A5051204793- Astro and Planetary Science
- Solar and Space Plasma Dynamics
- Ionosphere and magnetosphere dynamics
- Planetary Science and Exploration
- Geomagnetism and Paleomagnetism Studies
- Space Exploration and Technology
- Geophysics and Gravity Measurements
- Stellar, planetary, and galactic studies
- Earthquake Detection and Analysis
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Space Science and Extraterrestrial Life
- Dark Matter and Cosmic Phenomena
- Isotope Analysis in Ecology
- Atmospheric Ozone and Climate
- Spacecraft and Cryogenic Technologies
- Space exploration and regulation
- Laser-induced spectroscopy and plasma
- Geology and Paleoclimatology Research
- Solar Radiation and Photovoltaics
- Radiation Therapy and Dosimetry
- Nuclear Physics and Applications
- Spacecraft Design and Technology
- Atomic and Molecular Physics
- High-pressure geophysics and materials
Johns Hopkins University Applied Physics Laboratory
2015-2024
Academy of Athens
2014-2023
Johns Hopkins University
2001-2023
Earth Resources Technology (United States)
1990-2018
Charles River Laboratories (Netherlands)
2018
Kavli Institute for Particle Astrophysics and Cosmology
2010
Goddard Space Flight Center
2008-2010
Los Alamos National Laboratory
1981-2010
Max Planck Institute for Solar System Research
2006-2008
University College London
2008
The Sun moves through the local interstellar medium, continuously emitting ionized, supersonic solar wind plasma and carving out a cavity in space called heliosphere. recently launched Interstellar Boundary Explorer (IBEX) spacecraft has completed its first all-sky maps of interaction at edge heliosphere by imaging energetic neutral atoms (ENAs) emanating from this region. We found bright ribbon ENA emission, unpredicted prior models or theories, that may be ordered magnetic field...
New Horizons' views of Pluto The flyby and its moon Charon by the Horizons spacecraft generated news coverage around world. Now Stern et al. report first scientific results from high-speed encounter. surface is surprisingly diverse, with large regions differing brightness composition. There ample evidence for ongoing rich geological processes that act to sculpt surface. Charon's similarly complex, numerous relief structures varied coloration. Pluto's atmosphere extensive but less dense than...
Voyager 1 (V1) began measuring precursor energetic ions and electrons from the heliospheric termination shock (TS) in July 2002. During ensuing 2.5 years, average particle intensities rose as V1 penetrated deeper into foreshock of TS. Throughout 2004, observed even larger, fluctuating 40 kiloelectron volts (keV) to >/=50 megaelectron per nucleon >26 keV >/=350 keV. On day 350 2004 (2004/350), an intensity spike that was followed by a sustained factor 10 increase at lowest energies lesser...
We analyze the radial distribution of electron populations inside 20 R s in Saturn's magnetosphere, and we calculate moments for these by a forward modeling method using composite spectra produced CAPS/ELS (0.6 eV to 26 keV) MIMI/LEMMS (15 keV 10 MeV) instruments on board Cassini. first harmonize both data sets physical units apply corrections taking into account biases introduced spacecraft interaction with magnetospheric environment. then test different bimodal isotropic models, deciding...
The low energy charged particle (LECP) experiment on the Voyager 1 and 2 spacecraft made measurements of intensity, spectra, spatial distributions ions (30 keV ≲ E 150 MeV) electrons (22 20 during encounters with Saturnian magnetosphere in November 1980 August 1981, respectively. Detailed analysis data has revealed following: (1) Energetic are present interplanetary medium both upstream (to ∼200 R s ) off dawn bow shock ∼400 magnetosphere, maximum energies ∼100 keV. (2) Low‐energy (≳22 keV)...
A detailed study of energetic (Ep ≳ 0.29 MeV; Ee 0.22 MeV) proton and electron bursts in the vicinity magnetosphere over a 1-year period (day 270 1972 to day 1973) using Johns Hopkins University/Applied Physics Laboratory (JHU/APL) experiment on board near-circular (∼32 RE by ∼38 RE) orbiting Explorer 47 (Imp 7) satellite has been performed with greater sensitivity (jp 10−2 cm−2 s−1 sr−1 MeV−1) than previously possible at these energies. The results reveal that electrons protons energies are...
Unexpected Magnetic Highway The heliopause is thought to separate the heliosphere (the bubble of plasma and magnetic field originating at Sun) from interstellar field. In August last year, Voyager 1 spacecraft, which was launched 35 years ago, 18.5 billion kilometers away Sun, close expected location heliopause. Krimigis et al. (p. 144 , published online 27 June) report observations energetic ions electrons by that suggest a sharp distinct boundary crossed five times over ∼30 days. Burlaga...
The Integrated Science Investigation of the Sun (ISIS) is a complete science investigation on Solar Probe Plus (SPP) mission, which flies to within nine solar radii Sun’s surface. ISIS comprises two-instrument suite measure energetic particles over very broad energy range, as well coordinated management, operations, data processing, and scientific analysis. Together, observations allow us explore mechanisms dynamics, including their: (1) Origins—defining seed populations physical conditions...
Spectra, integral moments, and composition (H, He, O, S) of energetic ions (50 keV to 50 MeV) are presented for selected Jupiter magnetospheric positions near the equator between radial distances ∼6 ∼46 radii ( R J ), as revealed by analysis Galileo Energetic Particle Detector data. These characteristics then used basis interpreting modeling reported signatures ion/neutral gas interactions within Jupiter's inner magnetosphere, particularly neutral atom emissions measured during Cassini...
Solar wind energy transfer to planetary magnetospheres and ionospheres is controlled by magnetic reconnection, a process that determines the degree of connectivity between interplanetary field (IMF) planet's field. During MESSENGER's second flyby Mercury, steady southward IMF was observed magnetopause threaded strong field, indicating reconnection rate ~10 times typical at Earth. Moreover, large flux event in magnetosheath, plasmoid multiple traveling compression regions were Mercury's...
On 1 Jun 1985 the AMPTE/CCE spacecraft (at a geocentric distance of ∼8.8 R E at midnight neutral sheet region) observed dispersionless energetic particle injection and an increase in magnetic field magnitude, which are features commonly attributed to disruption near‐earth cross‐tail current during substorm expansion onsets. An analysis based on high time‐resolution measurements from magnetometer detector indicates that region exhibited localized (< ) transient min) intensity enhancements,...
The progressive developments in the radial profiles of particle pressure, plasma beta, and electric currents storm time ring current are investigated with data from medium energy analyzer on AMPTE Charged Particle Explorer spacecraft. Measurements ions 25 keV to 1 MeV, which carry 70–85% density entire population, used this work. Two geomagnetic storms September 1984 selected four traversals equatorial region during course each studied. It is shown that enhancements pressure occur initially...
Voyager 1 and 2 low‐energy charged particle (LECP) observations of 30‐keV to 2‐MeV electron ion energy spectra angular distributions have been used calculate phase space densities at constant first second adiabatic invariants in the Saturnian magnetosphere. The results are generally consistent with inward radial diffusion from an external source. data obtained also indicate a source ions located within orbital distance Enceladus capable producing 10‐ 40‐MeV/Gauss as well electrons about 3.5...
The low‐energy charged particle (LECP) experiment on the Voyager 1 and 2 spacecraft made measurements of intensity, energy spectra, angular distributions, composition ions (30 keV ≲ E ≲150 MeV) electrons (14 ≲10 during encounters with Jovian magnetosphere in 1979. Detailed analysis multicomponent (H, He, O, S) (∼30 to ∼4 ion population reveals environment be dominated by magnetospheric distances ≳200 R J upstream ≳350 downstream from planet. Inside magnetosphere, move generally sense...
We have surveyed the 0.1-10 MeV nucleon-1 elemental abundances at 72 interplanetary (IP) shocks observed by Ultra-Low-Energy Isotope Spectrometer on board Advanced Composition Explorer from 1997 October through 2002 September. find following: (1) The C/O ratios in IP were substantially depleted (by more than ~40%) relative to solar wind values. (2) shock poorly correlated with those measured slow and fast wind. (3) Energetic ions above ~0.1 impulsive gradual energetic particle events (SEPs)...
During MESSENGER's third flyby of Mercury, the magnetic field in planet's tail increased by factors 2 to 3.5 over intervals 3 minutes. Magnetospheric substorms at Earth are powered similar loading, but amplitude is lower a factor approximately 10 and typical durations 1 hour. The extreme loading observed Mercury implies that relative intensity must be much larger than Earth. correspondence between duration enhancements characteristic time for Dungey cycle, which describes plasma circulation...
Observations by MESSENGER show that Mercury's magnetosphere is immersed in a comet-like cloud of planetary ions. The most abundant, Na+, broadly distributed but exhibits flux maxima the magnetosheath, where local plasma flow speed high, and near spacecraft's closest approach, atmospheric density should peak. magnetic field showed reconnection signatures form transfer events, azimuthal rotations consistent with Kelvin-Helmholtz waves along magnetopause, extensive ultralow-frequency wave...
Comprehensive energy (a few eV ≲ E 5 MeV), charge state, and mass coverage of the particle instrumentation on AMPTE Charge Composition Explorer (CCE) satellite, together with field wave instruments, has made possible compositional studies equatorial distributions ring current ions during magnetic storm September 4, 1984. Examination ion spectra at L ≃ 4 in local evening sector (∼ 1700 MLT), where maximum depression ground-based Dst were seen, shows that density was dominated by protons,...