows only a partial or ambiguous correlation with permanently shadowed areas, thus suggesting another mechanism may contribute to locally enhancing concentrations. We show under suitable conditions, molecules be pumped down into by day–night temperature cycles, leading an enrichment H2O excess surface...