A5040699602- Planetary Science and Exploration
- Astro and Planetary Science
- Space Exploration and Technology
- Geology and Paleoclimatology Research
- Space Satellite Systems and Control
- Geophysics and Gravity Measurements
- Space Science and Extraterrestrial Life
- Radio Astronomy Observations and Technology
- Space exploration and regulation
- Gamma-ray bursts and supernovae
- GNSS positioning and interference
- Ionosphere and magnetosphere dynamics
- Geomagnetism and Paleomagnetism Studies
- Astronomical Observations and Instrumentation
- Astronomy and Astrophysical Research
- Astrophysics and Cosmic Phenomena
- Spacecraft Design and Technology
- Spaceflight effects on biology
- Solar and Space Plasma Dynamics
- earthquake and tectonic studies
- Peripheral Artery Disease Management
- Isotope Analysis in Ecology
- Stellar, planetary, and galactic studies
- Spacecraft Dynamics and Control
- Scientific Research and Discoveries
Yale University
2012-2024
Jet Propulsion Laboratory
2008-2021
California Institute of Technology
1989-2021
California Library Association
2021
Yale New Haven Hospital
2016
Cornell University
2007
University of California, Santa Barbara
2007
Space Research Institute
2007
Qinetiq (United Kingdom)
2001
Advanced Science Research Center
2000
Observations of radar speckle patterns tied to the rotation Mercury establish that planet occupies a Cassini state with obliquity 2.11 +/- 0.1 arc minutes. The measurements show exhibits librations in longitude are forced at 88-day orbital period, as predicted by theory. large amplitude oscillations, 35.8 2 seconds, together Mariner 10 determination gravitational harmonic coefficient C22, indicates mantle is decoupled from core least partially molten.
The first unambiguous full-disk radar mapping of Mercury at 3.5-centimeter wavelength, with the Goldstone 70-meter antenna transmitting and 26 antennas Very Large Array receiving, has provided evidence for presence polar ice. experiments, conducted on 8 23 August 1991, were designed to image half not photographed by Mariner 10. orbital geometry allowed viewing beyond north pole Mercury; a highly reflective region was clearly visible during both experiments. This areas in which circular...
Radar images of near-Earth asteroid 2000 DP107 show that it is composed an ∼800-meter-diameter primary and ∼300-meter-diameter secondary revolving around their common center mass. The orbital period 1.755 ± 0.007 days semimajor axis 2620 160 meters constrain the total mass system to 4.6 0.5 × 10 11 kilograms bulk density 1.7 1.1 grams per cubic centimeter. This other binary asteroids have spheroidal primaries spinning near breakup point for strengthless bodies, suggesting binaries formed by...
The first full‐disk radar images of Mercury were obtained on August 8 and 23, 1991. These constructed using the Very Large Array (VLA) in Socorro, New Mexico, to receive map flux at 3.5 cm ( X band) which was continuously transmitted from 70‐m Jet Propulsion Laboratory/Deep Space Network antenna Goldstone, California. Approximately 77% surface imaged, resolutions as good 150 km. About half hemisphere photographed by Mariner 10 well most has not previously been photographed. At time...
A random-code technique has been used at Arecibo to obtain delay-Doppler radar images of the full disk Mercury. Anomalously bright features were found north and south poles. The polar feature is oblong (4° by 8°) offset from pole. smaller mostly confined floor crater Chao Meng-Fu. locations properties these indicate that they may be produced volume scattering in ice. also reveal a variety more subdued reflectivity ranging size hundreds thousands kilometers; some appear have an impact origin.
An analysis of six years lunar-laser-ranging data gives a zero amplitude for the Nordtvedt term in Earth-Moon distance yielding parameter $\ensuremath{\eta}=0.00\ifmmode\pm\else\textpm\fi{}0.03$ Thus, Earth's gravitational self-energy contributes equally, \ifmmode\pm\else\textpm\fi{}3%, to its inertial mass and passive mass. At 70% confidence level this result is only consistent with Brans-Dicke theory $\ensuremath{\omega}>29$. We obtain...
Detailed topographic maps of the lunar poles have been obtained by Earth-based radar interferometry with 3.5-centimeter wavelength Goldstone Solar System Radar. The interferometer provided 300 kilometers 1000 both polar regions at 150-meter spatial resolution and 50-meter height resolution. Using ray tracing, these digital elevation models were used to locate that are in permanent shadow from solar illumination may harbor ice deposits. Estimates total extent shadowed areas poleward 87.5...
Full disk images of Mars have been obtained with the use Very Large Array (VLA) to map radar reflected flux density. The transmitter system was 70-m antenna Deep Space Network at Goldstone, California. surface illuminated continuous wave radiation a wavelength 3,5 cm. energy mapped in individual 12-minute snapshots VLA its largest configuration; fringe spacings as small 67 km were obtained. reveal near-surface features including region Tharsis volcano area, over 2000 east-west extent, that...
The present understanding of the atmosphere and surface conditions on Saturn's largest moon, Titan, including stability methane, an application thermodynamics leads to a strong prediction liquid hydrocarbons in ethane-methane mixture surface. Such would have nearly unique microwave reflection properties due low dielectric constant. Attempts were made obtain reflections at wavelength 3.5 centimeters by means 70-meter antenna California as transmitter Very Large Array New Mexico receiving...
Delay-Doppler images of the Earth-crossing asteroid 4179 Toutatis achieve resolutions as fine 125 nanoseconds (19 meters in range) and 8.3 millihertz (0.15 millimeter per second radial velocity) place hundreds to thousands pixels on asteroid, which appears be several kilometers long, topographically bifurcated, heavily cratered. The image sequence reveals an extremely slow, non-principal axis rotation state.
Mars radar imaging results from Arecibo 12.6‐cm observations are presented. The images were derived delay‐Doppler mapping using a coded‐long‐pulse technique to mitigate the effects of echo overspreading. Images depolarized used identify regions high decimeter‐scale roughness. Some strongest features located on major shield volcanoes or relatively young off‐shield flows such as Olympus and Pavonis lava aprons. shields themselves have highly irregular signatures suggesting complex volcanic...
Observations of near-Earth asteroid 1998 KY26 shortly after its discovery reveal a slightly elongated spheroid with diameter about 30 meters, composition analogous to carbonaceous chondritic meteorites, and rotation period 10.7 minutes, which is an order magnitude shorter than that measured for any other solar system object. The too rapid consist multiple components bound together just by their mutual gravitational attraction. This monolithic object probably fragment derived from cratering...
Radar observations of comet Hyakutake (C/1996 B2) made at the Goldstone Deep Space Communications Complex in California have detected echoes from nucleus and large grains inner coma. The this bright was estimated to be only 2 3 kilometers diameter. Models coma echo indicate backscatter porous, centimeter-size ejected anisotropically velocities tens meters per second. radar suggest that a comet's activity may poor indicator its size provide evidence constitute an important component mass loss...
The Venus radius of 6085 +/- 10 kilometers, deduced from combining observations made with the Venera 4 and Mariner V space probes is incompatible value 6050 kilometers determined Earth-based radar mesurements.