Found 938 entries in the Bibliography.

Showing entries from 751 through 800


Competing source and loss mechanisms due to wave-particle interactions in Earth\textquoterights outer radiation belt during the 30 September to 3 October 2012 geomagnetic storm

Drastic variations of Earth\textquoterights outer radiation belt electrons ultimately result from various competing source, loss, and transport processes, to which wave-particle interactions are critically important. Using 15 spacecraft including NASA\textquoterights Van Allen Probes, THEMIS, and SAMPEX missions and NOAA\textquoterights GOES and POES constellations, we investigated the evolution of the outer belt during the strong geomagnetic storm of 30 September to 3 October 2012. This storm\textquoterights main phase drop ...

Turner, D.; Angelopoulos, V.; Li, W.; Bortnik, J.; Ni, B.; Ma, Q.; Thorne, R.; Morley, S.; Henderson, M.; Reeves, G.; Usanova, M.; Mann, I.; Claudepierre, S.; Blake, J.; Baker, D.; Huang, C.-L.; Spence, H.; Kurth, W.; Kletzing, C.; Rodriguez, J.;

YEAR: 2014     DOI: 10.1002/jgra.v119.310.1002/2014JA019770

Van Allen Probes

Cosmic ray physics in space: from fundamental physics to applications

One hundred years after their discovery by Victor Hess, cosmic rays are nowadays subject of intense research from space-based detectors, able to perform for the first time high precision measurement of their composition and spectra as well as of isotropy and time variability. On May 2011, the alpha magnetic spectrometer (AMS-02) has been installed on the International Space Station, to measure with high accuracy the cosmic ray properties searching for rare events which could be an indication of the nature of dark matter or p ...

Battiston, Roberto;

YEAR: 2014     DOI: 10.1007/s12210-014-0293-1

Anti matter; Cosmic rays; Dark matter; Seismology; Space research; Superconductivity; Van Allen Belts

Cost and risk analysis of small satellite constellations for earth observation

Distributed Space Missions (DSMs) are gaining momentum in their application to Earth science missions owing to their ability to increase observation sampling in spatial, spectral, temporal and angular dimensions. Past literature from academia and industry have proposed and evaluated many cost models for spacecraft as well as methods for quantifying risk. However, there have been few comprehensive studies quantifying the cost for multiple spacecraft, for small satellites and the cost risk for the operations phase of the proje ...

Nag, Sreeja; LeMoigne, Jacqueline; de Weck, Olivier;

YEAR: 2014     DOI: 10.1109/AERO.2014.6836396

artificial satellites; risk analysis

Design of a spacecraft integration and test facility at The Johns Hopkins University Applied Physics Laboratory

The Johns Hopkins University Applied Physics Laboratory (JHU/APL) is dedicated to solving critical challenges as set forth by the National Aeronautics and Space Administration and the Department of Defense. JHU/APL participates fully in the nation\textquoterights formulation of space science and exploration priorities, providing the needed science, engineering, and technology, including the production and operation of unique spacecraft, instruments, and subsystems.

Liggett, William; Handiboe, Jon; Theus, Eugene; Hartka, Ted; Navid, Hadi;

YEAR: 2014     DOI: 10.1109/AERO.2014.6836273

Spacecraft Design

Effect of EMIC waves on relativistic and ultrarelativistic electron populations: Ground-based and Van Allen Probes observations

We study the effect of electromagnetic ion cyclotron (EMIC) waves on the loss and pitch angle scattering of relativistic and ultrarelativistic electrons during the recovery phase of a moderate geomagnetic storm on 11 October 2012. The EMIC wave activity was observed in situ on the Van Allen Probes and conjugately on the ground across the Canadian Array for Real-time Investigations of Magnetic Activity throughout an extended 18 h interval. However, neither enhanced precipitation of >0.7 MeV electrons nor reductions in Van All ...

Usanova, M.; Drozdov, A.; Orlova, K.; Mann, I.; Shprits, Y.; Robertson, M.; Turner, D.; Milling, D.; Kale, A.; Baker, D.; Thaller, S.; Reeves, G.; Spence, H.; Kletzing, C.; Wygant, J.;

YEAR: 2014     DOI: 10.1002/2013GL059024

Van Allen Probes

Event-specific chorus wave and electron seed population models in DREAM3D using the Van Allen Probes

The DREAM3D diffusion model is applied to Van Allen Probes observations of the fast dropout and strong enhancement of MeV electrons during the October 2012 \textquotedblleftdouble-dip\textquotedblright storm. We show that in order to explain the very different behavior in the two \textquotedblleftdips,\textquotedblright diffusion in all three dimensions (energy, pitch angle, and L*) coupled with data-driven, event-specific inputs, and boundary conditions is required. Specifically, we find that outward radial diffusion to the ...

Tu, Weichao; Cunningham, G.; Chen, Y.; Morley, S.; Reeves, G.; Blake, J.; Baker, D.; Spence, H.;

YEAR: 2014     DOI: 10.1002/2013GL058819

Van Allen Probes

Gradual diffusion and punctuated phase space density enhancements of highly relativistic electrons: Van Allen Probes observations

The dual-spacecraft Van Allen Probes mission has provided a new window into mega electron volt (MeV) particle dynamics in the Earth\textquoterights radiation belts. Observations (up to E ~10 MeV) show clearly the behavior of the outer electron radiation belt at different timescales: months-long periods of gradual inward radial diffusive transport and weak loss being punctuated by dramatic flux changes driven by strong solar wind transient events. We present analysis of multi-MeV electron flux and phase space density (PSD) ch ...

Baker, D.; Jaynes, A.; Li, X.; Henderson, M.; Kanekal, S.; Reeves, G.; Spence, H.; Claudepierre, S.; Fennell, J.; Hudson, M.; Thorne, R.; Foster, J.; Erickson, P.; Malaspina, D.; Wygant, J.; Boyd, A.; Kletzing, C.; Drozdov, A.; . Y. Shprits, Y;

YEAR: 2014     DOI: 10.1002/2013GL058942

Van Allen Probes

Optimization of deep-space Ka-band link schedules

Downlink scheduling methods that minimize either contact time or data latency are described. For deep-space missions these two methods yield very different schedules. Optimal scheduling algorithms are straightforward for ideal mission scenarios. In practice, additional schedule requirements preclude a tractable optimal algorithm. In lieu of an optimal solution, an iterative sub-optimal algorithm is described. These methods are motivated in part by a need to balance mission risk, which increases with data latency, and mission ...

Adams, Norman; Copeland, David; Mick, Alan; Pinkine, Nickalaus;

YEAR: 2014     DOI: 10.1109/AERO.2014.6836351

optimisation; scheduling; space communication links; statistical analysis

Radial diffusion comparing a THEMIS statistical model with geosynchronous measurements as input

The outer boundary energetic electron flux is used as a driver in radial diffusion calculations, and its precise determination is critical to the solution. A new model was proposed recently based on Time History of Events and Macroscale Interactions during Substorms (THEMIS) measurements to express the boundary flux as three fit functions of solar wind parameters in a response window that depend on energy and which solar wind parameter is used: speed, density, or both. The Dartmouth radial diffusion model has been run using ...

Li, Zhao; Hudson, Mary; Chen, Yue;

YEAR: 2014     DOI: 10.1002/jgra.v119.310.1002/2013JA019320

outer boundary; radial diffusion; Radiation belt; Van Allen Probes

REPAD: An empirical model of pitch angle distributions for energetic electrons in the Earth\textquoterights outer radiation belt

We have recently conducted a statistical survey on pitch angle distributions of energetic electrons trapped in the Earth\textquoterights outer radiation belt, and a new empirical model was developed based upon survey results. This model\textemdashrelativistic electron pitch angle distribution (REPAD)\textemdashaims to present statistical pictures of electron equatorial pitch angle distributions, instead of the absolute flux levels, as a function of energy, L shell, magnetic local time, and magnetic activity. To quantify and ...

Chen, Yue; Friedel, Reiner; Henderson, Michael; Claudepierre, Seth; Morley, Steven; Spence, Harlan;

YEAR: 2014     DOI: 10.1002/jgra.v119.310.1002/2013JA019431

Earth\textquoterights outer radiation belt; energetic electrons; Pitch-angle distributions

REPAD: An Empirical Model of Pitch-angle Distributions for Energetic Electrons in the Earth\textquoterights Outer Radiation Belt

We have recently conducted a statistical survey on pitch angle distributions of energetic electrons trapped in the Earth\textquoterights outer radiation belt, and a new empirical model was developed based upon survey results. This model\textemdashrelativistic electron pitch angle distribution (REPAD)\textemdashaims to present statistical pictures of electron equatorial pitch angle distributions, instead of the absolute flux levels, as a function of energy, L shell, magnetic local time, and magnetic activity. To quantify and ...

Chen, Y.; Friedel, R.; Henderson, M.; Claudepierre, S.; Morley, S.; Spence, H.;

YEAR: 2014     DOI: 10.1002/2013JA019431

RBSP; Van Allen Probes

Resonant scattering of energetic electrons by unusual low-frequency hiss

We quantify the resonant scattering effects of the unusual low-frequency dawnside plasmaspheric hiss observed on 30 September 2012 by the Van Allen Probes. In contrast to normal (~100\textendash2000 Hz) hiss emissions, this unusual hiss event contained most of its wave power at ~20\textendash200 Hz. Compared to the scattering by normal hiss, the unusual hiss scattering speeds up the loss of ~50\textendash200 keV electrons and produces more pronounced pancake distributions of ~50\textendash100 keV electrons. It is demonstrate ...

Ni, Binbin; Li, Wen; Thorne, Richard; Bortnik, Jacob; Ma, Qianli; Chen, Lunjin; Kletzing, Craig; Kurth, William; Hospodarsky, George; Reeves, Geoffrey; Spence, Harlan; Blake, Bernard; Fennell, Joseph; Claudepierre, Seth;

YEAR: 2014     DOI: 10.1002/2014GL059389

Van Allen Probes

A scripting framework for automated flight SW testing: Van Allen Probes lessons learned

This paper summarizes the lessons learned from implementing and utilizing an automated flight software test framework for the Van Allen Probes mission. This includes a recommended list of features/characteristics that a test framework should support. This paper also presents two test scripting design patterns that are useful for constructing an automated regression test suite. These design patterns are intended for non-object-oriented scripting environments - which is typical of space mission ground systems. A process flow i ...

Finnigan, Jeremiah;

YEAR: 2014     DOI: 10.1109/AERO.2014.6836164

Automated flight software; Automated flight SW testing; Van Allen Probes

Signature modeling for LWIR spectrometer

Hyperspectral longwave infrared (LWIR) is used for a variety of targets such as gases and solids with the advantage of day or night data collections. A longwave infrared system must have the ability to convert the radiance data it measures to emissivity prior to running a detection algorithm, commonly called a temperature-emissivity separation (TES) algorithm. Key parts of this TES algorithm are accounting for the reflected down-welling radiation from the atmosphere, upwelling background radiance removal, and most importantl ...

Firpi, Alexer; Oxenrider, Jason; Ramachandran, Vignesh; Mitchell, Herbert; Tzeng, Nigel; Rodriguez, Benjamin;

YEAR: 2014     DOI: 10.1109/AERO.2014.6836439

hyperspectral imaging; infrared imaging; infrared spectrometers; radiance data conversion

Software controlled memory scrubbing for the Van Allen Probes Solid State Recorder (SSR) memory

The Van Allen Probes mission which was designed and built by the Johns Hopkins University, Applied Physics Laboratory (APL) is also being operated by the APL mission operations team in Laurel, Maryland. The two Van Allen Probes spacecraft have been successfully collecting data on orbit since they were launched on August 30, 2012. These twin probes are providing unprecedented insight into the physical dynamics of the Earth\textquoterights radiation belts and are giving scientists the data they need to make predictions of chan ...

Reid, Mark; Ottman, Geffrey;

YEAR: 2014     DOI: 10.1109/AERO.2014.6836406

Van Allen Probes

Space science: Near-Earth space shows its stripes

Using some of the first scientific satellites put into orbit during the late 1950s, teams led by physicists James Van Allen in the United States and Sergei Vernov in the Soviet Union independently reported1, 2 on defined regions of radiation in near-Earth space. These regions came to be known as Earth\textquoterights radiation belts, and they represent the first major scientific discovery of the space age. However, despite decades of study, many questions in radiation-belt physics remain unanswered, mostly concerning the nat ...

Turner, Drew;

YEAR: 2014     DOI: 10.1038/507308a

Space physics; Van Allen Probes

Spin stabilization design and testing of the Van Allen Probes

This paper describes the design decisions taken and the mass properties tracking and testing flow chosen for the Van Allen Probes spacecraft and their deployable systems to achieve the coning angle requirements. Topics include a list of major requirements, a brief description of the error budget, a description of the tracking process of the spacecraft mass properties prior to test, a description of the spin balance and mass properties testing of the spacecraft core and deployable systems, and a presentation of the final mass ...

Berman, Simmie; Cheng, Weilun; Borowski, Heather; Persons, David;

YEAR: 2014     DOI: 10.1109/AERO.2014.6836234

Van Allen Probes

Evidence for injection of relativistic electrons into the Earth\textquoterights outer radiation belt via intense substorm electric fields

Observation and model results accumulated in the last decade indicate that substorms can promptly inject relativistic \textquoteleftkiller\textquoteright electrons (>=MeV) in addition to 10\textendash100 keV subrelativistic populations. Using measurements from Cluster, Polar, LANL, and GOES satellites near the midnight sector, we show in two events that intense electric fields, as large as 20 mV/m, associated with substorm dipolarization are associated with injections of relativistic electrons into the outer radiation belt. ...

Dai, Lei; Wygant, John; Cattell, Cynthia; Thaller, Scott; Kersten, Kris; Breneman, Aaron; Tang, Xiangwei; Friedel, Reiner; Claudepierre, Seth; Tao, Xin;

YEAR: 2014     DOI: 10.1002/2014GL059228

radiation belt relativistic electrons; substorm dipolarization; substorm electric fields; substorm injection

Global time-dependent chorus maps from low-Earth-orbit electron precipitation and Van Allen Probes data

Substorm injected electrons (several\textendash100 s keV) produce whistler-mode chorus waves that are thought to have a major impact on the radiation belts by causing both energization and loss of relativistic electrons in the outer belt. High-altitude measurements, such as those from the Van Allen Probes, provide detailed wave measurements at a few points in the magnetosphere. But physics-based models of radiation-belt dynamics require knowledge of the global distribution of chorus waves. We demonstrate that time-dependent, ...

Chen, Yue; Reeves, Geoffrey; Friedel, Reiner; Cunningham, Gregory;

YEAR: 2014     DOI: 10.1002/2013GL059181

Van Allen Probes

Magnetosonic wave excitation by ion ring distributions in the Earth\textquoterights inner magnetosphere

Combining Time History of Events and Macroscale Interaction during Substorms (THEMIS) wave and particle observations and a quantitative calculation of linear wave growth rate, we demonstrate that magnetosonic (MS) waves can be locally excited by ion ring distributions in the Earth\textquoterights magnetosphere when the ion ring energy is comparable to the local Alfven energy. MS waves in association with ion ring distributions were observed by THEMIS A on 24 November 2010 in the afternoon sector, both outside the plasmapause ...

Ma, Qianli; Li, Wen; Chen, Lunjin; Thorne, Richard; Angelopoulos, Vassilis;

YEAR: 2014     DOI: 10.1002/2013JA019591

magnetosonic waves; ring current; THEMIS observation; wave excitation

Photoelectron-mediated spacecraft potential fluctuations

Electric field fluctuations such as those due to plasma waves in Earth\textquoterights magnetosphere may modulate photoelectrons emitted from spacecraft surface, causing fluctuations in spacecraft potential. We experimentally investigate such photoelectron-mediated spacecraft potential fluctuations. The photoelectric charge of a spacecraft model is found to increase with increasing applied electric field as more photoelectrons escape the spacecraft model surface and dissipates with a decrease in the electric field through co ...

Wang, X.; Malaspina, D.; Ergun, R.; M., Hor\;

YEAR: 2014     DOI: 10.1002/2013JA019502

chorus waves; electric field; Magnetosphere; photoelectrons; plasma density; spacecraft potential fluctuations

Quantifying hiss-driven energetic electron precipitation: A detailed conjunction event analysis

We analyze a conjunction event between the Van Allen Probes and the low-altitude Polar Orbiting Environmental Satellite (POES) to quantify hiss-driven energetic electron precipitation. A physics-based technique based on quasi-linear diffusion theory is used to estimate the ratio of precipitated and trapped electron fluxes (R), which could be measured by the two-directional POES particle detectors, using wave and plasma parameters observed by the Van Allen Probes. The remarkable agreement between modeling and observations sug ...

Li, W.; Ni, B.; Thorne, R.; Bortnik, J.; Nishimura, Y.; Green, J.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Blake, J.; Fennell, J.; Claudepierre, S.; Gu, X.;

YEAR: 2014     DOI: 10.1002/2013GL059132

Van Allen Probes

Quiet time observations of He ions in the inner magnetosphere as observed from the RBSPICE instrument aboard the Van Allen Probes mission

He ions contribute to Earth\textquoterights ring current energy and species population density and are important in understanding ion transport and charge exchange processes in the inner magnetosphere. He ion flux measurements made by the Van Allen Probes Radiation Belt Storm Probes Ion Composition Experiment (RBSPICE) instrument are presented in this paper. Particular focus is centered on geomagnetically quiet intervals in late 2012 and 2013 that show the flux, L-shell, and energy (65 keV to 518 keV) morphology of ring curr ...

Gerrard, Andrew; Lanzerotti, Louis; Gkioulidou, Matina; Mitchell, Donald; Manweiler, Jerry; Bortnik, Jacob;

YEAR: 2014     DOI: 10.1002/2013GL059175

Van Allen Probes

Rebuilding of the Earth\textquoterights outer electron belt during 8-10 October 2012

Geomagnetic storms often include strong magnetospheric convection caused by sustained periods of southward interplanetary magnetic field. During periods of strong convection, the Alfv\ en layer, which separates the region of sunward convection from closed drift shells, is displaced earthward allowing plasma sheet particles with energies in the hundreds of keV direct access inside of geosynchronous. Subsequent outward motion of the Alfv\ en boundary and adiabatic energization during storm recovery traps plasma sheet electrons ...

Kress, B.; Hudson, M.; Paral, J.;

YEAR: 2014     DOI: 10.1002/2013GL058588

radiation belt transport

The role of ring current particle injections: Global simulations and Van Allen Probes observations during 17 March 2013 storm

We simulate substorm injections observed by the Van Allen Probes during the 17 March 2013 storm using a self-consistent coupling between the ring current model RAM-SCB and the global MHD model BATS-R-US. This is a significant advancement compared to previous studies that used artificially imposed electromagnetic field pulses to mimic substorm dipolarization and associated inductive electric field. Several substorm dipolarizations and injections are reproduced in the MHD model, in agreement with the timing of shape changes in ...

Yu, Yiqun; Jordanova, Vania; Welling, Dan; Larsen, Brian; Claudepierre, Seth; Kletzing, Craig;

YEAR: 2014     DOI: 10.1002/2014GL059322

ring current dynamics; self-consistent treatment of fields and plasma; Substorm Injections; Van Allen Probes

Simulated magnetopause losses and Van Allen Probe flux dropouts

Three radiation belt flux dropout events seen by the Relativistic Electron Proton Telescope soon after launch of the Van Allen Probes in 2012 (Baker et al., 2013a) have been simulated using the Lyon-Fedder-Mobarry MHD code coupled to the Rice Convection Model, driven by measured upstream solar wind parameters. MHD results show inward motion of the magnetopause for each event, along with enhanced ULF wave power affecting radial transport. Test particle simulations of electron response on 8 October, prior to the strong flux en ...

Hudson, M.; Baker, D.; Goldstein, J.; Kress, B.; Paral, J.; Toffoletto, F.; Wiltberger, M.;

YEAR: 2014     DOI: 10.1002/2014GL059222

Van Allen Probes

\textquotedblleftSpacecraft Reveals Recent Geological Activity on the Moon\textquotedblright

Through a content analysis of 200 \textquotedbllefttweets,\textquotedblright this study was an exploration into the distinct features of text posted to NASA\textquoterights Twitter site and the potential for these posts to serve as more engaging scientific text than traditional textbooks for adolescents. Results of the content analysis indicated the tweets and linked texts on the NASA Twitter site were constructed primarily as a form of \textquotedblleftadapted primary literature\textquotedblright where science texts created ...

Lesley, Mellinee;

YEAR: 2014     DOI: 10.1002/jaal.2014.57.issue-510.1002/jaal.258

Adolescence; Content analyses; Content literacy; Digital/media literacies

Spatial localization and ducting of EMIC waves: Van Allen Probes and ground-based observations

On 11 October 2012, during the recovery phase of a moderate geomagnetic storm, an extended interval (> 18 h) of continuous electromagnetic ion cyclotron (EMIC) waves was observed by Canadian Array for Real-time Investigations of Magnetic Activity and Solar-Terrestrial Environment Program induction coil magnetometers in North America. At around 14:15 UT, both Van Allen Probes B and A (65\textdegree magnetic longitude apart) in conjunction with the ground array observed very narrow (ΔL ~ 0.1\textendash0.4) left-hand polarized ...

Mann, I.; Usanova, M.; Murphy, K.; Robertson, M.; Milling, D.; Kale, A.; Kletzing, C.; Wygant, J.; Thaller, S.; Raita, T.;

YEAR: 2014     DOI: 10.1002/2013GL058581

Van Allen Probes

Storm time observations of plasmasphere erosion flux in the magnetosphere and ionosphere

Plasmasphere erosion carries cold dense plasma of ionospheric origin in a storm-enhanced density plume extending from dusk toward and through the noontime cusp and dayside magnetopause and back across polar latitudes in a polar tongue of ionization. We examine dusk sector (20 MLT) plasmasphere erosion during the 17 March 2013 storm (Dst ~ -130 nT) using simultaneous, magnetically aligned direct sunward ion flux observations at high altitude by Van Allen Probes RBSP-A (at ~3.0 Re) and at ionospheric heights (~840 km) by DMSP ...

Foster, J.; Erickson, P.; Coster, A.; Thaller, S.; Tao, J.; Wygant, J.; Bonnell, J;

YEAR: 2014     DOI: 10.1002/2013GL059124

Van Allen Probes

Testing a two-loop pattern of the substorm current wedge (SCW2L)

Recent quantitative testing of the classical (region 1 sense) substorm current wedge (SCI) model revealed systematic discrepancies between the observed and predicted amplitudes, which suggested us to include additional region 2 sense currents (R2 loop) earthward of the dipolarized region (SCW2L model). Here we discuss alternative circuit geometries of the 3-D substorm current system and interpret observations of the magnetic field dipolarizations made between 6.6RE and 11RE, to quantitatively investigate the SCW2L model para ...

Sergeev, V.; Nikolaev, A.; Tsyganenko, N.; Angelopoulos, V.; Runov, A.; Singer, H.; Yang, J.;

YEAR: 2014     DOI: 10.1002/2013JA019629

injections; magnetotail; substorm current wedge; substorms

Chorus waves and spacecraft potential fluctuations: Evidence for wave-enhanced photoelectron escape

Chorus waves are important for electron energization and loss in Earth\textquoterights radiation belts and inner magnetosphere. Because the amplitude and spatial distribution of chorus waves can be strongly influenced by plasma density fluctuations and spacecraft floating potential can be a diagnostic of plasma density, the relationship between measured potential and chorus waves is examined using Van Allen Probes data. While measured potential and chorus wave electric fields correlate strongly, potential fluctuation propert ...

Malaspina, D.; Ergun, R.; Sturner, A.; Wygant, J.; Bonnell, J; Breneman, A.; Kersten, K.;

YEAR: 2014     DOI: 10.1002/2013GL058769

Van Allen Probes

An empirically observed pitch-angle diffusion eigenmode in the Earth\textquoterights electron belt near L * = 5.0

Using data from NASA\textquoterights Van Allen Probes, we have identified a synchronized exponential decay of electron flux in the outer zone, near L* = 5.0. Exponential decays strongly indicate the presence of a pure eigenmode of a diffusion operator acting in the synchronized dimension(s). The decay has a time scale of about 4 days with no dependence on pitch angle. While flux at nearby energies and L* is also decaying exponentially, the decay time varies in those dimensions. This suggests the primary decay mechanism is el ...

O\textquoterightBrien, T.; Claudepierre, S.; Blake, J.; Fennell, J.; Clemmons, J.; Roeder, J.; Spence, H.; Reeves, G.; Baker, D.;

YEAR: 2014     DOI: 10.1002/2013GL058713

Van Allen Probes

Fine structure of large-amplitude chorus wave packets

Whistler mode chorus waves in the outer Van Allen belt can have consequences for acceleration of relativistic electrons through wave-particle interactions. New multicomponent waveform measurements have been collected by the Van Allen Probes Electric and Magnetic Field Instrument Suite and Integrated Science\textquoterights Waves instrument. We detect fine structure of chorus elements with peak instantaneous amplitudes of a few hundred picotesla but exceptionally reaching up to 3 nT, i.e., more than 1\% of the background magn ...

Santolik, O.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Bounds, S.;

YEAR: 2014     DOI: 10.1002/2013GL058889

Van Allen Probes

Generation of electromagnetic waves in the very low frequency band by velocity gradient

It is shown that a magnetized plasma layer with a velocity gradient in the flow perpendicular to the ambient magnetic field is unstable to waves in the Very Low Frequency band that spans the ion and electron gyrofrequencies. The waves are formally electromagnetic. However, depending on wave vector k⎯⎯=kc/ωpe (normalized by the electron skin depth) and the obliqueness, k⊥/k|| , where k⊥,|||| are wave vectors perpendicular and parallel to the magnetic field, the waves are closer to electrostatic in nature when k⎯⎯ ...

Ganguli, G.; Tejero, E.; Crabtree, C.; Amatucci, W.; Rudakov, L.;

YEAR: 2014     DOI: 10.1063/1.4862032

Electromagnetic wave

Nonstorm time dynamics of electron radiation belts observed by the Van Allen Probes

Storm time electron radiation belt dynamics have been widely investigated for many years. Here we present a rarely reported nonstorm time event of electron radiation belt evolution observed by the Van Allen Probes during 21\textendash24 February 2013. Within 2 days, a new belt centering around L=5.8 formed and gradually merged with the original outer belt, with the enhancement of relativistic electron fluxes by a factor of up to 50. Strong chorus waves (with power spectral density up to 10-4nT2/Hz) occurred in the region L>5 ...

Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; He, Zhaoguo; Zhu, Hui; Zhang, Min; Shen, Chao; Wang, Yuming; Wang, Shui; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Spence, H.; Reeves, G.; Funsten, H.; Blake, J.; Baker, D.;

YEAR: 2014     DOI: 10.1002/2013GL058912

Van Allen Probes

A nonstorm time enhancement of relativistic electrons in the outer radiation belt

Despite the lack of a geomagnetic storm (based on the Dst index), relativistic electron fluxes were enhanced over 2.5 orders of magnitude in the outer radiation belt in 13 h on 13\textendash14 January 2013. The unusual enhancement was observed by Magnetic Electron Ion Spectrometer (MagEIS), onboard the Van Allen Probes; Relativistic Electron and Proton Telescope Integrated Little Experiment, onboard the Colorado Student Space Weather Experiment; and Solid State Telescope, onboard Time History of Events and Macroscale Interac ...

Schiller, Quintin; Li, Xinlin; Blum, Lauren; Tu, Weichao; Turner, Drew; Blake, J.;

YEAR: 2014     DOI: 10.1002/2013GL058485

Van Allen Probes

Observations of kinetic scale field line resonances

We identify electromagnetic field variations from the Van Allen Probes which have the properties of Doppler shifted kinetic scale Alfv\ enic field line resonances. These variations are observed during injections of energetic plasmas into the inner magnetosphere. These waves have scale sizes perpendicular to the magnetic field which are determined to be of the order of an ion gyro-radius (ρi) and less. Cross-spectral analysis of the electric and magnetic fields reveals phase transitions at frequencies correlated with enhance ...

Chaston, Christopher; Bonnell, J; Wygant, John; Mozer, Forrest; Bale, Stuart; Kersten, Kris; Breneman, Aaron; Kletzing, Craig; Kurth, William; Hospodarsky, George; Smith, Charles; MacDonald, Elizabeth;

YEAR: 2014     DOI: 10.1002/2013GL058507

Van Allen Probes

One year of on-orbit performance of the Colorado Student Space Weather Experiment (CSSWE)

The Colorado Student Space Weather Experiment is a 3-unit (10cm \texttimes 10cm \texttimes 30cm) CubeSat funded by the National Science Foundation and constructed at the University of Colorado (CU). The CSSWE science instrument, the Relativistic Electron and Proton Telescope integrated little experiment (REPTile), provides directional differential flux measurements of 0.5 to >3.3 MeV electrons and 9 to 40 MeV protons. Though a collaboration of 60+ multidisciplinary graduate and undergraduate students working with CU professo ...

Palo, Scott; Gerhardt, David; Li, Xinlin; Blum, Lauren; Schiller, Quintin; Kohnert, Rick;

YEAR: 2014     DOI: 10.1109/USNC-URSI-NRSM.2014.6928087

artificial satellites; atmospheric measuring apparatus; Ionosphere; Magnetic Storms; Magnetosphere; Van Allen Probes

Prompt energization of relativistic and highly relativistic electrons during a substorm interval: Van Allen Probes observations

On 17 March 2013, a large magnetic storm significantly depleted the multi-MeV radiation belt. We present multi-instrument observations from the Van Allen Probes spacecraft Radiation Belt Storm Probe A and Radiation Belt Storm Probe B at ~6 Re in the midnight sector magnetosphere and from ground-based ionospheric sensors during a substorm dipolarization followed by rapid reenergization of multi-MeV electrons. A 50\% increase in magnetic field magnitude occurred simultaneously with dramatic increases in 100 keV electron fluxes ...

Foster, J.; Erickson, P.; Baker, D.; Claudepierre, S.; Kletzing, C.; Kurth, W.; Reeves, G.; Thaller, S.; Spence, H.; . Y. Shprits, Y; Wygant, J.;

YEAR: 2014     DOI: 10.1002/2013GL058438

Van Allen Probes

Recent results from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) on the Van Allen Probes

The physics of the creation, loss, and transport of radiation belt particles is intimately connected to the electric and magnetic fields which mediate these processes. A large range of field and particle interactions are involved in this physics from large-scale ring current ion and magnetic field dynamics to microscopic kinetic interactions of whistler-mode chorus waves with energetic electrons. To measure these kinds of radiation belt interactions, NASA implemented the two-satellite Van Allen Probes mission. As part of the ...

Kletzing, C.;

YEAR: 2014     DOI: 10.1109/USNC-URSI-NRSM.2014.6928090

Magnetic field measurement; magnetic fields; Magnetic flux; Van Allen Probes

Rotationally driven 'zebra stripes' in Earth's inner radiation belt

Structured features on top of nominally smooth distributions of radiation-belt particles at Earth have been previously associated with particle acceleration and transport mechanisms powered exclusively by enhanced solar-wind activity1, 2, 3, 4. Although planetary rotation is considered to be important for particle acceleration at Jupiter and Saturn5, 6, 7, 8, 9, the electric field produced in the inner magnetosphere by Earth\textquoterights rotation can change the velocity of trapped particles by only about 1\textendash2 kil ...

. Y. Ukhorskiy, A; Sitnov, M.; Mitchell, D.; Takahashi, K; Lanzerotti, L.; Mauk, B.;

YEAR: 2014     DOI: 10.1038/nature13046

Magnetospheric physics; Van Allen Probes

Precipitation and energization of relativistic radiation belt electrons induced by ULF oscillations in the magnetosphere

There is a renewed interest in the study of the radiation belts with the recent launch of the Van Allen Probes satellites. The mechanisms that drive the global response of the radiation belts to geomagnetic storms are not yet well understood. Global simulations using magnetohydrodynamics (MHD) model fields as drivers provide a valuable tool for studying the dynamics of these MeV energetic particles. ACE satellite measurements of the MHD solar wind parameters are used as the upstream boundary condition for the Lyon-Fedder-Mob ...

Brito, Thiago;

YEAR: 2014     DOI:

0373:Geophysics; 0607:Electromagnetics; 0725:Atmospheric sciences; Atmospheric sciences; Earth sciences; Electromagnetics; Energization; Geophysics; precipitation; Pure sciences; Radiation belts; Ulf


Early Results From the Engineering Radiation Monitor (ERM) and Solar Cell Monitor on the Van Allen Probes Mission

The Engineering Radiation Monitor (ERM) measures dose, dose rate and charging currents on the Van Allen Probes mission to study the dynamics of earth\textquoterights Van Allen radiation belts. Early results from this monitor show a variation in dose rates with time, a correlation between the dosimeter and charging current data, a map of charging current versus orbit altitude and a comparison of cumulative dose to pre-launch modeling after 260 days. Solar cell degradation monitor patches track the decrease in solar array outp ...

Maurer, Richard; Goldsten, John; Peplowski, Patrick; Holmes-Siedle, Andrew; Butler, Michael; Herrmann, Carl; Mauk, Barry;

YEAR: 2013     DOI: 10.1109/TNS.2013.2281937

Comparison between POES energetic electron precipitation observations and riometer absorptions: Implications for determining true precipitation fluxes

Energetic electron precipitation (EEP) impacts the chemistry of the middle atmosphere with growing evidence of coupling to surface temperatures at high latitudes. To better understand this link, it is essential to have realistic observations to properly characterize precipitation and which can be incorporated into chemistry-climate models. The Polar-orbiting Operational Environmental Satellite (POES) detectors measure precipitating particles but only integral fluxes and only in a fraction of the bounce loss cone. Ground-base ...

Rodger, Craig; Kavanagh, Andrew; Clilverd, Mark; Marple, Steve;

YEAR: 2013     DOI: 10.1002/2013JA019439

electron precipitation; POES; Radiation belts; riometery

Determining the spectra of radiation belt electron losses: Fitting DEMETER electron flux observations for typical and storm times

The energy spectra of energetic electron precipitation from the radiation belts are studied in order to improve our understanding of the influence of radiation belt processes. The Detection of Electromagnetic Emissions Transmitted from Earthquake Regions (DEMETER) microsatellite electron flux instrument is comparatively unusual in that it has very high energy resolution (128 channels with 17.9 keV widths in normal survey mode), which lends itself to this type of spectral analysis. Here electron spectra from DEMETER have been ...

Whittaker, Ian; Gamble, Rory; Rodger, Craig; Clilverd, Mark; Sauvaud, \;

YEAR: 2013     DOI: 10.1002/2013JA019228

DEMETER; electron spectral fit; Radiation belts

Dynamics of the Earth\textquoterights Radiation Belts and Inner Magnetosphere

Trapped by Earth\textquoterights magnetic field far above the planet\textquoterights surface, the energetic particles that fill the radiation belts are a sign of the Sun\textquoterights influence and a threat to our technological future. In the AGU monograph Dynamics of the Earth\textquoterights Radiation Belts and Inner Magnetosphere, editors Danny Summers, Ian R. Mann, Daniel N. Baker, and Michael Schulz explore the inner workings of the magnetosphere. The book reviews current knowledge of the magnetosphere and recent rese ...

Schultz, Colin;

YEAR: 2013     DOI: 10.1002/eost.v94.5210.1002/2013EO520007

aurora; Magnetosphere; Radiation belts; Van Allen Probes

James Van Allen and His Namesake NASA Mission

In many ways, James A. Van Allen defined and \textquotedblleftinvented\textquotedblright modern space research. His example showed the way for government-university partners to pursue basic research that also served important national and international goals. He was a tireless advocate for space exploration and for the role of space science in the spectrum of national priorities.

Baker, D.; Hoxie, V.; Jaynes, A.; Kale, A.; Kanekal, S.; Li, X.; Reeves, G.; Spence, H.;

YEAR: 2013     DOI: 10.1002/eost.v94.4910.1002/2013EO490001

RBSP; Van Allen Probes

Megavolt Parallel Potentials Arising from Double-Layer Streams in the Earth\textquoterights Outer Radiation Belt

Huge numbers of double layers carrying electric fields parallel to the local magnetic field line have been observed on the Van Allen probes in connection with in situ relativistic electron acceleration in the Earth\textquoterights outer radiation belt. For one case with adequate high time resolution data, 7000 double layers were observed in an interval of 1 min to produce a 230 000 V net parallel potential drop crossing the spacecraft. Lower resolution data show that this event lasted for 6 min and that more than 1 000 000 v ...

Mozer, F.; Bale, S.; Bonnell, J; Chaston, C.; Roth, I.; Wygant, J.;

YEAR: 2013     DOI: 10.1103/PhysRevLett.111.235002

Van Allen Probes

\textquotedblleftNonempty\textquotedblright Gap Between Radiation Belts: The First Observations

The first space experiments carried out in 1958 by the scientific groups of James Van Allen (United States) on board the first Explorer satellites and Sergey Vernov (Soviet Union) on board the satellite Sputnik 3 led to the discovery of the Earth\textquoterights radiation belts\textemdashthe particles (mainly protons and electrons) captured by the magnetic field of the Earth. Two scientific groups independently came to the conclusion that the electrons in the geomagnetic trapping region fill two areas, inner and outer radiat ...

Panasyuk, Mikhail;

YEAR: 2013     DOI: 10.1002/2013EO510006

Earth\textquoterights radiation belts; history of discovery; particle dynamics

Rapid local acceleration of relativistic radiation-belt electrons by magnetospheric chorus

Recent analysis of satellite data obtained during the 9 October 2012 geomagnetic storm identified the development of peaks in electron phase space density1, which are compelling evidence for local electron acceleration in the heart of the outer radiation belt2, 3, but are inconsistent with acceleration by inward radial diffusive transport4, 5. However, the precise physical mechanism responsible for the acceleration on 9 October was not identified. Previous modelling has indicated that a magnetospheric electromagnetic emissio ...

Thorne, R.; Li, W.; Ni, B.; Ma, Q.; Bortnik, J.; Chen, L.; Baker, D.; Spence, H.; Reeves, G.; Henderson, M.; Kletzing, C.; Kurth, W.; Hospodarsky, G.; Blake, J.; Fennell, J.; Claudepierre, S.; Kanekal, S.;

YEAR: 2013     DOI: 10.1038/nature12889

RBSP; Van Allen Probes

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