Bibliography
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Found 4151 entries in the Bibliography.
Showing entries from 3951 through 4000
| 2013 |
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Mission Overview for the Radiation Belt Storm Probes Mission 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\textquoterights 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. Stratton, J.; Harvey, R.; Heyler, G.; Published by: Space Science Reviews Published on: 01/2013 YEAR: 2013 DOI: 10.1007/s11214-012-9933-x |
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A novel technique for rapid L* calculation using UBK coordinates [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\textquoterights (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 Belt Environment Modeling library (IRBEM-LIB) to demonstrate the performance of this new method. The method requires a preparation step, and thus may not be the optimal method for a single trajectory calculation; however, it presents a huge performance gain when adiabatically propagating a large population of particles in a given magnetic field configuration. Min, Kyungguk; Bortnik, J.; Lee, Jeongwoo; Published by: Journal of Geophysical Research Published on: 01/2013 YEAR: 2013 DOI: 10.1029/2012JA018177 |
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Rapid acceleration of protons upstream of earthward propagating dipolarization fronts [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 processes operate in a realistic magnetotail geometry. For this purpose we construct an analytical model of the front which is superimposed onto the ambient field of the magnetotail. According to our numerical simulations, both trapping and quasi-trapping can produce rapid acceleration of protons by more than an order of magnitude. In the case of trapping, the acceleration levels depend on the amount of time particles stay in phase with the front which is controlled by the magnetic field curvature ahead of the front and the front width. Quasi-trapping does not cause particle scattering out of the equatorial plane. Energization levels in this case are limited by the number of encounters particles have with the front before they get magnetized behind it. Ukhorskiy, A; Sitnov, M.; Merkin, V.; Artemyev, A.; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2013 YEAR: 2013 DOI: 10.1002/jgra.50452 |
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Rapid acceleration of protons upstream of earthward propagating dipolarization fronts [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 processes operate in a realistic magnetotail geometry. For this purpose we construct an analytical model of the front which is superimposed onto the ambient field of the magnetotail. According to our numerical simulations, both trapping and quasi-trapping can produce rapid acceleration of protons by more than an order of magnitude. In the case of trapping, the acceleration levels depend on the amount of time particles stay in phase with the front which is controlled by the magnetic field curvature ahead of the front and the front width. Quasi-trapping does not cause particle scattering out of the equatorial plane. Energization levels in this case are limited by the number of encounters particles have with the front before they get magnetized behind it. Ukhorskiy, A; Sitnov, M.; Merkin, V.; Artemyev, A.; Published by: Journal of Geophysical Research: Space Physics Published on: 01/2013 YEAR: 2013 DOI: 10.1002/jgra.50452 |
| 2012 |
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Energetic radiation belt electron precipitation showing ULF modulation 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\textendash600 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 electrons in a 3D test particle simulation that keeps track of attributes like energy, pitch-angle and L-shell. The simulation results are compared with balloon observations obtained during the January 21, 2005 CME-shock event. Rapid loss of 20 keV to 1.5 MeV electrons was detected by balloon-borne measurements ofbremsstrahlungX-rays during the MINIS campaign following the shock arrival at Earth. The global precipitation response of the radiation belts to this CME-shock driven storm was investigated focusing on their interaction with ULF waves. A primary cause for the precipitation modulation seen in both the simulation and the MINIS campaign is suggested based on the lowering of mirror points due to compressional magnetic field oscillations. Brito, T.; Woodger, L.; Hudson, M.; MILLAN, R; Published by: Geophysical Research Letters Published on: 11/2012 YEAR: 2012 DOI: 10.1029/2012GL053790 Charged particle motion and acceleration; Energetic particles: precipitating; Radiation belts; wave-particle interactions |
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1] The temporal and spatial development of the ring current is evaluated during the 23\textendash26 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\textquoteright 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 nondipolar magnetic field. The ring current contribution to Dst calculated using Biot-Savart integration differs little from the DPS relation except during quiet time. RAM-SCB simulations underestimate |SYM-H| minimum by \~25\% but reproduce very well the storm recovery phase. Increased anisotropies develop in the ion and electron velocity distributions in a self-consistent magnetic field due to energy dependent drifts, losses, and dispersed injections. There is sufficient free energy to excite whistler mode chorus, electromagnetic ion cyclotron (EMIC), and magnetosonic waves in the equatorial magnetosphere. The linear growth rate of whistler mode chorus intensifies in the postmidnight to noon sector, EMIC waves are predominantly excited in the afternoon to midnight sector, and magnetosonic waves are excited over a broad MLT range both inside and outside the plasmasphere. The wave growth rates in a dipolar magnetic field have significantly smaller magnitude and spatial extent. Jordanova, V.; Welling, D.; Zaharia, S.; Chen, L.; Thorne, R.; Published by: Journal of Geophysical Research Published on: 09/2012 YEAR: 2012 DOI: 10.1029/2011JA017433 |
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1] The temporal and spatial development of the ring current is evaluated during the 23\textendash26 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\textquoteright 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 nondipolar magnetic field. The ring current contribution to Dst calculated using Biot-Savart integration differs little from the DPS relation except during quiet time. RAM-SCB simulations underestimate |SYM-H| minimum by \~25\% but reproduce very well the storm recovery phase. Increased anisotropies develop in the ion and electron velocity distributions in a self-consistent magnetic field due to energy dependent drifts, losses, and dispersed injections. There is sufficient free energy to excite whistler mode chorus, electromagnetic ion cyclotron (EMIC), and magnetosonic waves in the equatorial magnetosphere. The linear growth rate of whistler mode chorus intensifies in the postmidnight to noon sector, EMIC waves are predominantly excited in the afternoon to midnight sector, and magnetosonic waves are excited over a broad MLT range both inside and outside the plasmasphere. The wave growth rates in a dipolar magnetic field have significantly smaller magnitude and spatial extent. Jordanova, V.; Welling, D.; Zaharia, S.; Chen, L.; Thorne, R.; Published by: Journal of Geophysical Research Published on: 09/2012 YEAR: 2012 DOI: 10.1029/2011JA017433 |
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1] The temporal and spatial development of the ring current is evaluated during the 23\textendash26 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\textquoteright 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 nondipolar magnetic field. The ring current contribution to Dst calculated using Biot-Savart integration differs little from the DPS relation except during quiet time. RAM-SCB simulations underestimate |SYM-H| minimum by \~25\% but reproduce very well the storm recovery phase. Increased anisotropies develop in the ion and electron velocity distributions in a self-consistent magnetic field due to energy dependent drifts, losses, and dispersed injections. There is sufficient free energy to excite whistler mode chorus, electromagnetic ion cyclotron (EMIC), and magnetosonic waves in the equatorial magnetosphere. The linear growth rate of whistler mode chorus intensifies in the postmidnight to noon sector, EMIC waves are predominantly excited in the afternoon to midnight sector, and magnetosonic waves are excited over a broad MLT range both inside and outside the plasmasphere. The wave growth rates in a dipolar magnetic field have significantly smaller magnitude and spatial extent. Jordanova, V.; Welling, D.; Zaharia, S.; Chen, L.; Thorne, R.; Published by: Journal of Geophysical Research Published on: 09/2012 YEAR: 2012 DOI: 10.1029/2011JA017433 |
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The RBSP Spacecraft Power System Design and Development 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 unregulated direct energy transfer (DET) system using an eight cell Li-Ion battery with cell balance electronics. The solar arrays are electrostatically clean with each string layout for magnetic self-cancellation. The spacecraft instruments electrostatic and magnetic cleanliness requirements impacted the design of the solar array, battery, and power system electronic boxes. The paper will cover the design and development of the RBSP spacecraft Power System including the battery, solar arrays, and the power electronics. Butler, Michael; Laughery, Sean; Published by: Published on: 08/2012 YEAR: 2012 DOI: 10.2514/MIECEC1210.2514/6.2012-4059 |
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The RBSP Spacecraft Power System Design and Development 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 unregulated direct energy transfer (DET) system using an eight cell Li-Ion battery with cell balance electronics. The solar arrays are electrostatically clean with each string layout for magnetic self-cancellation. The spacecraft instruments electrostatic and magnetic cleanliness requirements impacted the design of the solar array, battery, and power system electronic boxes. The paper will cover the design and development of the RBSP spacecraft Power System including the battery, solar arrays, and the power electronics. Butler, Michael; Laughery, Sean; Published by: Published on: 08/2012 YEAR: 2012 DOI: 10.2514/MIECEC1210.2514/6.2012-4059 |
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Radiation belt 2D and 3D simulations for CIR-driven storms during Carrington Rotation 2068 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\textendashIonosphere\textendashThermosphere (CMIT) model driven by ACE solar wind measurements at L1 have been used to drive both 2D and 3D weighted test particle simulations of electron dynamics for the CIR subset of the month-long CMIT fields. Dropout in electron flux at geosynchronous orbit and enhancement during recovery phase, characteristic of CIR-driven storms, is seen in these moderate (Dstmin=-56, -33 nT) events, while the two CIRs were characterized by increased solar wind velocity in the 650\textendash750 km/s range. The first beginning March 26 produced a greater enhancement in IMF Bz southward and stronger magnetospheric convection, leading to a greater radiation belt electron response at GOES. This study provides the first comparison of 2D and 3D particle dynamics in MHD simulation fields, incorporating the additional diffusive feature of Shebansky orbit trapping of electrons in the magnetic minima on the dayside above and below the equatorial plane. Overall loss occurs during the main phase for 2D and 3D simulations, while incorporation of plasmasheet injection in 2D runs produces a moderate enhancement for the March 26\textendash30 storm, less than observed at GOES, and recovery to initial flux levels as seen for the April 4\textendash7 storm. Hudson, M.; Brito, Thiago; Elkington, Scot; Kress, Brian; Li, Zhao; Wiltberger, Mike; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 07/2012 YEAR: 2012 DOI: 10.1016/j.jastp.2012.03.017 |
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Radiation belt 2D and 3D simulations for CIR-driven storms during Carrington Rotation 2068 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\textendashIonosphere\textendashThermosphere (CMIT) model driven by ACE solar wind measurements at L1 have been used to drive both 2D and 3D weighted test particle simulations of electron dynamics for the CIR subset of the month-long CMIT fields. Dropout in electron flux at geosynchronous orbit and enhancement during recovery phase, characteristic of CIR-driven storms, is seen in these moderate (Dstmin=-56, -33 nT) events, while the two CIRs were characterized by increased solar wind velocity in the 650\textendash750 km/s range. The first beginning March 26 produced a greater enhancement in IMF Bz southward and stronger magnetospheric convection, leading to a greater radiation belt electron response at GOES. This study provides the first comparison of 2D and 3D particle dynamics in MHD simulation fields, incorporating the additional diffusive feature of Shebansky orbit trapping of electrons in the magnetic minima on the dayside above and below the equatorial plane. Overall loss occurs during the main phase for 2D and 3D simulations, while incorporation of plasmasheet injection in 2D runs produces a moderate enhancement for the March 26\textendash30 storm, less than observed at GOES, and recovery to initial flux levels as seen for the April 4\textendash7 storm. Hudson, M.; Brito, Thiago; Elkington, Scot; Kress, Brian; Li, Zhao; Wiltberger, Mike; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 07/2012 YEAR: 2012 DOI: 10.1016/j.jastp.2012.03.017 |
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Radiation belt 2D and 3D simulations for CIR-driven storms during Carrington Rotation 2068 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\textendashIonosphere\textendashThermosphere (CMIT) model driven by ACE solar wind measurements at L1 have been used to drive both 2D and 3D weighted test particle simulations of electron dynamics for the CIR subset of the month-long CMIT fields. Dropout in electron flux at geosynchronous orbit and enhancement during recovery phase, characteristic of CIR-driven storms, is seen in these moderate (Dstmin=-56, -33 nT) events, while the two CIRs were characterized by increased solar wind velocity in the 650\textendash750 km/s range. The first beginning March 26 produced a greater enhancement in IMF Bz southward and stronger magnetospheric convection, leading to a greater radiation belt electron response at GOES. This study provides the first comparison of 2D and 3D particle dynamics in MHD simulation fields, incorporating the additional diffusive feature of Shebansky orbit trapping of electrons in the magnetic minima on the dayside above and below the equatorial plane. Overall loss occurs during the main phase for 2D and 3D simulations, while incorporation of plasmasheet injection in 2D runs produces a moderate enhancement for the March 26\textendash30 storm, less than observed at GOES, and recovery to initial flux levels as seen for the April 4\textendash7 storm. Hudson, M.; Brito, Thiago; Elkington, Scot; Kress, Brian; Li, Zhao; Wiltberger, Mike; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 07/2012 YEAR: 2012 DOI: 10.1016/j.jastp.2012.03.017 |
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Global distribution of EMIC waves derived from THEMIS observations [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\textendash12 RE where the helium band dominates the hydrogen band waves. The other is at dawn and 10\textendash12 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 waves have large normal angles (>45) in the hydrogen band and even larger normal angles Min, Kyungguk; Lee, Jeongwoo; Keika, Kunihiro; Li, W.; Published by: Journal of Geophysical Research Published on: 05/2012 YEAR: 2012 DOI: 10.1029/2012JA017515 EMIC wave occurrence; EMIC waves; plasma waves; RBSP; Van Allen Probes |
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Global distribution of EMIC waves derived from THEMIS observations [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\textendash12 RE where the helium band dominates the hydrogen band waves. The other is at dawn and 10\textendash12 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 waves have large normal angles (>45) in the hydrogen band and even larger normal angles Min, Kyungguk; Lee, Jeongwoo; Keika, Kunihiro; Li, W.; Published by: Journal of Geophysical Research Published on: 05/2012 YEAR: 2012 DOI: 10.1029/2012JA017515 EMIC wave occurrence; EMIC waves; plasma waves; RBSP; Van Allen Probes |
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Radiation Belt Storm Probe Spacecraft and Impact of Environment on Spacecraft Design NASA\textquoterights Radiation Belt Storm Probe (RBSP) is an Earth-orbiting mission scheduled to launch in September 2012 and is the next science mission in NASA\textquoterights 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\textquoterights 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 measurements over a range of spacecraft separation distances. A description of the spacecraft environment is provided along with spacecraft and subsystem key characteristics and accommodations that protect sensitive spacecraft electronics and support operations in the harsh radiation belt environment. Kirby, Karen; Bushman, Stewart; Butler, Michael; Conde, Rich; Fretz, Kristen; Herrmann, Carl; Hill, Adrian; Maurer, Richard; Nichols, Richard; Ottman, Geffrey; Reid, Mark; Rogers, Gabe; Srinivasan, Dipak; Troll, John; Williams, Bruce; Published by: Published on: 03/2012 YEAR: 2012 DOI: 10.1109/AERO.2012.6187020 |
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Radiation Belt Storm Probe Spacecraft and Impact of Environment on Spacecraft Design NASA\textquoterights Radiation Belt Storm Probe (RBSP) is an Earth-orbiting mission scheduled to launch in September 2012 and is the next science mission in NASA\textquoterights 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\textquoterights 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 measurements over a range of spacecraft separation distances. A description of the spacecraft environment is provided along with spacecraft and subsystem key characteristics and accommodations that protect sensitive spacecraft electronics and support operations in the harsh radiation belt environment. Kirby, Karen; Bushman, Stewart; Butler, Michael; Conde, Rich; Fretz, Kristen; Herrmann, Carl; Hill, Adrian; Maurer, Richard; Nichols, Richard; Ottman, Geffrey; Reid, Mark; Rogers, Gabe; Srinivasan, Dipak; Troll, John; Williams, Bruce; Published by: Published on: 03/2012 YEAR: 2012 DOI: 10.1109/AERO.2012.6187020 |
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Radiation Belt Storm Probe Spacecraft and Impact of Environment on Spacecraft Design NASA\textquoterights Radiation Belt Storm Probe (RBSP) is an Earth-orbiting mission scheduled to launch in September 2012 and is the next science mission in NASA\textquoterights 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\textquoterights 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 measurements over a range of spacecraft separation distances. A description of the spacecraft environment is provided along with spacecraft and subsystem key characteristics and accommodations that protect sensitive spacecraft electronics and support operations in the harsh radiation belt environment. Kirby, Karen; Bushman, Stewart; Butler, Michael; Conde, Rich; Fretz, Kristen; Herrmann, Carl; Hill, Adrian; Maurer, Richard; Nichols, Richard; Ottman, Geffrey; Reid, Mark; Rogers, Gabe; Srinivasan, Dipak; Troll, John; Williams, Bruce; Published by: Published on: 03/2012 YEAR: 2012 DOI: 10.1109/AERO.2012.6187020 |
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Radiation Belt Storm Probe Spacecraft and Impact of Environment on Spacecraft Design NASA\textquoterights Radiation Belt Storm Probe (RBSP) is an Earth-orbiting mission scheduled to launch in September 2012 and is the next science mission in NASA\textquoterights 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\textquoterights 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 measurements over a range of spacecraft separation distances. A description of the spacecraft environment is provided along with spacecraft and subsystem key characteristics and accommodations that protect sensitive spacecraft electronics and support operations in the harsh radiation belt environment. Kirby, Karen; Bushman, Stewart; Butler, Michael; Conde, Rich; Fretz, Kristen; Herrmann, Carl; Hill, Adrian; Maurer, Richard; Nichols, Richard; Ottman, Geffrey; Reid, Mark; Rogers, Gabe; Srinivasan, Dipak; Troll, John; Williams, Bruce; Published by: Published on: 03/2012 YEAR: 2012 DOI: 10.1109/AERO.2012.6187020 |
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Radiation Belt Storm Probe Spacecraft and Impact of Environment on Spacecraft Design NASA\textquoterights Radiation Belt Storm Probe (RBSP) is an Earth-orbiting mission scheduled to launch in September 2012 and is the next science mission in NASA\textquoterights 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\textquoterights 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 measurements over a range of spacecraft separation distances. A description of the spacecraft environment is provided along with spacecraft and subsystem key characteristics and accommodations that protect sensitive spacecraft electronics and support operations in the harsh radiation belt environment. Kirby, Karen; Bushman, Stewart; Butler, Michael; Conde, Rich; Fretz, Kristen; Herrmann, Carl; Hill, Adrian; Maurer, Richard; Nichols, Richard; Ottman, Geffrey; Reid, Mark; Rogers, Gabe; Srinivasan, Dipak; Troll, John; Williams, Bruce; Published by: Published on: 03/2012 YEAR: 2012 DOI: 10.1109/AERO.2012.6187020 |
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Radiation Belt Storm Probe Spacecraft and Impact of Environment on Spacecraft Design NASA\textquoterights Radiation Belt Storm Probe (RBSP) is an Earth-orbiting mission scheduled to launch in September 2012 and is the next science mission in NASA\textquoterights 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\textquoterights 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 measurements over a range of spacecraft separation distances. A description of the spacecraft environment is provided along with spacecraft and subsystem key characteristics and accommodations that protect sensitive spacecraft electronics and support operations in the harsh radiation belt environment. Kirby, Karen; Bushman, Stewart; Butler, Michael; Conde, Rich; Fretz, Kristen; Herrmann, Carl; Hill, Adrian; Maurer, Richard; Nichols, Richard; Ottman, Geffrey; Reid, Mark; Rogers, Gabe; Srinivasan, Dipak; Troll, John; Williams, Bruce; Published by: Published on: 03/2012 YEAR: 2012 DOI: 10.1109/AERO.2012.6187020 |
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Radiation Belt Storm Probe Spacecraft and Impact of Environment on Spacecraft Design NASA\textquoterights Radiation Belt Storm Probe (RBSP) is an Earth-orbiting mission scheduled to launch in September 2012 and is the next science mission in NASA\textquoterights 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\textquoterights 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 measurements over a range of spacecraft separation distances. A description of the spacecraft environment is provided along with spacecraft and subsystem key characteristics and accommodations that protect sensitive spacecraft electronics and support operations in the harsh radiation belt environment. Kirby, Karen; Bushman, Stewart; Butler, Michael; Conde, Rich; Fretz, Kristen; Herrmann, Carl; Hill, Adrian; Maurer, Richard; Nichols, Richard; Ottman, Geffrey; Reid, Mark; Rogers, Gabe; Srinivasan, Dipak; Troll, John; Williams, Bruce; Published by: Published on: 03/2012 YEAR: 2012 DOI: 10.1109/AERO.2012.6187020 |
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Explaining sudden losses of outer radiation belt electrons during geomagnetic storms 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\textquoterights 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 \textquoterightdropouts\textquoteright 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 concerning dropouts and the precise channels to which outer belt electrons are lost during these events. By analysing data collected at multiple altitudes by the THEMIS, GOES, and NOAA\textendashPOES spacecraft, we show that the sudden electron depletion observed during a recent storm\textquoterights main phase is primarily a result of outward transport rather than loss to the atmosphere. Turner, Drew; Shprits, Yuri; Hartinger, Michael; Angelopoulos, Vassilis; Published by: Nature Physics Published on: 01/2012 YEAR: 2012 DOI: 10.1038/nphys2185 |
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Explaining sudden losses of outer radiation belt electrons during geomagnetic storms 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\textquoterights 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 \textquoterightdropouts\textquoteright 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 concerning dropouts and the precise channels to which outer belt electrons are lost during these events. By analysing data collected at multiple altitudes by the THEMIS, GOES, and NOAA\textendashPOES spacecraft, we show that the sudden electron depletion observed during a recent storm\textquoterights main phase is primarily a result of outward transport rather than loss to the atmosphere. Turner, Drew; Shprits, Yuri; Hartinger, Michael; Angelopoulos, Vassilis; Published by: Nature Physics Published on: 01/2012 YEAR: 2012 DOI: 10.1038/nphys2185 |
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Explaining sudden losses of outer radiation belt electrons during geomagnetic storms 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\textquoterights 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 \textquoterightdropouts\textquoteright 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 concerning dropouts and the precise channels to which outer belt electrons are lost during these events. By analysing data collected at multiple altitudes by the THEMIS, GOES, and NOAA\textendashPOES spacecraft, we show that the sudden electron depletion observed during a recent storm\textquoterights main phase is primarily a result of outward transport rather than loss to the atmosphere. Turner, Drew; Shprits, Yuri; Hartinger, Michael; Angelopoulos, Vassilis; Published by: Nature Physics Published on: 01/2012 YEAR: 2012 DOI: 10.1038/nphys2185 |
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Weak turbulence in the magnetosphere: Formation of whistler wave cavity by nonlinear scattering 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 nonlinear scatterings and ionospheric reflections a long-lived wavecavity containing turbulent whistler waves can be formed with the appropriate properties to efficiently pitch-angle scatter trapped electrons. The primary consequence on the earth\textquoterights radiation belts is to reduce the lifetime of the trapped electron population. Crabtree, C.; Rudakov, L.; Ganguli, G.; Mithaiwala, M.; Galinsky, V.; Shevchenko, V.; Published by: Physics of Plasmas Published on: 01/2012 YEAR: 2012 DOI: 10.1063/1.3692092 |
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Weak turbulence in the magnetosphere: Formation of whistler wave cavity by nonlinear scattering 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 nonlinear scatterings and ionospheric reflections a long-lived wavecavity containing turbulent whistler waves can be formed with the appropriate properties to efficiently pitch-angle scatter trapped electrons. The primary consequence on the earth\textquoterights radiation belts is to reduce the lifetime of the trapped electron population. Crabtree, C.; Rudakov, L.; Ganguli, G.; Mithaiwala, M.; Galinsky, V.; Shevchenko, V.; Published by: Physics of Plasmas Published on: 01/2012 YEAR: 2012 DOI: 10.1063/1.3692092 |
| 2011 |
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Radiation belt storm probes: Resolving fundamental physics with practical consequences 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\textquoterights 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. Ukhorskiy, Aleksandr; Mauk, Barry; Fox, Nicola; Sibeck, David; Grebowsky, Joseph; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 07/2011 YEAR: 2011 DOI: 10.1016/j.jastp.2010.12.005 |
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Radiation belt storm probes: Resolving fundamental physics with practical consequences 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\textquoterights 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. Ukhorskiy, Aleksandr; Mauk, Barry; Fox, Nicola; Sibeck, David; Grebowsky, Joseph; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 07/2011 YEAR: 2011 DOI: 10.1016/j.jastp.2010.12.005 |
| 2010 |
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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\textdegreeS) Antarctic observatories in the range of 0600\textendash0900 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\textendash2400. 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 Antarctic observatories) also supports the deduced injection region. Since chorus waves are believed to be generated through the electron cyclotron instability by an anisotropic temperature distribution, we examine, by performing forward model tracing, whether the electrons injected during this substorm form a pancake-like pitch angle distribution when they arrive near the dawn-side magnetopause. We find that the onset time of the modeled pitch angle anisotropy is consistent with that of the observed chorus waves. We conclude that the development of the anisotropy is due to particle drift shell splitting. Min, Kyungguk; Lee, Jeongwoo; Keika, Kunihiro; Published by: American Geophysical Union Published on: 10/2010 YEAR: 2010 DOI: 10.1029/2010JA015474 chorus and substorm; electron drift; RBSP; Substorm Injections; Van Allen Probes |
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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\textdegreeS) Antarctic observatories in the range of 0600\textendash0900 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\textendash2400. 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 Antarctic observatories) also supports the deduced injection region. Since chorus waves are believed to be generated through the electron cyclotron instability by an anisotropic temperature distribution, we examine, by performing forward model tracing, whether the electrons injected during this substorm form a pancake-like pitch angle distribution when they arrive near the dawn-side magnetopause. We find that the onset time of the modeled pitch angle anisotropy is consistent with that of the observed chorus waves. We conclude that the development of the anisotropy is due to particle drift shell splitting. Min, Kyungguk; Lee, Jeongwoo; Keika, Kunihiro; Published by: American Geophysical Union Published on: 10/2010 YEAR: 2010 DOI: 10.1029/2010JA015474 chorus and substorm; electron drift; RBSP; Substorm Injections; Van Allen Probes |
| 2009 |
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Analysis of Spinning Spacecraft with Wire Booms Part 1: Derivation of Nonlinear Dynamics 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. Kemp, Brian; McGee, Timothy; Shankar, Uday; Published by: Published on: 08/2009 YEAR: 2009 DOI: 10.2514/6.2009-6202 |
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Analysis of Spinning Spacecraft with Wire Booms Part 1: Derivation of Nonlinear Dynamics 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. Kemp, Brian; McGee, Timothy; Shankar, Uday; Published by: Published on: 08/2009 YEAR: 2009 DOI: 10.2514/6.2009-6202 |
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Analysis of Spinning Spacecraft with Wire Booms Part 2: Out-of-Plane Dynamics and Maneuvers 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 spacecraft having multiple exible wire booms, the numeric parameters studied represent those of the satellites from the Radiation Belt Storm Probe (RBSP) mission. The mission, part of NASA\textquoterights Living With a Star Geospace Program, will launch two Earth-orbiting spacecraft to investigate how populations of relativistic electrons and ions in the region known as the Radiation Belts are formed and change in response to variable inputs of energy from the Sun. McGee, Timothy; Shankar, Uday; Kemp, Brian; Published by: Published on: 08/2009 YEAR: 2009 DOI: 10.2514/6.2009-6203 |
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Analysis of Spinning Spacecraft with Wire Booms Part 2: Out-of-Plane Dynamics and Maneuvers 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 spacecraft having multiple exible wire booms, the numeric parameters studied represent those of the satellites from the Radiation Belt Storm Probe (RBSP) mission. The mission, part of NASA\textquoterights Living With a Star Geospace Program, will launch two Earth-orbiting spacecraft to investigate how populations of relativistic electrons and ions in the region known as the Radiation Belts are formed and change in response to variable inputs of energy from the Sun. McGee, Timothy; Shankar, Uday; Kemp, Brian; Published by: Published on: 08/2009 YEAR: 2009 DOI: 10.2514/6.2009-6203 |
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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-plane dynamics. The sec- ond companion paper examines the out-of-plane dynamics and maneuvers. This paper examines the spin-plane dynamics of such a spin-stabilized spacecraft. It analyzes the fundamental modes and mode-shapes of the system, spin-plane ma- neuvers, and the effects of boom deployment. While this analysis is applicable to any spin-stabilized spacecraft with flexible radial booms, the analysis was driven by the needs of the Radiation Belt Storm Probes (RBSP) spacecraft currently being designed at the Johns Hopkins University Applied Physics Laboratory, as part of NASA\textquoterights \textquotedblleftLiving With a Star\textquotedblright program. This paper provides an analytical treatment of the spacecraft dynamics. These theoretical predictions are verified using fully non-linear six degree-of-freedom simulations. Shankar, Uday; McGee, Timothy; Kemp, Brian; Published by: Published on: 08/2009 YEAR: 2009 DOI: 10.2514/6.2009-6204 |
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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-plane dynamics. The sec- ond companion paper examines the out-of-plane dynamics and maneuvers. This paper examines the spin-plane dynamics of such a spin-stabilized spacecraft. It analyzes the fundamental modes and mode-shapes of the system, spin-plane ma- neuvers, and the effects of boom deployment. While this analysis is applicable to any spin-stabilized spacecraft with flexible radial booms, the analysis was driven by the needs of the Radiation Belt Storm Probes (RBSP) spacecraft currently being designed at the Johns Hopkins University Applied Physics Laboratory, as part of NASA\textquoterights \textquotedblleftLiving With a Star\textquotedblright program. This paper provides an analytical treatment of the spacecraft dynamics. These theoretical predictions are verified using fully non-linear six degree-of-freedom simulations. Shankar, Uday; McGee, Timothy; Kemp, Brian; Published by: Published on: 08/2009 YEAR: 2009 DOI: 10.2514/6.2009-6204 |
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[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 external conditions the dayside magnetopause moves closer to Earth, and the day-night magnetic asymmetry is enhanced. As a consequence the area of closed drift orbits shrinks. The magnetic field at the subsolar magnetopause, which is estimated from force balance with the solar wind dynamic pressure, is usually stronger than the nightside geosynchronous magnetic field during electron loss events. It is therefore suggested that geosynchronous MeV electrons on the night side are very often on open drift paths when geosynchronous MeV electrons are lost. Whereas the present result does not preclude the widely accepted idea that MeV electrons are lost to the atmosphere by wave-particle interaction, it suggests that magnetopause shadowing is another plausible loss process of geosynchronous MeV electrons. Ohtani, S.; Miyoshi, Y.; Singer, H.; Weygand, J.; Published by: Journal of Geophysical Research Published on: 01/2009 YEAR: 2009 DOI: 10.1029/2008JA013391 |
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[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 external conditions the dayside magnetopause moves closer to Earth, and the day-night magnetic asymmetry is enhanced. As a consequence the area of closed drift orbits shrinks. The magnetic field at the subsolar magnetopause, which is estimated from force balance with the solar wind dynamic pressure, is usually stronger than the nightside geosynchronous magnetic field during electron loss events. It is therefore suggested that geosynchronous MeV electrons on the night side are very often on open drift paths when geosynchronous MeV electrons are lost. Whereas the present result does not preclude the widely accepted idea that MeV electrons are lost to the atmosphere by wave-particle interaction, it suggests that magnetopause shadowing is another plausible loss process of geosynchronous MeV electrons. Ohtani, S.; Miyoshi, Y.; Singer, H.; Weygand, J.; Published by: Journal of Geophysical Research Published on: 01/2009 YEAR: 2009 DOI: 10.1029/2008JA013391 |
| 2008 |
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Test-particle trajectories are computed in fields from a global MHD magnetospheric model simulation of the 29 October 2003 Storm Commencement to investigate trapping and transport of solar energetic electrons (SEEs) in the magnetosphere during severe storms. SEEs are found to provide a source population for a newly formed belt of View the MathML source electrons in the Earth\textquoterights inner zone radiation belts, which was observed following the 29 October 2003 storm. Energy and pitch angle distributions of the new belt are compared with results previously obtained [Kress, B.T., Hudson, M.K., Looper, M.D., Albert, J., Lyon, J.G., Goodrich, C.C., 2007. Global MHD test particle simulations of >10 MeV radiation belt electrons during storm sudden commencement. Journal of Geophysical Research 112, A09215, doi:10.1029/2006JA012218], where outer belt electrons were used as a source for the new belt. KRESS, B; Hudson, M.; LOOPER, M; LYON, J; GOODRICH, C; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 11/2008 YEAR: 2008 DOI: 10.1016/j.jastp.2008.05.018 Shock-Induced Transport. Slot Refilling and Formation of New Belts. |
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Test-particle trajectories are computed in fields from a global MHD magnetospheric model simulation of the 29 October 2003 Storm Commencement to investigate trapping and transport of solar energetic electrons (SEEs) in the magnetosphere during severe storms. SEEs are found to provide a source population for a newly formed belt of View the MathML source electrons in the Earth\textquoterights inner zone radiation belts, which was observed following the 29 October 2003 storm. Energy and pitch angle distributions of the new belt are compared with results previously obtained [Kress, B.T., Hudson, M.K., Looper, M.D., Albert, J., Lyon, J.G., Goodrich, C.C., 2007. Global MHD test particle simulations of >10 MeV radiation belt electrons during storm sudden commencement. Journal of Geophysical Research 112, A09215, doi:10.1029/2006JA012218], where outer belt electrons were used as a source for the new belt. KRESS, B; Hudson, M.; LOOPER, M; LYON, J; GOODRICH, C; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 11/2008 YEAR: 2008 DOI: 10.1016/j.jastp.2008.05.018 Shock-Induced Transport. Slot Refilling and Formation of New Belts. |
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This paper focuses on the modeling of local acceleration and loss processes in the outer radiation belt. We begin by reviewing the statistical properties of waves that violate the first and second adiabatic invariants, leading to the loss and acceleration of high energy electrons in the outer radiation belt. After a brief description of the most commonly accepted methodology for computing quasi-linear diffusion coefficients, we present pitch-angle scattering simulations by (i) plasmaspheric hiss, (ii) a combination of plasmaspheric hiss and electromagnetic ion cyclotron (EMIC) waves, (iii) chorus waves, and (iv) a combination of chorus and EMIC waves. Simulations of the local acceleration and loss processes show that statistically, the net effect of chorus waves is acceleration at MeV energies and loss at hundreds of keV energies. The combination of three-dimensional (3D) simulations of the local processes and radial transport show that the complexity of the behavior of the radiation belts is due to a number of competing processes of acceleration and loss, and depends on the dynamics of the plasmasphere, ring current, and solar wind conditions. SHPRITS, Y; SUBBOTIN, D; MEREDITH, N; ELKINGTON, S; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 11/2008 YEAR: 2008 DOI: 10.1016/j.jastp.2008.06.014 |
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This paper focuses on the modeling of local acceleration and loss processes in the outer radiation belt. We begin by reviewing the statistical properties of waves that violate the first and second adiabatic invariants, leading to the loss and acceleration of high energy electrons in the outer radiation belt. After a brief description of the most commonly accepted methodology for computing quasi-linear diffusion coefficients, we present pitch-angle scattering simulations by (i) plasmaspheric hiss, (ii) a combination of plasmaspheric hiss and electromagnetic ion cyclotron (EMIC) waves, (iii) chorus waves, and (iv) a combination of chorus and EMIC waves. Simulations of the local acceleration and loss processes show that statistically, the net effect of chorus waves is acceleration at MeV energies and loss at hundreds of keV energies. The combination of three-dimensional (3D) simulations of the local processes and radial transport show that the complexity of the behavior of the radiation belts is due to a number of competing processes of acceleration and loss, and depends on the dynamics of the plasmasphere, ring current, and solar wind conditions. SHPRITS, Y; SUBBOTIN, D; MEREDITH, N; ELKINGTON, S; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 11/2008 YEAR: 2008 DOI: 10.1016/j.jastp.2008.06.014 |
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In this paper, we focus on the modeling of radial transport in the Earth\textquoterights outer radiation belt. A historical overview of the first observations of the radiation belts is presented, followed by a brief description of radial diffusion. We describe how resonant interactions with poloidal and toroidal components of the ULF waves can change the electron\textquoterights energy and provide radial displacements. We also present radial diffusion and guiding center simulations that show the importance of radial transport in redistributing relativistic electron fluxes and also in accelerating and decelerating radiation belt electrons. We conclude by presenting guiding center simulations of the coupled particle tracing and magnetohydrodynamic (MHD) codes and by discussing the origin of relativistic electrons at geosynchronous orbit. Local acceleration and losses and 3D simulations of the dynamics of the radiation belt fluxes are discussed in the companion paper [Shprits, Y.Y., Subbotin, D.A., Meredith, N.P., Elkington, S.R., 2008. Review of modeling of losses and sources of relativistic electrons in the outer radiation belt II: Local acceleration and loss. Journal of Atmospheric and Solar-Terrestrial Physics, this issue. doi:10.1016/j.jastp.2008.06.014]. SHPRITS, Y; ELKINGTON, S; MEREDITH, N; SUBBOTIN, D; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 11/2008 YEAR: 2008 DOI: 10.1016/j.jastp.2008.06.008 |
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In this paper, we focus on the modeling of radial transport in the Earth\textquoterights outer radiation belt. A historical overview of the first observations of the radiation belts is presented, followed by a brief description of radial diffusion. We describe how resonant interactions with poloidal and toroidal components of the ULF waves can change the electron\textquoterights energy and provide radial displacements. We also present radial diffusion and guiding center simulations that show the importance of radial transport in redistributing relativistic electron fluxes and also in accelerating and decelerating radiation belt electrons. We conclude by presenting guiding center simulations of the coupled particle tracing and magnetohydrodynamic (MHD) codes and by discussing the origin of relativistic electrons at geosynchronous orbit. Local acceleration and losses and 3D simulations of the dynamics of the radiation belt fluxes are discussed in the companion paper [Shprits, Y.Y., Subbotin, D.A., Meredith, N.P., Elkington, S.R., 2008. Review of modeling of losses and sources of relativistic electrons in the outer radiation belt II: Local acceleration and loss. Journal of Atmospheric and Solar-Terrestrial Physics, this issue. doi:10.1016/j.jastp.2008.06.014]. SHPRITS, Y; ELKINGTON, S; MEREDITH, N; SUBBOTIN, D; Published by: Journal of Atmospheric and Solar-Terrestrial Physics Published on: 11/2008 YEAR: 2008 DOI: 10.1016/j.jastp.2008.06.008 |
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[1] The interaction between relativistic, equatorially mirroring electrons and Pc5 Ultra Low Frequency (ULF) waves in the magnetosphere is investigated using a numerical MagnetoHydroDynamic (MHD) model for waves and a test-kinetic model for electron phase space density (PSD). The temporal and spatial characteristics of a ULF wave packet are constrained using ground-based observations of narrowband ULF activity following a geomagnetic storm on 24 March 1991, which occurred from 1200 to 1340 Universal Time (UT). A salient feature of the ULF waves during this interval was the apparent localization of the ULF wave power to the dayside of the magnetosphere and the antisunward propagation of ULF wave phase in the morning and afternoon sectors. This is interpreted to imply a localized source of ULF wave power close to noon Magnetic Local Time (MLT) at the magnetopause. The expected electron dynamics are investigated using model wavefields to predict the observable characteristics of the interaction in satellite electron flux data. The wave and kinetic models show that the localized radial motion of magnetic field lines associated with MHD fast waves propagating from the ULF source region acts to periodically inject electrons from high L to lower L within the magnetosphere. This action becomes resonant when the drift period of the electrons matches a multiple of the ULF wave period and leads to an enhancement in radial transport. Published by: Journal of Geophysical Research Published on: 10/2008 YEAR: 2008 DOI: 10.1029/2008JA013254 |
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Relativistic electron precipitation by EMIC waves from self-consistent global simulations [1] We study the effect of electromagnetic ion cyclotron (EMIC) wave scattering on radiation belt electrons during the large geomagnetic storm of 21 October 2001 with minimum Dst = -187 nT. We use our global physics-based model, which solves the kinetic equation for relativistic electrons and H+, O+, and He+ ions as a function of radial distance in the equatorial plane, magnetic local time, energy, and pitch angle. The model includes time-dependent convective transport and radial diffusion and all major loss processes and is coupled with a dynamic plasmasphere model. We calculate the excitation of EMIC waves self-consistently with the evolving plasma populations. Particle interactions with these waves are evaluated according to quasi-linear theory, using diffusion coefficients for a multicomponent plasma and including not only field-aligned but also oblique EMIC wave propagation. The pitch angle diffusion coefficients increase from 0\textdegree to \~60\textdegree during specific storm conditions. Pitch angle scattering by EMIC waves causes significant loss of radiation belt electrons at E >= 1 MeV and precipitation into the atmosphere. However, the relativistic electron flux dropout during the main phase at large L >= 5 is due mostly to outward radial diffusion, driven by the flux decrease at geosynchronous orbit. We show first results from global simulations indicating significant relativistic electron precipitation within regions of enhanced EMIC instability, whose location varies with time but is predominantly in the afternoon-dusk sector. The precipitating electron fluxes are usually collocated with precipitating ion fluxes but occur at variable energy range and magnitude. The minimum resonant energy increases at low L and relativistic electrons at E <= 1 MeV do not precipitate at L < 3 during this storm. Jordanova, V.; Albert, J.; Miyoshi, Y.; Published by: Journal of Geophysical Research Published on: 03/2008 YEAR: 2008 DOI: 10.1029/2008JA013239 |
| 2007 |
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Radiation Belt Storm Probes: The Next Generation of Space Weather Forecasting Published by: Space Weather Published on: 11/2007 YEAR: 2007 DOI: 10.1029/2007SW000341 |
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Dynamic evolution of energetic outer zone electrons due to wave-particle interactions during storms [1] Relativistic electrons in the outer radiation belt are subjected to pitch angle and energy diffusion by chorus, electromagnetic ion cyclotron (EMIC), and hiss waves. Using quasi-linear diffusion coefficients for cyclotron resonance with field-aligned waves, we examine whether the resonant interactions with chorus waves produce a net acceleration or loss of relativistic electrons. We also examine the effect of pitch angle scattering by EMIC and hiss waves during the main and recovery phases of a storm. The numerical simulations show that wave-particle interactions with whistler mode chorus waves with realistic wave spectral properties result in a net acceleration of relativistic electrons, while EMIC waves, which provide very fast scattering near the edge of the loss cone, may be a dominant loss mechanism during the main phase of a storm. In addition, hiss waves are effective in scattering equatorially mirroring electrons and may be an important mechanism of transporting high pitch angle electrons toward the loss cone. Li, W.; Shprits, Y; Thorne, R.; Published by: Journal of Geophysical Research Published on: 10/2007 YEAR: 2007 DOI: 10.1029/2007JA012368 |
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The energization of relativistic electrons in the outer Van Allen radiation belt The origin and dynamics of the Van Allen radiation belts is one of the longest-standing questions of the space age, and one that is increasingly important for space applications as satellite systems become more sophisticated, smaller and more susceptible to radiation effects. The precise mechanism by which the Earth\textquoterights magnetosphere is able to accelerate electrons from thermal to ultrarelativistic energies (Edouble greater than0.5 MeV) has been particularly difficult to definitively resolve. The traditional explanation is that large-scale, fluctuating electric and magnetic fields energize particles through radial diffusion1. More recent theories2, 3 and observations4, 5 have suggested that gyro-resonant wave\textendashparticle interactions may be comparable to or more important than radial diffusion. Using data collected simultaneously by multiple satellites passing through the magnetosphere at different distances from the Earth, we demonstrate that the latter of these is the dominant mechanism responsible for relativistic electron acceleration. Specifically, we identify frequent and persistent peaks in equatorial electron phase space density near or inside geosynchronous orbit that provide unambiguous evidence for local wave\textendashparticle acceleration. These observations represent an important step towards a more complete physical understanding of radiation belt dynamics and to the development of space-weather models. Chen, Yue; Reeves, Geoffrey; Friedel, Reiner; Published by: Nature Physics Published on: 09/2007 YEAR: 2007 DOI: 10.1038/nphys655 |