A5026996150- Planetary Science and Exploration
- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Space Exploration and Technology
- Space Science and Extraterrestrial Life
- Scientific Research and Discoveries
- Space exploration and regulation
- Geomagnetism and Paleomagnetism Studies
- Spaceflight effects on biology
- Geophysics and Gravity Measurements
- Space Satellite Systems and Control
- Astrophysics and Cosmic Phenomena
- Spacecraft and Cryogenic Technologies
- Magnetic and Electromagnetic Effects
- Dark Matter and Cosmic Phenomena
- Radiation Therapy and Dosimetry
- Atmospheric and Environmental Gas Dynamics
- Atmospheric Ozone and Climate
- Geology and Paleoclimatology Research
- Gamma-ray bursts and supernovae
- Marine and environmental studies
- Seismic Waves and Analysis
- Plasma Diagnostics and Applications
- Dust and Plasma Wave Phenomena
Goddard Space Flight Center
2016-2025
Monash University
2024
American Institute of Aeronautics and Astronautics
2024
Ames Research Center
2009-2023
Solar System Exploration Research Virtual Institute
2010-2023
University of Maryland, Baltimore County
2007-2014
NASA Research Park
2011
NOVA Scientific (United States)
2009
University of Leicester
2009
University of Maryland, Baltimore
2009
Some active asteroids have been proposed to be formed as a result of impact events1. Because are generally discovered by chance only after their tails fully formed, the process how ejecta evolve into tail has, our knowledge, not directly observed. The Double Asteroid Redirection Test (DART) mission NASA2, in addition having successfully changed orbital period Dimorphos3, demonstrated activation an asteroid resulting from under precisely known conditions. Here we report observations DART with...
We present an analysis of Lunar Prospector Electron Reflectometer data from selected time periods using newly developed methods to correct for spacecraft potential and self‐consistently utilizing the entire measured electron distribution remotely sense lunar surface electrostatic with respect ambient plasma. These new techniques enable first quantitative measurements potentials orbit. Knowledge also allows accurate characterization downward‐going fluxes that contribute charging, allowing us...
Shadowed locations near the lunar poles are almost certainly electrically complex regions. At these terminator, local solar wind flows nearly tangential to surface and interacts with large‐scale topographic features such as mountains deep large craters. In this work, we study orographic effects from obstructions along a rough surface. On leeward side of obstructions, plasma voids formed in because absorption on upstream obstacles. Solar expands into voids, producing an ambipolar potential...
Despite being trace constituents of the lunar exosphere, sodium and potassium are most readily observed species due to their bright line emission. Measurements these by Ultraviolet Visible Spectrometer (UVS) on Lunar Atmosphere Dust Environment Explorer (LADEE) have revealed unambiguous temporal spatial variations indicative a strong role for meteoroid bombardment surface composition in determining local time dependence Moon's exosphere. Observations show distinct day (monthly) cycles both...
Aims. Solar Orbiter launched in February 2020 with the goal of revealing connections between Sun’s interior, atmosphere, and heliosphere. The Heavy Ion Sensor (HIS) is a time-of-flight ion mass spectrometer dedicated to measuring heavy ions solar wind. Methods. We present an overview first measurements composition from HIS, reviewing methods used transform spectra obtained on board into scientific data products examining two wind case studies as well statistical properties observed by HIS....
We analyzed a series of solar energetic particle events in late April and early May 1998, during which lunar surface potentials reached values as large ∼−4.5 kV (the largest recorded by Lunar Prospector). The two charging this time period correspond to injections, when the electron flux between 50 keV 5 MeV exceeded proton over same energy range. searched entire Prospector data set for other negative events, found that they occur almost exclusively magnetotail crossings (when Moon encounters...
The lunar near‐surface electric field in the vicinity of terminator is very complex, with a surface polarity change from dayside‐positive to nightside‐negative potentials and formation intensely negative due low plasma density increased temperatures trailing wake region. Presented preliminary map E‐field magnitude discussion dust dynamics this structure, intense vertical fields tending give rise vertically directed trajectories (aligned normal). Application process wake‐generated E‐fields...
[1] Determining the plasma environment within permanently shadowed lunar craters is critical to understanding local processes such as surface charging, electrostatic dust transport, volatile sequestration, and space weathering. In order investigate nature of this environment, first two-dimensional kinetic simulations solar wind expansion into a crater with self-consistent plasma-surface interaction have been undertaken. The present results reveal how couples electrically-charged produce...
The only species that have been so far detected in the lunar exosphere are Na, K, Ar, and He. However, models for production loss of derived from regolith through micrometeoroid impact vaporization, sputtering, photon‐stimulated desorption, predict a host other should exist exosphere. Assuming processes limited to ballistic escape, photoionization, recycling surface, we computed column abundances compared them published upper limits Moon. Only Ca do modeled clearly exceed available...
The Signal of Opportunity using NASA’s Gravity Recovery and Interior Laboratory (GRAIL) radio signals to remotely sense the Lunar ionosphere has been successfully demonstrated. GRAIL mission consisted an identical pair spacecraft approximately 100 km apart in a circular polar orbit around Moon; during science period, GRAIL’s X-band Radio Science beacon (RSB) data provide applicability for occultation lunar electron density profiles with uncertainty frequency residual...
During 2001 and 2002, when the Imager for Magnetopause‐to‐Aurora Global Exploration (IMAGE) satellite had its apogee in Northern Hemisphere Polar spacecraft, owing to apsidal precession of orbit, reached higher altitudes Southern Hemisphere, two spacecraft offered a unique opportunity study aurora conjugate hemispheres simultaneously. Owing large fields view Visible Imaging System (VIS) Earth camera IMAGE‐FUV instruments, substorms auroral features were imaged on global scale both...
We analyzed lunar surface charging during solar energetic particle (SEP) events, utilizing Lunar Prospector measurements of potentials and electron fluxes, upstream data. Outside the magnetosphere, we find a nearly one‐to‐one correspondence between extreme negative large proton events. Using new techniques to correct for spacecraft potential, present first quantitative SEP which that nightside reaches up −4.5 kV, with kilovolt or larger often observed. These are far higher than typical few...
Within a permanently shadowed lunar crater the horizontal flow of solar wind is obstructed by upstream topography, forming plasma wake that electrostatically diverts ions toward floor and generates surface potential can reach kilovolts. In present work kinetic simulations are employed to investigate morphology during passage storm. Results cast in terms leading dimensionless ratios including ion Mach number, ratio depth Debye length, peak secondary electron yield, temperature versus impact...
Abstract During the 1994 Clementine lunar mapping mission, portions of 25 orbits were dedicated to a search for horizon glow (LHG) using spacecraft star tracker navigation cameras. Previous putative detections LHG believed result from forward scattering sunlight by exospheric dust grains with radii ≈ 0.1 µm, observable above limb within shadow Moon near orbital sunrise or sunset. We have examined image sequences five in which occulted Sun, and was at least partially shadowed earthshine,...