A5090168178- Astro and Planetary Science
- Planetary Science and Exploration
- Stellar, planetary, and galactic studies
- Isotope Analysis in Ecology
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Geology and Paleoclimatology Research
- Gamma-ray bursts and supernovae
- Space Satellite Systems and Control
- Astrophysics and Star Formation Studies
- Gas Dynamics and Kinetic Theory
- Geological and Geochemical Analysis
- Geophysics and Gravity Measurements
- High-pressure geophysics and materials
- Geomagnetism and Paleomagnetism Studies
- Atmospheric Ozone and Climate
- Comparative and International Law Studies
- Rocket and propulsion systems research
- Space Exploration and Technology
- Laser-induced spectroscopy and plasma
- Astronomical Observations and Instrumentation
- Origins and Evolution of Life
- Nuclear Physics and Applications
- Health Promotion and Cardiovascular Prevention
- Spacecraft and Cryogenic Technologies
Search for Extraterrestrial Intelligence
2016-2025
Ames Research Center
2015-2025
Royal Netherlands Meteorological Institute
1995-2019
Queen Mary University of London
2015
University of Michigan
2013
National Aeronautics and Space Administration
1994
Leiden University
1994
Leiden Observatory
1994
Netherlands Institute for Radio Astronomy
1989
The asteroid impact near the Russian city of Chelyabinsk on 15 February 2013 was largest airburst Earth since 1908 Tunguska event, causing a natural disaster in an area with population exceeding one million. Because it occurred era modern consumer electronics, field sensors, and laboratory techniques, unprecedented measurements were made event meteoroid that caused it. Here, we document account what happened, as understood now, using comprehensive data obtained from astronomy, planetary...
The zodiacal cloud is a thick circumsolar disk of small debris particles produced by asteroid collisions and comets. Here, we present model based on the orbital properties lifetimes comets asteroids, dynamical evolution dust after ejection. quantitatively constrained IRAS observations thermal emission, but also qualitatively consistent with other observations. We find that 85-95% observed mid-infrared emission from Jupiter-family (JFCs) $<$10% long period Asteroidal found to be at $<$10%....
Selected area electron diffraction is used to monitor structural changes of vapor-deposited water ice in vacuum during warm-up from 15 188 K. A progression three amorphous forms found with well-defined transitions. The formation a high-density form (I h) at K confirmed, and the transition more familiar low-density l) occurs gradually over range 38 68 At 131 K, transforms into third r), which precedes crystallization cubic c ) coexists metastably I 148 until least These transformations can be...
Active asteroids are those that show evidence of ongoing mass loss. We report repeated instances particle ejection from the surface (101955) Bennu, demonstrating it is an active asteroid. The events were imaged by OSIRIS-REx (Origins, Spectral Interpretation, Resource Identification, and Security-Regolith Explorer) spacecraft. For three largest observed events, we estimated ejected velocities sizes, event times, source regions, energies. also determined trajectories photometric properties...
Electron diffraction studies of vapor-deposited water ice have characterized the dynamical structural changes during crystallization that affect volatile retention in cometary materials. Crystallization is found to occur by nucleation small domains, while leaving a significant part amorphous material slightly more relaxed state coexists metastably with cubic crystalline ice. The onset relaxation prior and coincides glass transition. Above transition temperature, kinetics are consistent solid...
Doppler weather radar imaging enabled the rapid recovery of Sutter's Mill meteorite after a rare 4-kiloton TNT-equivalent asteroid impact over foothills Sierra Nevada in northern California. The recovered meteorites survived record high-speed entry 28.6 kilometers per second from an orbit close to that Jupiter-family comets (Tisserand's parameter = 2.8 ± 0.3). is regolith breccia composed CM (Mighei)-type carbonaceous chondrite and highly reduced xenolithic materials. It exhibits...
view Abstract Citations (158) References (75) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS High-Density Amorphous Ice, the Frost on Interstellar Grains Jenniskens, P. ; Blake, D. F. Wilson, M. A. Pohorille, Most water ice in universe is a form which does not occur naturally Earth and of only minimal amounts have been made laboratory. We encountered this "high-density amorphous ice" electron diffraction experiments low-temperature (T < 30 K) vapor-deposited...
The solar system is dusty, and would become dustier over time as asteroids collide comets disintegrate, except that small debris particles in interplanetary space do not last long. They can be ejected from the by Jupiter, thermally destroyed near Sun, or physically disrupted collisions. Also, some are swept Earth (and other planets), producing meteors. Here we develop a dynamical model for meteoroids use it to explain meteor radar observations. We find Jupiter Family Comets (JFCs) main...
Vapor-deposited amorphous water ice, when warmed above the glass transition temperature (120–140 K), is a viscous liquid which exhibits viscosity vs relationship different from that of at room temperature. New studies thin ice films now demonstrate persists in range 140–210 K, where it coexists with cubic crystalline ice. The character demonstrated by (1) changes morphology on nonwetting surface observed transmission electron microscopy (TEM) around 175 K during slow warming, (2) binding...
Covers advancements in spacecraft and tactical strategic missile systems, including subsystem design application, mission analysis, materials structures, developments space sciences, processing manufacturing, operations, applications of technologies to other fields.
Abstract– We performed a battery of analyses on 17 samples the Almahata Sitta meteorite, identifying three main lithologies and several minor ones present as clasts. The are (1) pyroxene‐dominated, very porous, highly reduced lithology, (2) pyroxene‐dominated compact (3) an olivine‐dominated lithology. Although it seems possible that all grade smoothly into each other at kg‐scale, g‐scale this is not apparent. meteorite polymict ureilite, with some intriguing features including exceptionally...
The Quadrantid meteor shower in early January is our most intense annual shower. Until now, the parent was thought to have evolved away from observable part of an old, widely dispersed meteoroid stream. A few years ago, it found a small dispersion new set precisely reduced orbits that stream only about 500 old. It predicted still be among meteoroids. I now find originated 2003 EH1, minor planet discovered by LONEOS on March 6, currently passing 0.213 AU outside Earth orbit high-inclination,...
Covers advancements in spacecraft and tactical strategic missile systems, including subsystem design application, mission analysis, materials structures, developments space sciences, processing manufacturing, operations, applications of technologies to other fields.
Abstract– On October 7, 2008, asteroid 2008 TC 3 impacted Earth and fragmented at 37 km altitude above the Nubian Desert in northern Sudan. The area surrounding asteroid’s approach path was searched, resulting first recovery of meteorites from an observed space. This also remains a fragile “cometary” PE = IIIa/b type fireball. In subsequent searches, over 600 mostly small 0.2–379 g (named “Almahata Sitta”) with total mass 10.7 kg were recovered 30 × 7 area. Meteorites fell along track 1.3 −1...
Covers advancements in spacecraft and tactical strategic missile systems, including subsystem design application, mission analysis, materials structures, developments space sciences, processing manufacturing, operations, applications of technologies to other fields.
Abstract– The Almahata Sitta fall event provides a unique opportunity to gain insight into the nature of ureilitic objects in space and delivery ureilite meteorites Earth. From thermal events recorded mineralogy, petrology, chemistry ureilites recovered from area, we reconstruct timeline that led their genesis. This history is similar other known supportive disrupted parent body hypothesis. Temperatures final mantle equilibrium were 1200–1300 °C, but this high‐temperature was abruptly...
Abstract The Novato L6 chondrite fragmental breccia fell in California on 17 October 2012, and was recovered after the Cameras for Allsky Meteor Surveillance ( CAMS ) project determined meteor's trajectory between 95 46 km altitude. final fragmentation from 42 to 22 altitude exceptionally well documented by digital photographs. first sample before rain hit area. First results a consortium study of meteorite's characterization, cosmogenic radiogenic nuclides, origin, conditions fall are...
Abstract Based upon our characterization of three separate stones by electron and X‐ray beam analyses, computed microtomography, Raman microspectrometry, visible‐ IR spectrometry, Sutter's Mill is a unique regolith breccia consisting mainly various CM lithologies. Most samples resemble existing available 2 chondrites, chondrules calcium‐aluminum‐rich inclusion (CAI) set within phyllosilicate‐dominated matrix (mainly serpentine), pyrrhotite, pentlandite, tochilinite, variable amounts Ca‐Mg‐Fe...
Abstract We determined the abundances and enantiomeric compositions of amino acids in Sutter's Mill fragment #2 (designated SM 2) recovered prior to heavy rains that fell April 25–26, 2012, two other meteorite fragments, 12 51, were postrain. also abundance, enantiomeric, isotopic soil from recovery site 51. The three stones experienced terrestrial acid contamination, as evidenced by low d/l ratios several proteinogenic acids. higher 2 than consistent with rain introducing additional l‐...