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Found 723 results

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2013
Authors: Kessel R L, Fox N J, and Weiss M
Title: The Radiation Belt Storm Probes (RBSP) and Space Weather
Abstract: Following the launch and commissioning of NASA’s Radiation Belt Storm Probes (RBSP) in 2012, space weather data will be generated and broadcast from the spacecraft in near real-time. The RBSP mission targets one part of the space weather chain: the very high energy electrons and ions magnetically trapped within Earth’s radiation belts. The understanding gained by RBSP will enable us to better predict the response of the radiation belts to solar storms in the future, and thereby protect space assets in the near-Earth environment. This chapter details the presently planned RBSP capabilities for generating and broadcasting near real-time space weather data, discusses the data products, the ground stations collecting the data, and the users/models that will incorporate the data into test-b. . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 531-543 DOI: 10.1007/s11214-012-9953-6 Available at: http://link.springer.com/article/10.1007%2Fs11214-012-9953-6
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Authors: Turney D, Matiella Novak A, Beisser K, and Fox N
Title: Radiation Belt Storm Probes (RBSP) Education and Public Outreach Program
Abstract: The Radiation Belt Storm Probes (RBSP) Education and Public Outreach (E/PO) program serves as a pipeline of activities to inspire and educate a broad audience about Heliophysics and the Sun-Earth system, specifically the Van Allen Radiation Belts. The program is comprised of a variety of formal, informal and public outreach activities that all align with the NASA Education Portfolio Strategic Framework outcomes. These include lesson plans and curriculum for use in the classroom, teacher workshops, internship opportunities, activities that target underserved populations, collaboration with science centers and NASA visitors’ centers and partnerships with experts in the Heliophysics and education disciplines. This paper will detail the activities that make up the RBSP E/PO program, their in. . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 617-646 DOI: 10.1007/s11214-012-9945-6 Available at: http://link.springer.com/article/10.1007%2Fs11214-012-9945-6
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Authors: Kirby Karen, Artis David, Bushman Stewart, Butler Michael, Conde Rich, et al.
Title: Radiation Belt Storm Probes—Observatory and Environments
Abstract: The National Aeronautics and Space Administration’s (NASA’s) Radiation Belt Storm Probe (RBSP) is an Earth-orbiting mission that launched August 30, 2012, and is the latest science mission in NASA’s Living with a Star Program. The RBSP mission will investigate, characterize and understand the physical dynamics of the radiation belts, as well as the influence of the Sun on the Earth’s environment, by measuring particles, electric and magnetic fields and waves that comprise geospace. The mission is composed of two identically instrumented spinning observatories in an elliptical orbit around earth with 600 km perigee, 30,000 km apogee and 10∘ inclination to provide full sampling of the Van Allen radiation belts. The twin RBSP observatories (recently renamed the Van Allen Probes) wil. . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 59-125 DOI: 10.1007/s11214-012-9949-2 Available at: http://link.springer.com/article/10.1007%2Fs11214-012-9949-2
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Authors: Baker D N, Kanekal S G, Hoxie V C, Batiste S, Bolton M, et al.
Title: The Relativistic Electron-Proton Telescope (REPT) Instrument on Board the Radiation Belt Storm Probes (RBSP) Spacecraft: Characterization of Earth’s Radiation Belt High-Energy Particle Populations
Abstract: Particle acceleration and loss in the million electron Volt (MeV) energy range (and above) is the least understood aspect of radiation belt science. In order to measure cleanly and separately both the energetic electron and energetic proton components, there is a need for a carefully designed detector system. The Relativistic Electron-Proton Telescope (REPT) on board the Radiation Belt Storm Probe (RBSP) pair of spacecraft consists of a stack of high-performance silicon solid-state detectors in a telescope configuration, a collimation aperture, and a thick case surrounding the detector stack to shield the sensors from penetrating radiation and bremsstrahlung. The instrument points perpendicular to the spin axis of the spacecraft and measures high-energy electrons (up to ∼20 MeV) with exc. . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 337-381 DOI: 10.1007/s11214-012-9950-9 Available at: http://link.springer.com/article/10.1007%2Fs11214-012-9950-9
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Authors: Mazur J, Friesen L, Lin A, Mabry D, Katz N, et al.
Title: The Relativistic Proton Spectrometer (RPS) for the Radiation Belt Storm Probes Mission
Abstract: The Relativistic Proton Spectrometer (RPS) on the Radiation Belt Storm Probes spacecraft is a particle spectrometer designed to measure the flux, angular distribution, and energy spectrum of protons from ∼60 MeV to ∼2000 MeV. RPS will investigate decades-old questions about the inner Van Allen belt proton environment: a nearby region of space that is relatively unexplored because of the hazards of spacecraft operation there and the difficulties in obtaining accurate proton measurements in an intense penetrating background. RPS is designed to provide the accuracy needed to answer questions about the sources and losses of the inner belt protons and to obtain the measurements required for the next-generation models of trapped protons in the magnetosphere. In addition to detailed informati. . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 221-261 DOI: 10.1007/s11214-012-9926-9 Available at: http://link.springer.com/article/10.1007%2Fs11214-012-9926-9
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Authors: Spence H E, Reeves G D, Baker D N, Blake J B, Bolton M, et al.
Title: Science Goals and Overview of the Energetic Particle, Composition, and Thermal Plasma (ECT) Suite on NASA’s Radiation Belt Storm Probes (RBSP) Mission
Abstract: The Radiation Belt Storm Probes (RBSP)-Energetic Particle, Composition, and Thermal Plasma (ECT) suite contains an innovative complement of particle instruments to ensure the highest quality measurements ever made in the inner magnetosphere and radiation belts. The coordinated RBSP-ECT particle measurements, analyzed in combination with fields and waves observations and state-of-the-art theory and modeling, are necessary for understanding the acceleration, global distribution, and variability of radiation belt electrons and ions, key science objectives of NASA’s Living With a Star program and the Van Allen Probes mission. The RBSP-ECT suite consists of three highly-coordinated instruments: the Magnetic Electron Ion Spectrometer (MagEIS), the Helium Oxygen Proton Electron (HOPE) senso. . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 311-336 DOI: DOI: 10.1007/s11214-013-0007-5 Available at: http://link.springer.com/article/10.1007%2Fs11214-013-0007-5
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Authors: Mauk B H, Fox N J, Kanekal S G, Kessel R L, Sibeck D G, et al.
Title: Science Objectives and Rationale for the Radiation Belt Storm Probes Mission
Abstract: The NASA Radiation Belt Storm Probes (RBSP) mission addresses how populations of high energy charged particles are created, vary, and evolve in space environments, and specifically within Earth’s magnetically trapped radiation belts. RBSP, with a nominal launch date of August 2012, comprises two spacecraft making in situ measurements for at least 2 years in nearly the same highly elliptical, low inclination orbits (1.1×5.8 RE, 10∘). The orbits are slightly different so that 1 spacecraft laps the other spacecraft about every 2.5 months, allowing separation of spatial from temporal effects over spatial scales ranging from ∼0.1 to 5 RE. The uniquely comprehensive suite of instruments, identical on the two spacecraft, measures all of the particle (electrons, ions, ion composition), fiel. . .
Date: 11/2013 Publisher: Space Science Reviews Pages: 3-27, DOI: 10.1007/s11214-012-9908-y Available at: http://link.springer.com/article/10.1007%2Fs11214-012-9908-y
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Authors: Shprits Yuri Y, Subbotin Dmitriy, Drozdov Alexander, Usanova Maria E., Kellerman Adam, et al.
Title: Unusual stable trapping of the ultrarelativistic electrons in the Van Allen radiation belts
Abstract: Radiation in space was the first discovery of the space age. Earth’s radiation belts consist of energetic particles that are trapped by the geomagnetic field and encircle the planet1. The electron radiation belts usually form a two-zone structure with a stable inner zone and a highly variable outer zone, which forms and disappears owing to wave–particle interactions on the timescale of a day, and is strongly influenced by the very-low-frequency plasma waves. Recent observations revealed a third radiation zone at ultrarelativistic energies2, with the additional medium narrow belt (long-lived ring) persisting for approximately 4 weeks. This new ring resulted from a combination of electron losses to the interplanetary medium and scattering by electromagnetic ion cyclotron waves to the Ear. . .
Date: 11/2013 Publisher: Nature Physics Pages: 699 - 703 DOI: 10.1038/nphys2760 Available at: http://www.nature.com/doifinder/10.1038/nphys2760
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Authors: Shprits Yuri, Kellerman Adam, Kondrashov Dmitri, and Subbotin Dmitriy
Title: Application of a new data operator-splitting data assimilation technique to the 3-D VERB diffusion code and CRRES measurements
Abstract: In this study we present 3-D data assimilation using CRRES data and 3-D Versatile Electron Radiation Belt Model (VERB) using a newly developed operator-splitting method. Simulations with synthetic data show that the operator-splitting Kalman filtering technique proposed in this study can successfully reconstruct the underlying dynamic evolution of the radiation belts. The method is further verified by the comparison with the conventional Kalman filter. We applied the new approach to 3-D data assimilation of real data to globally reconstruct the dynamics of the radiation belts using pitch angle, energy, and L shell dependent CRRES observations. An L shell time cross section of the global data assimilation results for nearly equatorially mirroring particles and high and low values of the fir. . .
Date: 10/2013 Publisher: Geophysical Research Letters Pages: 4998 - 5002 DOI: 10.1002/grl.50969 Available at: http://doi.wiley.com/10.1002/grl.50969
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Authors: Li X, Schiller Q., Blum L., Califf S., Zhao H., et al.
Title: First Results from CSSWE CubeSat: Characteristics of Relativistic Electrons in the Near-Earth Environment During the October 2012 Magnetic Storms
Abstract: Measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) on board the Colorado Student Space Weather Experiment (CSSWE) CubeSat mission, which was launched into a highly inclined (65°) low Earth orbit, are analyzed along with measurements from the Relativistic Electron and Proton Telescope (REPT) and the Magnetic Electron Ion Spectrometer (MagEIS) instruments aboard the Van Allen Probes, which are in a low inclination (10°) geo-transfer-like orbit. Both REPT and MagEIS measure the full distribution of energetic electrons as they traverse the heart of the outer radiation belt. However, due to the small equatorial loss cone (only a few degrees), it is difficult for REPT and MagEIS to directly determine which electrons will precipitate into the. . .
Date: 10/2013 Publisher: Journal of Geophysical Research: Space Physics DOI: 10.1002/2013JA019342 Available at: http://doi.wiley.com/10.1002/2013JA019342
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Authors: Allen R. C., Zhang J., Kistler L. M., Spence H E, Lin R. -L., et al.
Title: Multiple bidirectional EMIC waves observed by Cluster at middle magnetic latitudes in the dayside magnetosphere
Abstract: It is well accepted that the propagation of electromagnetic ion cyclotron (EMIC) waves are bidirectional near their source regions and unidirectional when away from these regions. The generally believed source region for EMIC waves is around the magnetic equatorial plane. Here we describe a series of EMIC waves in the Pc1 (0.2–5 Hz) frequency band above the local He+ cyclotron frequency observed in situ by all four Cluster spacecraft on 9 April 2005 at midmagnetic latitudes (MLAT = ~33°–49°) with L = 10.7–11.5 on the dayside (MLT = 10.3–10.4). A Poynting vector spectrum shows that the wave packets consist of multiple groups of packets propagating bidirectionally, rather than unidirectionally, away from the equator, while the local plasma conditions indicate that the spacecraft ar. . .
Date: 10/2013 Publisher: Journal of Geophysical Research: Space Physics Pages: n/a - n/a DOI: 10.1002/jgra.50600 Available at: http://doi.wiley.com/10.1002/jgra.50600
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Authors: Oliveira T C, Rocco E M, Prado A F B A, and Ferreira J L
Title: A Study of the Duration of the Passage through the Van Allen Belts for a Spacecraft going to the Moon
Abstract: This paper has the goal of estimating the fuel consumption and the duration of the transit in the Van Allen belts for a flight of a spacecraft going from the Earth to the Moon. This problem is very important because the region interior to the belts have a high density of energetic charged particles that can damage the satellite, so minimizing this transit time helps in protecting the equipments on board. The propulsive force is assumed to have a low magnitude and to be applied in the direction of the motion of the spacecraft to maximize the energy transferred to the space vehicle. Perturbation forces are considered in the dynamical model and they influence in both results, consumption and transit time.
Date: 10/2013 Publisher: Journal of Physics: Conference Series Pages: 012019 DOI: 10.1088/1742-6596/465/1/012019 Available at: http://stacks.iop.org/1742-6596/465/i=1/a=012019?key=crossref.8db9dc1daa7ce88541072ab6d8bc425b
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Authors: Li W, Ni B, Thorne R M, Bortnik J, Green J C, et al.
Title: Constructing the global distribution of chorus wave intensity using measurements of electrons by the POES satellites and waves by the Van Allen Probes
Abstract: We adopt a physics-based technique to infer chorus wave amplitudes from the low-altitude electron population (30–100 keV) measured by multiple Polar Orbiting Environmental Satellites (POES), which provide extensive coverage over a broad region in L-shell and magnetic local time (MLT). This technique is validated by analyzing conjunction events between the Van Allen Probes measuring chorus wave amplitudes near the equator and POES satellites measuring the 30–100 keV electron population at the conjugate low altitudes. We apply this technique to construct the chorus wave distributions during the 8–9 October storm in 2012 and demonstrate that the inferred chorus wave amplitudes agree reasonably well with conjugate measurements of chorus wave amplitudes from the Van Allen Probes. The . . .
Date: 09/2013 Publisher: Geophysical Research Letters Pages: 4526 - 4532 DOI: 10.1002/grl.v40.1710.1002/grl.50920 Available at: http://doi.wiley.com/10.1002/grl.v40.17http://doi.wiley.com/10.1002/grl.50920
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Authors: Smith Evan J., Butler Michael H., Fretz Kristin, and Wilhelm Benjamin
Title: Lithium Ion Battery Fault Management on the Van Allen Probes
Abstract: The Van Allen Probes (formerly known as the Radiation Belt Storm Probes or RBSP) mission launched on 30 August 2012 as part of NASA’s Living With a Star (LWS) Program. The ultimate goal of the mission is to understand how populations of relativistic electrons and penetrating ions in the Earth’s Van Allen Radiation Belts are affected by the Sun. The mission consists of two nearly identical observatories orbiting in highly-elliptical Earth orbits. The two satellite system allows for the study of the spatial and temporal effects the Sun has on the Earth’s radiation belts. Each observatory is equipped with a suite of instruments designed to continuously study ions, electrons and the local magnetic and electric fields. A brief overview of the Van Allen Probe mission is pre. . .
Date: 09/2013 Publisher: American Institute of Aeronautics and Astronautics DOI: 10.2514/6.2013-5526 Available at: http://arc.aiaa.org/doi/pdf/10.2514/6.2013-5526
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Authors: Morley S. K., Henderson M G, Reeves G D, Friedel R H W, and Baker D N
Title: Phase Space Density matching of relativistic electrons using the Van Allen Probes: REPT results
Abstract: 1] Phase Space Density (PSD) matching can be used to identify the presence of nonadiabatic processes, evaluate accuracy of magnetic field models, or to cross-calibrate instruments. Calculating PSD in adiabatic invariant coordinates requires a global specification of the magnetic field. For a well specified global magnetic field, nonadiabatic processes or inadequate cross calibration will give a poor PSD match. We have calculated PSD(μ, K) for both Van Allen Probes using a range of models and compare these PSDs at conjunctions in L* (for given μ, K). We quantitatively assess the relative goodness of each model for radiation belt applications. We also quantify the uncertainty in the model magnetic field magnitude and the related uncertainties in PSD, which has applications for modeling and. . .
Date: 09/2013 Publisher: Geophysical Research Letters Pages: 4798–4802 DOI: 10.1002/grl.50909 Available at: http://doi.wiley.com/10.1002/grl.50909
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Authors: de Soria-Santacruz M., Orlova K. G., Martinez-Sanchez M., and Shprits Y Y
Title: Scattering rates of inner belt protons by EMIC waves: A comparison between test particle and diffusion simulations
Abstract: Inner belt energetic protons are a hindrance to development of space technologies. The emission of electromagnetic ion cyclotron (EMIC) waves from spaceborne transmitters has been proposed as a way to solve this problem. The interaction between particles and narrowband emissions has been typically studied using nonlinear test particle simulations. We show that this formulation results in a random walk of the inner belt protons in velocity space. In this paper we compute bounce-averaged pitch angle diffusion rates from test particle simulations and compare them to those of quasi-linear theory for quasi-monochromatic EMIC waves interacting with inner belt protons. We find that the quasi-linear solution is not sensitive to the frequency bandwidth for narrow distributions. Bounce-averaged diff. . .
Date: 09/2013 Publisher: Geophysical Research Letters Pages: 4793–4797 DOI: 10.1002/grl.50925 Available at: http://doi.wiley.com/10.1002/grl.50925
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Authors: Harvey Raymond J., and Eichstedt John
Title: Van Allen Probes Low Cost Mission Operations Concept and Lessons Learned
Abstract: Following a successful 60-day commissioning period, NASA’s Radiation Belt Storm Probes (RBSP) mission, was renamed Van Allen Probes in honor of the discoverer of Earth’s radiation belts – James Van Allen. The Johns Hopkins University’s Applied Physics Laboratory (APL) executed the mission and is currently operating the twin spacecraft in their primary mission. Improving on the cost-savings concepts employed by prior APL projects, the Van Allen Probes mission operations was designed from the start for low-cost, highly-automated mission operations. This concept is realized with automated initial planning and contact scheduling, unattended real-time operations, and spacecraft performance assessment from the review of data products that have been automatically generat. . .
Date: 09/2013 Publisher: American Institute of Aeronautics and Astronautics DOI: 10.2514/MSPACE1310.2514/6.2013-5450 Available at: http://arc.aiaa.org/doi/abs/10.2514/6.2013-5450
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Authors: Claudepierre S G, Mann I R, Takahashi K, Fennell J F, Hudson M K, et al.
Title: Van Allen Probes observation of localized drift-resonance between poloidal mode ultra-low frequency waves and 60 keV electrons
Abstract: [1] We present NASA Van Allen Probes observations of wave-particle interactions between magnetospheric ultra-low frequency (ULF) waves and energetic electrons (20–500 keV) on 31 October 2012. The ULF waves are identified as the fundamental poloidal mode oscillation and are excited following an interplanetary shock impact on the magnetosphere. Large amplitude modulations in energetic electron flux are observed at the same period (≈ 3 min) as the ULF waves and are consistent with a drift-resonant interaction. The azimuthal mode number of the interacting wave is estimated from the electron measurements to be ~40, based on an assumed symmetric drift resonance. The drift-resonant interaction is observed to be localized and occur over 5–6 wave cycles, demonstrating peak electron flux modul. . .
Date: 09/2013 Publisher: Geophysical Research Letters Pages: 4491–4497 DOI: 10.1002/grl.50901 Available at: http://onlinelibrary.wiley.com/doi/10.1002/grl.50901/full
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Authors: Mauk B H
Title: Analysis of EMIC-wave-moderated flux limitation of measured energetic ion spectra in multispecies magnetospheric plasmas
Abstract: A differential Kennel-Petschek (KP) flux limit for magnetospheric energetic ions is devised taking into account multiple ion species effects on electromagnetic ion cyclotron (EMIC) waves that scatter the ions. The idea is that EMIC waves may limit the highest ion intensities during acceleration phases of storms and substorms (~ hour) while other mechanisms (e.g., charge exchange) may account for losses below those limits and over longer periods of time. This approach is applied to published Earth magnetosphere energetic ion spectra (~ keV to ~1 MeV) for radial positions (L) 3 to 6.7 RE. The flatness of the most intense spectral shapes for <100 keV indicate sculpting by just such a mechanism, but modifications of traditional KP parameters are needed to account for maximum fluxes up to 5. . .
Date: 08/2013 Publisher: Geophysical Research Letters Pages: 3804 - 3808 DOI: 10.1002/grl.50789 Available at: http://doi.wiley.com/10.1002/grl.50789
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Authors: Dai L, Takahashi K, Wygant J R, Chen L, Bonnell J W, et al.
Title: Excitation of Poloidal standing Alfven waves through the drift resonance wave-particle interaction
Abstract: Drift-resonance wave-particle interaction is a fundamental collisionless plasma process studied extensively in theory. Using cross-spectral analysis of electric field, magnetic field, and ion flux data from the Van Allen Probe (Radiation Belt Storm Probes) spacecraft, we present direct evidence identifying the generation of a fundamental mode standing poloidal wave through drift-resonance interactions in the inner magnetosphere. Intense azimuthal electric field (Eφ) oscillations as large as 10mV/m are observed, associated with radial magnetic field (Br) oscillations in the dawn-noon sector near but south of the magnetic equator at L∼5. The observed wave period, Eφ/Br ratio and the 90° phase lag between Br and Eφ are all consistent with fundamental mode standing Poloidal waves. Phase . . .
Date: 08/2013 Publisher: Geophysical Research Letters DOI: 10.1002/grl.50800 Available at: http://onlinelibrary.wiley.com/doi/10.1002/grl.50800/full
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Authors: Funsten H O, Skoug R M, Guthrie A A, MacDonald E A, Baldonado J R, et al.
Title: Helium, Oxygen, Proton, and Electron (HOPE) Mass Spectrometer for the Radiation Belt Storm Probes Mission
Abstract: The HOPE mass spectrometer of the Radiation Belt Storm Probes (RBSP) mission (renamed the Van Allen Probes) is designed to measure the in situ plasma ion and electron fluxes over 4π sr at each RBSP spacecraft within the terrestrial radiation belts. The scientific goal is to understand the underlying physical processes that govern the radiation belt structure and dynamics. Spectral measurements for both ions and electrons are acquired over 1 eV to 50 keV in 36 log-spaced steps at an energy resolution ΔE FWHM/E≈15 %. The dominant ion species (H+, He+, and O+) of the magnetosphere are identified using foil-based time-of-flight (TOF) mass spectrometry with channel electron multiplier (CEM) detectors. Angular measurements are derived using five polar pixels coplanar with the spacecraft spin. . .
Date: 08/2013 Publisher: Space Science Reviews DOI: 10.1007/s11214-013-9968-7 Available at: http://link.springer.com/article/10.1007%2Fs11214-013-9968-7
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Authors: Artemyev A. V., Agapitov O. V., Mourenas D., Krasnoselskikh V., and Zelenyi L. M.
Title: Storm-induced energization of radiation belt electrons: Effect of wave obliquity
Abstract: New Cluster statistics allow us to determine for the first time the variations of both the obliquity and intensity of lower-band chorus waves as functions of latitude and geomagnetic activity near L∼5. The portion of wave power in very oblique waves decreases during highly disturbed periods, consistent with increased Landau damping by inward-penetrating suprathermal electrons. Simple analytical considerations as well as full numerical calculations of quasi-linear diffusion rates demonstrate that early-time electron acceleration occurs in a regime of loss-limited energization. In this regime, the average wave obliquity plays a critical role in mitigating lifetime reduction as wave intensity increases with geomagnetic activity, suggesting that much larger energization levels should be reac. . .
Date: 08/2013 Publisher: Geophysical Research Letters Pages: 4138 - 4143 DOI: 10.1002/grl.50837 Available at: http://doi.wiley.com/10.1002/grl.50837
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Authors: Li W, Thorne R M, Bortnik J, Reeves G D, Kletzing C A, et al.
Title: An unusual enhancement of low-frequency plasmaspheric hiss in the outer plasmasphere associated with substorm-injected electrons
Abstract: Both plasmaspheric hiss and chorus waves were observed simultaneously by the two Van Allen Probes in association with substorm-injected energetic electrons. Probe A, located inside the plasmasphere in the postdawn sector, observed intense plasmaspheric hiss, whereas Probe B observed chorus waves outside the plasmasphere just before dawn. Dispersed injections of energetic electrons were observed in the dayside outer plasmasphere associated with significant intensification of plasmaspheric hiss at frequencies down to ~20 Hz, much lower than typical hiss wave frequencies of 100–2000 Hz. In the outer plasmasphere, the upper energy of injected electrons agrees well with the minimum cyclotron resonant energy calculated for the lower cutoff frequency of the observed hiss, and computed conve. . .
Date: 08/2013 Publisher: Geophysical Research Letters Pages: 3798 - 3803 DOI: 10.1002/grl.50787 Available at: http://doi.wiley.com/10.1002/grl.50787
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Authors: Reeves G D, Spence H E, Henderson M G, Morley S. K., Friedel R H W, et al.
Title: Electron Acceleration in the Heart of the Van Allen Radiation Belts
Abstract: The Van Allen radiation belts contain ultrarelativistic electrons trapped in Earth’s magnetic field. Since their discovery in 1958, a fundamental unanswered question has been how electrons can be accelerated to such high energies. Two classes of processes have been proposed: transport and acceleration of electrons from a source population located outside the radiation belts (radial acceleration) or acceleration of lower-energy electrons to relativistic energies in situ in the heart of the radiation belts (local acceleration). We report measurements from NASA’s Van Allen Radiation Belt Storm Probes that clearly distinguish between the two types of acceleration. The observed radial profiles of phase space density are characteristic of local acceleration in the heart of the radiation belt. . .
Date: 07/2013 Publisher: Science Pages: 991 - 994 DOI: 10.1126/science.1237743 Available at: http://www.sciencemag.org/cgi/doi/10.1126/science.1237743
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Authors: Butler M. H.
Title: The Van Allen Probes Power System Launch and Early Mission Performance
Abstract: The Van Allen Probes are twin NASA spacecraft that were launched August 30, 2012, into lapping highly elliptical earth orbits. The twin spacecraft will operate within the Van Allen radiation belts throughout their two-year mission. The Van Allen Probes are sponsored by NASA’s Living With a Star (LWS) Program. The Johns Hopkins University, Applied Physics Laboratory designed, fabricated, and operates the twin spacecraft for NASA. The power systems of the twin spacecraft are identical. A direct energy transfer topology was selected for the power system. The loads are connected directly to the eight-cell Lithium Ion battery. The solar panels consist of triple junction cells. The design average power of each spacecraft is about 350 Watts, nominal 28.8 volt bus. A single 50 AH . . .
Date: 07/2013 Publisher: American Institute of Aeronautics and Astronautics DOI: 10.2514/MIECEC1310.2514/6.2013-3737 Available at: http://arc.aiaa.org/doi/abs/10.2514/6.2013-3737
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Authors: Thorne R M, Li W, Ni B, Ma Q, Bortnik J, et al.
Title: Evolution and slow decay of an unusual narrow ring of relativistic electrons near L ~ 3.2 following the September 2012 magnetic storm
Abstract: A quantitative analysis is performed on the decay of an unusual ring of relativistic electrons between 3 and 3.5 RE, which was observed by the Relativistic Electron Proton Telescope instrument on the Van Allen probes. The ring formed on 3 September 2012 during the main phase of a magnetic storm due to the partial depletion of the outer radiation belt for L > 3.5, and this remnant belt of relativistic electrons persisted at energies above 2 MeV, exhibiting only slow decay, until it was finally destroyed during another magnetic storm on 1 October. This long-term stability of the relativistic electron ring was associated with the rapid outward migration and maintenance of the plasmapause to distances greater than L = 4. The remnant ring was thus immune from the dynamic process, whic. . .
Date: 06/2013 Publisher: Geophysical Research Letters DOI: 10.1002/grl.50627 Available at: http://onlinelibrary.wiley.com/doi/10.1002/grl.50627/full
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Authors: Min Kyungguk, Bortnik J, and Lee Jeongwoo
Title: A novel technique for rapid L∗ calculation: algorithm and implementation
Abstract: Computing the magnetic drift invariant, L*, rapidly and accurately has always been a challenge to magnetospheric modelers, especially given the im- portance of this quantity in the radiation belt community. Min et al. (2013) proposed a new method of calculating L* using the principle of energy con- servation. Continuing with the approach outlined therein, the present pa- per focuses on the technical details of the algorithm to outline the implemen- tation, systematic analysis of accuracy, and verification of the speed of the new method. We also show new improvements which enable near real-time computation of L*. The relative error is on the order of 10−3 when ∼ 0.1 RE grid resolution is used and the calculation speed is about two seconds per particle in the popular Tsyganenko. . .
Date: 05/2013 Publisher: Journal of Geophysical Research Pages: 1912-1921 DOI: 10.1002/jgra.50250 Available at: http://onlinelibrary.wiley.com/doi/10.1002/jgra.50250/full
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Authors: Lee Jeongwoo, Min Kyungguk, and Kim Kap-Sung
Title: Characteristic dimension of electromagnetic ion cyclotron wave activity in the magnetosphere
Abstract: [1] In this paper, we estimate the size of coherent activity of electromagnetic ion cyclotron (EMIC) waves using the multi‒spacecraft observations made during the Time History of Events and Macroscale Interactions during Substorms (THEMIS) mission. We calculate the cross‒correlations between EMIC wave powers measured by different THEMIS spacecraft, plot them over the separation distances between pairs of observing spacecraft, and determine the 1/e folding distance of the correlations as the characteristic dimension of the coherent wave activity. The characteristic radius in the direction transverse to the local magnetic field is found to lie in rather a wide range of 1500–8600 km varying from the AM to PM sectors and also from hydrogen to helium bands. However, the characteristic d. . .
Date: 04/2013 Publisher: Journal of Geophysical Research: Space Physics Pages: 1651 - 1658 DOI: 10.1002/jgra.50242 Available at: http://doi.wiley.com/10.1002/jgra.50242
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Authors: Baker D N, Kanekal S G, Hoxie V C, Henderson M G, Li X, et al.
Title: A Long-Lived Relativistic Electron Storage Ring Embedded in Earth's Outer Van Allen Belt
Abstract: Since their discovery more than 50 years ago, Earth’s Van Allen radiation belts have been considered to consist of two distinct zones of trapped, highly energetic charged particles. The outer zone is composed predominantly of megaelectron volt (MeV) electrons that wax and wane in intensity on time scales ranging from hours to days, depending primarily on external forcing by the solar wind. The spatially separated inner zone is composed of commingled high-energy electrons and very energetic positive ions (mostly protons), the latter being stable in intensity levels over years to decades. In situ energy-specific and temporally resolved spacecraft observations reveal an isolated third ring, or torus, of high-energy (>2 MeV) electrons that formed on 2 September 2012 and persisted largely unc. . .
Date: 04/2013 Publisher: Science Pages: 186-190 DOI: 10.1126/science.1233518 Available at: http://www.sciencemag.org/content/340/6129/186
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Authors: Kirby Karen, and Stratton Jim
Title: Van Allen Probes: Successful launch campaign and early operations exploring Earth's radiation belts
Abstract: The twin Van Allen Probe observatories developed at The Johns Hopkins University Applied Physics Laboratory for NASA's Heliophysics Division completed final observatory integration and environmental test activities and were successfully launched into orbit around the Earth on August 30, 2012. As the science operations phase begins, the mission is providing exciting new information about the impact of radiation belt activity on the earth. The on-board boom mounted magnetometers and other instruments are the most sensitive sensors of their type that have ever flown in the Van Allen radiation belts. The observatories are producing near-Earth space weather information that can be used to provide warnings of potential power grid interruptions or satellite damaging storms. The Van Allen Probes a. . .
Date: 03/2013 Publisher: IEEE DOI: 10.1109/AERO.2013.6496838 Available at: http://ieeexplore.ieee.org/lpdocs/epic03/wrapper.htm?arnumber=6496838
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Authors: Stratton J M, Harvey R J, and Heyler G A
Title: Mission Overview for the Radiation Belt Storm Probes Mission
Abstract: Provided here is an overview of Radiation Belt Storm Probes (RBSP) mission design. The driving mission and science requirements are presented, and the unique engineering challenges of operating in Earth’s radiation belts are discussed in detail. The implementation of both the space and ground segments are presented, including a discussion of the challenges inherent with operating multiple observatories concurrently and working with a distributed network of science operation centers. An overview of the launch vehicle and the overall mission design will be presented, and the plan for space weather data broadcast will be introduced.
Date: 01/2013 Publisher: Space Science Reviews DOI: 10.1007/s11214-012-9933-x Available at: http://link.springer.com/article/10.1007%2Fs11214-012-9933-x
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Authors: Min Kyungguk, Bortnik J, and Lee Jeongwoo
Title: A novel technique for rapid L* calculation using UBK coordinates
Abstract: [1] The magnetic drift invariant (L*) is an important quantity used for tracking and organizing particle dynamics in the radiation belts, but its accurate calculation has been computationally expensive in the past, thus making it difficult to employ this quantity in real-time space weather applications. In this paper, we propose a new, efficient method to calculate L* using the principle of energy conservation. This method uses Whipple's (U, B, K) coordinates to quickly and accurately determine trajectories of particles at the magnetic mirror point from two-dimensional isoenergy contours. The method works for any magnetic field configuration and is able to accommodate constant electric potential along field lines. We compare the result of this method with those of International Radiation B. . .
Date: 01/2013 Publisher: Journal of Geophysical Research DOI: 10.1029/2012JA018177
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Authors: Ukhorskiy A Y, Sitnov M I, Merkin V. G., and Artemyev A. V.
Title: Rapid acceleration of protons upstream of earthward propagating dipolarization fronts
Abstract: [1] Transport and acceleration of ions in the magnetotail largely occurs in the form of discrete impulsive events associated with a steep increase of the tail magnetic field normal to the neutral plane (Bz), which are referred to as dipolarization fronts. The goal of this paper is to investigate how protons initially located upstream of earthward moving fronts are accelerated at their encounter. According to our analytical analysis and simplified two-dimensional test-particle simulations of equatorially mirroring particles, there are two regimes of proton acceleration: trapping and quasi-trapping, which are realized depending on whether the front is preceded by a negative depletion in Bz. We then use three-dimensional test-particle simulations to investigate how these acceleration processe. . .
Date: 01/2013 Publisher: Journal of Geophysical Research: Space Physics Pages: 4952–4962, DOI: 10.1002/jgra.50452 Available at: http://doi.wiley.com/10.1002/jgra.50452
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Authors: Fox N. J., and Burch J. L.
Title: The Van Allen Probes Mission
Abstract: N/A
Date: Publisher: Springer Pages: 646 DOI: N/A Available at: http://www.springer.com/astronomy/extraterrestrial+physics,+space+sciences/book/978-1-4899-7432-7
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2012
Authors: Brito T, Woodger L, Hudson M K, and MILLAN R
Title: Energetic radiation belt electron precipitation showing ULF modulation
Abstract: 1] The energization and loss processes for energetic radiation belt electrons are not yet well understood. Ultra Low Frequency (ULF) waves have been correlated with both enhancement in outer zone radiation belt electron flux and modulation of precipitation loss to the atmosphere. This study considers the effects of ULF waves in the Pc-4 to Pc-5 period range (45 s–600 s) on electron loss to the atmosphere on a time scale of several minutes. 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-Mobarry (LFM) 3D MHD code calculation of fields, used to drive elec. . .
Date: 11/2012 Publisher: Geophysical Research Letters Pages: 28 DOI: 10.1029/2012GL053790 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2012GL053790/full
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Authors: Jordanova V K, Welling D T, Zaharia S G, Chen L, and Thorne R M
Title: Modeling ring current ion and electron dynamics and plasma instabilities during a high-speed stream driven storm
Abstract: 1] The temporal and spatial development of the ring current is evaluated during the 23–26 October 2002 high-speed stream (HSS) storm, using a kinetic ring current-atmosphere interactions model with self-consistent magnetic field (RAM-SCB). The effects of nondipolar magnetic field configuration are investigated on both ring current ion and electron dynamics. As the self-consistent magnetic field is depressed at large (>4RE) radial distances on the nightside during the storm main phase, the particles' drift velocities increase, the ion and electron fluxes are reduced and the ring current is confined closer to Earth. In contrast to ions, the electron fluxes increase closer to Earth and the fractional electron energy reaches ∼20% near storm peak due to better electron trapping in a nondipo. . .
Date: 09/2012 Publisher: Journal of Geophysical Research Pages: 1978–2012 DOI: 10.1029/2011JA017433 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2011JA017433/full
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Authors: Bushman Stewart
Title: Design, Fabrication, and Testing of the Radiation Belt Storm Probes Propulsion Systems
Abstract: The Radiation Belt Storm Probes spacecraft , part of NASA’s Living with a Star program, are scheduled for launch into Earth orbit in August 2012. 1,2,3 The twin spacecraft possess identical blowdown monopropellant hydrazine propulsion systems to provide spinup/spindown, precession, Delt a–V, and deorbit capability. Each spacecraft manifests eight Aerojet 0.2 lbf (0.9 N) MR–103G thrust ers, three ARDÉ Inconel 718 propellant tanks, and other components required to control the fl ow of propellant and monitor system health and performance. The propulsion systems were fabricated and installed by Aerojet Redmond and subsequently tested at the Jo hns Hopkins University / Applied Physics Laboratory (APL) in Laurel, MD. The test se quence at APL included thermal balance; . . .
Date: 08/2012 Publisher: American Institute of Aeronautics and Astronautics DOI: 10.2514/6.2012-4332 Available at: http://arc.aiaa.org/doi/abs/10.2514/6.2012-4332
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Authors: Butler Michael, and Laughery Sean
Title: The RBSP Spacecraft Power System Design and Development
Abstract: The RBSP (Radiation Belt Storm Probes) twin spacecraft are set to launch in August 2012. The spacecraft will be inserted into the highly elliptical regions of high energy particles trapped by the magnetic field of the earth. These regions are often referred to as the Van Allen Belts. The twin spacecraft will operate entirely within the radiation belts throughout their mission. Because of the intense environment of operation and to reduce cost and risk, the approach taken in the power system electronics was to use quasi conventional design, materials, and fabrication techniques encased in a 350mil thick aluminum enclosure. The spacecraft are spin stabilized with an axial boom that creates a shadow across the solar arrays. The power system topology selected was a 28V unregulat. . .
Date: 08/2012 Publisher: American Institute of Aeronautics and Astronautics DOI: 10.2514/MIECEC1210.2514/6.2012-4059 Available at: http://arc.aiaa.org/doi/pdf/10.2514/6.2012-4059
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Authors: Hudson M K, Brito Thiago, Elkington Scot, Kress Brian, Li Zhao, et al.
Title: Radiation belt 2D and 3D simulations for CIR-driven storms during Carrington Rotation 2068
Abstract: As part of the International Heliospheric Year, the Whole Heliosphere Interval, Carrington Rotation 2068, from March 20 to April 16, 2008 was chosen as an internationally coordinated observing and modeling campaign. A pair of solar wind structures identified as Corotating Interaction Regions (CIR), characteristic of the declining phase of the solar cycle and solar minimum, was identified in solar wind plasma measurements from the ACE satellite. Such structures have previously been determined to be geoeffective in producing enhanced outer zone radiation belt electron fluxes, on average greater than at solar maximum. MHD fields from the Coupled Magnetosphere–Ionosphere–Thermosphere (CMIT) model driven by ACE solar wind measurements at L1 have been used to drive both 2D and 3D weighted te. . .
Date: 07/2012 Publisher: Journal of Atmospheric and Solar-Terrestrial Physics Pages: 51 - 62 DOI: 10.1016/j.jastp.2012.03.017 Available at: http://www.sciencedirect.com/science/article/pii/S1364682612001010
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Authors: Min Kyungguk, Lee Jeongwoo, Keika Kunihiro, and Li W
Title: Global distribution of EMIC waves derived from THEMIS observations
Abstract: [1] Electromagnetic ion cyclotron (EMIC) waves play an important role in magnetospheric dynamics and their global distribution has been of great interest. This paper presents the distribution of EMIC waves over a broader range than ever before, as enabled by observations with the Time History of Events and Macroscale Interactions during Substorms (THEMIS) spacecraft from 2007 to 2010. Our major findings are: (1) There are two major peaks in the EMIC wave occurrence probability. One is at dusk and 8–12 RE where the helium band dominates the hydrogen band waves. The other is at dawn and 10–12 RE where the hydrogen band dominates the helium band waves. (2) In terms of wave spectral power the dusk events are stronger (≈10 nT2/Hz) than the dawn events (≈3 nT2/Hz). (3) The dawn . . .
Date: 05/2012 Publisher: Journal of Geophysical Research DOI: 10.1029/2012JA017515
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Authors: Kirby Karen, Bushman Stewart, Butler Michael, Conde Rich, Fretz Kristen, et al.
Title: Radiation Belt Storm Probe Spacecraft and Impact of Environment on Spacecraft Design
Abstract: NASA's Radiation Belt Storm Probe (RBSP) is an Earth-orbiting mission scheduled to launch in September 2012 and is the next science mission in NASA's Living with a Star Program. The RBSP mission will investigate, characterize and understand the physical dynamics of the radiation belts, and the influence of the sun on the earth's environment, by measuring particles, electric and magnetic fields and waves that comprise the geospace. The mission is composed of two identically instrumented spinning spacecraft in an elliptical orbit around earth from 600 km perigee to 30,000 km apogee at 10 degree inclination to provide full sampling of the Van Allen radiation belts. The twin spacecraft will follow slightly different orbits and will lap each other 4 times per year; this offers simultaneous meas. . .
Date: 03/2012 Publisher: IEEE DOI: 10.1109/AERO.2012.6187020 Available at: http://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=06187020
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Authors: Turner Drew L, Shprits Yuri, Hartinger Michael, and Angelopoulos Vassilis
Title: Explaining sudden losses of outer radiation belt electrons during geomagnetic storms
Abstract: The Van Allen radiation belts were first discovered in 1958 by the Explorer series of spacecraft1. The dynamic outer belt consists primarily of relativistic electrons trapped by the Earth’s magnetic field. Magnetospheric processes driven by the solar wind2 cause the electron flux in this belt to fluctuate substantially over timescales ranging from minutes to years3. The most dramatic of these events are known as flux ’dropouts’ and often occur during geomagnetic storms. During such an event the electron flux can drop by several orders of magnitude in just a few hours4, 5 and remain low even after a storm has abated. Various solar wind phenomena, including coronal mass ejections and co-rotating interaction regions6, can drive storm activity, but several outstanding questions remain co. . .
Date: 01/2012 Publisher: Nature Publishing Group Pages: 208–212 DOI: 10.1038/nphys2185 Available at: http://dx.doi.org/10.1038/nphys2185
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Authors: Crabtree C., Rudakov L., Ganguli G., Mithaiwala M., Galinsky V., et al.
Title: Weak turbulence in the magnetosphere: Formation of whistler wave cavity by nonlinear scattering
Abstract: We consider the weak turbulence of whistler waves in the in low-β inner magnetosphere of the earth. Whistler waves, originating in the ionosphere, propagate radially outward and can trigger nonlinear induced scattering by thermal electrons provided the wave energy density is large enough. Nonlinear scattering can substantially change the direction of the wave vector of whistler waves and hence the direction of energy flux with only a small change in the frequency. A portion of whistler waves return to the ionosphere with a smaller perpendicular wave vector resulting in diminished linear damping and enhanced ability to pitch-angle scatter trapped electrons. In addition, a portion of the scatteredwave packets can be reflected near the ionosphere back into the magnetosphere. Through multiple. . .
Date: 01/2012 Publisher: Physics of Plasmas Pages: 032903 DOI: 10.1063/1.3692092 Available at: http://scitation.aip.org/content/aip/journal/pop/19/3/10.1063/1.3692092
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2011
Authors: Ukhorskiy Aleksandr Y., Mauk Barry H., Fox Nicola J., Sibeck David G., and Grebowsky Joseph M.
Title: Radiation belt storm probes: Resolving fundamental physics with practical consequences
Abstract: The fundamental processes that energize, transport, and cause the loss of charged particles operate throughout the universe at locations as diverse as magnetized planets, the solar wind, our Sun, and other stars. The same processes operate within our immediate environment, the Earth's radiation belts. The Radiation Belt Storm Probes (RBSP) mission will provide coordinated two-spacecraft observations to obtain understanding of these fundamental processes controlling the dynamic variability of the near-Earth radiation environment. In this paper we discuss some of the profound mysteries of the radiation belt physics that will be addressed by RBSP and briefly describe the mission and its goals.
Date: 07/2011 Publisher: Journal of Atmospheric and Solar-Terrestrial Physics Pages: 1417 - 1424 DOI: 10.1016/j.jastp.2010.12.005 Available at: http://www.sciencedirect.com/science/article/pii/S1364682610003688
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Authors: Millan R.M.
Title: Understanding relativistic electron losses with BARREL
Abstract: The primary scientific objective of the Balloon Array for RBSP Relativistic Electron Losses (BARREL) is to understand the processes responsible for scattering relativistic electrons into Earth's atmosphere. BARREL is the first Living with a Star Geospace Mission of Opportunity, and will consist of two Antarctic balloon campaigns conducted in the 2012 and 2013 Austral summer seasons. During each campaign, a total of 20 small View the MathML source(∼20kg) balloon payloads will be launched, providing multi-point measurements of electron precipitation in conjunction with in situ measurements from the two RBSP spacecraft, scheduled to launch in May 2012. In this paper we outline the scientific objectives of BARREL, highlighting a few key science questions that will be addressed by BARREL in c. . .
Date: 07/2011 Publisher: Journal of Atmospheric and Solar-Terrestrial Physics Pages: 1425 - 1434 DOI: 10.1016/j.jastp.2011.01.006 Available at: http://www.sciencedirect.com/science/article/pii/S1364682611000071
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2010
Authors: Min Kyungguk, Lee Jeongwoo, and Keika Kunihiro
Title: Chorus wave generation near the dawnside magnetopause due to drift shell splitting of substorm-injected electrons
Abstract: We study the relationship between the electron injection and the chorus waves during a substorm event on 23 March 2007. The chorus waves were detected at high geomagnetic latitude (∼70°S) Antarctic observatories in the range of 0600–0900 h in magnetic local time (MLT). Electrons drifting from the injection event were measured by two LANL spacecraft at 0300 and 0900 MLT. The mapping of auroral brightening areas to the magnetic equator shows that the injection occurred in an MLT range of 2200–2400. This estimate is consistent with observations by the THEMIS A, B, and D spacecraft (which were located at 2100 MLT and did not observe electron injections). Our backward model tracing from the magnetic equator near the dawnside magnetopause (which magnetically connects to the Antar. . .
Date: 10/2010 Publisher: American Geophysical Union DOI: 10.1029/2010JA015474
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2009
Authors: Kemp Brian L, McGee Timothy G, and Shankar Uday J
Title: Analysis of Spinning Spacecraft with Wire Booms Part 1: Derivation of Nonlinear Dynamics
Abstract: Algebraic expressions for the governing equations of motion are developed to describe a spinning spacecraft with flexible appendages. Two limiting cases are investigated: appendages that are self-restoring and appendages that require spacecraft motion to restore. Solar panels have sufficient root stiffness to self-restore perturbations. Radial wire antennae have little intrinsic root stiffness and require centripetal acceleration from spacecraft rotations to restore perturbations. External forces applied for attitude corrections can displace spacecraft appendages from their steady-state position. The Radiation Belt Storm Probe (RBSP) satellite is used as an example to explore numerical results for several maneuvers.
Date: 08/2009 Publisher: AIAA Guidance, Navigation, and Control Conference DOI: 10.2514/6.2009-6202 Available at: http://arc.aiaa.org/doi/pdf/10.2514/6.2009-6202
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Authors: McGee Timothy G, Shankar Uday J, and Kemp Brian L
Title: Analysis of Spinning Spacecraft with Wire Booms Part 2: Out-of-Plane Dynamics and Maneuvers
Abstract: An analysis of the dynamics for a spin stabilized spacecraft consisting of a rigid central hub with four long exible wire booms is presented. The analysis focuses on the dynamics out of the spin plane of the spacecraft. Companion papers will focus on the derivations of the full nonlinear dynamics and analysis of the in plane dynamics. A linear analysis is used to estimate the mode shapes of the free response of the system, the e ects of various damping mechanisms on these modes, and the dynamic response of the system to various maneuvers. The results of an independent simulation of the full nonlinear dynamics of the system are also provided to support the linear analysis. While the dynamics and analysis approach presented can be applied to the general class of spin stabilized space. . .
Date: 08/2009 Publisher: AIAA Guidance, Navigation, and Control Conference DOI: 10.2514/6.2009-6203 Available at: http://arc.aiaa.org/doi/pdf/10.2514/6.2009-6203
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Authors: Shankar Uday J, McGee Timothy G, and Kemp Brian L
Title: Analysis of Spinning Spacecraft with Wire Booms Part 3: Spin-Plane Dynamics, Maneuvers, and Deployment
Abstract: Several science spacecraft use long wire booms as electric-field antennas and the spacecraft spins to maintain the orientation of these flexible wires. These booms account for a majority of the total spacecraft inertia while weighing only a small fraction of the total mass. The spacecraft dynamics is therefore dominated by these booms. The analysis of such spacecraft is further complicated by other flexible ap- pendages and the presence of damping in the system, both inherent in the sys- tem and from damping mechanisms deliberately added into the system. This pa- per and two companion papers analyze such spacecraft. The first of these derives the governing nonlinear equations from first principles. Under certain conditions, the dynamics neatly separate into spin-plane and out-of-p. . .
Date: 08/2009 Publisher: AIAA Guidance, Navigation, and Control Conference DOI: 10.2514/6.2009-6204 Available at: http://arc.aiaa.org/doi/pdf/10.2514/6.2009-6204
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Authors: Ohtani S, Miyoshi Y, Singer H J, and Weygand J M
Title: On the loss of relativistic electrons at geosynchronous altitude: Its dependence on magnetic configurations and external conditions
Abstract: [1] The present study statistically examines geosynchronous magnetic configurations and external conditions that characterize the loss of geosynchronous MeV electrons. The loss of MeV electrons often takes place during magnetospheric storms, but it also takes place without any clear storm activity. It is found that irrespective of storm activity, the day-night asymmetry of the geosynchronous H (north-south) magnetic component is pronounced during electron loss events. For the loss process, the magnitude, rather than the duration, of the magnetic distortion appears to be important, and its effective duration can be as short as ∼30 min. The solar wind dynamic pressure tends to be high and interplanetary magnetic field BZ tends to be southward during electron loss events. Under such externa. . .
Date: 01/2009 Publisher: Journal of Geophysical Research DOI: 10.1029/2008JA013391 Available at: http://onlinelibrary.wiley.com/doi/10.1029/2008JA013391/full
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