A5022938858- Astro and Planetary Science
- Geomagnetism and Paleomagnetism Studies
- Ionosphere and magnetosphere dynamics
- Planetary Science and Exploration
- Solar and Space Plasma Dynamics
- Atmospheric Ozone and Climate
- Space Exploration and Technology
- Geology and Paleoclimatology Research
- Stellar, planetary, and galactic studies
- Geophysics and Gravity Measurements
- Calibration and Measurement Techniques
- Astronomical Observations and Instrumentation
- Earthquake Detection and Analysis
- High-pressure geophysics and materials
- Optical Systems and Laser Technology
- Laser-induced spectroscopy and plasma
- Atmospheric aerosols and clouds
- Atomic and Molecular Physics
- Electron and X-Ray Spectroscopy Techniques
- Isotope Analysis in Ecology
- Gamma-ray bursts and supernovae
- Astrophysics and Cosmic Phenomena
- Infrared Target Detection Methodologies
- Aerospace Engineering and Control Systems
- Geophysics and Sensor Technology
Johns Hopkins University Applied Physics Laboratory
2011-2020
Johns Hopkins University
1979-2008
Allentown Public Library
1983
University of Alaska Fairbanks
1982
Los Alamos National Laboratory
1981
Rice University
1978
National Oceanic and Atmospheric Administration
1976
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)...
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...
For many years it has been known that Saturn emits intense radio emissions at kilometer wavelengths and this radiation is modulated by the rotation of planet a rate varies up to one percent on time scale years. Recent observations from Cassini spacecraft have revealed appearance second component, with period about 10.6 hours, significantly less than previously which currently 10.8 hours. In paper we show first component originates southern auroral region, northern region. This north‐south...
Measurements of the hot (electron and ion energies ≳20 ≳ 28 kiloelectron volts, respectively) plasma environment at Jupiter by low-energy charged particle (LECP) instrument on Voyager 2 have revealed several new unusual aspects Jovian magnetosphere. The magnetosphere is populated from its outer edge into a distance least ∼ 30 radii ( R J ) (3 × 10 8 to 5 K) multicomponent consisting primarily hydrogen, oxygen, sulfur ions. Outside exhibits densities –1 –6 per cubic centimeter energy –8 –13...
Abstract Although the exact rotation period of Saturn is unknown, Saturn's magnetosphere displays an abundance periodicities near ~10.7 h. Such modulations appear in charged particles, magnetic fields, energetic neutral atoms, radio emissions, motions plasma sheet and magnetopause, even rings themselves. Known to accuracy four significant figures, these do not remain constant but vary by ~1% over time scales a year or longer. Magnetospheric also display slightly different periods northern...
The low-energy charged particle instrument on Voyager was designed to measure the hot plasma (electron and ion energies greater, similar 15 30 kiloelectron volts, respectively) component of Jovian magnetosphere. Protons, heavier ions, electrons at these were detected nearly a third an astronomical unit before encounter with planet. near magnetosphere boundary is predominantly composed protons, oxygen, sulfur in comparable proportions nonthermal power-law tail; its temperature about 3 x 10(8)...
Ion conics accompanied by electron beams are observed regularly in Saturn's magnetosphere. The and seen throughout the outer magnetosphere, on field lines that nominally map from well into polar cap (L dipole > 50) to closed region < 10). ion often together but also sometimes separately. Typically, prominent at energies between about 30 keV 200 keV. extend below ∼20 lower energy threshold for instrument as high 1 MeV. electrons may be either unidirectional (upward) or bidirectional;...
The low-energy charged particle instrument on Voyager 1 measured electrons and ions (energies ≥ 26 40 kiloelectron volts, respectively) in Saturn's magnetosphere. first-order ion anisotropies the dayside are generally corotation direction with amplitude decreasing distance to planet. pitch-angle distributions peak at 90°, whereas electron tend have field-aligned bidirectional maxima outside L shell of Rhea. A large decrease fluxes is seen near Titan, while selective absorption (least...
The Low Energy Charged Particle (LECP) experiments on the Voyager 1 and 2 spacecraft performed measurements of electrons (∼22 keV to ∼20 MeV) ions (∼28 ∼150 during Saturn encounters in 1980 1981. Count rate ratios two low energy electron (22 35 183 500 keV) ion (43 80 137 215 channels exhibit an approximate 10 hour periodicity outer Saturnian magnetosphere beyond orbit Titan. Electron vary from ∼50 ∼300; ∼3 ∼20. Similar but less pronounced periodicities are observed for higher lower spectral...
A Lomb periodogram analysis is applied to charged particle data from the LEMMS/CHEMS instruments on Cassini spacecraft. The represent count rates, averaged within 30 min bins, electrons (28–330 keV) and protons oxygen ions (2.8–236 during 350 days in 2005 all 365 2006. Sun effects, spacecraft maneuvers, measurements 20 R S of Saturn were removed prior analysis. main peaks frequency periodograms (or power spectra) found a window 9.5 hours 12.5 hours. For signal‐to‐noise ratios exceeding 8,...
Short‐lived and long‐lived ion flux increases ( E ≥30 keV) of Jovian origin have been observed by the low energy charged particle (LECP) instrument on Voyager 1 2 spacecraft. The short‐lived events are more than 860 R J upstream 1500 downstream Jupiter. Observations appear to be confined ≲200 last from a few minutes couple hours, while 8 21 hours. Both types sharp onsets decays, usually energies below MeV total energy, show large general enrichment Z ≥6 particles relative proton helium when...
We present results from the Voyager 1 and 2 low‐energy charged particle measurements of ion anisotropies in outer Jovian magnetosphere ( R ≳20 J ). These represent first observed an instrument rotating spin plane Jupiter. For several species investigated first‐order are all strongly corotational sense throughout most out to magnetopause on dayside. There is some evidence for a small component outward flow corotating region. Beyond ∼ 130–150 along outbound trajectories indicate magnetospheric...
The Magnetospheric Imaging Instrument (MIMI) on the Cassini spacecraft has observed energetic neutral atoms (ENA) at Saturn for three years from 2004 to 2007. 20–50 keV hydrogen and 64–144 oxygen neutrals were examined periodic behavior by projecting their images onto a plane perpendicular Saturn's equatorial summing emissions along vertical. resulting “strip” then subjected Lomb periodogram analyses period between mid‐2004 mid‐2007. hydrogens display erratic periods in 8–13 hour range,...
The sizes of Saturn's ring particles range from meters (boulders) to nanometers (dust). Determination the rings' ages depends on loss processes, including transport dust into atmosphere. During Grand Finale orbits Cassini spacecraft, its instruments measured tiny grains that compose innermost D-ring Saturn. nanometer-sized experiences collisions with exospheric (upper atmosphere) hydrogen and molecular hydrogen, which forces it fall ionosphere lower We used Magnetospheric Imaging Instrument...
Abstract Moments of the charged particle distribution function provide a compact way studying transport, acceleration, and interactions plasma energetic particles in magnetosphere. We employ κ ‐distributions to describe energy spectra H + O , based on >20 keV measurements by three detectors Cassini's Magnetospheric Imaging Instrument, covering time period from DOY 183/2004 016/2016, 5 < L 20. From analytical we calculate equatorial distributions ion moments inside Saturn's...
The Magnetospheric Imaging Instrument (MIMI) on the Cassini spacecraft is providing first energetic neutral particle (ENA) measurements in magnetosphere of Saturn. Advantageous orbits during 120 days 2007 allowed ENA observations to be mapped equatorial plane planet and surveyed as a statistical ensemble Sun‐synchronous coordinate system. When projected onto plane, emissions from both hydrogen atoms (20–50 keV) oxygen (64–144 form toroidal distributions nearly concentric with planet. torus...
This investigation reports the statistical correlation of cusp latitude with interplanetary magnetic field (IMF) B z and AE (12) index. Eleven months data from 1979 were collected, subject only to criteria that IMP 8 spacecraft be outside magnetopause measure IMF daily average exceed 200 nT. In general, latitudes poleward boundaries display higher coefficients than do equatorward boundaries. The best correlations involve no time delay, while a 30‐min delay. strongest ( R = 0.77) occurs...
The low-energy charged particle instrument on Voyager 2 measured electrons and ions (energies greater, similar 22 28 kiloelectron volts, respectively) in Saturn's magnetosphere. magnetosphere structure population were modified from those observed during the 1 encounter November 1980 but a manner consistent with same global morphology. Major results include following. (i) A region containing an extremely hot ( approximately 30 to 50 volts) plasma was identified extends orbit of Tethys outward...
The low‐energy charged particle (LECP) experiment observed satellite microsignatures in ions (28 keV–4 MeV) and electrons (22 keV–20 during the Voyager encounters with Saturn 1980 1981. Each of five major satellites within orbit Titan had associated it at least one absorption feature high time resolution (400 ms) data. Generally, involve abrupt rate decreases factors up to 10 or more, lasting on scales less than 2 min. Occasionally, substructure microsignature is 5–10 s a single pitch angle....
Spectrographic images in the far ultraviolet, obtained from observations made 2007 to 2009, are used quantify and compare morphology of Saturn's northern southern aurora local time. Made by UVIS imager on Cassini spacecraft, these differ previous UV offering complete time coverage small zenith angles. A statistical picture emerges after combining over 10 5 spectrographic north south aurora. From its composite, exhibits an intensity peak ∼40 kR near 05 h time, while peaks at ∼60 same Aurora...
Saturn has a sufficiently strong dipole magnetic field to trap high-energy charged particles and form radiation belts, which have been observed outside its rings. Whether stable belts exist near the planet inward of rings was previously unknown. The Cassini spacecraft's Magnetosphere Imaging Instrument obtained measurements belt that lies just above Saturn's dense atmosphere is decoupled from rest magnetosphere by planet's A- C-rings. extends across D-ring comprises protons produced through...