A5024636188- Astro and Planetary Science
- Planetary Science and Exploration
- Geology and Paleoclimatology Research
- Space Exploration and Technology
- Stellar, planetary, and galactic studies
- Geomagnetism and Paleomagnetism Studies
- Isotope Analysis in Ecology
- Astrophysics and Star Formation Studies
- Gamma-ray bursts and supernovae
- earthquake and tectonic studies
- Spacecraft and Cryogenic Technologies
- Space Satellite Systems and Control
- Geological and Geochemical Analysis
- Maritime and Coastal Archaeology
- Solar and Space Plasma Dynamics
- Methane Hydrates and Related Phenomena
- Atmospheric Ozone and Climate
- Marine and environmental studies
- Archaeology and ancient environmental studies
- Atmospheric aerosols and clouds
- Astronomical Observations and Instrumentation
- Scientific Research and Discoveries
- Atmospheric and Environmental Gas Dynamics
- Aeolian processes and effects
- Geochemistry and Geologic Mapping
Cornell University
2012-2022
Planetary Science Institute
1994-2021
University of Virginia
2007
Wellesley College
2007
Search for Extraterrestrial Intelligence
2007
Jet Propulsion Laboratory
1994-2006
Space Science Institute
2005-2006
California Institute of Technology
2006
Massachusetts Institute of Technology
2006
Goddard Institute for Space Studies
2005
Cassini has identified a geologically active province at the south pole of Saturn's moon Enceladus. In images acquired by Imaging Science Subsystem (ISS), this region is circumscribed chain folded ridges and troughs approximately 55 degrees S latitude. The terrain southward boundary distinguished its albedo color contrasts, elevated temperatures, extreme geologic youth, narrow tectonic rifts that exhibit coarse-grained ice coincide with hottest temperatures measured in region. Jets fine icy...
The Cassini Imaging Science Subsystem acquired about 26,000 images of the Jupiter system as spacecraft encountered giant planet en route to Saturn. We report findings on Jupiter's zonal winds, convective storms, low-latitude upper troposphere, polar stratosphere, and northern aurora. also describe previously unseen emissions arising from Io Europa in eclipse, a volcanic plume over Io's north pole, disk-resolved satellite Himalia, circumstantial evidence for causal relation between satellites...
It has been proposed that Jupiter's satellite Europa currently possesses a global subsurface ocean of liquid water. Galileo gravity data verify the is differentiated into an outer H 2 O layer about 100 km thick but cannot determine current physical state this (liquid or solid). Here we summarize geological evidence regarding extant ocean, concentrating on imaging data. We describe and assess nine pertinent lines evidence: impact morphologies, lenticulae, cryovolcanic features, pull‐apart...
Images acquired of Saturn's rings and small moons by the Cassini Imaging Science Subsystem (ISS) during first 9 months operations at Saturn have produced many new findings. These include saturnian moons; refined orbits previously known narrow diffuse in F-ring region embedded gaps within main rings; exceptionally fine-scale ring structure moderate- to high-optical depth regions; estimates for masses ring-region moons, as well particle properties division, derived from analysis linear density...
Galileo images of Gaspra reveal it to be an irregularly shaped object (19 by 12 11 kilometers) that appears have been created a catastrophic collisional disruption precursor parent body. The cratering age the surface is about 200 million years. Subtle albedo and color variations appear correlate with morphological features: Brighter materials are associated craters especially along crests ridges, stronger 1-micrometer absorption, may represent freshly excavated mafic materials; darker...
The Cassini Imaging Science Subsystem acquired high-resolution imaging data on the outer Saturnian moon, Phoebe, during Cassini's close flyby 11 June 2004 and Iapetus a 31 December 2004. Phoebe has heavily cratered ancient surface, shows evidence of ice near distinct layering different materials, mean density that is indicative an ice-rock mixture. Iapetus's dark leading side (Cassini Regio) ancient, terrain bisected by equatorial ridge system reaches 20 kilometers relief. Local albedo...
We conducted a test of the Hapke (1981, 1984, 1986, 2002) photometric model to determine what physical parameters could be confidently linked surface's behavior. The first author selected and measured bidirectional reflectance distribution functions 14 different samples in up three wavelengths using Bloomsburg University Goniometer Laboratory. A total 29 data files were obtained, each file containing more than 700 measurements from viewing geometries; phase angles varied 3° 130°. initially...
We have applied computer stereophotogrammetry to Apollo Lunar Surface Closeup Camera (ALSCC) pictures of the lunar surface construct first-ever digital topographic relief maps undisturbed soil over spatial scales from 85 μm 8.5 cm. Using elevation histograms, fractal analysis, and Hapke's photometric roughness model we show that 14 (Fra Mauro) Imbrium ejecta is rougher than average 11 (Mare Tranquilitatis) 12 (Oceanus Procellarum) mare surfaces at submillimeter decimeter size-scales. confirm...
The Cassini Imaging Science Subsystem (ISS) began observing Saturn in early February 2004. From analysis of cloud motions through October 2004, we report vertical wind shear Saturn's equatorial jet and a maximum speed â¼375 meters per second, value that differs from both Hubble Space Telescope Voyager values. We also particularly active narrow southern mid-latitude region which dark ovals are observed to merge with each other arise the eruptions large, bright storms. Bright storm correlated...
Galileo images of Gaspra make it possible for the first time to determine a main-belt asteroid's photometric properties accurately by providing surface-resolved coverage over wide range incidence and emission angles extending phase angle phases not observable from Earth. We combine Earth-based telescopic photometry 2° ≤ α 25° with whole-disk disk-resolved data at 33° 51° derive average global in terms Hapke's model. The microscopic texture particle phase-function behavior Gaspra's surface...
As one of the most geologically active bodies in solar system, Saturn's moon Enceladus not only coats itself with water ice particles, it accounts for unusually high albedos other satellites orbiting within vast, tenuous E ring. This effect is evident Hubble Space Telescope observations obtained at true opposition on 13 and 14 January 2005 that reveal mean geometric embedded ring approximate or exceed unity.
We test the hypotheses that lunar opposition effect is due to shadow-hiding, coherent backscatter, or some combination of two phenomena. Hapke's photometric model extended include975726description backscatter effect. The was fit simultaneously toV-filter (λ = 0.55 μm) whole-disk photometry Moon over many phase angles (2° ≤ α 143°) and disk-resolved observations surface a broad range incidence, emission, angles. shape Moon's surge accurately represented by narrow coherent-backscatter peak...