A5024412577- Planetary Science and Exploration
- Astro and Planetary Science
- Nuclear Physics and Applications
- Space Exploration and Technology
- Scientific Research and Discoveries
- Space Science and Extraterrestrial Life
- Isotope Analysis in Ecology
- Gamma-ray bursts and supernovae
- Spacecraft and Cryogenic Technologies
- Radiation Detection and Scintillator Technologies
- Spaceflight effects on biology
- Geochemistry and Geologic Mapping
- Astronomical Observations and Instrumentation
- Methane Hydrates and Related Phenomena
- Radioactivity and Radon Measurements
- Space exploration and regulation
- Astronomy and Astrophysical Research
- Geology and Paleoclimatology Research
- Radiation Therapy and Dosimetry
- Analytical Chemistry and Sensors
- Advanced X-ray and CT Imaging
- Atmospheric and Environmental Gas Dynamics
- Atomic and Subatomic Physics Research
- Solar and Space Plasma Dynamics
- Non-Destructive Testing Techniques
Goddard Space Flight Center
2010-2023
George Washington University
2005-2007
University of America
2000
Catholic University of America
2000
University of Arizona
2000
Johns Hopkins University Applied Physics Laboratory
2000
Max Planck Institute for Chemistry
2000
Hydrogen has been inferred to occur in enhanced concentrations within permanently shadowed regions and, hence, the coldest areas of lunar poles. The Lunar Crater Observation and Sensing Satellite (LCROSS) mission was designed detect hydrogen-bearing volatiles directly. Neutron flux measurements Moon's south polar region from Exploration Detector (LEND) on Reconnaissance Orbiter (LRO) spacecraft were used select optimal impact site for LCROSS. LEND data show several where epithermal neutron...
Results are presented for the LEND instrument onboard LRO detection of local spots suppression and excess epithermal neutron emission at lunar poles. Twelve Neutron Suppression Regions (NSRs) Excess (NERs) detected. It is shown using data from LOLA Diviner instruments that six NSRs have empirical property “ less irradiation lower temperature – fewer neutrons. ” These may be identified with water‐ice rich permafrost on Moon. detected include in both permanently shadowed illuminated areas,...
We report major element composition ratios for regions of the asteroid 433 Eros imaged during two solar flares and quiet sun conditions period May to July 2000. Low aluminum abundances all argue against global differentiation Eros. Magnesium/silicon, aluminum/silicon, calcium/silicon, iron/silicon are best interpreted as a relatively primitive, chondritic composition. Marked depletions in sulfur possible calcium depletions, relative ordinary chondrites, may represent signatures limited...
Abstract— We report major element ratios determined for the S‐class asteroid 433 Eros using remote‐sensing x‐ray fluorescence spectroscopy with near‐Earth rendezvous Shoemaker spectrometer (XRS). Data analysis techniques and systematic errors are described in detail. acquired during five solar flares two extended “quiet Sun” periods presented; these results sample a representative portion of asteroid's surface. Although uncertainties potentially large, most internally consistent plausible...
We use measurements from the Lunar Exploration Neutron Detector (LEND) collimated sensors during more than one year of mapping phase NASA's Reconnaissance Orbiter (LRO) mission to make estimates epithermal neutron flux within known large Permanently Shadowed Regions (PSRs). These are compared with local background measured outside PSRs in sunlit regions. Individual and collective analyses PSR properties have been performed. Only three PSRs, Shoemaker Cabeus south Rozhdestvensky U north,...
The data from the collimated sensors of LEND instrument are shown to be exceptionally high quality. Counting uncertainties about 0.3% relative and only significant source random error, thus conclusions based on small differences in count rates valid. By comparison with topography Shoemaker crater, spatial resolution is consistent design value 5 km for radius circle over which half counts lunar surface would determined. observed epithermal‐neutron suppression factor due hydrogen deposit...
Transverse aeolian ridges (TARs) are unusual bedforms on the surface of Mars. TARs common but sparse Mars; TAR fields small, rarely continuous, and scattered, making manual mapping impractical. There have been many efforts to automatically classify Martian surface, they never explicitly located successfully. Here, we present a simple adaptation off-the-shelf neural network RetinaNet that is designed identify presence at 50-m scale. Once trained, was able with high precision (92.9%). Our...
The Lunar Exploration Neutron Detector (LEND), on the polar-orbiting Reconnaissance Orbiter (LRO) spacecraft, has detected suppression in Moon's naturally-occurring epithermal neutron leakage flux that is consistent with presence of diurnally varying quantities hydrogen regolith near equator. Peak concentration (neutron suppression) dayside dawn terminator and diminishes through dawn-to-noon sector. minimum late afternoon dusk chemical form not determinable from these measurements, but other...
The extremely energetic ( approximately 10-4 ergs cm-2) gamma-ray burst (GRB) of 1999 December 8 was triangulated to an 14 arcmin2 error box 1.8 days after its arrival at Earth with the third interplanetary network (IPN), which consists Ulysses, Near-Earth Asteroid Rendezvous, and Wind spacecraft. Radio observations Very Large Array 2.7 revealed a bright fading counterpart whose position is consistent that optical transient source redshift 0.707. We present time history, peak flux, fluence,...
Abstract— The near‐Earth asteroid rendezvous (NEAR)‐Shoemaker remote‐sensing x‐ray/gamma‐ray spectrometer (XGRS) completed more than a year of operation in orbit and on the surface 433 Eros. Elemental compositions for number regions Eros have been derived from analyses characteristic x‐ray gamma‐ray emission spectra. NEAR XGRS detection system was included as part interplanetary network (IPN) localization bursts (GRBs). Preliminary results both elemental composition GRBs obtained. In...
Between 2000 November and 2006 May, one or more spacecraft of the interplanetary network (IPN) detected 226 cosmic gamma-ray bursts that were also by French Gamma-Ray Telescope experiment on board High Energy Transient Experiment 2 spacecraft. During this period, IPN consisted up to nine spacecraft, using triangulation, localizations 157 obtained. We present localization data these events.
The European Spallation Source, currently under construction in Lund, Sweden, is a multidisciplinary international laboratory. Once completed to full specifications, it will operate the world's most powerful pulsed neutron source. Supported by 3 million Euro Research and Innovation Action within EU Horizon 2020 program, design study (HighNESS) has been develop second source located below spallation target. Compared first source, designed for high cold thermal brightness, new optimized...
Abstract We present the results of a 2‐year‐long systematic campaign to monitor lunar dust exosphere for enhancements in concentration at altitudes <20 km both during and outside major meteor stream periods. utilize radiometric capabilities Lunar Orbiter Laser Altimeter Ranging telescope onboard Reconnaissance search forward‐scattered sunlight from exospheric grains, called horizon glow (LHG). Specifically, we test hypothesis that streams can produce LHG similar what was measured Apollo...
Abstract The Probing In situ with Neutron and Gamma ray (PING) instrument is an innovative application of active neutron‐induced gamma technology. objective PING to measure the elemental composition Martian regolith. This manuscript presents PING's sensitivities as a function regolith depth uncertainties in measurements observation time passive mode. modeled show that mode, where both pulsed neutron generator (PNG) spectrometer (GRS) are used, can interrogate material below rover about 20 cm...