Sample records for nasa radiation belt

  1. ScienceCast 76: The Radiation Belt Storm Probes

    NASA Image and Video Library

    2012-08-30

    This morning NASA launched two heavily-shielded spacecraft directly into the Van Allen Belts. The Radiation Belt Storm Probes are on a two-year mission to study the Van Allen Belts and to unravel the mystery of their unpredictability.

  2. Survey of current situation in radiation belt modeling

    NASA Technical Reports Server (NTRS)

    Fung, Shing F.

    2004-01-01

    The study of Earth's radiation belts is one of the oldest subjects in space physics. Despite the tremendous progress made in the last four decades, we still lack a complete understanding of the radiation belts in terms of their configurations, dynamics, and detailed physical accounts of their sources and sinks. The static nature of early empirical trapped radiation models, for examples, the NASA AP-8 and AE-8 models, renders those models inappropriate for predicting short-term radiation belt behaviors associated with geomagnetic storms and substorms. Due to incomplete data coverage, these models are also inaccurate at low altitudes (e.g., <1000 km) where many robotic and human space flights occur. The availability of radiation data from modern space missions and advancement in physical modeling and data management techniques have now allowed the development of new empirical and physical radiation belt models. In this paper, we will review the status of modern radiation belt modeling. Published by Elsevier Ltd on behalf of COSPAR.

  3. Investigation of Moving Belt Radiator Technology Issues

    NASA Technical Reports Server (NTRS)

    Teagan, W. Peter; Aguilar, Jerry L.

    1994-01-01

    The development of an advanced spacecraft radiator technology is reported. The moving belt radiator is a thermal radiator concept with the promise of lower specific mass (per kW rejected) than that afforded by existing technologies. The results of a parametric study to estimate radiator mass for future space power systems is presented. It is shown that this technology can be scaled up to 200 MW for higher rejection temperatures. Several aspects of the design concept are discussed, including the dynamics of a large rotating belt in microgravity. The results of a computer code developed to model the belt dynamics are presented. A series of one-g experiments to investigate the dynamics of small belts is described. A comprehensive test program to investigate belt dynamics in microgravity aboard the NASA KC-135 aircraft is discussed. It was found that the desired circular shape can readily be achieved in microgravity. It is also shown that a rotating belt is stable when subjected to simulated attitude control maneuvers. Heat exchanger design is also investigated. Several sealing concepts were examined experimentally, and are discussed. Overall heat transfer coefficients to the rotating belt are presented. Material properties for various belt materials, including screen meshes, are also presented. The results presented in this report indicate that the moving belt radiator concept is technically feasible.

  4. Dynamics of the Earth's Radiation Belts and Inner Magnetosphere

    NASA Astrophysics Data System (ADS)

    Schultz, Colin

    2013-12-01

    Trapped by Earth's magnetic field far above the planet's surface, the energetic particles that fill the radiation belts are a sign of the Sun's influence and a threat to our technological future. In the AGU monograph Dynamics of the Earth's Radiation Belts and Inner Magnetosphere, editors Danny Summers, Ian R. Mann, Daniel N. Baker, and Michael Schulz explore the inner workings of the magnetosphere. The book reviews current knowledge of the magnetosphere and recent research results and sets the stage for the work currently being done by NASA's Van Allen Probes (formerly known as the Radiation Belt Storm Probes). In this interview, Eos talks to Summers about magnetospheric research, whistler mode waves, solar storms, and the effects of the radiation belts on Earth.

  5. Space Weather Effects in the Earth's Radiation Belts

    NASA Astrophysics Data System (ADS)

    Baker, D. N.; Erickson, P. J.; Fennell, J. F.; Foster, J. C.; Jaynes, A. N.; Verronen, P. T.

    2018-02-01

    The first major scientific discovery of the Space Age was that the Earth is enshrouded in toroids, or belts, of very high-energy magnetically trapped charged particles. Early observations of the radiation environment clearly indicated that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions. Recent observations by the NASA dual-spacecraft Van Allen Probes mission have revealed many novel properties of the radiation belts, especially for electrons at highly relativistic and ultra-relativistic kinetic energies. In this review we summarize the space weather impacts of the radiation belts. We demonstrate that many remarkable features of energetic particle changes are driven by strong solar and solar wind forcings. Recent comprehensive data show broadly and in many ways how high energy particles are accelerated, transported, and lost in the magnetosphere due to interplanetary shock wave interactions, coronal mass ejection impacts, and high-speed solar wind streams. We also discuss how radiation belt particles are intimately tied to other parts of the geospace system through atmosphere, ionosphere, and plasmasphere coupling. The new data have in many ways rewritten the textbooks about the radiation belts as a key space weather threat to human technological systems.

  6. Storm-time radiation belt electron dynamics: Repeatability in the outer radiation belt

    NASA Astrophysics Data System (ADS)

    Murphy, K. R.; Mann, I. R.; Rae, J.; Watt, C.; Boyd, A. J.; Turner, D. L.; Claudepierre, S. G.; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Blake, J. B.; Fennell, J. F.

    2017-12-01

    During intervals of enhanced solar wind driving the outer radiation belt becomes extremely dynamic leading to geomagnetic storms. During these storms the flux of energetic electrons can vary by over 4 orders of magnitude. Despite recent advances in understanding the nature of competing storm-time electron loss and acceleration processes the dynamic behavior of the outer radiation belt remains poorly understood; the outer radiation belt can exhibit either no change, an enhancement, or depletion in radiation belt electrons. Using a new analysis of the total radiation belt electron content, calculated from the Van Allen probes phase space density (PSD), we statistically analyze the time-dependent and global response of the outer radiation belt during storms. We demonstrate that by removing adiabatic effects there is a clear and repeatable sequence of events in storm-time radiation belt electron dynamics. Namely, the relativistic (μ=1000 MeV/G) and ultra-relativistic (μ=4000 MeV/G) electron populations can be separated into two phases; an initial phase dominated by loss followed by a second phase dominated by acceleration. At lower energies, the radiation belt seed population of electrons (μ=150 MeV/G) shows no evidence of loss but rather a net enhancement during storms. Further, we investigate the dependence of electron dynamics as a function of the second adiabatic invariant, K. These results demonstrate a global coherency in the dynamics of the source, relativistic and ultra-relativistic electron populations as function of the second adiabatic invariant K. This analysis demonstrates two key aspects of storm-time radiation belt electron dynamics. First, the radiation belt responds repeatably to solar wind driving during geomagnetic storms. Second, the response of the radiation belt is energy dependent, relativistic electrons behaving differently than lower energy seed electrons. These results have important implications in radiation belt research. In particular

  7. Moving belt radiator development status

    NASA Technical Reports Server (NTRS)

    White, K. Alan

    1988-01-01

    Development of the Moving Belt Radiator (MBR) as an advanced space radiator concept is discussed. The ralative merits of Solid Belt (SBR), Liquid Belt (LBR), and Hybrid Belt (HBR) Radiators are described. Analytical and experimental efforts related to the dynamics of a rotating belt in microgravity are reviewed. The development of methods for transferring heat to the moving belt is discussed, and the results from several experimental investigations are summarized. Limited efforts related to the belt deployment and stowage, and to fabrication of a hybrid belt, are also discussed. Life limiting factors such as seal wear and micrometeroid resistance are identified. The results from various MBR point design studies for several power levels are compared with advanced Heat Pipe Radiator technology. MBR designs are shown to compare favorable at both 300 and 1000 K temperature levels. However, additional effort will be required to resolve critical technology issues and to demonstrate the advantage of MBR systems.

  8. Extreme enhancements and depletions of relativistic electrons in Earth's radiation belts

    NASA Astrophysics Data System (ADS)

    Turner, D. L.; Claudepierre, S. G.; O'Brien, T. P., III; Fennell, J. F.; Blake, J. B.; Baker, D. N.; Jaynes, A. N.; Morley, S.; Geoffrey, R.

    2015-12-01

    Earth's electron radiation belts consist of toroidal zones in near-Earth space characterized by intense levels of relativistic electrons with distinct energy-dependent boundaries. It has been known for decades that the outer electron radiation belt is highly variable, with electron intensities varying by orders of magnitude on timescales ranging from minutes to years. Now, we are gaining much insight into the nature of this extreme variability thanks to the unprecedented number of observatories capable of measuring radiation belt electrons, the most recent of which is NASA's Van Allen Probes mission. In this presentation, we analyze and review several of the most extreme events observed in Earth's outer radiation belt. We begin with very sudden and strong enhancements of the outer radiation belt that can result in several orders of magnitude enhancements of electron intensities up to several MeV that sometimes occur in less than one day. We compare and contrast two of the most extreme cases of sudden and strong enhancements from the Van Allen Probes era, 08-09 October 2012 and 17-18 March 2015, and review evidence of the dominant acceleration mechanism in each event. Sudden enhancements of the radiation belts can also occur from injections by interplanetary shocks impacting the magnetosphere, such as occurred on 24 March 1991. We compare shock characteristics from previous injection events to those from the Van Allen Probes era to investigate why none of the interplanetary shocks since September 2012 have caused MeV electron injections into the slot region and inner radiation belt, which has surprisingly been devoid of measurable quantities of >~1 MeV electrons throughout the Van Allen Probes era. Our last topic concerns loss processes. We discuss drastic loss events, known as "flux dropouts", and present evidence that these loss events can eliminate the vast majority of relativistic electrons in the outer radiation belt on time scales of only a few hours. We

  9. Science Objectives and Rationale for the Radiation Belt Storm Probes Mission

    NASA Technical Reports Server (NTRS)

    Mauk, B.H.; Fox, Nicola J.; Kanekal, S. G.; Kessel, R. L.; Sibek, D. G.; Ukhorskiy, A.

    2012-01-01

    The NASA Radiation Belt Storm Probes (RBSP) mission addresses how populationsof high energy charged particles are created, vary, and evolve in space environments,and specifically within Earths magnetically trapped radiation belts. RBSP, with a nominallaunch date of August 2012, comprises two spacecraft making in situ measurements for atleast 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 every2.5 months, allowing separation of spatial from temporal effects over spatial scales rangingfrom 0.1 to 5 RE. The uniquely comprehensive suite of instruments, identical on the twospacecraft, measures all of the particle (electrons, ions, ion composition), fields (E and B),and wave distributions (dE and dB) that are needed to resolve the most critical science questions.Here we summarize the high level science objectives for the RBSP mission, providehistorical background on studies of Earth and planetary radiation belts, present examples ofthe most compelling scientific mysteries of the radiation belts, present the mission design ofthe RBSP mission that targets these mysteries and objectives, present the observation andmeasurement requirements for the mission, and introduce the instrumentation that will deliverthese measurements. This paper references and is followed by a number of companionpapers that describe the details of the RBSP mission, spacecraft, and instruments.

  10. Nonlinear Whistler Wave Physics in the Radiation Belts

    NASA Astrophysics Data System (ADS)

    Crabtree, Chris

    2016-10-01

    Wave particle interactions between electrons and whistler waves are a dominant mechanism for controlling the dynamics of energetic electrons in the radiation belts. They are responsible for loss, via pitch-angle scattering of electrons into the loss cone, and energization to millions of electron volts. It has previously been theorized that large amplitude waves on the whistler branch may scatter their wave-vector nonlinearly via nonlinear Landau damping leading to important consequences for the global distribution of whistler wave energy density and hence the energetic electrons. It can dramatically reduce the lifetime of energetic electrons in the radiation belts by increasing the pitch angle scattering rate. The fundamental building block of this theory has now been confirmed through laboratory experiments. Here we report on in situ observations of wave electro-magnetic fields from the EMFISIS instrument on board NASA's Van Allen Probes that show the signatures of nonlinear scattering of whistler waves in the inner radiation belts. In the outer radiation belts, whistler mode chorus is believed to be responsible for the energization of electrons from 10s of Kev to MeV energies. Chorus is characterized by bursty large amplitude whistler mode waves with frequencies that change as a function of time on timescales corresponding to their growth. Theories explaining the chirping have been developed for decades based on electron trapping dynamics in a coherent wave. New high time resolution wave data from the Van Allen probes and advanced spectral techniques are revealing that the wave dynamics is highly structured, with sub-elements consisting of multiple chirping waves with discrete frequency hops between sub-elements. Laboratory experiments with energetic electron beams are currently reproducing the complex frequency vs time dynamics of whistler waves and in addition revealing signatures of wave-wave and beat-wave nonlinear wave-particle interactions. These new data

  11. Canadian radiation belt science in the ILWS era

    NASA Astrophysics Data System (ADS)

    Mann, I. R.

    The Outer Radiation Belt Injection, Transport, Acceleration, and Loss Satellite (ORBITALS) is a Canadian Space Agency small satellite mission proposed as a Canadian contribution to the satellite infrastructure for the International Living With a Star (ILWS) program. Planned to operate contemporaneously with the NASA Radiation Belt Storm Probes (RBSP), the ORBITALS will monitor the energetic electron and ion populations in the inner magnetosphere across a wide range of energies (keV to tens of MeV) as well as the dynamic electric and magnetic fields, waves, and cold plasma environment which govern the injection, transport, acceleration and loss of these energetic and space weather critical particle populations in the inner magnetosphere. Currently in Phase A Design Study, the ORBITALS will be launched into a low-inclination GTO-like orbit which every second orbit maximizes the long lasting apogee-pass conjunctions with both the ground-based instruments of the Canadian Geospace Monitoring (CGSM) array as well as with the GOES East and West and geosynchronous communications satellites in the North American sector. In a twelve-hour orbit, every second apogee will conjunct with instrumentation 180 degree in longitude away in the Asian sector. Specifically, the ORBITALS will make the measurements necessary to reach reveal fundamental new understanding of the relative importance of different physical processes (for example VLF verses ULF waves) which shape the energetic particle populations in the inner magnetosphere, as well as providing the raw radiation measurements at MEO altitudes necessary for the development of the next-generation of radiation belt specification models. On-board experiments will also monitor the dose, single event upset, and deep-dielectric charging responses of electronic components on-orbit. Supporting ground-based measurements of ULF and higher frequency wave fields from the Canadian CARISMA (www.carisma.ca) magnetometer array, as well as from

  12. Radiation Belts Throughout the Solar System

    NASA Astrophysics Data System (ADS)

    Mauk, B. H.

    2008-12-01

    The several preceding decades of deep space missions have demonstrated that the generation of planetary radiation belts is a universal phenomenon. All strongly magnetized planets show well developed radiation regions, specifically Earth, Jupiter, Saturn, Uranus, and Neptune. The similarities occur despite the tremendous differences between the planets in size, levels of magnetization, external environments, and most importantly, in the fundamental processes that power them. Some planets like Jupiter are powered overwhelmingly by planetary rotation, much like astrophysical pulsars, whereas others, like Earth and probably Uranus, are powered externally by the interplanetary environment. Uranus is a particularly interesting case in that despite the peculiarities engendered by its ecliptic equatorial spin axis orientation, its magnetosphere shows dynamical behavior similar to that of Earth as well as radiation belt populations and associated wave emissions that are perhaps more intense than expected based on Earth-derived theories. Here I review the similarities and differences between the radiation regions of radiation belts throughout the solar system. I discuss the value of the comparative approach to radiation belt physics as one that allows critical factors to be evaluated in environments that are divorced from the special complex conditions that prevail in any one environment, such as those at Earth.

  13. What (maybe) you do not know about radiation belts

    NASA Astrophysics Data System (ADS)

    Boscher, D. M.; Sicard-Piet, A.; Rolland, G.

    2013-12-01

    As observed by several authors, the outer electron radiation belt reacts globally to the solar cycle. This is well known. Their trend at very low L shells is less known. Using NOAA POES 0° detector between L=1.16 and 1.18, we discovered a factor 10 increase of the 30-300keV electron flux in the declining phase of the solar cycle. It was observed in 2003, using SEM-2 detector on board POES 15, but the same trend was observed in 1983 and in 1991-1992 using the old SEM detector on the NOAA LEO satellites. Protons in the same range of energy (50-500keV) exhibits a similar behaviour. The second proton belt has been highlighted by the USAF-NASA CRRES satellite. Such proton belt was observed a few times in the past ( in 1963 by McIlwain, in February 1986 by Gussenhoven et al.), but if the good energy range is observed, this can appear several times in a solar cycle. We will show measurements of 10 MeV protons on board the SSO satellite SAC-C, showing the dynamics of the proton belt following the events of March and November 2001, October-November 2003 and September 2005. The NASA AP8 proton model is limited to 300MeV. Is it a physical limitation or simply a question of signal to noise limitation at the time this model was developed? Using old NOAA satellites which have on board a very high energy detector (HEPAD), we will show trapped particles at energies not far from 1GeV. This was measured during several years, from 1979 to 1986, showing the long beating of the belt with the solar cycle.

  14. Development of a new global radiation belt model

    NASA Astrophysics Data System (ADS)

    Sicard, Angelica; Boscher, Daniel; Bourdarie, Sébastien; Lazaro, Didier; Maget, Vincent; Ecoffet, Robert; Rolland, Guy; Standarovski, Denis

    2017-04-01

    The well known AP8 and AE8 NASA models are commonly used in the industry to specify the radiation belt environment. Unfortunately, there are some limitations in the use of these models, first due to the covered energy range, but also because in some regions of space, there are discrepancies between the predicted average values and the measurements. Therefore, our aim is to develop a radiation belt model, covering a large region of space and energy, from LEO altitudes to GEO and above, and from plasma to relativistic particles. The aim for the first version of this new model is to correct the AP8 and AE8 models where they are deficient or not defined. At geostationary, we developed ten years ago for electrons the IGE-2006 model which was proven to be more accurate than AE8, and used commonly in the industry, covering a broad energy range, from 1keV to 5MeV. From then, a proton model for geostationary orbit was also developed for material applications, followed by the OZONE model covering a narrower energy range but the whole outer electron belt, a SLOT model to asses average electron values for 2radiation belt model will be presented during the conference.

  15. Review of GEM Radiation Belt Dropout and Buildup Challenges

    NASA Astrophysics Data System (ADS)

    Tu, Weichao; Li, Wen; Morley, Steve; Albert, Jay

    2017-04-01

    In Summer 2015 the US NSF GEM (Geospace Environment Modeling) focus group named "Quantitative Assessment of Radiation Belt Modeling" started the "RB dropout" and "RB buildup" challenges, focused on quantitative modeling of the radiation belt buildups and dropouts. This is a community effort which includes selecting challenge events, gathering model inputs that are required to model the radiation belt dynamics during these events (e.g., various magnetospheric waves, plasmapause and density models, electron phase space density data), simulating the challenge events using different types of radiation belt models, and validating the model results by comparison to in situ observations of radiation belt electrons (from Van Allen Probes, THEMIS, GOES, LANL/GEO, etc). The goal is to quantitatively assess the relative importance of various acceleration, transport, and loss processes in the observed radiation belt dropouts and buildups. Since 2015, the community has selected four "challenge" events under four different categories: "storm-time enhancements", "non-storm enhancements", "storm-time dropouts", and "non-storm dropouts". Model inputs and data for each selected event have been coordinated and shared within the community to establish a common basis for simulations and testing. Modelers within and outside US with different types of radiation belt models (diffusion-type, diffusion-convection-type, test particle codes, etc.) have participated in our challenge and shared their simulation results and comparison with spacecraft measurements. Significant progress has been made in quantitative modeling of the radiation belt buildups and dropouts as well as accessing the modeling with new measures of model performance. In this presentation, I will review the activities from our "RB dropout" and "RB buildup" challenges and the progresses achieved in understanding radiation belt physics and improving model validation and verification.

  16. Radiation Belt response to the July 2017 Coronal Mass Ejection and the Interplanetary Shock

    NASA Astrophysics Data System (ADS)

    Kanekal, S. G.; Baker, D. N.; Jones, A. D.; Schiller, Q. A.; Sibeck, D. G.; Elkington, S. R.; Hoxie, V. C.; Jaynes, A. N.; Li, X.; Zhao, H.; Blake, J. B.; Claudepierre, S. G.; Fennell, J. F.; Turner, D. L.

    2017-12-01

    A coronal mass ejection that erupted on July 14, 2017 impacted the radiation belts on July 16, 2017 and resulted in a moderate geomagnetic storm. The immediate response of the energetic electrons to the interplanetary shock ahead of the CME, showed hock-induced energization as well as drift echoes in the L range of 4 to 5 . Increased electron fluxes were seen to energies up to 5 MeV as observed by the Relativistic Electron and Proton Telescope and the Magnetic Electron and Ion Sensors on board NASA's Van Allen Probes. We report on these observations, both immediately after the IP shock passage and the more gradual response to the CME. we discuss the observation in the context of electron dynamics in the terrestrial radiation belts.

  17. Bayesian inference of radiation belt loss timescales.

    NASA Astrophysics Data System (ADS)

    Camporeale, E.; Chandorkar, M.

    2017-12-01

    Electron fluxes in the Earth's radiation belts are routinely studied using the classical quasi-linear radial diffusion model. Although this simplified linear equation has proven to be an indispensable tool in understanding the dynamics of the radiation belt, it requires specification of quantities such as the diffusion coefficient and electron loss timescales that are never directly measured. Researchers have so far assumed a-priori parameterisations for radiation belt quantities and derived the best fit using satellite data. The state of the art in this domain lacks a coherent formulation of this problem in a probabilistic framework. We present some recent progress that we have made in performing Bayesian inference of radial diffusion parameters. We achieve this by making extensive use of the theory connecting Gaussian Processes and linear partial differential equations, and performing Markov Chain Monte Carlo sampling of radial diffusion parameters. These results are important for understanding the role and the propagation of uncertainties in radiation belt simulations and, eventually, for providing a probabilistic forecast of energetic electron fluxes in a Space Weather context.

  18. New Results About the Earth’s Van Allen Radiation Belts

    NASA Astrophysics Data System (ADS)

    Baker, Daniel

    2015-01-01

    The first great scientific discovery of the Space Age was that the Earth is enshrouded in toroids, or 'belts', of very high-energy magnetically trapped charged particles. Early observations of the radiation environment clearly indicated that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. Subsequent studies showed that electrons in the energy range 100 keV < E< 1 MeV often populated both the inner and outer zones with a pronounced 'slot' region relatively devoid of energetic electrons existing between them. This two-belt structure for the Van Allen moderate-energy electron component was explained as being due to strong interactions of electrons with electromagnetic waves just inside the cold plasma (plasmapause) boundary. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions. However, recent observations by the NASA dual-spacecraft Van Allen Probes mission have revealed wholly unexpected properties of the radiation belts, especially at highly relativistic (E > 2 MeV) and ultra-relativistic (E > 5 MeV) kinetic energies. In this presentation we show using high spatial and temporal resolution data from the Relativistic Electron-Proton Telescope (REPT) experiment on board the Van Allen Probes that multiple belts can exist concurrently and that an exceedingly sharp inner boundary exists for ultra-relativistic electrons. Using additionally available Van Allen Probes data, we demonstrate that these remarkable features of energetic electrons are not due to a physical boundary within Earth's intrinsic magnetic field. Neither is it likely that human-generated electromagnetic transmitter wave fields might produce such effects. Rather, we conclude from these unique measurements that slow natural inward radial diffusion combined with weak, but persistent, wave-particle pitch angle

  19. Jupiter's radiation belts: Can Pioneer 10 survive?

    NASA Technical Reports Server (NTRS)

    Hess, W. N.; Birmingham, T. J.; Mead, G. D.

    1973-01-01

    Model calculations of Jupiter's electron and proton radiation belts indicate that the Galilean satellites can reduce particle fluxes in certain regions of the inner magnetosphere by as much as six orders of magnitude. Average fluxes should be reduced by a factor of 100 or more along the Pioneer 10 trajectory through the heart of Jupiter's radiation belts in early December. This may be enough to prevent serious radiation damage to the spacecraft.

  20. Jupiter's Radiation Belts: Can Pioneer 10 Survive?

    PubMed

    Hess, W N; Birmingham, T J; Mead, G D

    1973-12-07

    Model calculations of Jupiter's electron and proton radiation belts indicate that the Galilean satellites can reduce particle fluxes in certain regions of the inner magnetosphere by as much as six orders of magnitude. Average fluxes should be reduced by a factor of 100 or more along the Pioneer 10 trajectory through the heart of Jupiter's radiation belts in early December. This may be enough to prevent serious radiation damage to the spacecraft.

  1. Power-line harmonic radiation - Can it significantly affect the earth's radiation belts

    NASA Technical Reports Server (NTRS)

    Thorne, R. M.; Tsurutani, B. T.

    1979-01-01

    It has been suggested that harmonic radiation from the earth's 50- and 60-hertz power transmission lines might significantly influence the distribution of electrons in the radiation belts. On the basis of observations presented here, it seems advisable to accept such a hypothesis with caution. New evidence suggests that power-line radiation does not play any major role in the nonadiabatic dynamics of radiation belt electrons.

  2. Radiation belt seed population and its association with the relativistic electron dynamics: A statistical study: Radiation Belt Seed Population

    DOE PAGES

    Tang, C. L.; Wang, Y. X.; Ni, B.; ...

    2017-05-19

    Using the Van Allen Probes data, we study the radiation belt seed population and it associated with the relativistic electron dynamics during 74 geomagnetic storm events. Based on the flux changes of 1 MeV electrons before and after the storm peak, these storm events are divided into two groups of “non-preconditioned” and “preconditioned”. The statistical study shows that the storm intensity is of significant importance for the distribution of the seed population (336 keV electrons) in the outer radiation belt. However, substorm intensity can also be important to the evolution of the seed population for some geomagnetic storm events. Formore » non-preconditioned storm events, the correlation between the peak fluxes and their L-shell locations of the seed population and relativistic electrons (592 keV, 1.0 MeV, 1.8 MeV, and 2.1 MeV) is consistent with the energy-dependent dynamic processes in the outer radiation belt. For preconditioned storm events, the correlation between the features of the seed population and relativistic electrons is not fully consistent with the energy-dependent processes. It is suggested that the good correlation between the radiation belt seed population and ≤1.0 MeV electrons contributes to the prediction of the evolution of ≤1.0 MeV electrons in the Earth’s outer radiation belt during periods of geomagnetic storms.« less

  3. Radiation belt seed population and its association with the relativistic electron dynamics: A statistical study: Radiation Belt Seed Population

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tang, C. L.; Wang, Y. X.; Ni, B.

    Using the Van Allen Probes data, we study the radiation belt seed population and it associated with the relativistic electron dynamics during 74 geomagnetic storm events. Based on the flux changes of 1 MeV electrons before and after the storm peak, these storm events are divided into two groups of “non-preconditioned” and “preconditioned”. The statistical study shows that the storm intensity is of significant importance for the distribution of the seed population (336 keV electrons) in the outer radiation belt. However, substorm intensity can also be important to the evolution of the seed population for some geomagnetic storm events. Formore » non-preconditioned storm events, the correlation between the peak fluxes and their L-shell locations of the seed population and relativistic electrons (592 keV, 1.0 MeV, 1.8 MeV, and 2.1 MeV) is consistent with the energy-dependent dynamic processes in the outer radiation belt. For preconditioned storm events, the correlation between the features of the seed population and relativistic electrons is not fully consistent with the energy-dependent processes. It is suggested that the good correlation between the radiation belt seed population and ≤1.0 MeV electrons contributes to the prediction of the evolution of ≤1.0 MeV electrons in the Earth’s outer radiation belt during periods of geomagnetic storms.« less

  4. Investigating the source of near-relativistic and relativistic electrons in Earth's inner radiation belt

    DOE PAGES

    Turner, Drew Lawson; O'Brien, T. P.; Fennell, J. F.; ...

    2017-01-30

    Using observations from NASA's Van Allen Probes, we study the role of sudden particle enhancements at low L shells (SPELLS) as a source of inner radiation belt electrons. SPELLS events are characterized by electron intensity enhancements of approximately an order of magnitude or more in less than 1 day at L < 3. During quiet and average geomagnetic conditions, the phase space density radial distributions for fixed first and second adiabatic invariants are peaked at 2 < L < 3 for electrons ranging in energy from ~50 keV to ~1 MeV, indicating that slow inward radial diffusion is not themore » dominant source of inner belt electrons under quiet/average conditions. During SPELLS events, the evolution of electron distributions reveals an enhancement of phase space density that can exceed 3 orders of magnitude in the slot region and continues into the inner radiation belt, which is evidence that these events are an important—and potentially dominant—source of inner belt electrons. Electron fluxes from September 2012 through February 2016 reveal that SPELLS occur frequently (~2.5/month at 200 keV), but the number of observed events decreases exponentially with increasing electron energy for ≥100 keV. After SPELLS events, the slot region reforms due to slow energy-dependent decay over several day time scales, consistent with losses due to interactions with plasmaspheric hiss. Altogether, these results indicate that the peaked phase space density distributions in the inner electron radiation belt result from an “on/off,” geomagnetic-activity-dependent source from higher radial distances.« less

  5. Investigating the source of near-relativistic and relativistic electrons in Earth's inner radiation belt

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Turner, Drew Lawson; O'Brien, T. P.; Fennell, J. F.

    Using observations from NASA's Van Allen Probes, we study the role of sudden particle enhancements at low L shells (SPELLS) as a source of inner radiation belt electrons. SPELLS events are characterized by electron intensity enhancements of approximately an order of magnitude or more in less than 1 day at L < 3. During quiet and average geomagnetic conditions, the phase space density radial distributions for fixed first and second adiabatic invariants are peaked at 2 < L < 3 for electrons ranging in energy from ~50 keV to ~1 MeV, indicating that slow inward radial diffusion is not themore » dominant source of inner belt electrons under quiet/average conditions. During SPELLS events, the evolution of electron distributions reveals an enhancement of phase space density that can exceed 3 orders of magnitude in the slot region and continues into the inner radiation belt, which is evidence that these events are an important—and potentially dominant—source of inner belt electrons. Electron fluxes from September 2012 through February 2016 reveal that SPELLS occur frequently (~2.5/month at 200 keV), but the number of observed events decreases exponentially with increasing electron energy for ≥100 keV. After SPELLS events, the slot region reforms due to slow energy-dependent decay over several day time scales, consistent with losses due to interactions with plasmaspheric hiss. Altogether, these results indicate that the peaked phase space density distributions in the inner electron radiation belt result from an “on/off,” geomagnetic-activity-dependent source from higher radial distances.« less

  6. NASA's Van Allen Probes Discover a Surprise Circling Earth

    NASA Image and Video Library

    2017-12-08

    Two giant swaths of radiation, known as the Van Allen Belts, surrounding Earth were discovered in 1958. In 2012, observations from the Van Allen Probes showed that a third belt can sometimes appear. The radiation is shown here in yellow, with green representing the spaces between the belts. Credit: NASA/Van Allen Probes/Goddard Space Flight Center To read more go to: www.nasa.gov/mission_pages/rbsp/news/third-belt.html NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  7. Wave-Particle Interactions in the Radiation Belts, Aurora,and Solar Wind: Opportunities for Lab Experiments

    NASA Astrophysics Data System (ADS)

    Kletzing, C.

    2017-12-01

    The physics of the creation, loss, and transport of radiation belt particles is intimately connected to the electric and magnetic fields which mediate these processes. A large range of field and particle interactions are involved in this physics from large-scale ring current ion and magnetic field dynamics to microscopic kinetic interactions of whistler-mode chorus waves with energetic electrons. To measure these kinds of radiation belt interactions, NASA implemented the two-satellite Van Allen Probes mission. As part of the mission, the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) investigation is an integrated set of instruments consisting of a triaxial fluxgate magnetometer (MAG) and a Waves instrument which includes a triaxial search coil magnetometer (MSC). We show a variety of waves thought to be important for wave particle interactionsin the radiation belts: low frequency ULF pulsations, EMIC waves, and whistler mode waves including upper and lower band chorus. Outside ofthe radiation belts, Alfven waves play a key role in both solar wind turbulenceand auroral particle acceleration. Several of these wave modes could benefit (or have benefitted) from laboratory studies to further refineour understanding of the detailed physics of the wave-particle interactionswhich lead to energization, pitch angle scattering, and cross-field transportWe illustrate some of the processes and compare the wave data with particle measurements to show relationships between wave activity and particle processobserved in the inner magnetosphere and heliosphere.

  8. From the IGY to the IHY: A Changing View of the Van Allen Radiation Belts

    NASA Astrophysics Data System (ADS)

    Hudson, M. K.

    2006-12-01

    Discovery of the Van Allen radiation belts by instrumentation flown on Explorer 1 in 1958 was the first major discovery of the Space Age. A view of the belts as static inner and outer zones of energetic particles with different sources, a double-doughnut encircling the Earth, became iconic to the point that their dynamic behavior and solar connection receded from public awareness and apparent scientific import. Then the Cycle 23 maximum in solar activity arrived in 1989-1991, the first approaching the activity level of the International Geophysical Year of 1957-58, when the Van Allen belts were first discovered. Delay in launch of the NASA-Air Force Combined Radiation Release and Effects Satellite, following the Challenger accident in 1986, led to having the right instruments in the right orbit at the right time to detect prompt injection of outer belt electrons and solar energetic protons into the `slot region' between the inner and outer belts, forming new trapped populations which lasted for years in an otherwise benign location. This event in March 1991, along with the great geomagnetic storm of March 1989, and our increased dependence on space technology since the early Explorer days, led to a resurgence of interest in the Van Allen radiation belts and understanding of their connectivity to the Sun. Additional instrumentation from NASA's International Solar Terrestrial Physics Program, the Solar Anomalous and Magnetospheric Particle Explorer (SAMPEX) and IMAGE spacecraft from the Explorer program, NOAA and DOD spacecraft, and improved worldwide linkages of groundbased measurements have contributed much since 1991 to our understanding of the dynamic characteristics of the Van Allen belts. Further, the presence of continuous solar wind measurements beginning with the launch of WIND in 1994, and SOHO images of Coronal Mass Ejections and coronal hole sources of high speed solar wind flow have filled in the connection with solar activity qualitatively anticipated

  9. The Radiation Belt Storm Probes (RBSP) Energetic Particle, Composition, and Thermal plasma (ECT) Suite: Upcoming Opportunties for Testing Radiation Belt Acceleration Mechanisms

    NASA Astrophysics Data System (ADS)

    Spence, Harlan; Reeves, Geoffrey

    2012-07-01

    The Radiation Belt Storm Probes (RBSP) mission will launch in late summer 2012 and begin its exploration of acceleration and dynamics of energetic particles in the inner magnetosphere. In this presentation, we discuss opportunities afforded by the RBSP Energetic Particle, Composition, and Thermal plasma (ECT) instrument suite to advance our understanding of acceleration processes in the radiation belts. The RBSP-ECT instrument suite comprehensively measures the electron and major ion populations of the inner magnetosphere, from the lowest thermal plasmas of the plasmasphere, to the hot plasma of the ring current, to the relativistic populations of the radiation belts. Collectively, the ECT measurements will reveal the complex cross-energy coupling of these colocated particle populations, which along with concurrent RBSP wave measurements, will permit various wave-particle acceleration mechanisms to be tested. We review the measurement capabilities of the RBSP-ECT instrument suite, and demonstrate several examples of how these measurements will be used to explore candidate acceleration mechanisms and dynamics of radiation belt particles.

  10. Liquid belt radiator design study

    NASA Technical Reports Server (NTRS)

    Teagan, W. P.; Fitzgerald, K. F.

    1986-01-01

    The Liquid Belt Radiator (LBR) is an advanced concept developed to meet the needs of anticipated future space missions. A previous study documented the advantages of this concept as a lightweight, easily deployable alternative to present day space heat rejection systems. The technical efforts associated with this study concentrate on refining the concept of the LBR as well as examining the issues of belt dynamics and potential application of the LBR to intermediate and high temperature heat rejection applications. A low temperature point design developed in previous work is updated assuming the use of diffusion pump oil, Santovac-6, as the heat transfer media. Additional analytical and design effort is directed toward determining the impact of interface heat exchanger, fluid bath sealing, and belt drive mechanism designs on system performance and mass. The updated design supports the earlier result by indicating a significant reduction in system specific system mass as compared to heat pipe or pumped fluid radiator concepts currently under consideration (1.3 kg/sq m versus 5 kg/sq m).

  11. Particle Energization in Earth's Van Allen Radiation Belts Due to Solar Wind Forcing

    NASA Astrophysics Data System (ADS)

    Baker, D. N.

    2017-12-01

    Early observations of the Earth's radiation environment clearly indicated that the Van Allen belts could be delineated into an inner zone dominated by high-energy protons and an outer zone dominated by high-energy electrons. The energy distribution, spatial extent and particle species makeup of the Van Allen belts has been subsequently explored by several space missions. However, recent observations by the NASA dual-spacecraft Van Allen Probes mission have revealed unexpected properties of the radiation belts, especially for electrons at highly relativistic (E > 2 MeV) and ultra-relativistic (E > 5 MeV) kinetic energies. In this presentation we show using high spatial and temporal resolution data from the experiments on board the Van Allen Probes that multiple belts can exist concurrently and that an exceedingly sharp inner boundary exists for ultra-relativistic electrons. Using additionally available Van Allen Probes data, we demonstrate that these remarkable features of energetic electrons are driven by strong solar and solar wind forcings. The comprehensive Van Allen Probes data show more broadly and in many ways how extremely high energy particles are accelerated, transported, and lost in the magnetosphere due to interplanetary shock wave interactions, coronal mass ejection impacts, and high-speed solar wind streams. The new data have shown especially how dayside processes play a key role in electron acceleration and loss processes.

  12. Electron Radiation Belts of the Solar System

    NASA Astrophysics Data System (ADS)

    Mauk, Barry; Fox, Nicola

    To address the question of what factors dictate similarities and differences between radiation belts, we present comparisons between the electron radiation belt spectra of all five strongly magnetized planets within the solar system: Earth, Jupiter, Saturn, Uranus, and Neptune. We choose the highest intensity observed electron spectrum within each system (highest specifically near 1 MeV) and compare them against expectations based on the so-called Kennel-Petschek limit (KP; 1966) for each system. For evaluating the KP limit, we begin with the new relativis-tically correct formulation of Summers et al. (2009) but then add several refinements of our own. Specifically, we: 1) utilized a much more flexible analytic spectral shape that allows us to accurately fit observed radiation belt spectra; 2) adopt the point of view that the anisotropy parameter is not a free parameter but must take on a minimal value, as originally proposed by Kennel and Petschek (1966); and 3) examine the differential characteristics of the KP limit along the lines of what Schulz and Davidson (1988) performed for the non-relativistic formula-tion. We find that three factors limit the highest electron radiation belt intensities within solar system planetary magnetospheres: a) whistler mode interactions that limit spectral intensities to a differential Kennel-Petschek limit (3 planets); b) the absence of robust acceleration pro-cesses associated with injection dynamics (1 planet); and c) material interactions between the radiation particles and clouds of gas and dust (1 planet).

  13. The earth's trapped radiation belts

    NASA Technical Reports Server (NTRS)

    Noll, R. B.; Mcelroy, M. B.

    1975-01-01

    The near-earth charged particle environment is discussed in terms of spacecraft design criteria. Models are presented of the trapped radiation belts and based on in-situ data obtained from spacecraft.

  14. Dependence of radiation belt simulations to assumed radial diffusion rates

    NASA Astrophysics Data System (ADS)

    Drozdov, A.; Shprits, Y.; Aseev, N.; Kellerman, A. C.; Reeves, G. D.

    2017-12-01

    Radial diffusion is one of the dominant physical mechanisms that drives acceleration and loss of the radiation belt electrons due to wave-particle interaction with ultra low frequency (ULF) waves, which makes it very important for radiation belt modeling and forecasting. We investigate the sensitivity of several parameterizations of the radial diffusion including Brautigam and Albert [2000], Ozeke et al. [2014] and Ali et al. [2016] on long-term radiation belt modeling using the Versatile Electron Radiation Belt (VERB). Following previous studies, we first perform 1-D radial diffusion simulations. To take into account effects of local acceleration and loss, we perform additional 3-D simulations, including pitch-angle, energy and mixed diffusion. The obtained result demonstrates that the inclusion of local acceleration and pitch-angle diffusion can provide a negative feedback effect, such that the result is largely indistinguishable between simulations conducted with different radial diffusion parameterizations. We also perform a number of sensitivity tests by multiplying radial diffusion rates by constant factors and show that such an approach leads to unrealistic predictions of radiation belt dynamics.

  15. Radiation Belt Storm Probes: Resolving Fundamental Physics with Practical Consequences

    NASA Technical Reports Server (NTRS)

    Ukhorskiy, Aleksandr Y.; Mauk, Barry H.; Fox, Nicola J.; Sibeck, David G.; Grebowsky, Joseph M.

    2011-01-01

    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.

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

    PubMed

    Ukhorskiy, A Y; Sitnov, M I; Mitchell, D G; Takahashi, K; Lanzerotti, L J; Mauk, B H

    2014-03-20

    Structured features on top of nominally smooth distributions of radiation-belt particles at Earth have been previously associated with particle acceleration and transport mechanisms powered exclusively by enhanced solar-wind activity. Although planetary rotation is considered to be important for particle acceleration at Jupiter and Saturn, the electric field produced in the inner magnetosphere by Earth's rotation can change the velocity of trapped particles by only about 1-2 kilometres per second, so rotation has been thought inconsequential for radiation-belt electrons with velocities of about 100,000 kilometres per second. Here we report that the distributions of energetic electrons across the entire spatial extent of Earth's inner radiation belt are organized in regular, highly structured and unexpected 'zebra stripes', even when the solar-wind activity is low. Modelling reveals that the patterns are produced by Earth's rotation. Radiation-belt electrons are trapped in Earth's dipole-like magnetic field, where they undergo slow longitudinal drift motion around the planet because of the gradient and curvature of the magnetic field. Earth's rotation induces global diurnal variations of magnetic and electric fields that resonantly interact with electrons whose drift period is close to 24 hours, modifying electron fluxes over a broad energy range into regular patterns composed of multiple stripes extending over the entire span of the inner radiation belt.

  17. Monitoring, Analyzing and Assessing Radiation Belt Loss and Energization

    NASA Astrophysics Data System (ADS)

    Daglis, I.; Balasis, G.; Bourdarie, S.; Horne, R.; Khotyaintsev, Y.; Mann, I.; Santolik, O.; Turner, D.; Anastasiadis, A.; Georgiou, M.; Giannakis, O.; Papadimitriou, C.; Ropokis, G.; Sandberg, I.; Angelopoulos, V.; Glauert, S.; Grison, B., Kersten T.; Kolmasova, I.; Lazaro, D.; Mella, M.; Ozeke, L.; Usanova, M.

    2013-09-01

    We present the concept, objectives and expected impact of the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Loss and Energization) project, which is being implemented by a consortium of seven institutions (five European, one Canadian and one US) with support from the European Community's Seventh Framework Programme. The MAARBLE project employs multi-spacecraft monitoring of the geospace environment, complemented by ground-based monitoring, in order to analyze and assess the physical mechanisms leading to radiation belt particle energization and loss. Particular attention is paid to the role of ULF/VLF waves. A database containing properties of the waves is being created and will be made available to the scientific community. Based on the wave database, a statistical model of the wave activity dependent on the level of geomagnetic activity, solar wind forcing, and magnetospheric region will be developed. Multi-spacecraft particle measurements will be incorporated into data assimilation tools, leading to new understanding of the causal relationships between ULF/VLF waves and radiation belt dynamics. Data assimilation techniques have been proven as a valuable tool in the field of radiation belts, able to guide 'the best' estimate of the state of a complex system. The MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Energization and Loss) collaborative research project has received funding from the European Union’s Seventh Framework Programme (FP7-SPACE-2011-1) under grant agreement no. 284520.

  18. 10 Years of Student Questions about the Radiation Belts

    NASA Astrophysics Data System (ADS)

    Gross, N. A.; Hughes, W. J.; Wiltberger, M. J.

    2016-12-01

    The NSF funded CISM Space Weather Summer School is targeted to graduate students just starting in space physics and provides a comprehensive conceptual background to the field. Insights from this summer school can provide valuable information to graduate instructors and graduate student mentors. During the school, students are invited to submit questions at the end of the lecture component each day. The lecturers then take the time to respond to these questions. We have collected over 3000 student questions over the last 10 years. The radiation belts, solar energetic particles, and the operational impacts of high energy particles are among the topics covered during the summer school, and these topics consistently generate a share of the questions following those lectures. The collection includes questions about: the structure and variability of the radiation belts, the distinction between solar energetic particles (SEPs) and the radiation belts, the distinction between the ring current and the radiation belts, the impact radiation belt particles and SEPs have on the magnetosphere, the risks high energy particles pose to spacecraft and humans, their impact on operations, regulations for human exposure, and others. The presentation will catalog the questions asked by students and provide insight into students prior conceptions and misunderstandings about this topic. We hope this work informs instructors who teach these topics.

  19. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang

    The Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. So, our results demonstrate that the ULFmore » waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons.« less

  20. Ultra-low-frequency wave-driven diffusion of radiation belt relativistic electrons

    DOE PAGES

    Su, Zhenpeng; Zhu, Hui; Xiao, Fuliang; ...

    2015-12-22

    The Van Allen radiation belts are typically two zones of energetic particles encircling the Earth separated by the slot region. How the outer radiation belt electrons are accelerated to relativistic energies remains an unanswered question. Recent studies have presented compelling evidence for the local acceleration by very-low-frequency (VLF) chorus waves. However, there has been a competing theory to the local acceleration, radial diffusion by ultra-low-frequency (ULF) waves, whose importance has not yet been determined definitively. Here we report a unique radiation belt event with intense ULF waves but no detectable VLF chorus waves. So, our results demonstrate that the ULFmore » waves moved the inner edge of the outer radiation belt earthward 0.3 Earth radii and enhanced the relativistic electron fluxes by up to one order of magnitude near the slot region within about 10 h, providing strong evidence for the radial diffusion of radiation belt relativistic electrons.« less

  1. Recent Developments in the Radiation Belt Environment Model

    NASA Technical Reports Server (NTRS)

    Fok, M.-C.; Glocer, A.; Zheng, Q.; Horne, R. B.; Meredith, N. P.; Albert, J. M.; Nagai, T.

    2010-01-01

    The fluxes of energetic particles in the radiation belts are found to be strongly controlled by the solar wind conditions. In order to understand and predict the radiation particle intensities, we have developed a physics-based Radiation Belt Environment (RBE) model that considers the influences from the solar wind, ring current and plasmasphere. Recently, an improved calculation of wave-particle interactions has been incorporated. In particular, the model now includes cross diffusion in energy and pitch-angle. We find that the exclusion of cross diffusion could cause significant overestimation of electron flux enhancement during storm recovery. The RBE model is also connected to MHD fields so that the response of the radiation belts to fast variations in the global magnetosphere can be studied.Weare able to reproduce the rapid flux increase during a substorm dipolarization on 4 September 2008. The timing is much shorter than the time scale of wave associated acceleration.

  2. A virtual radiation belt observatory: Looking forward to the electronic geophysical year

    NASA Astrophysics Data System (ADS)

    Baker, D. N.; Green, J. C.; Kroehl, H. W.; Kihn, E.; Virbo Team

    During the International Geophysical Year (1957-1958), member countries established many new capabilities pursuing the major IGY objectives of collecting geophysical data as widely as possible and providing free access to these data for all scientists around the globe. A key achievement of the IGY was the establishment of a worldwide system of data centers and physical observatories. The worldwide scientific community has now endorsed and is promoting an electronic Geophysical Year (eGY) initiative. The proposed eGY concept would both commemorate the 50th anniversary of the IGY in 2007-2008 and would provide a forward impetus to geophysics in the 21st century, similar to that provide by the IGY fifty years ago. The eGY concept advocates the establishment of a series of virtual geophysical observatories now being deployed in cyberspace. We are developing the concept of a Virtual Radiation Belt Observatory (ViRBO) that will bring together near-earth particle and field measurements acquired by NASA, NOAA, DoD, DOE, and other spacecraft. We discuss plans to aggregate these measurements into a readily accessible database along with analysis, visualization, and display tools that will make radiation belt information available and useful both to the scientific community and to the user community. We envision that data from the various agencies along with models being developed under the auspices of the National Science Foundation Center for Integrated Space Weather Modeling (CISM) will help us to provide an excellent `climatology' of the radiation belts over the past several decades. In particular, we would plan to use these data to drive physical models of the radiation belts to form a gridded database which would characterize particle and field properties on solar-cycle (11-year) time scales. ViRBO will also provide up-to-date specification of conditions for event analysis and anomaly resolution. We are even examining the possibilities for near-realtime acquisition of

  3. Response of radiation belt simulations to different radial diffusion coefficients

    NASA Astrophysics Data System (ADS)

    Drozdov, A.; Shprits, Y.; Subbotin, D.; Kellerman, A. C.

    2013-12-01

    Resonant interactions between Ultra Low Frequency (ULF) waves and relativistic electrons may violate the third adiabatic invariant of motion, which produces radial diffusion in the electron radiation belts. This process plays an important role in the formation and structure of the outer electron radiation belt and is important for electron acceleration and losses in that region. Two parameterizations of the resonant wave-particle interaction of electrons with ULF waves in the magnetosphere by Brautigam and Albert [2000] and Ozeke et al. [2012] are evaluated using the Versatile Electron Radiation Belt (VERB) diffusion code to estimate their relative effect on the radiation belt simulation. The period of investigation includes quiet time and storm time geomagnetic activity and is compared to data based on satellite observations. Our calculations take into account wave-particle interactions represented by radial diffusion transport, local acceleration, losses due to pitch-angle diffusion, and mixed diffusion. We show that the results of the 3D diffusion simulations depend on the assumed parametrization of waves. The differences between the simulations and potential missing physical mechanisms are discussed. References Brautigam, D. H., and J. M. Albert (2000), Radial diffusion analysis of outer radiation belt electrons during the October 9, 1990, magnetic storm, J. Geophys. Res., 105(A1), 291-309, doi:10.1029/1999JA900344 Ozeke, L. G., I. R. Mann, K. R. Murphy, I. J. Rae, D. K. Milling, S. R. Elkington, A. A. Chan, and H. J. Singer (2012), ULF wave derived radiation belt radial diffusion coefficients, J. Geophys. Res., 117, A04222, doi:10.1029/2011JA017463.

  4. Characterizing Total Radiation Belt Electron Content Using Van Allen Probes Data

    NASA Astrophysics Data System (ADS)

    Huang, C. L.; Spence, H. E.; Boyd, A. J.; Jordan, A.; Paulson, K. W.; Zhang, J.; Blake, J. B.; Kletzing, C.

    2014-12-01

    The comprehensive particle and wave measurements of the Van Allen Probes enable us to monitor the entire radiation belt near the equator from L-shells of 2.5 to 6. Using the particle measurements, we create an improved, high-level quantity representing the entire outer belt. This quantity, the total radiation belt electron content (TRBEC), is the half-orbit sum of outer belt electrons over the radiation belt energy ranges of importance and all pitch angles using data from RBSP-ECT instrument on board both spacecraft. The goal is to characterize statistically the dynamics of the entire radiation belt by comparing TRBEC with solar wind parameters, magnetospheric waves, and electron seed population. When comparing TRBEC with solar wind velocity, our result shows a triangle-distribution similar to that which Reeves et al. (2011) found using geosynchronous electron flux. We also correlate TRBEC with other solar wind parameters to identify which solar wind conditions effectively enhance or deplete radiation belt electrons. In addition, plasma waves in the inner magnetosphere, via wave-particle interaction, are key elements affecting the dynamics of the radiation belt. Therefore, we compare TRBEC with integrated EMIC and chorus (upper and lower bands) wave power calculated from EMFISIS wave measurements to determine the relative importance between each wave-particle process. Finally, we demonstrate the ~100 keV seed population's characteristics that correspond to the MeV population enhancement. While the gross features of the two populations are similar, the MeV population's dynamics lag behind those of the seed population by 5 to 60 hours, which implies the acceleration or loss processes vary by event.

  5. Radiation Belt Dynamics

    DTIC Science & Technology

    2015-12-27

    is unlimited. 15 DISTRIBUTION LIST DTIC/OCP 8725 John J. Kingman Rd, Suite 0944 Ft Belvoir, VA 22060-6218 1 cy AFRL /RVIL Kirtland AFB, NM 87117... AFRL -RV-PS- AFRL -RV-PS- TR-2016-0007 TR-2016-0007 RADIATION BELT DYNAMICS Jay M. Albert, et al. 27 December 2015 Final Report APPROVED FOR... KIRTLAND AIR FORCE BASE, NM 87117-5776 DTIC COPY NOTICE AND SIGNATURE PAGE Using Government drawings, specifications, or other data included in this

  6. Explaining the dynamics of the ultra-relativistic third Van Allen radiation belt

    DOE PAGES

    Mann, I. R.; Ozeke, L. G.; Murphy, K. R.; ...

    2016-06-20

    Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding the recently discovered ultra-relativistic third electron radiation belt. Current theory asserts that loss in the heart of the outer belt, essential to the formation of the third belt, must be controlled by high-frequency plasma wave–particle scattering into the atmosphere, via whistler mode chorus, plasmaspheric hiss, or electromagnetic ion cyclotron waves. However, this has failed to accurately reproduce the third belt. In this paper, using a data-driven, time-dependent specification of ultra-low-frequency (ULF) waves we showmore » for the first time how the third radiation belt is established as a simple, elegant consequence of storm-time extremely fast outward ULF wave transport. High-frequency wave–particle scattering loss into the atmosphere is not needed in this case. Finally, when rapid ULF wave transport coupled to a dynamic boundary is accurately specified, the sensitive dynamics controlling the enigmatic ultra-relativistic third radiation belt are naturally explained.« less

  7. Explaining the dynamics of the ultra-relativistic third Van Allen radiation belt

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Mann, I. R.; Ozeke, L. G.; Murphy, K. R.

    Since the discovery of the Van Allen radiation belts over 50 years ago, an explanation for their complete dynamics has remained elusive. Especially challenging is understanding the recently discovered ultra-relativistic third electron radiation belt. Current theory asserts that loss in the heart of the outer belt, essential to the formation of the third belt, must be controlled by high-frequency plasma wave–particle scattering into the atmosphere, via whistler mode chorus, plasmaspheric hiss, or electromagnetic ion cyclotron waves. However, this has failed to accurately reproduce the third belt. In this paper, using a data-driven, time-dependent specification of ultra-low-frequency (ULF) waves we showmore » for the first time how the third radiation belt is established as a simple, elegant consequence of storm-time extremely fast outward ULF wave transport. High-frequency wave–particle scattering loss into the atmosphere is not needed in this case. Finally, when rapid ULF wave transport coupled to a dynamic boundary is accurately specified, the sensitive dynamics controlling the enigmatic ultra-relativistic third radiation belt are naturally explained.« less

  8. Monitoring, Analyzing and Assessing Radiation Belt Loss and Energization

    NASA Astrophysics Data System (ADS)

    Daglis, I. A.; Bourdarie, S.; Khotyaintsev, Y.; Santolik, O.; Horne, R.; Mann, I.; Turner, D.; Anastasiadis, A.; Angelopoulos, V.; Balasis, G.; Chatzichristou, E.; Cully, C.; Georgiou, M.; Glauert, S.; Grison, B.; Kolmasova, I.; Lazaro, D.; Macusova, E.; Maget, V.; Papadimitriou, C.; Ropokis, G.; Sandberg, I.; Usanova, M.

    2012-09-01

    We present the concept, objectives and expected impact of the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Loss and Energization) project, which is being implemented by a consortium of seven institutions (five European, one Canadian and one US) with support from the European Community's Seventh Framework Programme. The MAARBLE project employs multi-spacecraft monitoring of the geospace environment, complemented by ground-based monitoring, in order to analyze and assess the physical mechanisms leading to radiation belt particle energization and loss. Particular attention is paid to the role of ULF/VLF waves. A database containing properties of the waves is being created and will be made available to the scientific community. Based on the wave database, a statistical model of the wave activity dependent on the level of geomagnetic activity, solar wind forcing, and magnetospheric region will be developed. Furthermore, we will incorporate multi-spacecraft particle measurements into data assimilation tools, aiming at a new understanding of the causal relationships between ULF/VLF waves and radiation belt dynamics. Data assimilation techniques have been proven to be a valuable tool in the field of radiation belts, able to guide 'the best' estimate of the state of a complex system.

  9. Radiation Belt and Plasma Model Requirements

    NASA Technical Reports Server (NTRS)

    Barth, Janet L.

    2005-01-01

    Contents include the following: Radiation belt and plasma model environment. Environment hazards for systems and humans. Need for new models. How models are used. Model requirements. How can space weather community help?

  10. The Magnetic and Shielding Effects of Ring Current on Radiation Belt Dynamics

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching

    2012-01-01

    The ring current plays many key roles in controlling magnetospheric dynamics. A well-known example is the magnetic depression produced by the ring current, which alters the drift paths of radiation belt electrons and may cause significant electron flux dropout. Little attention is paid to the ring current shielding effect on radiation belt dynamics. A recent simulation study that combines the Comprehensive Ring Current Model (CRCM) with the Radiation Belt Environment (RBE) model has revealed that the ring current-associated shielding field directly and/or indirectly weakens the relativistic electron flux increase during magnetic storms. In this talk, we will discuss how ring current magnetic field and electric shielding moderate the radiation belt enhancement.

  11. The atmospheric implications of radiation belt remediation

    NASA Astrophysics Data System (ADS)

    Rodger, C. J.; Clilverd, M. A.; Ulich, Th.; Verronen, P. T.; Turunen, E.; Thomson, N. R.

    2006-08-01

    High altitude nuclear explosions (HANEs) and geomagnetic storms can produce large scale injections of relativistic particles into the inner radiation belts. It is recognised that these large increases in >1 MeV trapped electron fluxes can shorten the operational lifetime of low Earth orbiting satellites, threatening a large, valuable population. Therefore, studies are being undertaken to bring about practical human control of the radiation belts, termed "Radiation Belt Remediation" (RBR). Here we consider the upper atmospheric consequences of an RBR system operating over either 1 or 10 days. The RBR-forced neutral chemistry changes, leading to NOx enhancements and Ox depletions, are significant during the timescale of the precipitation but are generally not long-lasting. The magnitudes, time-scales, and altitudes of these changes are no more significant than those observed during large solar proton events. In contrast, RBR-operation will lead to unusually intense HF blackouts for about the first half of the operation time, producing large scale disruptions to radio communication and navigation systems. While the neutral atmosphere changes are not particularly important, HF disruptions could be an important area for policy makers to consider, particularly for the remediation of natural injections.

  12. What effect do substorms have on the content of the radiation belts?

    PubMed Central

    Rae, I. J.; Murphy, K. R.; Freeman, M. P.; Huang, C.‐L.; Spence, H. E.; Boyd, A. J.; Coxon, J. C.; Jackman, C. M.; Kalmoni, N. M. E.; Watt, C. E. J.

    2016-01-01

    Abstract Substorms are fundamental and dynamic processes in the magnetosphere, converting captured solar wind magnetic energy into plasma energy. These substorms have been suggested to be a key driver of energetic electron enhancements in the outer radiation belts. Substorms inject a keV “seed” population into the inner magnetosphere which is subsequently energized through wave‐particle interactions up to relativistic energies; however, the extent to which substorms enhance the radiation belts, either directly or indirectly, has never before been quantified. In this study, we examine increases and decreases in the total radiation belt electron content (TRBEC) following substorms and geomagnetically quiet intervals. Our results show that the radiation belts are inherently lossy, shown by a negative median change in TRBEC at all intervals following substorms and quiet intervals. However, there are up to 3 times as many increases in TRBEC following substorm intervals. There is a lag of 1–3 days between the substorm or quiet intervals and their greatest effect on radiation belt content, shown in the difference between the occurrence of increases and losses in TRBEC following substorms and quiet intervals, the mean change in TRBEC following substorms or quiet intervals, and the cross correlation between SuperMAG AL (SML) and TRBEC. However, there is a statistically significant effect on the occurrence of increases and decreases in TRBEC up to a lag of 6 days. Increases in radiation belt content show a significant correlation with SML and SYM‐H, but decreases in the radiation belt show no apparent link with magnetospheric activity levels. PMID:27656336

  13. An Experimental Concept for Probing Nonlinear Physics in Radiation Belts

    NASA Astrophysics Data System (ADS)

    Crabtree, C. E.; Ganguli, G.; Tejero, E. M.; Amatucci, B.; Siefring, C. L.

    2017-12-01

    A sounding rocket experiment, Space Measurement of Rocket-Released Turbulence (SMART), can be used to probe the nonlinear response to a known stimulus injected into the radiation belt. Release of high-speed neutral barium atoms (8- 10 km/s) generated by a shaped charge explosion in the ionosphere can be used as the source of free energy to seed weak turbulence in the ionosphere. The Ba atoms are photo-ionized forming a ring velocity distribution of heavy Ba+ that is known to generate lower hybrid waves. Induced nonlinear scattering will convert the lower hybrid waves into EM whistler/magnetosonic waves. The escape of the whistlers from the ionospheric region into the radiation belts has been studied and their observable signatures quantified. The novelty of the SMART experiment is to make coordinated measurement of the cause and effect of the turbulence in space plasmas and from that to deduce the role of nonlinear scattering in the radiation belts. Sounding rocket will carry a Ba release module and an instrumented daughter section that includes vector wave magnetic and electric field sensors, Langmuir probes and energetic particle detectors. The goal of these measurements is to determine the whistler and lower hybrid wave amplitudes and spectrum in the ionospheric source region and look for precipitated particles. The Ba release may occur at 600-700 km near apogee. Ground based cameras and radio diagnostics can be used to characterize the Ba and Ba+ release. The Van Allen Probes can be used to detect the propagation of the scattering-generated whistler waves and their effects in the radiation belts. By detecting whistlers and measuring their energy density in the radiation belts the SMART mission will confirm the nonlinear generation of whistlers through scattering of lower hybrid along with other nonlinear responses of the radiation belts and their connection to weak turbulence.

  14. Conceptual design of a Moving Belt Radiator (MBR) shuttle-attached experiment

    NASA Technical Reports Server (NTRS)

    Aguilar, Jerry L.

    1990-01-01

    The conceptual design of a shuttle-attached Moving Belt Radiator (MBR) experiment is presented. The MBR is an advanced radiator concept in which a rotating belt is used to radiate thermal energy to space. The experiment is developed with the primary focus being the verification of the dynamic characteristics of a rotating belt with a secondary objective of proving the thermal and sealing aspects in a reduced gravity, vacuum environment. The mechanical design, selection of the belt material and working fluid, a preliminary test plan, and program plan are presented. The strategy used for selecting the basic sizes and materials of the components are discussed. Shuttle and crew member requirements are presented with some options for increasing or decreasing the demands on the STS. An STS carrier and the criteria used in the selection process are presented. The proposed carrier for the Moving Belt Radiator experiment is the Hitchhiker-M. Safety issues are also listed with possible results. This experiment is designed so that a belt can be deployed, run at steady state conditions, run with dynamic perturbations imposed, verify the operation of the interface heat exchanger and seals, and finally be retracted into a stowed position for transport back to earth.

  15. First Results of Modeling Radiation Belt Electron Dynamics with the SAMI3 Plasmasphere Model

    NASA Astrophysics Data System (ADS)

    Komar, C. M.; Glocer, A.; Huba, J.; Fok, M. C. H.; Kang, S. B.; Buzulukova, N.

    2017-12-01

    The radiation belts were one of the first discoveries of the Space Age some sixty years ago and radiation belt models have been improving since the discovery of the radiation belts. The plasmasphere is one region that has been critically important to determining the dynamics of radiation belt populations. This region of space plays a critical role in describing the distribution of chorus and magnetospheric hiss waves throughout the inner magnetosphere. Both of these waves have been shown to interact with energetic electrons in the radiation belts and can result in the energization or loss of radiation belt electrons. However, radiation belt models have been historically limited in describing the distribution of cold plasmaspheric plasma and have relied on empirically determined plasmasphere models. Some plasmasphere models use an azimuthally symmetric distribution of the plasmasphere which can fail to capture important plasmaspheric dynamics such as the development of plasmaspheric drainage plumes. Previous work have coupled the kinetic bounce-averaged Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model used to model ring current and radiation belt populations with the Block-adaptive Tree Solar wind Roe-type Upwind Scheme (BATSRUS) global magnetohydrodynamic model to self-consistently obtain the magnetospheric magnetic field and ionospheric potential. The present work will utilize this previous coupling and will additionally couple the SAMI3 plasmasphere model to better represent the dynamics on the plasmasphere and its role in determining the distribution of waves throughout the inner magnetosphere. First results on the relevance of chorus, hiss, and ultralow frequency waves on radiation belt electron dynamics will be discussed in context of the June 1st, 2013 storm-time dropout event.

  16. Quantitative Simulation of QARBM Challenge Events During Radiation Belt Enhancements

    NASA Astrophysics Data System (ADS)

    Li, W.; Ma, Q.; Thorne, R. M.; Bortnik, J.; Chu, X.

    2017-12-01

    Various physical processes are known to affect energetic electron dynamics in the Earth's radiation belts, but their quantitative effects at different times and locations in space need further investigation. This presentation focuses on discussing the quantitative roles of various physical processes that affect Earth's radiation belt electron dynamics during radiation belt enhancement challenge events (storm-time vs. non-storm-time) selected by the GEM Quantitative Assessment of Radiation Belt Modeling (QARBM) focus group. We construct realistic global distributions of whistler-mode chorus waves, adopt various versions of radial diffusion models (statistical and event-specific), and use the global evolution of other potentially important plasma waves including plasmaspheric hiss, magnetosonic waves, and electromagnetic ion cyclotron waves from all available multi-satellite measurements. These state-of-the-art wave properties and distributions on a global scale are used to calculate diffusion coefficients, that are then adopted as inputs to simulate the dynamical electron evolution using a 3D diffusion simulation during the storm-time and the non-storm-time acceleration events respectively. We explore the similarities and differences in the dominant physical processes that cause radiation belt electron dynamics during the storm-time and non-storm-time acceleration events. The quantitative role of each physical process is determined by comparing against the Van Allen Probes electron observations at different energies, pitch angles, and L-MLT regions. This quantitative comparison further indicates instances when quasilinear theory is sufficient to explain the observed electron dynamics or when nonlinear interaction is required to reproduce the energetic electron evolution observed by the Van Allen Probes.

  17. Van Allen Probes Observations of the Plasmasphere and Radiation Belts

    NASA Astrophysics Data System (ADS)

    Goldstein, J.; Jahn, J. M.; De Pascuale, S.; Kletzing, C.; Kurth, W. S.; Genestreti, K. J.; Skoug, R. M.; Larsen, B.; Kistler, L. M.; Mouikis, C.; Spence, H. E.; Reeves, G. D.; Baker, D. N.; Blake, J. B.

    2014-12-01

    Van Allen Probes (RBSP) observations during 15-20 January 2013 are the basis of this study of the spatial relationship between the plasmasphere and radiation belts, and its influence on energy dependent lifetimes of energetic electrons. We use a convection-driven plasmapause test particle (PTP) simulation to provide contextual information for in situ measurements by RBSP during 15-20 January 2013, and find that the model reproduces the observed plasmapause radial locations to within 0.40 Earth radii (RE). We use analysis of the RBSP data to examine the radial structure of both the plasmasphere and radiation belts for the selected 5-day period, which includes a moderate geomagnetic disturbance on 17 January. RBSP observed three belts (inner, outer, and storage ring) prior to the 17 January disturbance, and two belts (inner and outer) afterward. The plasmapause aligns with the outermost belt. We examine the energy dependence of the radial structure and decay lifetimes of energetic electrons, both inside and outside the plasmasphere.

  18. OUTER RADIATION BELT AND AURORAS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gorchakov, E.V.

    1961-01-01

    Data obtained from Sputnik IH were used to determine the high-latitude boundary of the outer radiation belt and to interpret the nature of auroras. At the heights at which the auroras were observed, the outer boundary of the belt (69 deg north geomagnetic latitude) practically coincides with the auroral zone maximum (70 deg north geomagnetic latitude), while the maximum intensity of the outer belt near the earth lies at about 55 deg north geomagnetic latitude, i.e., at latitudes 15 deg below the auroral maximum. Consequently, auroras near the zone of maximum cannot be caused by the penetration into the atmospheremore » of electrons from the outer belt with energies on the order of 0.1 Mev (the mean energy of electrons in the outer belt). Other investigators have reported the detection of lowenergy streams at 55,000 to 75,000 km from the center of the earth in the equatorial plane. Moving toward the surface of the earth along the force lines of the magnetic field, electron streams of this type will reach the earth precisely in the region of the auroral zone maximum. It is considered possible that the electron streams are trapped at these distances from the earth and are at least partially responsible for auroras in the region of maximum. The existence of two maxima in the latitudinal distribution of auroral frequency, which attests to differert mechanisms of aurora formation, favors this hypothesis. In the region of the basic auroral maximum (70 deg north geomagnetic latitude) the auroras are the result of the invasion of belt particles, while in the region of the additional maximum (about 80 deg north geomagnetic latitude) they are caused by the direct penetration of corpuscular streams into the atmosphere. (OTS)« less

  19. Radiation Belts of Antiparticles in Planetary Magnetospheres

    NASA Astrophysics Data System (ADS)

    Pugacheva, G. I.; Gusev, A. A.; Jayanthi, U. B.; Martin, I. M.; Spjeldvik, W. N.

    2007-05-01

    The Earth's radiation belts could be populated, besides with electrons and protons, also by antiparticles, such as positrons (Basilova et al., 1982) and antiprotons (pbar). Positrons are born in the decay of pions that are directly produced in nuclear reactions of trapped relativistic inner zone protons with the residual atmosphere at altitudes in the range of about 500 to 3000 km over the Earth's surface. Antiprotons are born by high energy (E > 6 GeV) cosmic rays in p+p - p+p+p+ pbar and in p+p - p+p+n+nbar reactions. The trapping and storage of these charged anti-particles in the magnetosphere result in radiation belts similar to the classical Van Allen belts of protons and electrons. We describe the mathematical techniques used for numerical simulation of the trapped positron and antiproton belt fluxes. The pion and antiproton yields were simulated on the basis of the Russian nuclear reaction computer code MSDM, a Multy Stage Dynamical Model, Monte Carlo code, (i.e., Dementyev and Sobolevsky, 1999). For estimates of positron flux there we have accounted for ionisation, bremsstrahlung, and synchrotron energy losses. The resulting numerical estimates show that the positron flux with energy >100 MeV trapped into the radiation belt at L=1.2 is of the order ~1000 m-2 s-1 sr-1, and that it is very sensitive to the shape of the trapped proton spectrum. This confined positron flux is found to be greater than that albedo, not trapped, mixed electron/positron flux of about 50 m-2 s-1 sr-1 produced by CR in the same region at the top of the geomagnetic field line at L=1.2. As we show in report, this albedo flux also consists mostly of positrons. The trapped antiproton fluxes produced by CR in the Earth's upper rarified atmosphere were calculated in the energy range from 10 MeV to several GeV. In the simulations we included a mathematic consideration of the radial diffusion process, both an inner and an outer antiproton source, losses of particles due to ionization process

  20. Explaining the Diverse Response of the Ultra-relativistic Van Allen Radiation Belt to Solar Wind Forcing

    NASA Astrophysics Data System (ADS)

    Mann, I. R.; Ozeke, L.; Murphy, K. R.; Claudepierre, S. G.; Rae, J.; Milling, D. K.; Kale, A.; Baker, D. N.

    2017-12-01

    The NASA Van Allen Probes have opened a new window on the dynamics of ultra-relativistic electrons in the Van Allen radiation belts. Under different solar wind forcing the outer belt is seen to respond in a variety of apparently diverse and sometimes remarkable ways. For example, sometimes a third radiation belt is carved out (e.g., September 2012), or the belts can remain depleted for 10 days or more (September 2014). More usually there is a sequential response of a strong and sometimes rapid depletion followed by a re-energization, the latter increasing outer belt electron flux by orders of magnitude on hour timescales during some of the strongest storms of this solar cycle (e.g., March 2013, March 2015). Such dynamics also appear to be often bounded at low-L by an apparently impenetrable barrier at L 2.8 through which ultra-relativistic electrons do not penetrate. Many studies in the Van Allen Probes era have sought explanations for these apparently diverse features, often incorporating the effects from multiple plasma waves. In contrast, we show how this apparently diverse behaviour can instead be explained by one dominant process: ULF wave radial transport. Once ULF wave transport rates are accurately specified by observations, and coupled to the dynamical variation of the outer boundary condition at the edge of the outer belt, the observed diverse responses can all be explained. However, in order to get good agreement with observations, the modeling reveals the importance of still currently unexplained very fast loss in the main phase which results in an almost total extinction of the belts and decouples pre- and post-storm ultra-relativistic electron flux on hour timescales. Similarly, varying plasmasheet source populations are seen to be of critical importance such that near-tail dynamics play a crucial role in Van Allen belt dynamics. Nonetheless, simple models incorporating accurate transport rates derived directly from ULF wave measurements are shown to

  1. Rapid Loss of Radiation Belt Relativistic Electrons by EMIC Waves

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Su, Zhenpeng; Gao, Zhonglei; Zheng, Huinan

    How relativistic electrons are lost is an important question surrounding the complex dynamics of the Earth's outer radiation belt. Radial loss to the magnetopause and local loss to the atmosphere are two main competing paradigms. Here on the basis of the analysis of a radiation belt storm event on 27 February 2014, we present new evidence for the electromagnetic ion cyclotron (EMIC) wave-driven local precipitation loss of relativistic electrons in the heart of the outer radiation belt. During the main phase of this storm, the radial profile of relativistic electron phase space density was quasi-monotonic, qualitatively inconsistent with the predictionmore » of radial loss theory. The local loss at low L shells was required to prevent the development of phase space density peak resulting from the radial loss process at high L shells. The rapid loss of relativistic electrons in the heart of outer radiation belt was observed as a dip structure of the electron flux temporal profile closely related to intense EMIC waves. Our simulations further confirm that the observed EMIC waves within a quite limited longitudinal region were able to reduce the off-equatorially mirroring relativistic electron fluxes by up to 2 orders of magnitude within about 1.5 h.« less

  2. Rapid Loss of Radiation Belt Relativistic Electrons by EMIC Waves

    DOE PAGES

    Su, Zhenpeng; Gao, Zhonglei; Zheng, Huinan; ...

    2017-08-31

    How relativistic electrons are lost is an important question surrounding the complex dynamics of the Earth's outer radiation belt. Radial loss to the magnetopause and local loss to the atmosphere are two main competing paradigms. Here on the basis of the analysis of a radiation belt storm event on 27 February 2014, we present new evidence for the electromagnetic ion cyclotron (EMIC) wave-driven local precipitation loss of relativistic electrons in the heart of the outer radiation belt. During the main phase of this storm, the radial profile of relativistic electron phase space density was quasi-monotonic, qualitatively inconsistent with the predictionmore » of radial loss theory. The local loss at low L shells was required to prevent the development of phase space density peak resulting from the radial loss process at high L shells. The rapid loss of relativistic electrons in the heart of outer radiation belt was observed as a dip structure of the electron flux temporal profile closely related to intense EMIC waves. Our simulations further confirm that the observed EMIC waves within a quite limited longitudinal region were able to reduce the off-equatorially mirroring relativistic electron fluxes by up to 2 orders of magnitude within about 1.5 h.« less

  3. Conceptual design of a moving belt radiator shuttle-attached experiments: Technical requirement Document

    NASA Technical Reports Server (NTRS)

    Aguilar, Jerry L.

    1989-01-01

    The technical requirements for a shuttle-attached Moving Belt Radiator (MBR) experiment are defined. The MBR is an advanced radiator concept in which a rotating belt radiates thermal energy to space. The requirements for integrating the MBR experiment in the shuttle bay are discussed. Requirements for the belt material and working fluid are outlined along with some possible options. The proposed size and relationship to a full scale Moving Belt Radiator are defined. The experiment is defined with the primary goal of dynamic testing and a secondary goal of demonstrating the sealing and heat transfer characteristics. A perturbation system which will simulate a docking maneuver or other type of short term acceleration is proposed for inclusion in the experimental apparatus. A deployment and retraction capability which will aid in evaluating the dynamics of a belt during such a maneuver is also described. The proposed test sequence for the experiment is presented. Details of the conceptual design are not presented herein, but rather in a separate Final Report.

  4. The evolution of Saturn's radiation belts modulated by changes in radial diffusion

    NASA Astrophysics Data System (ADS)

    Kollmann, P.; Roussos, E.; Kotova, A.; Paranicas, C.; Krupp, N.

    2017-12-01

    Globally magnetized planets, such as the Earth1 and Saturn2, are surrounded by radiation belts of protons and electrons with kinetic energies well into the million electronvolt range. The Earth's proton belt is supplied locally from galactic cosmic rays interacting with the atmosphere3, as well as from slow inward radial transport4. Its intensity shows a relationship with the solar cycle4,5 and abrupt dropouts due to geomagnetic storms6,7. Saturn's proton belts are simpler than the Earth's because cosmic rays are the principal source of energetic protons8 with virtually no contribution from inward transport, and these belts can therefore act as a prototype to understand more complex radiation belts. However, the time dependence of Saturn's proton belts had not been observed over sufficiently long timescales to test the driving mechanisms unambiguously. Here we analyse the evolution of Saturn's proton belts over a solar cycle using in-situ measurements from the Cassini Saturn orbiter and a numerical model. We find that the intensity in Saturn's proton radiation belts usually rises over time, interrupted by periods that last over a year for which the intensity is gradually dropping. These observations are inconsistent with predictions based on a modulation in the cosmic-ray source, as could be expected4,9 based on the evolution of the Earth's proton belts. We demonstrate that Saturn's intensity dropouts result instead from losses due to abrupt changes in magnetospheric radial diffusion.

  5. Detailed Characteristics of Radiation Belt Electrons Revealed by CSSWE/REPTile Measurements

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Li, X.; Schiller, Q.; Gerhardt, D. T.; Millan, R. M.

    2016-12-01

    The outer radiation belt electrons are highly dynamic. We study the detailed characteristics of the relativistic electrons in the outer belt using measurements from the Colorado Student Space Weather Experiment (CSSWE) mission, a low Earth orbit Cubesat, which transverses the radiation belt four times in one orbit ( 1.5 hr) and has the advantage of measuring the dynamic activities of the electrons including their rapid precipitations. Among the features of the relativistic electrons, we show the measured electron distribution as a function of geomagnetic activities and local magnetic field strength. Moreover, a specific precipitation band, which happened on 19 Jan 2013, is investigated based on the conjunctive measurement of CSSWE and the Balloon Array for Radiation belt Relativistic Electron Losses (BARREL). In this precipitation band event, the net loss of the 0.58 1.63 MeV electrons (L=3.5 6) is estimated to account for 6.84% of the total electron content.

  6. Exploring the Earth's Radiation Belts

    NASA Astrophysics Data System (ADS)

    Daglis, I. A.; Anastasiadis, A.; Chatzichristou, E. T.; Ropokis, G.; Giannakis, O.

    2012-09-01

    We present the outreach efforts of the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Loss and Energization) project, intended to provide the general public with simplified information concerning the scientific objectives of the project, its focus and its expected outcomes. MAARBLE involves monitoring of the geospace environment through space and ground-based observations, in order to understand various aspects of the radiation belts (torus-shaped regions encircling the Earth, in which high-energy charged particles are trapped by the geomagnetic field), which have direct impact on human endeavors in space (spacecraft and astronauts exposure). The public outreach website of MAARBLE, besides regular updates with relevant news, also employs a variety of multimedia (image and video galleries) and impressive sounds of space (characteristic sounds such as whistlers or tweeks) related to very low and ultra low frequency (VLF/ULF) electromagnetic waves. It also provides links to some of the most interesting relevant educational activities, including those at partner institutions such as the Institute of Geophysics and Planetary Physics at UCLA, the University of Alberta, the Swedish Institute of Space Physics and the Institute of Atmospheric Physics of the Academy of Sciences of the Czech Republic.

  7. The Global Statistical Response of the Outer Radiation Belt During Geomagnetic Storms

    NASA Astrophysics Data System (ADS)

    Murphy, K. R.; Watt, C. E. J.; Mann, I. R.; Jonathan Rae, I.; Sibeck, D. G.; Boyd, A. J.; Forsyth, C. F.; Turner, D. L.; Claudepierre, S. G.; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Blake, J. B.; Fennell, J.

    2018-05-01

    Using the total radiation belt electron content calculated from Van Allen Probe phase space density, the time-dependent and global response of the outer radiation belt during storms is statistically studied. Using phase space density reduces the impacts of adiabatic changes in the main phase, allowing a separation of adiabatic and nonadiabatic effects and revealing a clear modality and repeatable sequence of events in storm time radiation belt electron dynamics. This sequence exhibits an important first adiabatic invariant (μ)-dependent behavior in the seed (150 MeV/G), relativistic (1,000 MeV/G), and ultrarelativistic (4,000 MeV/G) populations. The outer radiation belt statistically shows an initial phase dominated by loss followed by a second phase of rapid acceleration, while the seed population shows little loss and immediate enhancement. The time sequence of the transition to the acceleration is also strongly μ dependent and occurs at low μ first, appearing to be repeatable from storm to storm.

  8. Prompt enhancement of the Earth's outer radiation belt due to substorm electron injections

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tang, C. L.; Zhang, J. -C.; Reeves, G. D.

    Here, we present multipoint simultaneous observations of the near-Earth magnetotail and outer radiation belt during the substorm electron injection event on 16 August 2013. Time History of Events and Macroscale Interactions during Substorms A in the near-Earth magnetotail observed flux-enhanced electrons of 300 keV during the magnetic field dipolarization. Geosynchronous orbit satellites also observed the intensive electron injections. Located in the outer radiation belt, RBSP-A observed enhancements of MeV electrons accompanied by substorm dipolarization. The phase space density (PSD) of MeV electrons at L* ~5.4 increased by 1 order of magnitude in 1 h, resulting in a local PSD peakmore » of MeV electrons, which was caused by the direct effect of substorm injections. We also detected an enhanced MeV electrons in the heart of the outer radiation belt within 2 h, which may be associated with intensive substorm electron injections and subsequent local acceleration by chorus waves. Multipoint observations have shown that substorm electron injections not only can be the external source of MeV electrons at the outer edge of the outer radiation belt (L* ~5.4) but also can provide the intensive seed populations in the outer radiation belt. These initial higher-energy electrons from injection can reach relativistic energy much faster. Furthermore, these observations also provide evidence that enhanced substorm electron injections can explain rapid enhancements of MeV electrons in the outer radiation belt.« less

  9. Prompt enhancement of the Earth's outer radiation belt due to substorm electron injections

    DOE PAGES

    Tang, C. L.; Zhang, J. -C.; Reeves, G. D.; ...

    2016-12-17

    Here, we present multipoint simultaneous observations of the near-Earth magnetotail and outer radiation belt during the substorm electron injection event on 16 August 2013. Time History of Events and Macroscale Interactions during Substorms A in the near-Earth magnetotail observed flux-enhanced electrons of 300 keV during the magnetic field dipolarization. Geosynchronous orbit satellites also observed the intensive electron injections. Located in the outer radiation belt, RBSP-A observed enhancements of MeV electrons accompanied by substorm dipolarization. The phase space density (PSD) of MeV electrons at L* ~5.4 increased by 1 order of magnitude in 1 h, resulting in a local PSD peakmore » of MeV electrons, which was caused by the direct effect of substorm injections. We also detected an enhanced MeV electrons in the heart of the outer radiation belt within 2 h, which may be associated with intensive substorm electron injections and subsequent local acceleration by chorus waves. Multipoint observations have shown that substorm electron injections not only can be the external source of MeV electrons at the outer edge of the outer radiation belt (L* ~5.4) but also can provide the intensive seed populations in the outer radiation belt. These initial higher-energy electrons from injection can reach relativistic energy much faster. Furthermore, these observations also provide evidence that enhanced substorm electron injections can explain rapid enhancements of MeV electrons in the outer radiation belt.« less

  10. Simulation of high-energy radiation belt electron fluxes using NARMAX-VERB coupled codes

    PubMed Central

    Pakhotin, I P; Drozdov, A Y; Shprits, Y Y; Boynton, R J; Subbotin, D A; Balikhin, M A

    2014-01-01

    This study presents a fusion of data-driven and physics-driven methodologies of energetic electron flux forecasting in the outer radiation belt. Data-driven NARMAX (Nonlinear AutoRegressive Moving Averages with eXogenous inputs) model predictions for geosynchronous orbit fluxes have been used as an outer boundary condition to drive the physics-based Versatile Electron Radiation Belt (VERB) code, to simulate energetic electron fluxes in the outer radiation belt environment. The coupled system has been tested for three extended time periods totalling several weeks of observations. The time periods involved periods of quiet, moderate, and strong geomagnetic activity and captured a range of dynamics typical of the radiation belts. The model has successfully simulated energetic electron fluxes for various magnetospheric conditions. Physical mechanisms that may be responsible for the discrepancies between the model results and observations are discussed. PMID:26167432

  11. Radiation Belt Transport Driven by Solar Wind Dynamic Pressure Fluctuations

    NASA Astrophysics Data System (ADS)

    Kress, B. T.; Hudson, M. K.; Ukhorskiy, A. Y.; Mueller, H.

    2012-12-01

    The creation of the Earth's outer zone radiation belts is attributed to earthward transport and adiabatic acceleration of electrons by drift-resonant interactions with electromagnetic fluctuations in the magnetosphere. Three types of radial transport driven by solar wind dynamic pressure fluctuations that have been identified are: (1) radial diffusion [Falthammer, 1965], (2) significant changes in the phase space density radial profile due to a single or few ULF drift-resonant interactions [Ukhorskiy et al., 2006; Degeling et al., 2008], and (3) shock associated injections of radiation belt electrons occurring in less than a drift period [Li et al., 1993]. A progress report will be given on work to fully characterize different forms of radial transport and their effect on the Earth's radiation belts. The work is being carried out by computing test-particle trajectories in electric and magnetic fields from a simple analytic ULF field model and from global MHD simulations of the magnetosphere. Degeling, A. W., L. G. Ozeke, R. Rankin, I. R. Mann, and K. Kabin (2008), Drift resonant generation of peaked relativistic electron distributions by Pc 5 ULF waves, textit{J. Geophys. Res., 113}, A02208, doi:10.1029/2007JA012411. Fälthammar, C.-G. (1965), Effects of Time-Dependent Electric Fields on Geomagnetically Trapped Radiation, J. Geophys. Res., 70(11), 2503-2516, doi:10.1029/JZ070i011p02503. Li, X., I. Roth, M. Temerin, J. R. Wygant, M. K. Hudson, and J. B. Blake (1993), Simulation of the prompt energization and transport of radiation belt particles during the March 24, 1991 SSC, textit{Geophys. Res. Lett., 20}(22), 2423-2426, doi:10.1029/93GL02701. Ukhorskiy, A. Y., B. J. Anderson, K. Takahashi, and N. A. Tsyganenko (2006), Impact of ULF oscillations in solar wind dynamic pressure on the outer radiation belt electrons, textit{Geophys. Res. Lett., 33}(6), L06111, doi:10.1029/2005GL024380.

  12. Dynamics of Quasi-Electrostatic Whistler waves in Earth's Radiation belts

    NASA Astrophysics Data System (ADS)

    Goyal, R.; Sharma, R. P.; Gupta, D. N.

    2017-12-01

    A numerical model is proposed to study the dynamics of high amplitude quasi-electrostatic whistler waves propagating near resonance cone angle and their interaction with finite frequency kinetic Alfvén waves (KAWs) in Earth's radiation belts. The quasi-electrostatic character of whistlers is narrated by dynamics of wave propagating near resonance cone. A high amplitude whistler wave packet is obtained using the present analysis which has also been observed by S/WAVES instrument onboard STEREO. The numerical simulation technique employed to study the dynamics, leads to localization (channelling) of waves as well as turbulent spectrum suggesting the transfer of wave energy over a range of frequencies. The turbulent spectrum also indicates the presence of quasi-electrostatic whistlers and density fluctuations associated with KAW in radiation belts plasma. The ponderomotive force of pump quasi-electrostatic whistlers (high frequency) is used to excite relatively much lower frequency waves (KAWs). The wave localization and steeper spectra could be responsible for particle energization or heating in radiation belts.

  13. A Maximum Likelihood Ensemble Data Assimilation Method Tailored to the Inner Radiation Belt

    NASA Astrophysics Data System (ADS)

    Guild, T. B.; O'Brien, T. P., III; Mazur, J. E.

    2014-12-01

    The Earth's radiation belts are composed of energetic protons and electrons whose fluxes span many orders of magnitude, whose distributions are log-normal, and where data-model differences can be large and also log-normal. This physical system thus challenges standard data assimilation methods relying on underlying assumptions of Gaussian distributions of measurements and data-model differences, where innovations to the model are small. We have therefore developed a data assimilation method tailored to these properties of the inner radiation belt, analogous to the ensemble Kalman filter but for the unique cases of non-Gaussian model and measurement errors, and non-linear model and measurement distributions. We apply this method to the inner radiation belt proton populations, using the SIZM inner belt model [Selesnick et al., 2007] and SAMPEX/PET and HEO proton observations to select the most likely ensemble members contributing to the state of the inner belt. We will describe the algorithm, the method of generating ensemble members, our choice of minimizing the difference between instrument counts not phase space densities, and demonstrate the method with our reanalysis of the inner radiation belt throughout solar cycle 23. We will report on progress to continue our assimilation into solar cycle 24 using the Van Allen Probes/RPS observations.

  14. Comparison of lighting activity and inner radiation belt particle fluxes perturbations

    NASA Astrophysics Data System (ADS)

    Martinez Calderon, C.; Bortnik, J.; Li, W.; Spence, H. E.; Rodger, C. J.

    2016-12-01

    Lightning discharges are known to inject whistlers into the inner magnetosphere over a wide range of latitudes around their source. When a discharge occurs, it radiates electromagnetic energy, some of which propagates in the whistler-mode wave through the ionospheric plasma travelling away from the Earth. Previous studies have discussed the effects of whistler-induced electron precipitation and radiation belt losses associated with lightning but there has been little research on the long term effects of these precipitation on the inner radiation belts [Rodger et al. (2004), Clilverd et al. (2004)].Here, we use data from the World Wide Lightning Location Network (WWLLN), which has continuously monitored global lightning since 2004, to examine one year of lightning data and locate the L-shells with high lighting activity. We use Van Allen Probes' Energetic Particle, Composition, and Thermal Plasma Suite (ECT) from both satellites (RBSP-A/B) to measure electron fluxes in the inner radiation belt at the L-shells of interest. We compare these fluxes to a globally-integrated count of lightning strikes and investigate the relationship between global lightning occurrence and RBSP electron fluxes. We examine several factors, such as different energy ranges, timescales ranging from a few weeks to the entire year and seasonal changes in order to quantify the loss process driven by lightning in the inner radiation belts.

  15. Modeling the Radiation Belts During a Geomagnetic Storm

    NASA Astrophysics Data System (ADS)

    Glocer, A.; Fok, M.; Toth, G.

    2009-05-01

    We utilize the Radiation Belt Environment (RBE) model to simulate the radiation belt electrons during a geomagnetic storm. Particularly, we focus on the relative contribution of whistler mode wave-particle interactions and radial diffusion associated with rapid changes in the magnetospheric magnetic field. In our study, the RBE model obtains a realistic magnetic field from the BATS-R-US magnetosphere model at a regular, but adjustable, cadence. We simulate the storm with and without wave particle interactions, and with different frequencies for updating the magnetic field. The impacts of the wave-particle interactions, and the rapid variations in the magnetospheric magnetic field, can then be studied. Simulation results are also extracted along various satellite trajectories for direct comparison where appropriate.

  16. Precipitated Fluxes of Radiation Belt Electrons via Injection of Whistler-Mode Waves

    NASA Astrophysics Data System (ADS)

    Kulkarni, P.; Inan, U. S.; Bell, T. F.

    2005-12-01

    Inan et al. (U.S. Inan et al., Controlled precipitation of radiation belt electrons, Journal of Geophysical Research-Space Physics, 108 (A5), 1186, doi: 10.1029/2002JA009580, 2003.) suggested that the lifetime of energetic (a few MeV) electrons in the inner radiation belts may be moderated by in situ injection of whistler mode waves at frequencies of a few kHz. We use the Stanford 2D VLF raytracing program (along with an accurate estimation of the path-integrated Landau damping based on data from the HYDRA instrument on the POLAR spacecraft) to determine the distribution of wave energy throughout the inner radiation belts as a function of injection point, wave frequency and injection wave normal angle. To determine the total wave power injected and its initial distribution in k-space (i.e., wave-normal angle), we apply the formulation of Wang and Bell ( T.N.C. Wang and T.F. Bell, Radiation resistance of a short dipole immersed in a cold magnetoionic medium, Radio Science, 4 (2), 167-177, February 1969) for an electric dipole antenna placed at a variety of locations throughout the inner radiation belts. For many wave frequencies and wave normal angles the results establish that most of the radiated power is concentrated in waves whose wave normals are located near the resonance cone. The combined use of the radiation pattern and ray-tracing including Landau damping allows us to make quantitative estimates of the magnetospheric distribution of wave power density for different source injection points. We use these results to estimate the number of individual space-based transmitters needed to significantly impact the lifetimes of energetic electrons in the inner radiation belts. Using the wave power distribution, we finally determine the energetic electron pitch angle scattering and the precipitated flux signatures that would be detected.

  17. "Inner electron" radiation belt: problems of model creation

    NASA Astrophysics Data System (ADS)

    Temnyi, V.

    The contents of intensive fluxes of trapped electrons J_e with energies E_e>40 keV in center of the inner terrestrial radiation belt is remains uncertain in model Vette AE-8, 1991. It is explained by methodical difficulties of discrete measurements of electrons by narrow-angle spectrometers with background from omnidirectional penetrating protons with energies E_p>40 MeV and electrons with E_e>1 MeV after STARFISH burst. The results of integral measurements of trapped electrons by 2 groups: Krassovsky V.I. on III Soviet satellite (May 1958) and J. Van Allen on EXPLORER-IV (July-August 1958) and on INJUN-1 (1961) heave given a performances concerning electron energy fluxes I_e(E_e>20 keV) ˜ (20-100) erg cm-2 c-1 into inner radiation belt. Improved integral measurements of electrons by Krassovsky group on satellites KOSMOS-3,-5 and ELECTRON-1,-3 (1962-1964) allow to determine the distributions of their intensities in the whole inner belt. They can add the central part of inner belt of AE-8 model (see report Bolunova et al., COSPAR-1965, publ. in SPACE RESEARCH VI, 1967, p. 649-661). From these data a maximum of trapped electrons J_e(E_e>40 keV)=2\\cdot10^9 cm-2 c-1 is placed on L=1,6, B/B_0=1. Intensities up to 2\\cdot10^7 cm-2 c-1 are determined only by coordinates (L, B). For smaller intensities become essential dependence from longitude along a drift shell. So, in the center of the inner radiation belt the energy fluxes I_e(E_e>40 keV) reach 500 erg cm-2 c-1 and density n_e=0,2 cm-3 while for trapped protons I_p(E_p>40 MeV) is less than 3 erg cm-2 c-1 and n_p< 5\\cdot10-6 cm-3. It forces to search a more powerful sources trapped electron than beta-decay of neutrons albedo of cosmic rays.

  18. The Foundations of Radiation Belt Research

    NASA Astrophysics Data System (ADS)

    Ludwig, G. H.

    2008-12-01

    phenomenon. It also provided the first hint that there were two distinct radiation belts, although that conclusion was not reached until later. Although that new information was quickly announced, the results of the high altitude nuclear detonations were kept secret until well into 1959. They clearly revealed the charged particle shells created by the Argos nuclear detonations. The next major step in mapping and understanding the high-intensity radiation involved the launch of deep space probes Pioneers III and IV in December 1958 and March 1959. Although both launches fell short in their primary objective, to reach the moon, they traveled far enough from the Earth to fully meet the needs of the scientific experiment. They very clearly showed the two-radiation belt structure, and mapped its extent. They also showed the probable effect of a magnetic storm on 25 February, thus indicating the direct influence of solar activity on the outer belt. By the end of 1959, the existence of the Van Allen Radiation Belts and their general structure were solidly established, early information about the composition of the radiation was appearing in print, and energetic work was under way to understand the physics of the processes involved.

  19. The impact of radiation belts region on top side ionosphere condition during last solar minimum.

    NASA Astrophysics Data System (ADS)

    Rothkaehl, Hanna; Przepiórka, Dororta; Matyjasiak, Barbara

    2014-05-01

    The wave particle interactions in radiation belts region are one of the key parameters in understanding the global physical processes which govern the near Earth environment. The populations of outer radiation belts electrons increasing in response to changes in the solar wind and the interplanetary magnetic field, and decreasing as a result of scattering into the loss cone and subsequent absorption by the atmosphere. The most important question in relation to understanding the physical processes in radiation belts region relates to estimate the ratio between acceleration and loss processes. This can be also very useful for construct adequate models adopted in Space Weather program. Moreover the wave particle interaction in inner radiation zone and in outer radiation zone have significant influence on the space plasma property at ionospheric altitude. The aim of this presentation is to show the manifestation of radiation belts region at the top side ionosphere during the last long solar minimum. The presentation of longitude and seasonal changes of plasma parameters affected by process occurred in radiation belts region has been performed on the base of the DEMETER and COSMIC 3 satellite registration. This research is partly supported by grant O N517 418440

  20. Coordinates for Representing Radiation Belt Particle Flux

    NASA Astrophysics Data System (ADS)

    Roederer, Juan G.; Lejosne, Solène

    2018-02-01

    Fifty years have passed since the parameter "L-star" was introduced in geomagnetically trapped particle dynamics. It is thus timely to review the use of adiabatic theory in present-day studies of the radiation belts, with the intention of helping to prevent common misinterpretations and the frequent confusion between concepts like "distance to the equatorial point of a field line," McIlwain's L-value, and the trapped particle's adiabatic L* parameter. And too often do we miss in the recent literature a proper discussion of the extent to which some observed time and space signatures of particle flux could simply be due to changes in magnetospheric field, especially insofar as off-equatorial particles are concerned. We present a brief review on the history of radiation belt parameterization, some "recipes" on how to compute adiabatic parameters, and we illustrate our points with a real event in which magnetospheric disturbance is shown to adiabatically affect the particle fluxes measured onboard the Van Allen Probes.

  1. The Role of the Dynamic Plasmapause on Outer Radiation Belt Electron Flux Enhancement and Three-Belt Structure Formation

    NASA Astrophysics Data System (ADS)

    Bruff, M.; Jaynes, A. N.; Zhao, H.; Malaspina, D.

    2017-12-01

    The plasmasphere is a highly dynamic toroidal region of cold, dense plasma around Earth. Plasma waves exist both inside and outside this region and can contribute to the loss and acceleration of high energy outer radiation belt electrons. Early observational studies found an apparent correlation on long time scales between the observed inner edge of the outer radiation belt and the simulated innermost plasmapause location. More recent work using high resolution Van Allen Probe satellite data has found a more complex relationship. The aim of this project was to provide a systematic study of the location and dynamics of the plasmapause compared to the MeV electrons in the outer radiation belt. We used spin-averaged electron flux data from the Relativistic Electron Proton Telescope (REPT) and density data derived from the EFW instrument on the Van Allen Probe satellites. We analyzed these data to determine the standoff distance of the location of peak electron flux of the outer belt MeV electrons from the plasmapause. We found that the location of peak flux was consistently outside but within ΔL=2.5 from the innermost location of the plasmapause at enhancement times, with an average standoff distance ΔL=1.0 +/- 0.5. This is consistent with the current model of chorus enhancement and previous observations of chorus activity. Finally, we identified "three-belt" structure events where a second outer belt formed and found a repeated pattern of plasmapause dynamics associated with specific changes in electron flux required to generate and sustain these structures. This study is significant to improving our understanding of how the plasmasphere under differing conditions can both shield Earth from or worsen the impacts of geomagnetic activity.

  2. Rapid flattening of butterfly pitch angle distributions of radiation belt electrons by whistler-mode chorus

    NASA Astrophysics Data System (ADS)

    Yang, Chang; Su, Zhenpeng; Xiao, Fuliang; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H. E.; Reeves, G. D.; Baker, D. N.; Blake, J. B.; Funsten, H. O.

    2016-08-01

    Van Allen radiation belt electrons exhibit complex dynamics during geomagnetically active periods. Investigation of electron pitch angle distributions (PADs) can provide important information on the dominant physical mechanisms controlling radiation belt behaviors. Here we report a storm time radiation belt event where energetic electron PADs changed from butterfly distributions to normal or flattop distributions within several hours. Van Allen Probes observations showed that the flattening of butterfly PADs was closely related to the occurrence of whistler-mode chorus waves. Two-dimensional quasi-linear STEERB simulations demonstrate that the observed chorus can resonantly accelerate the near-equatorially trapped electrons and rapidly flatten the corresponding electron butterfly PADs. These results provide a new insight on how chorus waves affect the dynamic evolution of radiation belt electrons.

  3. Rapid flattening of butterfly pitch angle distributions of radiation belt electrons by whistler-mode chorus

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, Chang; Su, Zhenpeng; Xiao, Fuliang

    Van Allen radiation belt electrons exhibit complex dynamics during geomagnetically active periods. Investigation of electron pitch angle distributions (PADs) can provide important information on the dominant physical mechanisms controlling radiation belt behaviors. In this paper, we report a storm time radiation belt event where energetic electron PADs changed from butterfly distributions to normal or flattop distributions within several hours. Van Allen Probes observations showed that the flattening of butterfly PADs was closely related to the occurrence of whistler-mode chorus waves. Two-dimensional quasi-linear STEERB simulations demonstrate that the observed chorus can resonantly accelerate the near-equatorially trapped electrons and rapidly flatten themore » corresponding electron butterfly PADs. Finally, these results provide a new insight on how chorus waves affect the dynamic evolution of radiation belt electrons.« less

  4. Rapid flattening of butterfly pitch angle distributions of radiation belt electrons by whistler-mode chorus

    DOE PAGES

    Yang, Chang; Su, Zhenpeng; Xiao, Fuliang; ...

    2016-08-16

    Van Allen radiation belt electrons exhibit complex dynamics during geomagnetically active periods. Investigation of electron pitch angle distributions (PADs) can provide important information on the dominant physical mechanisms controlling radiation belt behaviors. In this paper, we report a storm time radiation belt event where energetic electron PADs changed from butterfly distributions to normal or flattop distributions within several hours. Van Allen Probes observations showed that the flattening of butterfly PADs was closely related to the occurrence of whistler-mode chorus waves. Two-dimensional quasi-linear STEERB simulations demonstrate that the observed chorus can resonantly accelerate the near-equatorially trapped electrons and rapidly flatten themore » corresponding electron butterfly PADs. Finally, these results provide a new insight on how chorus waves affect the dynamic evolution of radiation belt electrons.« less

  5. Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013

    NASA Astrophysics Data System (ADS)

    Su, Zhenpeng; Gao, Zhonglei; Zhu, Hui; Li, Wen; Zheng, Huinan; Wang, Yuming; Wang, Shui; Spence, H. E.; Reeves, G. D.; Baker, D. N.; Blake, J. B.; Funsten, H. O.; Wygant, J. R.

    2016-07-01

    Radiation belt electron flux dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt electron fluxes exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances (L > 4.5), energies (˜500 keV to several MeV) and equatorial pitch angles (0°≤αe≤180°). STEERB simulations show that the relativistic electron loss in the region L = 4.5-6.0 was primarily caused by the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.

  6. Wave-induced loss of ultra-relativistic electrons in the Van Allen radiation belts.

    PubMed

    Shprits, Yuri Y; Drozdov, Alexander Y; Spasojevic, Maria; Kellerman, Adam C; Usanova, Maria E; Engebretson, Mark J; Agapitov, Oleksiy V; Zhelavskaya, Irina S; Raita, Tero J; Spence, Harlan E; Baker, Daniel N; Zhu, Hui; Aseev, Nikita A

    2016-09-28

    The dipole configuration of the Earth's magnetic field allows for the trapping of highly energetic particles, which form the radiation belts. Although significant advances have been made in understanding the acceleration mechanisms in the radiation belts, the loss processes remain poorly understood. Unique observations on 17 January 2013 provide detailed information throughout the belts on the energy spectrum and pitch angle (angle between the velocity of a particle and the magnetic field) distribution of electrons up to ultra-relativistic energies. Here we show that although relativistic electrons are enhanced, ultra-relativistic electrons become depleted and distributions of particles show very clear telltale signatures of electromagnetic ion cyclotron wave-induced loss. Comparisons between observations and modelling of the evolution of the electron flux and pitch angle show that electromagnetic ion cyclotron waves provide the dominant loss mechanism at ultra-relativistic energies and produce a profound dropout of the ultra-relativistic radiation belt fluxes.

  7. Wave-induced loss of ultra-relativistic electrons in the Van Allen radiation belts

    PubMed Central

    Shprits, Yuri Y.; Drozdov, Alexander Y.; Spasojevic, Maria; Kellerman, Adam C.; Usanova, Maria E.; Engebretson, Mark J.; Agapitov, Oleksiy V.; Zhelavskaya, Irina S.; Raita, Tero J.; Spence, Harlan E.; Baker, Daniel N.; Zhu, Hui; Aseev, Nikita A.

    2016-01-01

    The dipole configuration of the Earth's magnetic field allows for the trapping of highly energetic particles, which form the radiation belts. Although significant advances have been made in understanding the acceleration mechanisms in the radiation belts, the loss processes remain poorly understood. Unique observations on 17 January 2013 provide detailed information throughout the belts on the energy spectrum and pitch angle (angle between the velocity of a particle and the magnetic field) distribution of electrons up to ultra-relativistic energies. Here we show that although relativistic electrons are enhanced, ultra-relativistic electrons become depleted and distributions of particles show very clear telltale signatures of electromagnetic ion cyclotron wave-induced loss. Comparisons between observations and modelling of the evolution of the electron flux and pitch angle show that electromagnetic ion cyclotron waves provide the dominant loss mechanism at ultra-relativistic energies and produce a profound dropout of the ultra-relativistic radiation belt fluxes. PMID:27678050

  8. Effects of chorus, hiss and electromagnetic ion cyclotron waves on radiation belt dynamics (Invited)

    NASA Astrophysics Data System (ADS)

    Horne, R. B.

    2013-12-01

    Wave-particle interactions are known to play an important role in the acceleration and loss of radiation belt electrons, and in the heating and loss of ring current ions. The effectiveness of each wave type on radiation belt dynamics depends on the solar wind interaction with the magnetosphere and the properties of the waves which vary considerably with magnetic local time, radial distance and latitude. Furthermore the interaction of the waves with the particles is usually nonlinear. These factors present a major challenge to test and verify the theories. Here we discuss the role of several types of waves, including whistler mode chorus, plasmaspheric hiss, magnetosonic and electromagnetic ion cyclotron waves, in relation to radiation belt and ring current dynamics. We present simulations of the radiation belts using the BAS radiation belt model which includes the effects of chorus, hiss and EMIC waves along with radial diffusion. We show that chorus waves are required to form the peaks in the electron phase space density during storms, and that this occurs inside geostationary orbit. We compare simulations against observations in medium Earth orbit and the new results from Van Allen probes mission that shows conclusive evidence for a local electron acceleration process near L=4.5. We show the relative importance of plasmaspheric hiss and chorus and the location of the plasmapause for radiation belt dynamics near L=4.5 and demonstrate the losses due to EMIC waves that should occur at high energies. Finally we show how improving our basic physical understanding through missions such as Van Allen probes go to improve space weather forecasting in projects such as SPACECAST and have a direct benefit to society.

  9. Nonlinear Scattering of VLF Waves in the Radiation Belts

    NASA Astrophysics Data System (ADS)

    Crabtree, Chris; Rudakov, Leonid; Ganguli, Guru; Mithaiwala, Manish

    2014-10-01

    Electromagnetic VLF waves, such as whistler mode waves, control the lifetime of trapped electrons in the radiation belts by pitch-angle scattering. Since the pitch-angle scattering rate is a strong function of the wave properties, a solid understanding of VLF wave sources and propagation in the magnetosphere is critical to accurately calculate electron lifetimes. Nonlinear scattering (Nonlinear Landau Damping) is a mechanism that can strongly alter VLF wave propagation [Ganguli et al. 2010], primarily by altering the direction of propagation, and has not been accounted for in previous models of radiation belt dynamics. Laboratory results have confirmed the dramatic change in propagation direction when the pump wave has sufficient amplitude to exceed the nonlinear threshold [Tejero et al. 2014]. Recent results show that the threshold for nonlinear scattering can often be met by naturally occurring VLF waves in the magnetosphere, with wave magnetic fields of the order of 50-100 pT inside the plasmapause. Nonlinear scattering can then dramatically alter the macroscopic dynamics of waves in the radiation belts leading to the formation of a long-lasting wave-cavity [Crabtree et al. 2012] and, when amplification is present, a multi-pass amplifier [Ganguli et al. 2012]. By considering these effects, the lifetimes of electrons can be dramatically reduced. This work is supported by the Naval Research Laboratory base program.

  10. Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013

    DOE PAGES

    Su, Zhenpeng; Gao, Zhonglei; Reeves, Geoffrey D.; ...

    2016-07-01

    Radiation belt electron flux dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt electron fluxes exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances ( L > 4.5), energies (~500 keV to several MeV) and equatorial pitch angles (0° ≤ α e ≤ 180°). STEERB simulations show that the relativistic electron loss in the region L = 4.5–6.0 was primarilymore » caused by the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Furthermore, our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.« less

  11. Nonstorm time dropout of radiation belt electron fluxes on 24 September 2013

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Su, Zhenpeng; Gao, Zhonglei; Reeves, Geoffrey D.

    Radiation belt electron flux dropouts during the main phase of geomagnetic storms have received increasing attention in recent years. Here we focus on a rarely reported nonstorm time dropout event observed by Van Allen Probes on 24 September 2013. Within several hours, the radiation belt electron fluxes exhibited a significant (up to 2 orders of magnitude) depletion over a wide range of radial distances ( L > 4.5), energies (~500 keV to several MeV) and equatorial pitch angles (0° ≤ α e ≤ 180°). STEERB simulations show that the relativistic electron loss in the region L = 4.5–6.0 was primarilymore » caused by the pitch angle scattering of observed plasmaspheric hiss and electromagnetic ion cyclotron waves. Furthermore, our results emphasize the complexity of radiation belt dynamics and the importance of wave-driven precipitation loss even during nonstorm times.« less

  12. A new Predictive Model for Relativistic Electrons in Outer Radiation Belt

    NASA Astrophysics Data System (ADS)

    Chen, Y.

    2017-12-01

    Relativistic electrons trapped in the Earth's outer radiation belt present a highly hazardous radiation environment for spaceborne electronics. These energetic electrons, with kinetic energies up to several megaelectron-volt (MeV), manifest a highly dynamic and event-specific nature due to the delicate interplay of competing transport, acceleration and loss processes. Therefore, developing a forecasting capability for outer belt MeV electrons has long been a critical and challenging task for the space weather community. Recently, the vital roles of electron resonance with waves (including such as chorus and electromagnetic ion cyclotron) have been widely recognized; however, it is still difficult for current diffusion radiation belt models to reproduce the behavior of MeV electrons during individual geomagnetic storms, mainly because of the large uncertainties existing in input parameters. In this work, we expanded our previous cross-energy cross-pitch-angle coherence study and developed a new predictive model for MeV electrons over a wide range of L-shells inside the outer radiation belt. This new model uses NOAA POES observations from low-Earth-orbits (LEOs) as inputs to provide high-fidelity nowcast (multiple hour prediction) and forecast (> 1 day prediction) of the energization of MeV electrons as well as the evolving MeV electron distributions afterwards during storms. Performance of the predictive model is quantified by long-term in situ data from Van Allen Probes and LANL GEO satellites. This study adds new science significance to an existing LEO space infrastructure, and provides reliable and powerful tools to the whole space community.

  13. Characterization of radiation belt electron energy spectra from CRRES observations

    NASA Astrophysics Data System (ADS)

    Johnston, W. R.; Lindstrom, C. D.; Ginet, G. P.

    2010-12-01

    Energetic electrons in the outer radiation belt and the slot region exhibit a wide variety of energy spectral forms, more so than radiation belt protons. We characterize the spatial and temporal dependence of these forms using observations from the CRRES satellite Medium Electron Sensor A (MEA) and High-Energy Electron Fluxmeter (HEEF) instruments, together covering an energy range 0.15-8 MeV. Spectra were classified with two independent methods, data clustering and curve-fitting analyses, in each case defining categories represented by power law, exponential, and bump-on-tail (BOT) or other complex shapes. Both methods yielded similar results, with BOT, exponential, and power law spectra respectively dominating in the slot region, outer belt, and regions just beyond the outer belt. The transition from exponential to power law spectra occurs at higher L for lower magnetic latitude. The location of the transition from exponential to BOT spectra is highly correlated with the location of the plasmapause. In the slot region during the days following storm events, electron spectra were observed to evolve from exponential to BOT yielding differential flux minima at 350-650 keV and maxima at 1.5-2 MeV; such evolution has been attributed to energy-dependent losses from scattering by whistler hiss.

  14. Statistical properties of the radiation belt seed population

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Boyd, A. J.; Spence, H. E.; Huang, C. -L.

    Here, we present a statistical analysis of phase space density data from the first 26 months of the Van Allen Probes mission. In particular, we investigate the relationship between the tens and hundreds of keV seed electrons and >1 MeV core radiation belt electron population. Using a cross-correlation analysis, we find that the seed and core populations are well correlated with a coefficient of ≈0.73 with a time lag of 10–15 h. We present evidence of a seed population threshold that is necessary for subsequent acceleration. The depth of penetration of the seed population determines the inner boundary of themore » acceleration process. However, we show that an enhanced seed population alone is not enough to produce acceleration in the higher energies, implying that the seed population of hundreds of keV electrons is only one of several conditions required for MeV electron radiation belt acceleration.« less

  15. Statistical properties of the radiation belt seed population

    DOE PAGES

    Boyd, A. J.; Spence, H. E.; Huang, C. -L.; ...

    2016-07-25

    Here, we present a statistical analysis of phase space density data from the first 26 months of the Van Allen Probes mission. In particular, we investigate the relationship between the tens and hundreds of keV seed electrons and >1 MeV core radiation belt electron population. Using a cross-correlation analysis, we find that the seed and core populations are well correlated with a coefficient of ≈0.73 with a time lag of 10–15 h. We present evidence of a seed population threshold that is necessary for subsequent acceleration. The depth of penetration of the seed population determines the inner boundary of themore » acceleration process. However, we show that an enhanced seed population alone is not enough to produce acceleration in the higher energies, implying that the seed population of hundreds of keV electrons is only one of several conditions required for MeV electron radiation belt acceleration.« less

  16. The NASA Space Radiation Research Program

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.

    2006-01-01

    We present a comprehensive overview of the NASA Space Radiation Research Program. This program combines basic research on the mechanisms of radiobiological action relevant for improving knowledge of the risks of cancer, central nervous system and other possible degenerative tissue effects, and acute radiation syndromes from space radiation. The keystones of the NASA Program are five NASA Specialized Center's of Research (NSCOR) investigating space radiation risks. Other research is carried out through peer-reviewed individual investigations and in collaboration with the US Department of Energies Low-Dose Research Program. The Space Radiation Research Program has established the Risk Assessment Project to integrate data from the NSCOR s and other peer-reviewed research into quantitative projection models with the goals of steering research into data and scientific breakthroughs that will reduce the uncertainties in current risk projections and developing the scientific knowledge needed for future individual risk assessment approaches and biological countermeasure assessments or design. The NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory was created by the Program to simulate space radiation on the ground in support of the above research programs. New results from NSRL will be described.

  17. Simulating the Outer Radiation Belt During the Rising Phase of Solar Cycle 24

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching; Glocer, Alex; Zheng, Qiuhua; Chen, Sheng-Hsien; Kanekal, Shri; Nagai, Tsungunobu; Albert, Jay

    2011-01-01

    After prolonged period of solar minimum, there has been an increase in solar activity and its terrestrial consequences. We are in the midst of the rising phase of solar cycle 24, which began in January 2008. During the initial portion of the cycle, moderate geomagnetic storms occurred follow the 27 day solar rotation. Most of the storms were accompanied by increases in electron fluxes in the outer radiation belt. These enhancements were often preceded with rapid dropout at high L shells. We seek to understand the similarities and differences in radiation belt behavior during the active times observed during the of this solar cycle. This study includes extensive data and simulations our Radiation Belt Environment Model. We identify the processes, transport and wave-particle interactions, that are responsible for the flux dropout and the enhancement and recovery.

  18. NASA's Van Allen Probes RBSP-ECT and NSF's FIREBIRD Data Products and Access to Them: An Insider's Outlook on the Inner and Outer Belts.

    NASA Astrophysics Data System (ADS)

    Smith, S. S.; Spence, H. E.; Geoffrey, R.; Klumpar, D. M.

    2017-12-01

    In this poster, we present a summary of access to data products Radiation Belt Storm Probes - Energetic Particle Composition, and Thermal plasma (RBSP-ECT) suite of NASA's Van Allen Probes mission. The RBSP-ECT science investigation (http://rbsp-ect.sr.unh.edu) measures comprehensively the near-Earth charged particle environment in order to understand the processes that control the acceleration, global distribution, and variability of radiation belt electrons and ions. RBSP-ECT data products derive from the three instrument elements that comprise the suite, which collectively covers the broad energies that define the source and seed populations, the core radiation belts, and also their highest energy ultra-relativistic extensions. These RBSP-ECT instruments include, from lowest to highest energies: the Helium, Oxygen, Proton, and Electron (HOPE) sensor, the Magnetic Electron and Ion Spectrometer (MagEIS), and the Relativistic Electron and Proton Telescope (REPT). We provide a brief overview of their principles of operation, as well as a description of the Level 1-3 data products that the HOPE, MagEIS, and REPT instruments produce, both separately and together. We provide a summary of how to access these RBSP-ECT data products at our Science Operation Center and Science Data Center (http://www.rbsp-ect.lanl.gov/rbsp_ect.php ) as well as caveats for their use. In addition, we also provide a summary of access to the data products from NSF's CubeSat mission called Focused Investigation of Relativistic Electron Burst: Intensity, Range, and Dynamics (FIREBIRD). The dual CubeSat FIREBIRD missions provide data on energetic radiation belt electrons precipitating into the atmosphere at low altitudes, which complements and is contemporary with RBSP-ECT measurements. We provide a similar summary of how to access these data (https://ssel.montana.edu/firebird2.html). Finally, in the spirit of efficiently and effectively promoting and encouraging new collaborations, we present a

  19. Understanding the Mechanisms of Radiation Belt Dropouts Observed by Van Allen Probes

    NASA Astrophysics Data System (ADS)

    Xiang, Zheng; Tu, Weichao; Li, Xinlin; Ni, Binbin; Morley, S. K.; Baker, D. N.

    2017-10-01

    To achieve a better understanding of the dominant loss mechanisms for the rapid dropouts of radiation belt electrons, three distinct radiation belt dropout events observed by Van Allen Probes are comprehensively investigated. For each event, observations of the pitch angle distribution of electron fluxes and electromagnetic ion cyclotron (EMIC) waves are analyzed to determine the effects of atmospheric precipitation loss due to pitch angle scattering induced by EMIC waves. Last closed drift shells (LCDS) and magnetopause standoff position are obtained to evaluate the effects of magnetopause shadowing loss. Evolution of electron phase space density (PSD) versus L* profiles and the μ and K (first and second adiabatic invariants) dependence of the electron PSD drops are calculated to further analyze the dominant loss mechanisms at different L*. Our findings suggest that these radiation belt dropouts can be classified into distinct classes in terms of dominant loss mechanisms: magnetopause shadowing dominant, EMIC wave scattering dominant, and combination of both mechanisms. Different from previous understanding, our results show that magnetopause shadowing can deplete electrons at L* < 4, while EMIC waves can efficiently scatter electrons at L* > 4. Compared to the magnetopause standoff position, it is more reliable to use LCDS to evaluate the impact of magnetopause shadowing. The evolution of electron PSD versus L* profile and the μ, K dependence of electron PSD drops can provide critical and credible clues regarding the mechanisms responsible for electron losses at different L* over the outer radiation belt.

  20. Metallurgical Design and Development of NASA Crawler/Transporter Tread Belt Shoe Castings

    NASA Technical Reports Server (NTRS)

    Parker, Donald S.

    2006-01-01

    The NASA Crawler/Transporters (CT-1 and CT-2) used to transport the Space Shuffles are one of the largest tracked vehicles in existence today. Two of these machines have been used to move space flight vehicles at Kennedy Space Center since the Apollo missions of the 1960's and relatively few modifications have been made to keep them operational. In September of 2003 during normal Crawler/Transporter operations cracks were observed along the roller pad surfaces of several tread belt shoes. Further examination showed 20 cracked shoes on CT-1 and 40 cracked shoes on CT-2 and a formal failure analysis investigation was undertaken while the cracked shoes were replaced. Six shoes were cross-sectioned with the fracture surfaces exposed and it was determined that the cracks were due to fatigue that initiated on the internal casting web channels at pre-existing casting defects and propagated through thickness both transgranularly and intergranularly between internal shrinkage cavities, porosity, and along austenitic and ferritic grain boundaries. The original shoes were cast during the 1960's using a modified 861330 steel with slightly higher levels of chromium, nickel and molybdenum followed by heat treatment to achieve a minimum tensile strength of 11 Oksi. Subsequent metallurgical analysis of the tread belt shoes after multiple failures showed excessive internal defects, alloy segregation, a nonuniform ferritic/ bainitic/martensitic microstructure, and low average tensile properties indicative of poor casting and poor heat-treatment. As a result, NASA funded an initiative to replace all of the tread belt shoes on both crawler/transporters along with a redesign of the alloy, manufacturing, and heat-treatment to create a homogeneous cast structure with uniform mechanical and metallurgical properties. ME Global, a wholly owned subsidiary of ME Elecmetal based in Minneapolis, MN was selected as manufacturing and design partner to develop the new shoes and this paper

  1. Innermost Van Allen Radiation Belt for High Energy Protons at Saturn

    NASA Technical Reports Server (NTRS)

    Cooper, John F.

    2008-01-01

    The high energy proton radiation belts of Saturn are energetically dominated by the source from cosmic ray albedo neutron decay (CRAND), trapping of protons from beta decay of neutrons emitted from galactic cosmic ray nuclear interactions with the main rings. These belts were originally discovered in wide gaps between the A-ring, Janus/Epimetheus, Mimas, and Enceladus. The narrow F and G rings significant affected the CRAND protons but did not produce total depletion. Voyager 2 measurements subsequently revealed an outermost CRAND proton belt beyond Enceladus. Although the source rate is small, the trapping times limited by radial magnetospheric diffusion are very long, about ten years at peak measured flux inwards of the G ring, so large fluxes can accumulate unless otherwise limited in the trapping region by neutral gas, dust, and ring body interactions. One proposed final extension of the Cassini Orbiter mission would place perikrone in a 3000-km gap between the inner D ring and the upper atmosphere of Saturn. Experience with CRAND in the Earth's inner Van Allen proton belt suggests that a similar innermost belt might be found in this comparably wide region at Saturn. Radial dependence of magnetospheric diffusion, proximity to the ring neutron source, and northward magnetic offset of Saturn's magnetic equator from the ring plane could potentially produce peak fluxes several orders of magnitude higher than previously measured outside the main rings. Even brief passes through such an intense environment of highly penetrating protons would be a significant concern for spacecraft operations and science observations. Actual fluxes are limited by losses in Saturn's exospheric gas and in a dust environment likely comparable to that of the known CRAND proton belts. The first numerical model of this unexplored radiation belt is presented to determine limits on peak magnitude and radial profile of the proton flux distribution.

  2. Coupling of Outward Radial Diffusion and Losses at the Magnetopause in the Outer Radiation Belt

    NASA Astrophysics Data System (ADS)

    Castillo Tibocha, A. M.; Shprits, Y.; Drozdov, A.; Kellerman, A. C.; Aseev, N.

    2017-12-01

    Sudden dropouts observed in relativistic electron fluxes within the radiation belts are one the most studied and yet poorly understood features of the dynamics of radiation belts. A number of physical processes contributing to these dropout events are triggered by solar wind drivers. Magnetopause losses are one of the most effective mechanisms involved here and usually occur when drifting particles reach the boundary or when inward motion of the magnetopause crosses closed particle drift shells. In both cases, particles are rapidly transported into interplanetary space generating sharp gradients in electron PSD that will promote further outward radial diffusion of particles due to adiabatic transport and the influence of outward ULF waves. Studies suggest that the coupling of these two mechanisms explains nearly all the depletion of MeV electrons observed in the outer region of the radiation belts (L*>5). In this study, we present a simple approach to model electron losses at the magnetopause and outward radial diffusion in the outer radiation belt during geomagnetic storm time. Measured upstream solar wind parameters were used to calculate the radial distance of the subsolar point as proposed by Shue et al. (1997), which was defined as the radial extent of our assumed dipole field configuration. Radial diffusion was modelled using the empirical Kp-dependent DLL [Brautigam and Albert, JGR 2000] diffusion coefficient, which is included in the 3D Versatile Electron Radiation Belt (VERB) code. Simulations of geomagnetic storms were performed in order to evaluate the effects of the integrated mechanisms and the results were compared with Van Allen probe satellite data. Our simulation results reproduce well the observed loss at the magnetopause and electron depletion in the outer radiation belt.

  3. Radiation Belt Storm Probes (RBSP) Payload Safety Introduction Briefing

    NASA Technical Reports Server (NTRS)

    Loftin, Chuck; Lampert, Dianna; Herrburger, Eric; Smith, Clay; Hill, Stuart; VonMehlem, Judi

    2008-01-01

    Mission of the Geospace Radiation Belt Storm Probes (RBSP) is: Gain s cientific understanding (to the point of predictability) of how populations of relativistic electrons and ions in space form or change in response to changes in solar activity and the solar wind.

  4. Saturn Neutron Exosphere as Source for Inner and Innermost Radiation Belts

    NASA Technical Reports Server (NTRS)

    Cooper, John; Lipatov, Alexander; Sittler, Edward; Sturner, Steven

    2011-01-01

    Energetic proton and electron measurements by the ongoing Cassini orbiter mission are expanding our knowledge of the highest energy components of the Saturn magnetosphere in the inner radiation belt region after the initial discoveries of these belts by the Pioneer 11 and Voyager 2 missions. Saturn has a neutron exosphere that extends throughout the magnetosphere from the cosmic ray albedo neutron source at the planetary main rings and atmosphere. The neutrons emitted from these sources at energies respectively above 4 and 8 eV escape the Saturn system, while those at lower energies are gravitationally bound. The neutrons undergo beta decay in average times of about 1000 seconds to provide distributed sources of protons and electrons throughout Saturn's magnetosphere with highest injection rates close to the Saturn and ring sources. The competing radiation belt source for energetic electrons is rapid inward diffusion and acceleration of electrons from the middle magnetosphere and beyond. Minimal losses during diffusive transport across the moon orbits, e.g. of Mimas and Enceladus, and local time asymmetries in electron intensity, suggest that drift resonance effects preferentially boost the diffusion rates of electrons from both sources. Energy dependences of longitudinal gradient-curvature drift speeds relative to the icy moons are likely responsible for hemispheric differences (e.g., Mimas, Tethys) in composition and thermal properties as at least partly produced by radiolytic processes. A continuing mystery is the similar radial profiles of lower energy (<10 MeV) protons in the inner belt region. Either the source of these lower energy protons is also neutron decay, but perhaps alternatively from atmospheric albedo, or else all protons from diverse distributed sources are similarly affected by losses at the moon' orbits, e.g. because the proton diffusion rates are extremely low. Enceladus cryovolcanism, and radiolytic processing elsewhere on the icy moon and

  5. The Detection of a Striking Increase in the Microwave Emission from Jupiter's Radiation Belts in June and July 2003.

    NASA Astrophysics Data System (ADS)

    Klein, M. J.; Bolton, S. J.; Levin, S. M.; Mac Laren, D.

    2004-12-01

    Synchrotron emission from energetic electrons in Jupiter's radiation belts has been routinely measured by ground-based radio telescopes for three decades. The NASA-JPL Jupiter Patrol, using NASA's Deep Space Network (DSN) antennas at Goldstone, CA., has reported significant (5 %-to-30 %) variations in Jupiter's flux density near 13-cm wavelength with timescales from a few days to several months. In this paper we report observations of an unusually sudden increase in flux density from 3.8 to 4.3 Jy that occurred between 20 June and 15 July 2003. The rate of increase (approximately 0.6 percent per day) is the steepest increase that we have detected with the exception of the increase in 1994 following the impacts of fragments from comet Shoemaker-Levy 9. More than half of the reported observations were conducted by middle- and high school students from classrooms across the nation. The students and their teachers are participants in the Goldstone-Apple Valley Radio Telescope (GAVRT) science education project, which is a partnership involving NASA, the Jet Propulsion Laboratory and the Lewis Center for Educational Research (LCER) in Apple Valley, CA. Working with the Lewis Center over the Internet, GAVRT students conduct remotely controlled radio astronomy observations using 34-m antennas at Goldstone. We also report preliminary results from a special GAVRT observing campaign conducted in the fall of 2003 before, during and after the controlled impact of the Galileo spacecraft into the Jovian atmosphere. Simultaneous observations were made at 3.5 and 13 cm wavelengths three-to-four days per week. These data are being incorporated into synchrotron emission studies of the state of the radiation belts during the last weeks of the Galileo mission. The JPL contribution to this paper was performed at the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration.

  6. Space Radiation Research at NASA

    NASA Technical Reports Server (NTRS)

    Norbury, John

    2016-01-01

    The harmful effects of space radiation on astronauts is one of the most important limiting factors for human exploration of space beyond low Earth orbit, including a journey to Mars. This talk will present an overview of space radiation issues that arise throughout the solar system and will describe research efforts at NASA aimed at studying space radiation effects on astronauts, including the experimental program at the NASA Space Radiation Laboratory at Brookhaven National Laboratory. Recent work on galactic cosmic ray simulation at ground based accelerators will also be presented. The three major sources of space radiation, namely geomagnetically trapped particles, solar particle events and galactic cosmic rays will be discussed as well as recent discoveries of the harmful effects of space radiation on the human body. Some suggestions will also be given for developing a space radiation program in the Republic of Korea.

  7. Understanding the mechanisms of radiation belt dropouts observed by Van Allen Probes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Xiang, Zheng; Tu, Weichao; Li, Xinlin

    To achieve a better understanding of the dominant loss mechanisms for the rapid dropouts of radiation belt electrons, three distinct radiation belt dropout events observed by Van Allen Probes are comprehensively investigated. For each event, observations of the pitch angle distribution of electron fluxes and electromagnetic ion cyclotron (EMIC) waves are analyzed to determine the effects of atmospheric precipitation loss due to pitch angle scattering induced by EMIC waves. Last closed drift shells (LCDS) and magnetopause standoff position are obtained to evaluate the effects of magnetopause shadowing loss. Evolution of electron phase space density (PSD) versus L* profiles and themore » μ and K (first and second adiabatic invariants) dependence of the electron PSD drops are calculated to further analyze the dominant loss mechanisms at different L*. Here, our findings suggest that these radiation belt dropouts can be classified into distinct classes in terms of dominant loss mechanisms: magnetopause shadowing dominant, EMIC wave scattering dominant, and combination of both mechanisms. Different from previous understanding, our results show that magnetopause shadowing can deplete electrons at L* < 4, while EMIC waves can efficiently scatter electrons at L* > 4. Compared to the magnetopause standoff position, it is more reliable to use LCDS to evaluate the impact of magnetopause shadowing. Finally, the evolution of electron PSD versus L* profile and the μ, K dependence of electron PSD drops can provide critical and credible clues regarding the mechanisms responsible for electron losses at different L* over the outer radiation belt.« less

  8. Understanding the mechanisms of radiation belt dropouts observed by Van Allen Probes

    DOE PAGES

    Xiang, Zheng; Tu, Weichao; Li, Xinlin; ...

    2017-08-30

    To achieve a better understanding of the dominant loss mechanisms for the rapid dropouts of radiation belt electrons, three distinct radiation belt dropout events observed by Van Allen Probes are comprehensively investigated. For each event, observations of the pitch angle distribution of electron fluxes and electromagnetic ion cyclotron (EMIC) waves are analyzed to determine the effects of atmospheric precipitation loss due to pitch angle scattering induced by EMIC waves. Last closed drift shells (LCDS) and magnetopause standoff position are obtained to evaluate the effects of magnetopause shadowing loss. Evolution of electron phase space density (PSD) versus L* profiles and themore » μ and K (first and second adiabatic invariants) dependence of the electron PSD drops are calculated to further analyze the dominant loss mechanisms at different L*. Here, our findings suggest that these radiation belt dropouts can be classified into distinct classes in terms of dominant loss mechanisms: magnetopause shadowing dominant, EMIC wave scattering dominant, and combination of both mechanisms. Different from previous understanding, our results show that magnetopause shadowing can deplete electrons at L* < 4, while EMIC waves can efficiently scatter electrons at L* > 4. Compared to the magnetopause standoff position, it is more reliable to use LCDS to evaluate the impact of magnetopause shadowing. Finally, the evolution of electron PSD versus L* profile and the μ, K dependence of electron PSD drops can provide critical and credible clues regarding the mechanisms responsible for electron losses at different L* over the outer radiation belt.« less

  9. Magnetopause Losses of Radiation Belt Electrons During a Recent Magnetic Storm

    NASA Astrophysics Data System (ADS)

    Lemon, C. L.; Chen, M.; Roeder, J. L.; Fennell, J. F.; Mulligan, T. L.; Claudepierre, S. G.

    2013-12-01

    We present results from Van Allen Probes observations during the magnetic storm of June 1, 2013, and compare them with simulations of the same event using the RCM-E model. The RCM-E calculates ion and electron transport in self-consistently computed electric and magnetic fields. We examine the effect of the perturbed ring current magnetic field on the transport of energetic electrons, and the significance of this transport for explaining the observed evolution of radiation belt fluxes during this event. The event is notable because it is a relatively simple storm in which strong convection persists for approximately 7 hours, injecting a moderately strong ring current (minimum Dst of -120 nT); convection then quickly shuts off, leading to a long and smooth recovery phase. We use RCM-E simulations, constrained by Van Allen Probes data, to asses the rate of magnetopause losses of electrons (magnetopause shadowing), and to calculate electron drift times and the evolution of electron phase space densities during the storm event. We recently modified the RCM-E plasma drift calculations to include relativistic treatment of electrons and a more realistic electron loss model. The new electron loss model, although still somewhat simplistic, gives much more accurate loss rates in the inner magnetosphere (including the radiation belts), which significantly affects the resulting electron fluxes compared to previous simulations. This, in turn, modifies the transport of ions and electrons via feedback with both the electric and magnetic fields. Our results highlight the effect of the ring current on the evolution of the radiation belt electrons, with particular emphasis on the role that magnetopause losses play in the observed variation of radiation belt electron fluxes during the storm.

  10. Radiation belt electron observations following the January 1997 magnetic cloud event

    NASA Astrophysics Data System (ADS)

    Selesnick, R. S.; Blake, J. B.

    Relativistic electrons in the outer radiation belt associated with the January 1997 magnetic cloud event were observed by the HIST instrument on POLAR at kinetic energies from 0.7 to 7 MeV and L shells from 3 to 9. The electron enhancement occurred on a time scale of hours or less throughout the outer radiation belt, except for a more gradual rise in the higher energy electrons at the lower L values indicative of local acceleration and inward radial diffusion. At the higher L values, variations on a time scale of several days following the initial injection on January 10 are consistent with data from geosynchronous orbit and may be an adiabatic response.

  11. Diffusive vs. impulsive energetic electron transport during radiation belt storms

    NASA Astrophysics Data System (ADS)

    Vassiliadis, D.; Koepke, M.; Tornquist, M.

    2008-12-01

    Earth's electron radiation belts are continually replenished by inward particle transport (as well as other, local acceleration processes) taking place during radiation belt storms. For some storms the radial transport is primarily diffusive while for others it is impulsive, or characterized by injections. To distinguish between these types of inward transport, we first use a dynamic model of the phase-space density as measured by POLAR/HIST and expressed in terms of adiabatic invariants [Green and Kivelson, 2004]. In a review of storms from 1997 to 2004 the coefficients of the model are peaked at characteristic temporal and phase- space (mu, k, L*) scales during specific storms. The transport is quantified in terms of those invariants which are violated and identified with peaks of the electron distribution in invariant space. Second, we run guiding- center simulations in wave fields fitted to in situ measurements complemented at low and high L by ground ULF pulsations. The modes of response identified in earlier studies from SAMPEX and POLAR electron flux measurements are now associated with primarily diffusive transport in the central range of the outer belt, L=4-8, and primarily impulsive transport near the plasmapause boundary, L=3-4.

  12. Source and seed populations for relativistic electrons: Their roles in radiation belt changes

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jaynes, A. N.; Baker, D. N.; Singer, H. J.

    Strong enhancements of outer Van Allen belt electrons have been shown to have a clear dependence on solar wind speed and on the duration of southward interplanetary magnetic field. However, individual case study analyses also have demonstrated that many geomagnetic storms produce little in the way of outer belt enhancements and, in fact, may produce substantial losses of relativistic electrons. In this study, focused upon a key period in August–September 2014, we use GOES geostationary orbit electron flux data and Van Allen Probes particle and fields data to study the process of radiation belt electron acceleration. One particular interval, 13–22more » September, initiated by a short-lived geomagnetic storm and characterized by a long period of primarily northward interplanetary magnetic field (IMF), showed strong depletion of relativistic electrons (including an unprecedented observation of long-lasting depletion at geostationary orbit) while an immediately preceding, and another immediately subsequent, storm showed strong radiation belt enhancement. We demonstrate with these data that two distinct electron populations resulting from magnetospheric substorm activity are crucial elements in the ultimate acceleration of highly relativistic electrons in the outer belt: the source population (tens of keV) that give rise to VLF wave growth and the seed population (hundreds of keV) that are, in turn, accelerated through VLF wave interactions to much higher energies. ULF waves may also play a role by either inhibiting or enhancing this process through radial diffusion effects. Furthermore, if any components of the inner magnetospheric accelerator happen to be absent, the relativistic radiation belt enhancement fails to materialize.« less

  13. Source and seed populations for relativistic electrons: Their roles in radiation belt changes

    DOE PAGES

    Jaynes, A. N.; Baker, D. N.; Singer, H. J.; ...

    2015-09-09

    Strong enhancements of outer Van Allen belt electrons have been shown to have a clear dependence on solar wind speed and on the duration of southward interplanetary magnetic field. However, individual case study analyses also have demonstrated that many geomagnetic storms produce little in the way of outer belt enhancements and, in fact, may produce substantial losses of relativistic electrons. In this study, focused upon a key period in August–September 2014, we use GOES geostationary orbit electron flux data and Van Allen Probes particle and fields data to study the process of radiation belt electron acceleration. One particular interval, 13–22more » September, initiated by a short-lived geomagnetic storm and characterized by a long period of primarily northward interplanetary magnetic field (IMF), showed strong depletion of relativistic electrons (including an unprecedented observation of long-lasting depletion at geostationary orbit) while an immediately preceding, and another immediately subsequent, storm showed strong radiation belt enhancement. We demonstrate with these data that two distinct electron populations resulting from magnetospheric substorm activity are crucial elements in the ultimate acceleration of highly relativistic electrons in the outer belt: the source population (tens of keV) that give rise to VLF wave growth and the seed population (hundreds of keV) that are, in turn, accelerated through VLF wave interactions to much higher energies. ULF waves may also play a role by either inhibiting or enhancing this process through radial diffusion effects. Furthermore, if any components of the inner magnetospheric accelerator happen to be absent, the relativistic radiation belt enhancement fails to materialize.« less

  14. Role of ULF Waves in Radiation Belt and Ring Current Dynamics

    NASA Astrophysics Data System (ADS)

    Mann, I. R.; Murphy, K. R.; Rae, I. J.; Ozeke, L.; Milling, D. K.

    2013-12-01

    combination of data from ground arrays such as CARISMA and the contemporaneous operation of the NASA Van Allen Probes (VAP) mission offers an excellent basis for understanding this cross-energy plasma coupling which spans more than 6 orders of magnitude in energy. Explaining the casual connections between plasmas in the plasmasphere (eV), ring current (keV), and radiation belt (MeV), via the intermediaries of plasma waves, is key to understanding inner magnetosphere dynamics. This work has received funding from the European Union under the Seventh Framework Programme (FP7-Space) under grant agreement n 284520 for the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Energization and Loss) collaborative research project.

  15. Internal Charging Design Environments for the Earths Radiation Belts

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Edwards, David L.

    2009-01-01

    Relativistic electrons in the Earth's radiation belts are a widely recognized threat to spacecraft because they penetrate lightly shielded vehicle hulls and deep into insulating materials where they accumulate to sufficient levels to produce electrostatic discharges. Strategies for evaluating the magnitude of the relativistic electron flux environment and its potential for producing ESD events are varied. Simple "rule of thumb" estimates such as the widely used 10(exp 10) e-/sq cm fluence within 10 hour threshold for the onset of pulsing in dielectric materials provide a quick estimate of when to expect charging issues. More sophisticated strategies based on models of the trapped electron flux within the Earth s magnetic field provide time dependent estimates of electron flux along spacecraft orbits and orbit integrate electron flux. Finally, measurements of electron flux can be used to demonstrate mean and extreme relativistic electron environments. This presentation will evaluate strategies used to specify energetic electron flux and fluence environments along spacecraft trajectories in the Earth s radiation belts.

  16. Modeling the Inner Magnetosphere: Radiation Belts, Ring Current, and Composition

    NASA Technical Reports Server (NTRS)

    Glocer, Alex

    2011-01-01

    The space environment is a complex system defined by regions of differing length scales, characteristic energies, and physical processes. It is often difficult, or impossible, to treat all aspects of the space environment relative to a particular problem with a single model. In our studies, we utilize several models working in tandem to examine this highly interconnected system. The methodology and results will be presented for three focused topics: 1) Rapid radiation belt electron enhancements, 2) Ring current study of Energetic Neutral Atoms (ENAs), Dst, and plasma composition, and 3) Examination of the outflow of ionospheric ions. In the first study, we use a coupled MHD magnetosphere - kinetic radiation belt model to explain recent Akebono/RDM observations of greater than 2.5 MeV radiation belt electron enhancements occurring on timescales of less than a few hours. In the second study, we present initial results of a ring current study using a newly coupled kinetic ring current model with an MHD magnetosphere model. Results of a dst study for four geomagnetic events are shown. Moreover, direct comparison with TWINS ENA images are used to infer the role that composition plays in the ring current. In the final study, we directly model the transport of plasma from the ionosphere to the magnetosphere. We especially focus on the role of photoelectrons and and wave-particle interactions. The modeling methodology for each of these studies will be detailed along with the results.

  17. Middle atmosphere NO/x/ production due to ion propulsion induced radiation belt proton precipitation

    NASA Technical Reports Server (NTRS)

    Aikin, A. C.; Jackman, C. H.

    1980-01-01

    The suggestion that keV Ar(+) resulting from ion propulsion operations during solar power satellite construction could cause energetic proton precipitation from the inner radiation belt is examined to determine if such precipitation could cause significant increases in middle atmosphere nitric oxide concentrations thereby adversely affecting stratospheric ozone. It is found that the initial production rate of NO (mole/cu cm-sec) at 50 km is 130 times that due to nitrous oxide reacting with excited oxygen. However, since the time required to empty the inner belt of protons is about 1 sec and short compared to the replenishment time due to neutron decay, precipitation of inner radiation belt protons will have no adverse atmospheric environmental effect.

  18. Response of radiation belt simulations to different radial diffusion coefficients for relativistic and ultra-relativistic electrons

    NASA Astrophysics Data System (ADS)

    Drozdov, Alexander; Mann, Ian; Baker, Daniel N.; Subbotin, Dmitriy; Ozeke, Louis; Shprits, Yuri; Kellerman, Adam

    Two parameterizations of the resonant wave-particle interactions of electrons with ULF waves in the magnetosphere by Brautigam and Albert [2000] and Ozeke et al. [2012] are evaluated using the Versatile Electron Radiation Belt (VERB) diffusion code to estimate the effect of changing a diffusion coefficient on the radiation belt simulation. The period of investigation includes geomagnetically quiet and active time. The simulations take into account wave-particle interactions represented by radial diffusion transport, local acceleration, losses due to pitch-angle diffusion, and mixed diffusion. 1. Brautigam, D. H., and J. M. Albert (2000), Radial diffusion analysis of outer radiation belt electrons during the October 9, 1990, magnetic storm, J. Geophys. Res., 105(A1), 291-309, doi:10.1029/1999JA900344 2. Ozeke, L. G., I. R. Mann, K. R. Murphy, I. J. Rae, D. K. Milling, S. R. Elkington, A. A. Chan, and H. J. Singer (2012), ULF wave derived radiation belt radial diffusion coefficients, J. Geophys. Res., 117, A04222, doi:10.1029/2011JA017463.

  19. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    Four reindeer walk past the BARREL payload on the launch pad at Esrange Space Center near Kiruna, Sweden. The BARREL team is at Esrange Space Center launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carry instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Image credit: NASA/University of Houston/Samar Mathur NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  20. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    A member of the BARREL team prepares a payload for launch from Esrange Space Center on Aug. 29, 2016. Throughout August 2016, the BARREL team was at Esrange Space Center near Kiruna, Sweden, launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carried instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Credit: NASA/Dartmouth/Alexa Halford NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  1. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    The fourth BARREL balloon of this campaign sits on the launch pad shortly before it launched on Aug. 21, 2016. The BARREL team is at Esrange Space Center near Kiruna, Sweden, launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carry instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Credit: NASA/University of Houston/Michael Greer NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  2. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    The third BARREL balloon floats towards the stratosphere on Aug. 21, 2016. This payload flew for nearly 30 hours, measuring X-rays in Earth’s atmosphere. The BARREL team is at Esrange Space Center near Kiruna, Sweden, launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carry instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Credit: NASA/University of Houston/Michael Greer NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  3. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    A BARREL payload sits on the launch pad at Esrange Space Center near Kiruna, Sweden. The BARREL team is at Esrange Space Center launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carry instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Image credit: NASA/University of Houston/Edgar Bering NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  4. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    A BARREL team member recovers the second payload after it landed. The BARREL team is at Esrange Space Center near Kiruna, Sweden, launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carry instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Image credit: NASA/Montana State University/Arlo Johnson NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  5. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    Prior to launch, the BARREL team works on the payload from the launch pad at Esrange Space Center near Kiruna, Sweden. The BARREL team is at Esrange Space Center launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carry instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Image credit: NASA/Dartmouth/Robyn Millan NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  6. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    The BARREL team prepares to launch their third payload from Esrange Space Center near Kiruna, Sweden, on Aug. 21, 2016. The BARREL team is at Esrange Space Center launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carry instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Credit: NASA/University of Houston/Michael Greer NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  7. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    A BARREL team member watches as one of their payloads launches from Esrange Space Center on Aug. 29, 2016. Throughout August 2016, the BARREL team was at Esrange Space Center near Kiruna, Sweden, launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carried instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Credit: NASA/Dartmouth/Alexa Halford NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  8. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    A BARREL balloon inflates on the launch pad at Esrange Space Center on Aug. 29, 2016. Throughout August 2016, the BARREL team was at Esrange Space Center near Kiruna, Sweden, launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carried instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Credit: NASA/Dartmouth/Alexa Halford NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  9. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    The first BARREL balloon is inflated just before its launch on Aug. 13, 2016, from Esrange Space Center near Kiruna, Sweden. The BARREL team is at Esrange Space Center launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carry instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Image credit: NASA/University of Houston/Edgar Bering NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  10. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    The BARREL team inflates the balloon to launch their fifth scientific payload from Esrange Space Center near Kiruna, Sweden, on Aug. 24, 2016. The BARREL team is at Esrange Space Center launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carry instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Credit: NASA/University of Houston/Michael Greer NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  11. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    A BARREL payload sits on the launch pad at Esrange Space Center near Kiruna, Sweden. The BARREL team is at Esrange Space Center launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carry instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Image credit: NASA/Dartmouth/Robyn Millan NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  12. Radiation Belt Electron Energy Spectra Characterization and Evolution Based on the Van Allen Probes Measurements

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Baker, D. N.; Jaynes, A. N.; Li, X.; Kanekal, S. G.; Blum, L. W.; Schiller, Q. A.; Leonard, T. W.; Elkington, S. R.

    2017-12-01

    The electron energy spectra, as an important characteristic of radiation belt electrons, provide valuable information on the physical mechanisms affecting different electron populations. Based on the measurements of 30 keV - 10 MeV electrons from MagEIS and REPT instruments on the Van Allen Probes, case studies and statistical analysis of the radiation belt electron energy spectra characterization and evolution have been performed. Generally the radiation belt electron energy spectra can be represented by one of the three types of distributions: exponential, power law, and bump-on-tail. Statistical analysis shows that the exponential spectra are usually dominant in the outer radiation belt; as the geomagnetic storms occur, energy spectra in the outer belt soften at first due to injection of lower-energy electrons and loss of higher-energy electrons, and gradually get harder due to loss of lower-energy electrons and delayed enhancement of higher energy electron fluxes. Power law spectra generally dominate the inner belt and higher L region (L>6) during injections. Bump-on-tail spectra commonly exist inside the plasmasphere following the geomagnetic storms and/or the compression of plasmasphere, while the energy of flux maxima is usually 1.8 MeV as the bump-on-tail spectra form and gradually moves to higher energies as the spectra evolve, with the ratio of flux maxima to minima up to >10. Detailed event study indicates that the appearance of bump-on-tail spectra are mainly due to energy-dependent losses caused by the plasmaspheric hiss wave scattering, while the disappearance of these spectra can be attributed to fast flux enhancements of lower-energy electrons during storms.

  13. NASA's Van Allen Probes Discover a Surprise Circling Earth

    NASA Image and Video Library

    2017-12-08

    On Aug. 31, 2012, a giant prominence on the sun erupted, sending out particles and a shock wave that traveled near Earth. This event may have been one of the causes of a third radiation belt that appeared around Earth a few days later, a phenomenon that was observed for the very first time by the newly-launched Van Allen Probes. This image of the prominence before it erupted was captured by NASA's Solar Dynamics Observatory (SDO). Credit: NASA/SDO/AIA/Goddard Space Flight Center To read more go to: www.nasa.gov/mission_pages/rbsp/news/third-belt.html NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  14. Solar wind conditions leading to efficient radiation belt electron acceleration: A superposed epoch analysis

    DOE PAGES

    Li, W.; Thorne, R. M.; Bortnik, J.; ...

    2015-09-07

    In this study by determining preferential solar wind conditions leading to efficient radiation belt electron acceleration is crucial for predicting radiation belt electron dynamics. Using Van Allen Probes electron observations (>1 MeV) from 2012 to 2015, we identify a number of efficient and inefficient acceleration events separately to perform a superposed epoch analysis of the corresponding solar wind parameters and geomagnetic indices. By directly comparing efficient and inefficient acceleration events, we clearly show that prolonged southward Bz, high solar wind speed, and low dynamic pressure are critical for electron acceleration to >1 MeV energies in the heart of the outermore » radiation belt. We also evaluate chorus wave evolution using the superposed epoch analysis for the identified efficient and inefficient acceleration events and find that chorus wave intensity is much stronger and lasts longer during efficient electron acceleration events, supporting the scenario that chorus waves play a key role in MeV electron acceleration.« less

  15. Overview of the NASA space radiation laboratory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    La Tessa, Chiara; Sivertz, Michael; Chiang, I-Hung

    The NASA Space Radiation Laboratory (NSRL) is a multidisciplinary center for space radiation research funded by NASA and located at the Brookhaven National Laboratory (BNL), Upton NY. Operational since 2003, the scope of NSRL is to provide ion beams in support of the NASA Humans in Space program in radiobiology, physics and engineering to measure the risk and ameliorate the effect of radiation in space. Recently, it has also been recognized as the only facility in the U.S. currently capable of contributing to heavy ion radiotherapy research. Finally, this work contains a general overview of NSRL structure, capabilities and operation.

  16. Overview of the NASA space radiation laboratory

    DOE PAGES

    La Tessa, Chiara; Sivertz, Michael; Chiang, I-Hung; ...

    2016-11-11

    The NASA Space Radiation Laboratory (NSRL) is a multidisciplinary center for space radiation research funded by NASA and located at the Brookhaven National Laboratory (BNL), Upton NY. Operational since 2003, the scope of NSRL is to provide ion beams in support of the NASA Humans in Space program in radiobiology, physics and engineering to measure the risk and ameliorate the effect of radiation in space. Recently, it has also been recognized as the only facility in the U.S. currently capable of contributing to heavy ion radiotherapy research. Finally, this work contains a general overview of NSRL structure, capabilities and operation.

  17. Biophysics of NASA radiation quality factors.

    PubMed

    Cucinotta, Francis A

    2015-09-01

    NASA has implemented new radiation quality factors (QFs) for projecting cancer risks from space radiation exposures to astronauts. The NASA QFs are based on particle track structure concepts with parameters derived from available radiobiology data, and NASA introduces distinct QFs for solid cancer and leukaemia risk estimates. The NASA model was reviewed by the US National Research Council and approved for use by NASA for risk assessment for International Space Station missions and trade studies of future exploration missions to Mars and other destinations. A key feature of the NASA QFs is to represent the uncertainty in the QF assessments and evaluate the importance of the QF uncertainty to overall uncertainties in cancer risk projections. In this article, the biophysical basis for the probability distribution functions representing QF uncertainties was reviewed, and approaches needed to reduce uncertainties were discussed. © The Author 2015. Published by Oxford University Press. All rights reserved. For Permissions, please email: journals.permissions@oup.com.

  18. Study the Precipitation of Radiation Belt Electrons during the Rapid Dropout Events

    NASA Astrophysics Data System (ADS)

    Tu, W.; Cunningham, G.; Li, X.; Chen, Y.

    2015-12-01

    During the main phase of storms, the relativistic electron flux in the radiation belt can drop by orders of magnitude on timescales of a few hours. Where do the electrons go? This is one of the most important outstanding questions in radiation belt studies. Radiation belt electrons can be lost either by transport across the magnetopause into interplanetary space or by precipitation into the atmosphere. In this work we first conduct a survey of the MeV electron dropouts using the Van Allen Probes data in conjunction with the low-altitude measurements of precipitating electrons by 6 NOAA/POES satellites. The dropout events are categorized into three types: precipitation-loss dominant, outward radial diffusion dominant, or with contributions from both mechanisms. The survey results suggest the relative importance of precipitation and outward radial diffusion to the fast dropouts of radiation belt electrons, and their extent in L-shell and electron energy. Then, for specific events identified as dominated by precipitation loss, we use the Drift-Diffusion model, which includes the effects of azimuthal drift and pitch angle diffusion, to simulate both the electron dropout observed by Van Allen Probes and the distributions of drift-loss-cone electrons observed by multiple low-earth-orbit satellites (6 POES and the Colorado Student Space Weather Experiment). The model quantifies the electron precipitation loss and pitch angle diffusion coefficient, Dxx, with high temporal and spatial resolution. Finally, by comparing the Dxx derived from the model with those estimated from the quasi-linear theory using wave data from Van Allen Probes and other event-specific wave models, we are able to test the validity of quasi-linear theory and seek direct evidence of the wave-particle interactions during the dropouts.

  19. Usability of NASA Satellite Imagery-Based Daily Solar Radiation for Crop Yield Simulation and Management Decisions

    NASA Astrophysics Data System (ADS)

    Yang, H.; Cassman, K. G.; Stackhouse, P. W.; Hoell, J. M.

    2007-12-01

    We tested the usability of NASA satellite imagery-based daily solar radiation for farm-specific crop yield simulation and management decisions using the Hybrid-Maize model (www.hybridmaize.unl.edu). Solar radiation is one of the key inputs for crop yield simulation. Farm-specific crop management decisions using simulation models require long-term (i.e., 20 years or longer) daily local weather data including solar radiation for assessing crop yield potential and its variation, optimizing crop planting date, and predicting crop yield in a real time mode. Weather stations that record daily solar radiation have sparse coverage and many of them have record shorter than 15 years. Based on satellite imagery and other remote sensed information, NASA has provided estimates of daily climatic data including solar radiation at a resolution of 1 degree grid over the earth surface from 1983 to 2005. NASA is currently continuing to update the database and has plans to provide near real-time data in the future. This database, which is free to the public at http://power.larc.nasa.gov, is a potential surrogate for ground- measured climatic data for farm-specific crop yield simulation and management decisions. In this report, we quantified (1) the similarities between NASA daily solar radiation and ground-measured data atr 20 US sites and four international sites, and (2) the accuracy and precision of simulated corn yield potential and its variability using NASA solar radiation coupled with other weather data from ground measurements. The 20 US sites are in the western Corn Belt, including Iowa, South Dakota, Nebraska, and Kansas. The four international sites are Los Banos in the Philippines, Beijing in China, Cali in Columbia, and Ibatan in Nigeria. Those sites were selected because of their high quality weather record and long duration (more than 20 years on average). We found that NASA solar radiation was highly significantly correlated (mean r2 =0.88**) with the ground

  20. The Earth's radiation belts modelling : main issues and key directions for improvement

    NASA Astrophysics Data System (ADS)

    Maget, Vincent; Boscher, Daniel

    The Earth's radiation belts can be considered as an opened system covering a wide part of the inner magnetosphere which closely interacts with the surrounding cold plasma. Although its population constitutes only the highly energetic tail of the global inner magnetosphere plasma (electrons from a few tens of keV to more than 5 MeV and protons up to 500MeV), their modelling is of prime importance for satellite robustness design. They have been modelled at ONERA for more than 15 years now through the Salammbˆ code, which models the dynamic of the Earth's radiation belts at the drift timescale (order of the hour). It takes into accounts the main processes acting on the trapped particles, which depends on the electromagnetic configuration and on the characteristics of the surrounding cold plasma : the ionosphere as losses terms, the plasmasheet as sources ones and the plasmasphere through interactions (waves-particles interactions, coulomb scattering, electric fields shielding, . . . ). Consequently, a fine knowledge of these environments and their interactions with the radiation belts is of prime importance in their modelling. Issues in the modelling currently exist, but key directions for improvements can also be highlighted. This talk aims at presenting both of them according to recent developments performed at ONERA besides the Salammbˆ code. o

  1. The Radiation Belt Electron Scattering by Magnetosonic Wave: Dependence on Key Parameters

    NASA Astrophysics Data System (ADS)

    Lei, Mingda; Xie, Lun; Li, Jinxing; Pu, Zuyin; Fu, Suiyan; Ni, Binbin; Hua, Man; Chen, Lunjin; Li, Wen

    2017-12-01

    Magnetosonic (MS) waves have been found capable of creating radiation belt electron butterfly distributions in the inner magnetosphere. To investigate the physical nature of the interactions between radiation belt electrons and MS waves, and to explore a preferential condition for MS waves to scatter electrons efficiently, we performed a comprehensive parametric study of MS wave-electron interactions using test particle simulations. The diffusion coefficients simulated by varying the MS wave frequency show that the scattering effect of MS waves is frequency insensitive at low harmonics (f < 20 fcp), which has great implications on modeling the electron scattering caused by MS waves with harmonic structures. The electron scattering caused by MS waves is very sensitive to wave normal angles, and MS waves with off 90° wave normal angles scatter electrons more efficiently. By simulating the diffusion coefficients and the electron phase space density evolution at different L shells under different plasma environment circumstances, we find that MS waves can readily produce electron butterfly distributions in the inner part of the plasmasphere where the ratio of electron plasma-to-gyrofrequency (fpe/fce) is large, while they may essentially form a two-peak distribution outside the plasmapause and in the inner radiation belt where fpe/fce is small.

  2. A New Perspective on Trapped Radiation Belts in Planetary Atmospheres

    NASA Technical Reports Server (NTRS)

    Diaz, A.; Lodhi, M. A. K.; Wilson, T. L.

    2005-01-01

    The charged particle fluxes trapped in the magnetic dipole fields of certain planets in our Solar System are interesting signatures of planetary properties in space physics. They also represent a source of potentially hazardous radiation to spacecraft during planetary and interplanetary exploration. The Earth s trapped radiation belts have been studied for years and the physical mechanisms by which primary radiation from the Sun and Galaxy is captured is well understood. The higher-energy particles collide with molecules in the planetary atmosphere and initiate large cascades of secondary radiation which itself becomes trapped by the magnetic dipole field of the planet. Some of it is even backscattered as albedo neutrons.

  3. Resonant Scattering of Radiation Belt Electrons by Off-Equatorial Magnetosonic Waves

    NASA Astrophysics Data System (ADS)

    Ni, Binbin; Zou, Zhengyang; Fu, Song; Cao, Xing; Gu, Xudong; Xiang, Zheng

    2018-02-01

    Fast magnetosonic (MS) waves are commonly regarded as electromagnetic waves that are characteristically confined within ±3° of the geomagnetic equator. We report two typical off-equatorial MS events observed by Van Allen Probes, that is, the 8 May 2014 event that occurred at the geomagnetic latitudes of 7.5°-9.2° both inside and outside the plasmasphere with the wave amplitude up to 590 pT and the 9 January 2014 event that occurred at the latitudes of—(15.7°-17.5°) outside the plasmasphere with a smaller amplitude about 81 pT. Detailed test particle simulations quantify the electron resonant scattering rates by the off-equatorial MS waves to find that they can cause the pitch angle scattering and momentum diffusion of radiation belt electrons with equatorial pitch angles < 75° or < 58° (depending on the wave latitudinal coverage) on timescales of a day. Subsequent two-dimensional Fokker-Planck diffusion simulations indicate that the strong off-equatorial MS waves are capable of efficiently transporting high pitch angle electrons to lower pitch angles to facilitate the formation of radiation belt electron butterfly distributions for a broad energy range from 100 keV to >1 MeV within an hour. Our study clearly demonstrates that the presence of off-equatorial MS waves, in addition to equatorial MS waves, can contribute importantly to the dynamical variations of radiation belt electron fluxes and their pitch angle distribution.

  4. Modeling radiation belt dynamics using a 3-D layer method code

    NASA Astrophysics Data System (ADS)

    Wang, C.; Ma, Q.; Tao, X.; Zhang, Y.; Teng, S.; Albert, J. M.; Chan, A. A.; Li, W.; Ni, B.; Lu, Q.; Wang, S.

    2017-08-01

    A new 3-D diffusion code using a recently published layer method has been developed to analyze radiation belt electron dynamics. The code guarantees the positivity of the solution even when mixed diffusion terms are included. Unlike most of the previous codes, our 3-D code is developed directly in equatorial pitch angle (α0), momentum (p), and L shell coordinates; this eliminates the need to transform back and forth between (α0,p) coordinates and adiabatic invariant coordinates. Using (α0,p,L) is also convenient for direct comparison with satellite data. The new code has been validated by various numerical tests, and we apply the 3-D code to model the rapid electron flux enhancement following the geomagnetic storm on 17 March 2013, which is one of the Geospace Environment Modeling Focus Group challenge events. An event-specific global chorus wave model, an AL-dependent statistical plasmaspheric hiss wave model, and a recently published radial diffusion coefficient formula from Time History of Events and Macroscale Interactions during Substorms (THEMIS) statistics are used. The simulation results show good agreement with satellite observations, in general, supporting the scenario that the rapid enhancement of radiation belt electron flux for this event results from an increased level of the seed population by radial diffusion, with subsequent acceleration by chorus waves. Our results prove that the layer method can be readily used to model global radiation belt dynamics in three dimensions.

  5. DISPOSITION OF THE INNER RADIATION BELT AND MAGNETIC FIELD OF THE EARTH

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    GORCHAKOV, IE. V.

    1963-02-01

    A scintillation counter on Sputnik III was used to conduct ionization measurement in a sodium iodide crystal and register the number of events releasing more than 35 kev in the crystal. The boundary of the inner radiation belt shows a strong longitudinal effect. The observed dependence on longitude of the boundary was explained by the fact that the inner belt consists of particles captured by the geomagnetic field and constitutes a noncentral dipole field. (C.E.S.)

  6. Meeting Report--NASA Radiation Biomarker Workshop

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Straume, Tore; Amundson, Sally A,; Blakely, William F.

    2008-05-01

    A summary is provided of presentations and discussions from the NASA Radiation Biomarker Workshop held September 27-28, 2007, at NASA Ames Research Center in Mountain View, California. Invited speakers were distinguished scientists representing key sectors of the radiation research community. Speakers addressed recent developments in the biomarker and biotechnology fields that may provide new opportunities for health-related assessment of radiation-exposed individuals, including for long-duration space travel. Topics discussed include the space radiation environment, biomarkers of radiation sensitivity and individual susceptibility, molecular signatures of low-dose responses, multivariate analysis of gene expression, biomarkers in biodefense, biomarkers in radiation oncology, biomarkers and triagemore » following large-scale radiological incidents, integrated and multiple biomarker approaches, advances in whole-genome tiling arrays, advances in mass-spectrometry proteomics, radiation biodosimetry for estimation of cancer risk in a rat skin model, and confounding factors. Summary conclusions are provided at the end of the report.« less

  7. Overview of the NASA space radiation laboratory.

    PubMed

    La Tessa, Chiara; Sivertz, Michael; Chiang, I-Hung; Lowenstein, Derek; Rusek, Adam

    2016-11-01

    The NASA Space Radiation Laboratory (NSRL) is a multidisciplinary center for space radiation research funded by NASA and located at the Brookhaven National Laboratory (BNL), Upton NY. Operational since 2003, the scope of NSRL is to provide ion beams in support of the NASA Humans in Space program in radiobiology, physics and engineering to measure the risk and ameliorate the effect of radiation in space. Recently, it has also been recognized as the only facility in the U.S. currently capable of contributing to heavy ion radiotherapy research. This work contains a general overview of NSRL structure, capabilities and operation. Copyright © 2016 The Committee on Space Research (COSPAR). All rights reserved.

  8. Galactic Cosmic Rays impact on Saturn innermost radiation belt formation

    NASA Astrophysics Data System (ADS)

    Kotova, A.; Roussos, E.; Krupp, N.; Dandouras, I.

    2014-04-01

    Rely on Cassini observations of ENAs during the orbital insertion in 2004, Krimigis et al. pointed out possible existence of the innermost radiation belt between Saturn 's atmosphere and D-ring (1). In the end of mission in 2017, Cassini is going to come again to this enigmatic and various region and pass directly through this narrow gap between planet and its rings. In our study we would like to simulate possible sources and losses for energetic particles population there and model the environment, which Cassini will meet during these last orbits. As a main possible sources for the innermost radiation belt we assume the interaction of the Galactic Cosmic Rays (GCR) with the Saturn's atmosphere and rings, which due to CRAND process can produce the keV-MeV ions or electrons in the region and the double charge exchange of the ENAs, coming from the middle magnetosphere, what can bring the keV ions to the region of our interest. Both of these possible sources are possible to evaluate using the charged particle tracer, which we developed in our group. It works in different modes (Newton-Lorentz full equation of motion, guiding centre or bounce averaged approximations), and allows use of different magnetic field models (from simple dipole magnetic field till complex realistic magnetic field model like Khurana model of Saturn's magnetosphere) for both forward and backward tracing simulations. This charged particle tracer was validated using the comparison of the simulation results and observations during several flybys of Cassini by icy moons of Saturn. Through the backward-tracing of GCRs around the planet we evaluate how the ring shadow filters the GCR spectrum that hits the Saturn's atmosphere and how non-dipolar effects change the Strömer cutoff rigidities of GCRs, especially for the high-latitude atmosphere that maps magnetically in the outer magnetosphere. Also we estimate the production of secondaries (and from the multiple impacts of these secondaries on the

  9. A comparison of outer electron radiation belt dropouts during solar wind stream interface and magnetic cloud driven storms

    NASA Astrophysics Data System (ADS)

    Ogunjobi, O.; Sivakumar, V.; Mtumela, Z.

    2017-06-01

    Energetic electrons are trapped in the Earth's radiation belts which occupy a toroidal region between 3 and 7 \\hbox {R}E above the Earth's surface. Rapid loss of electrons from the radiation belts is known as dropouts. The source and loss mechanisms regulating the radiation belts population are not yet understood entirely, particularly during geomagnetic storm times. Nevertheless, the dominant loss mechanism may require an event based study to be better observed. Utilizing multiple data sources from the year 1997-2007, this study identifies radiation belt electron dropouts which are ultimately triggered when solar wind stream interfaces (SI) arrived at Earth, or when magnetic clouds (MC) arrived. Using superposed epoch analysis (SEA) technique, a synthesis of multiple observations is performed to reveal loss mechanism which might, perhaps, be a major contributor to radiation belt losses under SI and MC driven storms. Results show an abrupt slower decaying precipitation of electron peak (about 3000 counts/sec) on SI arrival within 5.05 < L < 6.05, which persist till 0.5 day before gradual recovery. This pattern is interpreted as an indication of depleted electrons from bounce lost cone via precipitating mechanism known as relativistic electron microburst. On the other hand, MC shows a pancake precipitating peak extending to lower L (Plasmapause); indicating a combination of electron cyclotron harmonic (ECH) and whistler mode waves as the contributing mechanisms.

  10. Examining Relativistic Electron Loss in the Outer Radiation Belt

    NASA Astrophysics Data System (ADS)

    Green, J. C.; Onsager, T. G.; O'Brien, P.

    2003-12-01

    Since the discovery of earth's radiation belts researchers have sought to identify the mechanisms that dictate the seemingly erratic relativistic electron flux levels in the outer belt. Contrary to intuition, relativistic electron flux levels do not always increase during geomagnetic storms even though these storms signify enhanced energy input from the solar wind to the magnetosphere [Reeves et al., 2003; O'Brien et al., 2001]. The fickle response of the radiation belt electrons to geomagnetic activity suggests that flux levels are determined by the outcome of a continuous competition between acceleration and loss. Some progress has been made developing and testing acceleration mechanisms but little is known about how relativistic electrons are lost. We examine relativistic electron losses in the outer belt focusing our attention on flux decrease events of the type first described by Onsager et al. [2002]. The study showed a sudden decrease of geosynchronous >2MeV electron flux occurring simultaneously with local stretching of the magnetic field. The decrease was first observed near 15:00 MLT and progressed to all local times after a period of ˜10 hours. Expanding on the work of Onsager et al. [2002], we have identified ˜ 51 such flux decrease events in the GOES and LANL data and present the results of a superposed epoch analysis of solar wind data, geomagnetic activity indicators, and locally measured magnetic field and plasma data. The analysis shows that flux decreases occur after 1-2 days of quiet condition. They begin when either the solar wind dynamic pressure increases or Bz turns southward pushing hot dense plasma earthward to form a partial ring current and stretched magnetic field at dusk. Adiabatic electron motion in response to the stretched magnetic field may explain the initial flux reduction; however, often the flux does not recover with the magnetic field recovery, indicating that true loss from the magnetosphere is occurring. Using Polar and

  11. Dependence of radiation belt simulations to assumed radial diffusion rates tested for two empirical models of radial transport

    NASA Astrophysics Data System (ADS)

    Drozdov, Alexander; Shprits, Yuri; Aseev, Nikita; Kellerman, Adam; Reeves, Geoffrey

    2017-04-01

    Radial diffusion is one of the dominant physical mechanisms that drives acceleration and loss of the radiation belt electrons, which makes it very important for nowcasting and forecasting space weather models. We investigate the sensitivity of the two parameterizations of the radial diffusion of Brautigam and Albert [2000] and Ozeke et al. [2014] on long-term radiation belt modeling using the Versatile Electron Radiation Belt (VERB). Following Brautigam and Albert [2000] and Ozeke et al. [2014], we first perform 1-D radial diffusion simulations. Comparison of the simulation results with observations shows that the difference between simulations with either radial diffusion parameterization is small. To take into account effects of local acceleration and loss, we perform 3-D simulations, including pitch-angle, energy and mixed diffusion. We found that the results of 3-D simulations are even less sensitive to the choice of parameterization of radial diffusion rates than the results of 1-D simulations at various energies (from 0.59 to 1.80 MeV). This result demonstrates that the inclusion of local acceleration and pitch-angle diffusion can provide a negative feedback effect, such that the result is largely indistinguishable simulations conducted with different radial diffusion parameterizations. We also perform a number of sensitivity tests by multiplying radial diffusion rates by constant factors and show that such an approach leads to unrealistic predictions of radiation belt dynamics. References Brautigam, D. H., and J. M. Albert (2000), Radial diffusion analysis of outer radiation belt electrons during the October 9, 1990, magnetic storm, J. Geophys. Res., 105(A1), 291-309, doi:10.1029/1999ja900344. Ozeke, L. G., I. R. Mann, K. R. Murphy, I. Jonathan Rae, and D. K. Milling (2014), Analytic expressions for ULF wave radiation belt radial diffusion coefficients, J. Geophys. Res. [Space Phys.], 119(3), 1587-1605, doi:10.1002/2013JA019204.

  12. Exploring the Jupiter's and Saturn's radiation belts with LOFAR

    NASA Astrophysics Data System (ADS)

    Girard, Julien N.; Zarka, Philippe; de Pater, Imke; Hess, Sebastien; Tasse, Cyril; Courtin, Regis; Hofstadter, Mark; Santos-Costa, Daniel; Nettelmann, Nadine; lorenzato, Lise

    2014-05-01

    Since its detection in the mid-fifties, the decimeter synchrotron radiation (DIM), originating from the radiation belts of Jupiter, has been extensively observed over a wide spectrum (from >300 MHz to 22 GHz) by various radio instruments (VLA, ATCA, WSRT, Cassini...). They provided accurate flux measurements as well as resolved maps of the emission that revealed spatial, temporal and spectral variabilities. The strong magnetic field (~4.2 G at the equator) is responsible for the radio emission generated by relativistic electrons. The emission varies at different time scales (short-time variations of hours to long-term variation over decades) due to the combination of visibility configuration (fast rotating 'dipole' magnetic field, beamed radio emission) and intrinsic local variations (interaction between relativistic electrons and satellites/dust, delayed effect of the solar wind ram pressure, impacts events) (e.g. de Pater & Klein, 1989; de Pater & Dunn, 2003; Bagenal (ed.) et al., 2004; Santos-Costa, 2009, 2011). A complete framework is necessary to fully understand the source, loss and transport processes of the electrons populating the inner magnetosphere over a wide frequency range. The low frequencies are associated with electron of lower energies situated in weaker magnetic field regions. LOFAR, the LOw Frequency ARray (LOFAR) (van Haarlem et al., 2012), the last generation of versatile and digital ground-based radio interferometer operates in the [30-250] MHz bandwidth. It brings very high time (~μsec), frequency (~kHz) and angular (~asec) resolutions and huge sensitivities (~mJy). In November 2011, a single 10-hour track enabled to cover an entire planetary rotation and led to image, for the first time, the radiation belts between 127-172 MHz (Girard et al. 2012, 2013). In Feb 2013, an 11-hour joint LOFAR/WSRT observing campaign seized the dyname state of the radiation belts from 45 MHz up to 5 GHz. We will present the current study of the radiation belts

  13. NASA's Van Allen Probes RBSP-ECT Data Products and Access to Them: An Insider's Outlook on the Inner and Outer Belts (and We Don't Mean the Nation's Beltway...)

    NASA Astrophysics Data System (ADS)

    Smith, S. S.; Friedel, R. H. W.; Henderson, M. G.; Larsen, B.; Reeves, G. D.; Spence, H. E.

    2014-12-01

    In this poster, we present a summary of access to the data products of the Radiation Belt Storm Probes - Energetic Particle Composition, and Thermal plasma (RBSP-ECT) suite of NASA's Van Allen Probes mission. The RBSP-ECT science investigation (http://rbsp-ect.sr.unh.edu) measures comprehensively the near-Earth charged particle environment in order to understand the processes that control the acceleration, global distribution, and variability of radiation belt electrons and ions. RBSP-ECT data products derive from the three instrument elements that comprise the suite, which collectively covers the broad energies that define the source and seed populations, the core radiation belts, and also their highest energy ultra-relativistic extensions. These RBSP-ECT instruments include, from lowest to highest energies: the Helium, Oxygen, Proton, and Electron (HOPE) sensor, the Magnetic Electron and Ion Spectrometer (MagEIS), and the Relativistic Electron and Proton Telescope (REPT). We provide a brief overview of their principles of operation, as well as a description of the Level 1-3 data products that the HOPE, MagEIS, and REPT instruments produce, both separately and together. We provide a summary of how to access these RBSP-ECT data products at our Science Operation Center and Science Data Center (http://www.rbsp-ect.lanl.gov/rbsp_ect.php ) as well as caveats for their use. Finally, in the spirit of efficiently and effectively promoting and encouraging new collaborations, we present a summary of past publications, current studies, and opportunities for your future participation in RBSP-ECT science analyses.

  14. Magnetic Local Time dependency in modeling of the Earth radiation belts

    NASA Astrophysics Data System (ADS)

    Herrera, Damien; Maget, Vincent; Bourdarie, Sébastien; Rolland, Guy

    2017-04-01

    For many years, ONERA has been at the forefront of the modeling of the Earth radiation belts thanks to the Salammbô model, which accurately reproduces their dynamics over a time scale of the particles' drift period. This implies that we implicitly assume an homogeneous repartition of the trapped particles along a given drift shell. However, radiation belts are inhomogeneous in Magnetic Local Time (MLT). So, we need to take this new coordinate into account to model rigorously the dynamical structures, particularly induced during a geomagnetic storm. For this purpose, we are working on both the numerical resolution of the Fokker-Planck diffusion equation included in the model and on the MLT dependency of physic-based processes acting in the Earth radiation belts. The aim of this talk is first to present the 4D-equation used and the different steps we used to build Salammbô 4D model before focusing on physical processes taken into account in the Salammbô code, specially transport due to convection electric field. Firstly, we will briefly introduce the Salammbô 4D code developped by talking about its numerical scheme and physic-based processes modeled. Then, we will focus our attention on the impact of the outer boundary condition (localisation and spectrum) at lower L∗ shell by comparing modeling performed with geosynchronous data from LANL-GEO satellites. Finally, we will discuss the prime importance of the convection electric field to the radial and drift transport of low energy particles around the Earth.

  15. High Altitude Balloons as a Platform for Space Radiation Belt Science

    NASA Astrophysics Data System (ADS)

    Mazzino, L.; Buttenschoen, A.; Farr, Q.; Hodgson, C.; Johnson, W.; Mann, I. R.; Rae, J.; University of Alberta High Altitude Balloons (UA-HAB)

    2011-12-01

    Space Consortium (LaSpace), and sponsored by NASA. The HASP platform was launched from Fort Sumner, New Mexico, and to an altitude of about 36kilometers with flight durations of 15 to 20 hours using a small volume, low pressure balloon. The main objectives of the program, the challenges involved in developing it, and the major achievements and outcomes will be discussed. Future opportunities for the use of high altitude balloons for solar-terrestrial science, such as the diagnosis of radiation belt loss through the flight of alternative X-ray scintillator payloads, on short duration weather balloon flights will also be discussed. The UA-HAB project is undertaken with the financial support of the Canadian Space Agency.

  16. Multi-Point Measurements to Characterize Radiation Belt Electron Precipitation Loss

    NASA Astrophysics Data System (ADS)

    Blum, L. W.

    2017-12-01

    Multipoint measurements in the inner magnetosphere allow the spatial and temporal evolution of various particle populations and wave modes to be disentangled. To better characterize and quantify radiation belt precipitation loss, we utilize multi-point measurements both to study precipitating electrons directly as well as the potential drivers of this loss process. Magnetically conjugate CubeSat and balloon measurements are combined to estimate of the temporal and spatial characteristics of dusk-side precipitation features and quantify loss due to these events. To then understand the drivers of precipitation events, and what determines their spatial structure, we utilize measurements from the dual Van Allen Probes to estimate spatial and temporal scales of various wave modes in the inner magnetosphere, and compare these to precipitation characteristics. The structure, timing, and spatial extent of waves are compared to those of MeV electron precipitation during a few individual events to determine when and where EMIC waves cause radiation belt electron precipitation. Magnetically conjugate measurements provide observational support of the theoretical picture of duskside interaction of EMIC waves and MeV electrons leading to radiation belt loss. Finally, understanding the drivers controlling the spatial scales of wave activity in the inner magnetosphere is critical for uncovering the underlying physics behind the wave generation as well as for better predicting where and when waves will be present. Again using multipoint measurements from the Van Allen Probes, we estimate the spatial and temporal extents and evolution of plasma structures and their gradients in the inner magnetosphere, to better understand the drivers of magnetospheric wave characteristic scales. In particular, we focus on EMIC waves and the plasma parameters important for their growth, namely cold plasma density and cool and warm ion density, anisotropy, and composition.

  17. NASA's BARREL Mission in Sweden

    NASA Image and Video Library

    2017-12-08

    The faint green glow of aurora can be seen above the clouds at Esrange Space Center in this photo from Aug. 23, 2016. Auroras are created by energetic electrons, which rain down from Earth’s magnetic bubble and interact with particles in the upper atmosphere to create glowing lights that stretch across the sky. The BARREL team is at Esrange Space Center near Kiruna, Sweden, launching a series of six scientific payloads on miniature scientific balloons. The NASA-funded BARREL – which stands for Balloon Array for Radiation-belt Relativistic Electron Losses – primarily measures X-rays in Earth’s atmosphere near the North and South Poles. These X-rays are produced by electrons raining down into the atmosphere from two giant swaths of radiation that surround Earth, called the Van Allen belts. Learning about the radiation near Earth helps us to better protect our satellites. Several of the BARREL balloons also carry instruments built by undergraduate students to measure the total electron content of Earth’s ionosphere, as well as the low-frequency electromagnetic waves that help to scatter electrons into Earth’s atmosphere. Though about 90 feet in diameter, the BARREL balloons are much smaller than standard football stadium-sized scientific balloons. This is the fourth campaign for the BARREL mission. BARREL is led by Dartmouth College in Hanover, New Hampshire. The undergraduate student instrument team is led by the University of Houston and funded by the Undergraduate Student Instrument Project out of NASA’s Wallops Flight Facility. For more information on NASA’s scientific balloon program, visit: www.nasa.gov/scientificballoons. Credit: NASA/University of Houston/Michael Greer NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling

  18. Combined Global MHD and Test-Particle Simulation of a Radiation Belt Storm: Comparing Depletion, Recovery and Enhancement with in Situ Measurements

    NASA Astrophysics Data System (ADS)

    Sorathia, K.; Ukhorskiy, A. Y.; Merkin, V. G.; Wiltberger, M. J.; Lyon, J.; Claudepierre, S. G.; Fennell, J. F.

    2017-12-01

    During geomagnetic storms the intensities of radiation belt electrons exhibit dramatic variability. In the main phase electron intensities exhibit deep depletion over a broad region of the outer belt. The intensities then increase during the recovery phase, often to levels that significantly exceed their pre-storm values. In this study we analyze the depletion, recovery and enhancement of radiation belt intensities during the 2013 St. Patrick's geomagnetic storm. We simulate the dynamics of high-energy electrons using our newly-developed test-particle radiation belt model (CHIMP) based on a hybrid guiding-center/Lorentz integrator and electromagnetic fields derived from high-resolution global MHD (LFM) simulations. Our approach differs from previous work in that we use MHD flow information to identify and seed test-particles into regions of strong convection in the magnetotail. We address two science questions: 1) what are the relative roles of magnetopause losses, transport-driven atmospheric precipitation, and adiabatic cooling in the radiation belt depletion during the storm main phase? and 2) to what extent can enhanced convection/mesoscale injections account for the radiation belt buildup during the recovery phase? Our analysis is based on long-term model simulation and the comparison of our model results with electron intensity measurements from the MAGEIS experiment of the Van Allen Probes mission.

  19. NASA Space Radiation Program Integrative Risk Model Toolkit

    NASA Technical Reports Server (NTRS)

    Kim, Myung-Hee Y.; Hu, Shaowen; Plante, Ianik; Ponomarev, Artem L.; Sandridge, Chris

    2015-01-01

    NASA Space Radiation Program Element scientists have been actively involved in development of an integrative risk models toolkit that includes models for acute radiation risk and organ dose projection (ARRBOD), NASA space radiation cancer risk projection (NSCR), hemocyte dose estimation (HemoDose), GCR event-based risk model code (GERMcode), and relativistic ion tracks (RITRACKS), NASA radiation track image (NASARTI), and the On-Line Tool for the Assessment of Radiation in Space (OLTARIS). This session will introduce the components of the risk toolkit with opportunity for hands on demonstrations. The brief descriptions of each tools are: ARRBOD for Organ dose projection and acute radiation risk calculation from exposure to solar particle event; NSCR for Projection of cancer risk from exposure to space radiation; HemoDose for retrospective dose estimation by using multi-type blood cell counts; GERMcode for basic physical and biophysical properties for an ion beam, and biophysical and radiobiological properties for a beam transport to the target in the NASA Space Radiation Laboratory beam line; RITRACKS for simulation of heavy ion and delta-ray track structure, radiation chemistry, DNA structure and DNA damage at the molecular scale; NASARTI for modeling of the effects of space radiation on human cells and tissue by incorporating a physical model of tracks, cell nucleus, and DNA damage foci with image segmentation for the automated count; and OLTARIS, an integrated tool set utilizing HZETRN (High Charge and Energy Transport) intended to help scientists and engineers study the effects of space radiation on shielding materials, electronics, and biological systems.

  20. NASA Self-Assessment of Space Radiation Research

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.

    2010-01-01

    Space exploration involves unavoidable exposures to high-energy galactic cosmic rays whose penetration power and associated secondary radiation makes radiation shielding ineffective and cost prohibitive. NASA recognizing the possible health dangers from cosmic rays notified the U.S. Congress as early as 1959 of the need for a dedicated heavy ion accelerator to study the largely unknown biological effects of galactic cosmic rays on astronauts. Information and scientific tools to study radiation health effects expanded over the new decades as NASA exploration programs to the moon and preparations for Mars exploration were carried out. In the 1970 s through the early 1990 s a more than 3-fold increase over earlier estimates of fatal cancer risks from gamma-rays, and new knowledge of the biological dangers of high LET radiation were obtained. Other research has increased concern for degenerative risks to the central nervous system and other tissues at lower doses compared to earlier estimates. In 1996 a review by the National Academy of Sciences Space Science Board re-iterated the need for a dedicated ground-based accelerator facility capable of providing up to 2000 research hours per year to reduce uncertainties in risks projections and develop effective mitigation measures. In 1998 NASA appropriated funds for construction of a dedicated research facility and the NASA Space Radiation Laboratory (NSRL) opened for research in October of 2003. This year marks the 8th year of NSRL research were about 1000 research hours per year have been utilized. In anticipation of the approaching ten year milestone, funded investigators and selected others are invited to participate in a critical self-assessment of NSRL research progress towards NASA s goals in space radiation research. A Blue and Red Team Assessment format has been integrated into meeting posters and special plenary sessions to allow for a critical debate on the progress of the research and major gaps areas. Blue

  1. A Century after Van Allen's Birth: Conclusion of Reconnaissance of Radiation Belts in the Solar System

    NASA Astrophysics Data System (ADS)

    Krimigis, S. M.

    2014-12-01

    On May 1, 1958 in the Great Hall of the US National Academy of Sciences, James A. Van Allen, having instrumented Explorer-1 and follow-on satellites with radiation detectors, announced the discovery of intense radiation at high altitudes above Earth. The press dubbed the doughnut-shaped structures "Van Allen Belts" (VAB). Soon thereafter, the search began for VAB at nearby planets. Mariner 2 flew by Venus in 1962 at a distance of 41,000 km, but no radiation was detected. The Mariner 4 mission to Mars did not observe planet-associated increase in radiation, but scaling arguments with Earth's magnetosphere yielded an upper limit to the ratio of magnetic moments of MM/ME < 0.001 (Van Allen et al, 1965). Similarly, the Mariner 5 flyby closer to Venus resulted in a ratio of magnetic moments < 0.001 (Van Allen et al, 1967), dealing a blow to the expectation that all planetary bodies must possess significant VAB. The flyby of Mercury in 1974 by Mariner 10 revealed a weak magnetic field, but the presence of durably trapped higher energy particles remained controversial until MESSENGER in 2011.The first flybys of Jupiter by Pioneers 10, 11 in 1973 and 1974, respectively, measured a plethora of energetic particles in Jupiter's magnetosphere and established the fact that their intensities were rotationally modulated. Later flybys of Jupiter and Saturn by the two Voyagers in 1979 and 1981 revealed that those magnetospheres possessed their own internal plasma source(s) and radiation belts. Subsequent discoveries of Van Allen belts at Uranus and Neptune by Voyager 2 demonstrated that VAB are the rule rather than the exception in planetary environments. We now know from the Voyagers and through Energetic Neutral Atom images from Cassini and IBEX that an immense energetic particle population surrounds the heliosphere itself. Thus, the reconnaissance of radiation belts of our solar system has been completed, some 56 years after the discovery of the Van Allen Belts at Earth.

  2. The quest for discovery of planetary radiation belts: From Explorer 1 to MESSENGER (Jean Dominique Cassini Medal Lecture)

    NASA Astrophysics Data System (ADS)

    Krimigis, Stamatios M.

    2014-05-01

    May 1, 1958 was an exciting time in the Great Hall of the US National Academy of Sciences. An announcement was made that the Earth possessed radiation belts at high altitudes with intensities thousands of times greater than those of galactic cosmic rays (GCR) that were known to penetrate the atmosphere and produce secondaries detectable at ground level. The leading scientist at the time was James A. Van Allen, head of the Physics Department at the University of Iowa, who instrumented Explorer-1 and follow-on satellites with radiation detectors, and the press labeled the doughnut-shaped structures Van Allen Belts. Once the basic properties of what was subsequently named Earth' s Magnetosphere were established, the quest began to search for Van Allen Belts at other nearby planets, namely Venus and Mars. Mariner 2 was launched to Venus in 1962, but did not have radiation detectors, although a plasma instrument was used to firmly establish the properties of the solar wind. The Mariner 4 mission to Mars was properly instrumented and expectations were high that radiation belts were likely to be present. No planet-associated increase in radiation was measured, however, but use of scaling arguments with Earth' s magnetosphere established an upper limit to the ratio of magnetic moments of MM/ME

  3. A Comparison of Van Allen Belt Radiation Environment Modeling Programs: AE8/AP8 Legacy, AE9/AP9, and SPENVIS

    NASA Technical Reports Server (NTRS)

    Reed, Evan; Pellish, Jonathan

    2016-01-01

    In the space surrounding Earth there exists an active radiation environment consisting mostly of electrons and protons that have been trapped by Earths magnetic field. This radiation, also known as the Van Allen Belts, has the potential to damage man-made satellites in orbit; thus, proper precautions must be taken to shield NASA assets from this phenomenon. Data on the Van Allen Belts has been collected continuously by a multitude of space-based instruments since the beginning of space exploration. Subsequently, using theory to fill in the gaps in the collected data, computer models have been developed that take in the orbital information of a hypothetical mission and output the expected particle fluence and flux for that orbit. However, as new versions of the modeling system are released, users are left wondering how the new version differs from the old. Therefore, we performed a comparison of three different editions of the modeling system: AE8/AP8 (legacy), which is included in the model 9 graphical user interface as an option for ones calculations, AE9/AP9, and the Space Environment Information System (SPENVIS), which is an online-based form of AE8/AP8 developed by NASA and the European Space Agency that changed the code to allow the program to extrapolate data to predict fluence and flux at higher energies. Although this evaluation is still ongoing, it is predicted that the model 8 (legacy) and SPENVIS version will have identical outputs with the exception of the extended energy levels from SPENVIS, while model 9 will provide different fluences than model 8 based on additional magnetic field descriptions and on-orbit data.

  4. Triangular Libration Points in the CR3BP with Radiation, Triaxiality and Potential from a Belt

    NASA Astrophysics Data System (ADS)

    Singh, Jagadish; Taura, Joel John

    2017-07-01

    In this paper the equations of motion of the circular restricted three body problem is modified to include radiation of the bigger primary, triaxiality of the smaller primary; and gravitational potential created by a belt. We have obtained that due to the perturbations, the locations of the triangular libration points and their linear stability are affected. The points move towards the bigger primary due to the resultant effect of the perturbations. Triangular libration points are stable for 0<μ<μc0<μ<μc and unstable for μc≤μ≤12μc≤μ≤12, where μcμc is the critical mass ratio affected by the perturbations. The radiation of the bigger primary and triaxiality of the smaller primary have destabilizing propensities, whereas the potential created by the belt has stabilizing propensity. This model could be applied in the study of the motion of a dust particle near radiating -triaxial binary system surrounded by a belt.

  5. Inner Radiation Belt Dynamics and Climatology

    NASA Astrophysics Data System (ADS)

    Guild, T. B.; O'Brien, P. P.; Looper, M. D.

    2012-12-01

    We present preliminary results of inner belt proton data assimilation using an augmented version of the Selesnick et al. Inner Zone Model (SIZM). By varying modeled physics parameters and solar particle injection parameters to generate many ensembles of the inner belt, then optimizing the ensemble weights according to inner belt observations from SAMPEX/PET at LEO and HEO/DOS at high altitude, we obtain the best-fit state of the inner belt. We need to fully sample the range of solar proton injection sources among the ensemble members to ensure reasonable agreement between the model ensembles and observations. Once this is accomplished, we find the method is fairly robust. We will demonstrate the data assimilation by presenting an extended interval of solar proton injections and losses, illustrating how these short-term dynamics dominate long-term inner belt climatology.

  6. Short-Term Forecasting of Radiation Belt and Ring Current

    NASA Technical Reports Server (NTRS)

    Fok, Mei-Ching

    2007-01-01

    A computer program implements a mathematical model of the radiation-belt and ring-current plasmas resulting from interactions between the solar wind and the Earth s magnetic field, for the purpose of predicting fluxes of energetic electrons (10 keV to 5 MeV) and protons (10 keV to 1 MeV), which are hazardous to humans and spacecraft. Given solar-wind and interplanetary-magnetic-field data as inputs, the program solves the convection-diffusion equations of plasma distribution functions in the range of 2 to 10 Earth radii. Phenomena represented in the model include particle drifts resulting from the gradient and curvature of the magnetic field; electric fields associated with the rotation of the Earth, convection, and temporal variation of the magnetic field; and losses along particle-drift paths. The model can readily accommodate new magnetic- and electric-field submodels and new information regarding physical processes that drive the radiation-belt and ring-current plasmas. Despite the complexity of the model, the program can be run in real time on ordinary computers. At present, the program can calculate present electron and proton fluxes; after further development, it should be able to predict the fluxes 24 hours in advance

  7. Upper limit on the inner radiation belt MeV electron intensity

    NASA Astrophysics Data System (ADS)

    Li, X.; Selesnick, R. S.; Baker, D. N.; Jaynes, A. N.; Kanekal, S. G.; Schiller, Q.; Blum, L.; Fennell, J.; Blake, J. B.

    2015-02-01

    No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (tens of MeV to GeV). The inner belt proton flux level, however, is relatively stable; thus, for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment on board Colorado Student Space Weather Experiment CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because their flux level is orders of magnitude higher than the background, while higher-energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, quantified upper limits on MeV electron fluxes in various energy ranges in the inner belt. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about 1 order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, which have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt.

  8. On the Connection Between Microbursts and Nonlinear Electronic Structures in Planetary Radiation Belts

    NASA Technical Reports Server (NTRS)

    Osmane, Adnane; Wilson, Lynn B., III; Blum, Lauren; Pulkkinen, Tuija I.

    2016-01-01

    Using a dynamical-system approach, we have investigated the efficiency of large-amplitude whistler waves for causing microburst precipitation in planetary radiation belts by modeling the microburst energy and particle fluxes produced as a result of nonlinear wave-particle interactions. We show that wave parameters, consistent with large amplitude oblique whistlers, can commonly generate microbursts of electrons with hundreds of keV-energies as a result of Landau trapping. Relativistic microbursts (greater than 1 MeV) can also be generated by a similar mechanism, but require waves with large propagation angles Theta (sub k)B greater than 50 degrees and phase-speeds v(sub phi) greater than or equal to c/9. Using our result for precipitating density and energy fluxes, we argue that holes in the distribution function of electrons near the magnetic mirror point can result in the generation of double layers and electron solitary holes consistent in scales (of the order of Debye lengths) to nonlinear structures observed in the radiation belts by the Van Allen Probes. Our results indicate a relationship between nonlinear electrostatic and electromagnetic structures in the dynamics of planetary radiation belts and their role in the cyclical production of energetic electrons (E greater than or equal to 100 keV) on kinetic timescales, which is much faster than previously inferred.

  9. Analytic expressions for ULF wave radiation belt radial diffusion coefficients

    PubMed Central

    Ozeke, Louis G; Mann, Ian R; Murphy, Kyle R; Jonathan Rae, I; Milling, David K

    2014-01-01

    We present analytic expressions for ULF wave-derived radiation belt radial diffusion coefficients, as a function of L and Kp, which can easily be incorporated into global radiation belt transport models. The diffusion coefficients are derived from statistical representations of ULF wave power, electric field power mapped from ground magnetometer data, and compressional magnetic field power from in situ measurements. We show that the overall electric and magnetic diffusion coefficients are to a good approximation both independent of energy. We present example 1-D radial diffusion results from simulations driven by CRRES-observed time-dependent energy spectra at the outer boundary, under the action of radial diffusion driven by the new ULF wave radial diffusion coefficients and with empirical chorus wave loss terms (as a function of energy, Kp and L). There is excellent agreement between the differential flux produced by the 1-D, Kp-driven, radial diffusion model and CRRES observations of differential electron flux at 0.976 MeV—even though the model does not include the effects of local internal acceleration sources. Our results highlight not only the importance of correct specification of radial diffusion coefficients for developing accurate models but also show significant promise for belt specification based on relatively simple models driven by solar wind parameters such as solar wind speed or geomagnetic indices such as Kp. Key Points Analytic expressions for the radial diffusion coefficients are presented The coefficients do not dependent on energy or wave m value The electric field diffusion coefficient dominates over the magnetic PMID:26167440

  10. Detailed characteristics of radiation belt electrons revealed by CSSWE/REPTile measurements: Geomagnetic activity response and precipitation observation

    NASA Astrophysics Data System (ADS)

    Zhang, K.; Li, X.; Schiller, Q.; Gerhardt, D.; Zhao, H.; Millan, R.

    2017-08-01

    Earth's outer radiation belt electrons are highly dynamic. We study the detailed characteristics of relativistic electrons in the outer belt using measurements from the Colorado Student Space Weather Experiment (CSSWE) mission, a low Earth orbit (LEO) CubeSat, which traverses the radiation belt four times in one orbit ( 1.5 h) and has the advantage of measuring the dynamic activities of the electrons including their rapid precipitation. We focus on the measured electron response to geomagnetic activity for different energies to show that there are abundant sub-MeV electrons in the inner belt and slot region. These electrons are further enhanced during active times, while there is a lack of >1.63 MeV electrons in these regions. We also show that the variation of measured electron flux at LEO is strongly dependent on the local magnetic field strength, which is far from a dipole approximation. Moreover, a specific precipitation band, which happened on 19 January 2013, is investigated based on the conjunctive measurement of CSSWE, the Balloon Array for Radiation belt Relativistic Electron Losses, and one of the Polar Operational Environmental Satellites. In this precipitation band event, the net loss of the 0.58-1.63 MeV electrons (L = 3.5-6) is estimated to account for 6.8% of the total electron content.

  11. Upper limit on the inner radiation belt MeV electron intensity.

    PubMed

    Li, X; Selesnick, R S; Baker, D N; Jaynes, A N; Kanekal, S G; Schiller, Q; Blum, L; Fennell, J; Blake, J B

    2015-02-01

    No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (tens of MeV to GeV). The inner belt proton flux level, however, is relatively stable; thus, for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment on board Colorado Student Space Weather Experiment CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because their flux level is orders of magnitude higher than the background, while higher-energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, quantified upper limits on MeV electron fluxes in various energy ranges in the inner belt. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about 1 order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, which have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt. Quantified upper limit of MeV electrons in the inner beltActual MeV electron intensity likely much lower than the upper limitMore detailed understanding of relativistic electrons in the magnetosphere.

  12. Upper limit on the inner radiation belt MeV electron intensity

    PubMed Central

    Li, X; Selesnick, RS; Baker, DN; Jaynes, AN; Kanekal, SG; Schiller, Q; Blum, L; Fennell, J; Blake, JB

    2015-01-01

    No instruments in the inner radiation belt are immune from the unforgiving penetration of the highly energetic protons (tens of MeV to GeV). The inner belt proton flux level, however, is relatively stable; thus, for any given instrument, the proton contamination often leads to a certain background noise. Measurements from the Relativistic Electron and Proton Telescope integrated little experiment on board Colorado Student Space Weather Experiment CubeSat, in a low Earth orbit, clearly demonstrate that there exist sub-MeV electrons in the inner belt because their flux level is orders of magnitude higher than the background, while higher-energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Detailed analysis of high-quality measurements from the Relativistic Electron and Proton Telescope on board Van Allen Probes, in a geo-transfer-like orbit, provides, for the first time, quantified upper limits on MeV electron fluxes in various energy ranges in the inner belt. These upper limits are rather different from flux levels in the AE8 and AE9 models, which were developed based on older data sources. For 1.7, 2.5, and 3.3 MeV electrons, the upper limits are about 1 order of magnitude lower than predicted model fluxes. The implication of this difference is profound in that unless there are extreme solar wind conditions, which have not happened yet since the launch of Van Allen Probes, significant enhancements of MeV electrons do not occur in the inner belt even though such enhancements are commonly seen in the outer belt. Key Points Quantified upper limit of MeV electrons in the inner belt Actual MeV electron intensity likely much lower than the upper limit More detailed understanding of relativistic electrons in the magnetosphere PMID:26167446

  13. From Low Altitude to High Altitude: Assimilating SAMPEX Data in Global Radiation Belt Models by Quantifying Precipitation and Loss

    NASA Astrophysics Data System (ADS)

    Tu, W.; Reeves, G. D.; Cunningham, G.; Selesnick, R. S.; Li, X.; Looper, M. D.

    2012-12-01

    Since its launch in 1992, SAMPEX has been continuously providing measurements of radiation belt electrons at low altitude, which are not only ideal for the direct quantification of the electron precipitation loss in the radiation belt, but also provide data coverage in a critical region for global radiation belt data assimilation models. However, quantitatively combining high-altitude and low-earth-orbit (LEO) measurements on the same L-shell is challenging because LEO measurements typically contain a dynamic mixture of trapped and precipitating populations. Specifically, the electrons measured by SAMPEX can be distinguished as trapped, quasi-trapped (in the drift loss cone), and precipitating (in the bounce loss cone). To simulate the low-altitude electron distribution observed by SAMPEX/PET, a drift-diffusion model has been developed that includes the effects of azimuthal drift and pitch angle diffusion. The simulation provides direct quantification of the rates and variations of electron loss to the atmosphere, a direct input to our Dynamic Radiation Environment Assimilation Model (DREAM) as the electron loss lifetimes. The current DREAM uses data assimilation to combine a 1D radial diffusion model with observational data of radiation belt electrons. In order to implement the mixed electron measurements from SAMPEX into DREAM, we need to map the SAMPEX data from low altitude to high altitudes. To perform the mapping, we will first examine the well-known 'global coherence' of radiation belt electrons by comparing SAMPEX electron fluxes with the energetic electron data from LANL GEO and GPS spacecraft. If the correlation is good, we can directly map the SAMPEX fluxes to high altitudes based on the global coherence; if not, we will use the derived pitch angle distribution from the drift-diffusion model to map up the field and test the mapping by comparing to the high-altitude flux measurements. Then the globally mapped electron fluxes can be assimilated into DREAM

  14. Epsilon Eridani Inner Asteroid Belt

    NASA Image and Video Library

    2017-09-14

    SCI2017_0004: Artist's illustration of the Epsilon Eridani system showing Epsilon Eridani b, right foreground, a Jupiter-mass planet orbiting its parent star at the outside edge of an asteroid belt. In the background can be seen another narrow asteroid or comet belt plus an outermost belt similar in size to our solar system's Kuiper Belt. The similarity of the structure of the Epsilon Eridani system to our solar system is remarkable, although Epsilon Eridani is much younger than our sun. SOFIA observations confirmed the existence of the asteroid belt adjacent to the orbit of the Jovian planet. Credit: NASA/SOFIA/Lynette Cook

  15. The Role of the Auroral Processes in the Formation of the Outer Electron Radiation Belt

    NASA Astrophysics Data System (ADS)

    Stepanova, M. V.; Antonova, E. E.; Pinto, V. A.; Moya, P. S.; Riazantseva, M.; Ovchinnikov, I.

    2016-12-01

    The role of the auroral processes in the formation of the outer electron radiation belt during storms is analyzed using the data of RBSP mission, low orbiting satellites and ground based observations. We analyze fluxes of the low energy precipitating ions using data of the Defense Meteorological Satellite Program (DMSP). The location of the auroral electrojet is obtained from the IMAGE magnetometer network, and of the electron distribution in the outer radiation belt from the RBSP mission. We take into account the latest results on the auroral oval mapping in accordance with which the most part of the auroral oval maps not to the plasma sheet. It maps into the surrounding the Earth plasma ring in which transverse currents are closed inside the magnetosphere. Such currents constitute the high latitude continuation of the ordinary ring current. The development of the ring current and its high latitude continuation generates strong distortion of the Earth's magnetic field and corresponding adiabatic variation of the relativistic electron fluxes. This adiabatic variation should be considered for the analysis of the processes of the acceleration of relativistic electrons and formation of the outer radiation belt. We also analyze the plasma pressure profiles during storms and demonstrate the formation of sharp plasma pressure peak at the equatorial boundary of the auroral oval. It is shown that the observed this peak is directly connected to the creation of the seed population of relativistic electrons. We discuss the possibility to predict the position of new radiation belt during recovery phase of the magnetic storm using data of low orbiting and ground based observations.

  16. Electron radiation belt dynamics during magnetic storms and in quiet time

    NASA Astrophysics Data System (ADS)

    Lazutin, Leonid; Dmitriev, Aleksey; Suvorova, Alla

    2018-03-01

    The paper discusses the dynamics of the outer electron belt, adiabatic and nonadiabatic mechanisms of replenishment and losses of energetic electrons. Under undisturbed conditions, the outer electron belt gradually empties: in the inner magnetosphere due to electron precipitation in the atmosphere and in the quasi-trapping region due to losses at the magnetopause because drift shells of electrons are not closed there. The latter process does not occur in normal years due to the masking replenishment by freshly accelerated particles, but in years of extremely low activity, it leads to a significant decrease in the electron population of the belt. During the magnetic storm main phase, the first reason for the decrease in the electron flux intensity is the adiabatic cooling associated with conservation of adiabatic invariants and complemented by precipitation of electrons into the atmosphere and their dropout at the magnetopause. Electron flux increases involve E×B electron injection by the induction electric field of substorm activation and by the large-scale solar wind electric field, with pitch energy diffusion along with adiabatic heating in the recovery phase. The rate of electron flux recovery after a storm is determined by the ratio of nonadiabatic increases and losses; hence the electron flux represents a continuous series from low to very high values. The combination of these processes determines the individual character of radiation belt development during each magnetic storm and the behavior of the belt in the quiet time.

  17. Overview of NASA's space radiation research program.

    PubMed

    Schimmerling, Walter

    2003-06-01

    NASA is developing the knowledge required to accurately predict and to efficiently manage radiation risk in space. The strategy employed has three research components: (1) ground-based simulation of space radiation components to develop a science-based understanding of radiation risk; (2) space-based measurements of the radiation environment on planetary surfaces and interplanetary space, as well as use of space platforms to validate predictions; and, (3) implementation of countermeasures to mitigate risk. NASA intends to significantly expand its support of ground-based radiation research in line with completion of the Booster Applications Facility at Brookhaven National Laboratory, expected in summer of 2003. A joint research solicitation with the Department of Energy is under way and other interagency collaborations are being considered. In addition, a Space Radiation Initiative has been submitted by the Administration to Congress that would provide answers to most questions related to the International Space Station within the next 10 years.

  18. NASA Radiation Belt Models AP-8 and AE-8

    DTIC Science & Technology

    1989-09-30

    MeV). The quiet day solar cycle variation is defined by taking the ratio of the omni-directional flux measured from solar minimum to a standard...Note 1: Model Evaluation, TREND issued at IASB , Printed at MATRA, ESTEC/Contract #8011/88/NIJMAC, 28 June 1989. "Models of the Trapped Radiation

  19. GPU Multi-Scale Particle Tracking and Multi-Fluid Simulations of the Radiation Belts

    NASA Astrophysics Data System (ADS)

    Ziemba, T.; Carscadden, J.; O'Donnell, D.; Winglee, R.; Harnett, E.; Cash, M.

    2007-12-01

    The properties of the radiation belts can vary dramatically under the influence of magnetic storms and storm-time substorms. The task of understanding and predicting radiation belt properties is made difficult because their properties determined by global processes as well as small-scale wave-particle interactions. A full solution to the problem will require major innovations in technique and computer hardware. The proposed work will demonstrates liked particle tracking codes with new multi-scale/multi-fluid global simulations that provide the first means to include small-scale processes within the global magnetospheric context. A large hurdle to the problem is having sufficient computer hardware that is able to handle the dissipate temporal and spatial scale sizes. A major innovation of the work is that the codes are designed to run of graphics processing units (GPUs). GPUs are intrinsically highly parallelized systems that provide more than an order of magnitude computing speed over a CPU based systems, for little more cost than a high end-workstation. Recent advancements in GPU technologies allow for full IEEE float specifications with performance up to several hundred GFLOPs per GPU and new software architectures have recently become available to ease the transition from graphics based to scientific applications. This allows for a cheap alternative to standard supercomputing methods and should increase the time to discovery. A demonstration of the code pushing more than 500,000 particles faster than real time is presented, and used to provide new insight into radiation belt dynamics.

  20. Solar Modulation of Inner Trapped Belt Radiation Flux as a Function of Atmospheric Density

    NASA Technical Reports Server (NTRS)

    Lodhi, M. A. K.

    2005-01-01

    No simple algorithm seems to exist for calculating proton fluxes and lifetimes in the Earth's inner, trapped radiation belt throughout the solar cycle. Most models of the inner trapped belt in use depend upon AP8 which only describes the radiation environment at solar maximum and solar minimum in Cycle 20. One exception is NOAAPRO which incorporates flight data from the TIROS/NOAA polar orbiting spacecraft. The present study discloses yet another, simple formulation for approximating proton fluxes at any time in a given solar cycle, in particular between solar maximum and solar minimum. It is derived from AP8 using a regression algorithm technique from nuclear physics. From flux and its time integral fluence, one can then approximate dose rate and its time integral dose.

  1. Inward diffusion and loss of radiation belt protons

    NASA Astrophysics Data System (ADS)

    Selesnick, R. S.; Baker, D. N.; Jaynes, A. N.; Li, X.; Kanekal, S. G.; Hudson, M. K.; Kress, B. T.

    2016-03-01

    Radiation belt protons in the kinetic energy range 24 to 76 MeV are being measured by the Relativistic Electron Proton Telescope on each of the two Van Allen Probes. Data have been processed for the purpose of studying variability in the trapped proton intensity during October 2013 to August 2015. For the lower energies (≲32 MeV), equatorial proton intensity near L = 2 showed a steady increase that is consistent with inward diffusion of trapped solar protons, as shown by positive radial gradients in phase space density at fixed values of the first two adiabatic invariants. It is postulated that these protons were trapped with enhanced efficiency during the 7 March 2012 solar proton event. A model that includes radial diffusion, along with known trapped proton source and loss processes, shows that the observed average rate of increase near L = 2 is predicted by the same model diffusion coefficient that is required to form the entire proton radiation belt, down to low L, over an extended (˜103 year) interval. A slower intensity decrease for lower energies near L = 1.5 may also be caused by inward diffusion, though it is faster than predicted by the model. Higher-energy (≳40 MeV) protons near the L = 1.5 intensity maximum are from cosmic ray albedo neutron decay. Their observed intensity is lower than expected by a factor ˜2, but the discrepancy is resolved by adding an unspecified loss process to the model with a mean lifetime ˜120 years.

  2. DoD Space Radiation Concerns.

    DTIC Science & Technology

    1992-07-15

    cosmic - ray transport. NASA TM X-2440, 1972:117-122. DoD Space Radiation Concerns 8 2. Atkins SG, Small JT, McFarland TH. Military Man-in Space (MMIS...136. 29. Silberberg R, Tsao CH, Adams JH Jr., Letaw JR. Radiation doses and LET distributions of cosmic rays . Rad. Res., 1984, 98:209-226. 30. Stauber...levels on mission success and completion. Natural Radiation Trapped Radiation Belts Galactic Cosmic Rays (GCR) Solar Particle Events (SPEs) Man-Made

  3. The NASA Space Radiation Health Program

    NASA Technical Reports Server (NTRS)

    Schimmerling, W.; Sulzman, F. M.

    1994-01-01

    The NASA Space Radiation Health Program is a part of the Life Sciences Division in the Office of Space Science and Applications (OSSA). The goal of the Space Radiation Health Program is development of scientific bases for assuring adequate radiation protection in space. A proposed research program will determine long-term health risks from exposure to cosmic rays and other radiation. Ground-based animal models will be used to predict risk of exposures at varying levels from various sources and the safe levels for manned space flight.

  4. Earth's magnetosphere and outer radiation belt under sub-Alfvénic solar wind.

    PubMed

    Lugaz, Noé; Farrugia, Charles J; Huang, Chia-Lin; Winslow, Reka M; Spence, Harlan E; Schwadron, Nathan A

    2016-10-03

    The interaction between Earth's magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000-100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached steady values <1 for several hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft in the near-Earth environment reveal the evanescence of the bow shock, the sunward motion of the magnetopause and the extremely rapid and intense loss of electrons in the outer radiation belt. This study allows us to directly observe the state of the inner magnetosphere, including the radiation belts during a type of solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets.

  5. Jupiter Great Red Spot and South Equatorial Belt

    NASA Image and Video Library

    1996-09-26

    NASA Voyager 2 shows the Great Red Spot and the south equatorial belt extending into the equatorial region. At right is an interchange of material between the south equatorial belt and the equatorial zone. The clouds in the equatorial zone are more diffuse and do not display the structures seen in other locations. Considerable structure is evident within the Great Red Spot. http://photojournal.jpl.nasa.gov/catalog/PIA00456

  6. Relative abundance of heavy ions in the inner zone of the radiation belts of the earth

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Panasyuk, M.I.

    1986-03-01

    The energy dependences of the relative abundances of energetic (E > 1 MeV/nucleon) H, He, and O ions in the radiation belts are analyzed on the basis of experimental results obtained from measurement of their spectral characteristics on several satellites: Molniya-2, Kosmos-900, Prognoz-5, Explorer-45, ISEE-1, and OV1-19. It is shown that the formation of the energy dependence of He/H and O/H can be explained with a model providing for ion diffusion into the interior of the radiation belts with Coulomb losses taken into account under thecondition that the total-energy spectra at the boundary are more rigid for the heavy ionsmore » and are determined by such parameters of the quiet solar wind as the relative concentrations of the individual ion components and their charge states. It is shown that the fluxes of O and Fe ions with E > 1 MeV/nucleon measured on the orbital stations Salyut-6 and Skylab have an energy dependence of the relative abundances not inconsistent with above-noted mechanism for the formation of energetic ions of the inner radiation belt.« less

  7. The magnetic local time distribution of energetic electrons in the radiation belt region

    NASA Astrophysics Data System (ADS)

    Allison, Hayley J.; Horne, Richard B.; Glauert, Sarah A.; Zanna, Giulio Del

    2017-08-01

    Using 14 years of electron flux data from the National Oceanic and Atmospheric Administration Polar Operational Environmental Satellites, a statistical study of the magnetic local time (MLT) distribution of the electron population is performed across a range of activity levels, defined by AE, AE*, Kp, solar wind velocity (Vsw), and VswBz. Three electron energies (>30, >100, and >300 keV) are considered. Dawn-dusk flux asymmetries larger than order of magnitude were observed for >30 and >100 keV electrons. For >300 keV electrons, dawn-dusk asymmetries were primarily due to a decrease in the average duskside flux beyond L* ˜ 4.5 that arose with increasing activity. For the >30 keV population, substorm injections enhance the dawnside flux, which may not reach the duskside as the electrons can be on open drift paths and lost to the magnetopause. The asymmetries in the >300 keV population are attributed to the combination of magnetopause shadowing and >300 keV electron injections by large electric fields. We suggest that 3-D radiation belt models could set the minimum energy boundary (Emin) to 30 keV or above at L* ˜ 6 during periods of low activity. However, for more moderate conditions, Emin should be larger than 100 keV and, for very extreme activities, ˜300 keV. Our observations show the extent that in situ electron flux readings may vary during active periods due to the MLT of the satellite and highlight the importance of 4-D radiation belt models to fully understand radiation belt processes.

  8. The Magnetic Local Time Distribution of Energetic Electrons in the Radiation Belt Region

    NASA Astrophysics Data System (ADS)

    Allison, H. J.

    2017-12-01

    Using fourteen years of electron flux data from the National Oceanic and Atmospheric Administration Polar Operational Environmental Satellites (POES), a statistical study of the magnetic local time (MLT) distribution of the electron population is performed across a range of activity levels, defined by AE, AE*, Kp, solar wind velocity (Vsw), and VswBz. Three electron energies (>30, >100, and >300 keV) are considered. Dawn-dusk flux asymmetries larger than order of magnitude were observed for >30 and >100 keV electrons. For >300 keV electrons, dawn-dusk asymmetries were primarily due to a decrease in the average dusk-side flux beyond L* ˜ 4.5 that arose with increasing activity. For the >30 keV population, substorm injections enhance the dawn-side flux, which may not reach the dusk-side as the electrons can be on open drift paths and lost to the magnetopause. The asymmetries in the >300 keV population are attributed to the combination of magnetopause shadowing and >300 keV electron injections by large electric fields. We suggest that 3D radiation belt models could set the minimum energy boundary (Emin) to 30 keV or above at L* ˜6 during periods of low activity. However, for more moderate conditions, Emin should be larger than 100 keV and, for very extreme activities, ˜300 keV. Our observations show the extent that in-situ electron flux readings may vary during active periods due to the MLT of the satellite and highlight the importance of 4D radiation belt models to fully understand radiation belt processes.

  9. Quantifying the Precipitation Loss of Radiation Belt Electrons During a Rapid Dropout Event

    NASA Astrophysics Data System (ADS)

    Pham, K. H.; Tu, W.; Xiang, Z.

    2017-10-01

    Relativistic electron flux in the radiation belt can drop by orders of magnitude within the timespan of hours. In this study, we used the drift-diffusion model that includes azimuthal drift and pitch angle diffusion of electrons to simulate low-altitude electron distribution observed by POES/MetOp satellites for rapid radiation belt electron dropout event occurring on 1 May 2013. The event shows fast dropout of MeV energy electrons at L > 4 over a few hours, observed by the Van Allen Probes mission. By simulating the electron distributions observed by multiple POES satellites, we resolve the precipitation loss with both high spatial and temporal resolutions and a range of energies. We estimate the pitch angle diffusion coefficients as a function of energy, pitch angle, and L-shell and calculate corresponding electron lifetimes during the event. The simulation results show fast electron precipitation loss at L > 4 during the electron dropout, with estimated electron lifetimes on the order of half an hour for MeV energies. The electron loss rate shows strong energy dependence with faster loss at higher energies, which suggest that this dropout event is dominated by quick and localized scattering process that prefers higher energy electrons. The improved temporal and spatial resolutions of electron precipitation rates provided by multiple low-altitude observations can resolve fast-varying electron loss during rapid electron dropouts (over a few hours), which occur too fast for a single low-altitude satellite. The capability of estimating the fast-varying electron lifetimes during rapid dropout events is an important step in improving radiation belt model accuracy.

  10. Quantification of the Precipitation Loss of Radiation Belt Electrons Observed by SAMPEX

    NASA Astrophysics Data System (ADS)

    Tu, W.; Selesnick, R. S.; Li, X.; Looper, M. D.

    2009-12-01

    Based on SAMPEX/PET observations, the rates and the spatial and temporal variations of electron loss to the atmosphere in the Earth’s radiation belt were quantified using a Drift-Diffusion model that includes the effects of azimuthal drifts and pitch angle diffusion. The measured electrons detected by SAMPEX can be distinguished as trapped, quasi-trapped (in the drift loss cone), and precipitating (in the bounce loss cone). The Drift-Diffusion model simulates the low-altitude electron distribution from SAMPEX. After fitting the model results to the data, the magnitudes and variations of the electron lifetime can be quantitatively determined based on the optimum model parameter values. Three magnetic storms of different types of magnitude were selected to estimate the various loss rates of ~0.5 to 3 MeV electrons during different phases of the storm and at L shells ranging from L=3.5 to L=6.5 (L represents the radial distance in the equatorial plane under a dipole field approximation). They are a small storm and a moderate storm in the current solar minimum and an intense storm right after the previous solar maximum. Model results for the three individual events showed that fast precipitation losses of energetic radiation belt electrons, as short as hours, persistently occurred in the storm main phases and with more efficient loss at higher energies, over wide range of L regions and over all the SAMPEX covered local times. In addition to this newly discovered common feature of the main phase electron lifetimes for all the storm events and at all L locations, some other properties of the electron loss rates that vary with time or locations, were also estimated and discussed. This method combining model with the low-altitude observations provides direct quantification of the electron loss rate, a prerequisite for any comprehensive modeling of the radiation belt electron dynamics.

  11. Using Phase Space Density Profiles to Investigate the Radiation Belt Seed Population

    NASA Astrophysics Data System (ADS)

    Boyd, A. J.; Spence, H.; Reeves, G. D.; Blake, J. B.; Fennell, J. F.; Claudepierre, S. G.; Turner, D. L.

    2013-12-01

    It is believed that particles with energies of 100s of keV play a critical role in the acceleration of electrons within the radiation belt. Through wave particle interactions, these so called 'seed electrons' can be accelerated up to energies greater than 1 MeV. Using data from the MagEIS (Magnetic Electron Ion Spectrometer) Instrument onboard the Van Allen Probes we calculate phase space density within the radiation belts over a wide range of mu and K values. These phase space density profiles are combined with those from THEMIS, in order to see how the phase space density evolves over a large range of L*. In this presentation we examine how the seed electron population evolves in both time and L* during acceleration events. Comparing this to the evolution of the higher mu electron population allows us to determine what role the seed electrons played in the acceleration process. Finally, we compare several of these storms to examine the importance of the seed population to the acceleration process.

  12. Jupiter's Colorful Cloud Belts

    NASA Image and Video Library

    2018-01-12

    Colorful swirling cloud belts dominate Jupiter's southern hemisphere in this image captured by NASA's Juno spacecraft. Jupiter appears in this color-enhanced image as a tapestry of vibrant cloud bands and storms. The dark region in the far left is called the South Temperate Belt. Intersecting the belt is a ghost-like feature of slithering white clouds. This is the largest feature in Jupiter's low latitudes that's a cyclone (rotating with clockwise motion). This image was taken on Dec. 16, 2017 at 10:12 PST (1:12 p.m. EST), as Juno performed its tenth close flyby of Jupiter. At the time the image was taken, the spacecraft was about 8,453 miles (13,604 kilometers) from the tops of the clouds of the planet at a latitude of 27.9 degrees south. The spatial scale in this image is 5.6 miles/pixel (9.1 kilometers/pixel). Citizen scientist Kevin M. Gill processed this image using data from the JunoCam imager. https://photojournal.jpl.nasa.gov/catalog/PIA21974

  13. Earth's magnetosphere and outer radiation belt under sub-Alfvénic solar wind

    PubMed Central

    Lugaz, Noé; Farrugia, Charles J.; Huang, Chia-Lin; Winslow, Reka M.; Spence, Harlan E.; Schwadron, Nathan A.

    2016-01-01

    The interaction between Earth's magnetic field and the solar wind results in the formation of a collisionless bow shock 60,000–100,000 km upstream of our planet, as long as the solar wind fast magnetosonic Mach (hereafter Mach) number exceeds unity. Here, we present one of those extremely rare instances, when the solar wind Mach number reached steady values <1 for several hours on 17 January 2013. Simultaneous measurements by more than ten spacecraft in the near-Earth environment reveal the evanescence of the bow shock, the sunward motion of the magnetopause and the extremely rapid and intense loss of electrons in the outer radiation belt. This study allows us to directly observe the state of the inner magnetosphere, including the radiation belts during a type of solar wind-magnetosphere coupling which is unusual for planets in our solar system but may be common for close-in extrasolar planets. PMID:27694887

  14. Effects of Complex Interplanetary Structures on the Dynamics of the Earth's Outer Radiation Belt During the 16-30 September 2014 Period: II) Corotating Solar Wind Stream

    NASA Astrophysics Data System (ADS)

    Souza, V. M. C. E. S.; Da Silva, L. A.; Sibeck, D. G.; Alves, L. R.; Jauer, P. R.; Dias Silveira, M. V.; Medeiros, C.; Marchezi, J.; Rockenbach, M.; Baker, D. N.; Kletzing, C.; Kanekal, S. G.; Georgiou, M.; Mendes, O., Jr.; Dal Lago, A.; Vieira, L. E. A.

    2015-12-01

    We present a case study describing the dynamics of the outer radiation belt for two different solar wind conditions. First, we discuss a dropout of outer belt energetic electron fluxes corresponding to the arrival of an interplanetary coronal mass ejection (ICME) followed by a corotating stream in September 2014. Second, we discuss the reformation of the outer radiation belt that began on September 22nd. We find that the arrival of the ICME and the corotating interaction region that preceded the stream cause a long-duration (many day) dropout of high-energy electrons. The recovery in radiation belt fluxes only begins when the high-speed stream begins to develop IMF Bz fluctuations and auroral activity resumes. Furthermore, during periods in which several consecutive solar wind structures appear, the first structure primes the outer radiation belt prior to the interaction of the subsequent solar wind structures with the magnetosphere. Consequently, the evolution of the outer radiation belt through the solar cycle is significantly affected by the dominant structure of each phase of the cycle. We use energetic electron and magnetic field observations provided by the Van Allen Probes, THEMIS, and GOES missions.

  15. Solar cyclic behavior of trapped energetic electrons in Earth's inner radiation belt

    NASA Astrophysics Data System (ADS)

    Abel, Bob; Thorne, Richard M.

    1994-10-01

    Magnetic electron spectrometer data from six satellites (OV3-3, OV1-14, OGO 5, S3-2, S3-3, and CRRES) have been used to study long-term (1966-1991) behavior of trapped energetic electrons in the inner radiation belt. Comparison of the observed energy spectra at L equal to or greater than 1.35 for different phases of the solar cycle reveals a clear trend toward enhanced fluxes during periods of solar maximum for energies below a few hundred keV; we suggest that this is caused by an increase in the rate of inward radial diffusion from a source at higher L. In contrast, for L less than 1.30, where atmospheric collisions become increasingly important, the electron flux is reduced during solar maximum; we attribute this to the expected increase in upper atmospheric densities. The electron flux above 1 MeV exhibits a systematic decay beyond 1979 to values well below the current NASA AE-8 model. This indicates that the natural background of high-energy electrons has previously been overestimated due to the long lasting presence of electrons produced by nuclear detonations in the upper atmosphere in the late 1950s and early 1960s.

  16. Solar cyclic behavior of trapped energetic electrons in Earth's inner radiation belt

    NASA Technical Reports Server (NTRS)

    Abel, Bob; Thorne, Richard M.

    1994-01-01

    Magnetic electron spectrometer data from six satellites (OV3-3, OV1-14, OGO 5, S3-2, S3-3, and CRRES) have been used to study long-term (1966-1991) behavior of trapped energetic electrons in the inner radiation belt. Comparison of the observed energy spectra at L equal to or greater than 1.35 for different phases of the solar cycle reveals a clear trend toward enhanced fluxes during periods of solar maximum for energies below a few hundred keV; we suggest that this is caused by an increase in the rate of inward radial diffusion from a source at higher L. In contrast, for L less than 1.30, where atmospheric collisions become increasingly important, the electron flux is reduced during solar maximum; we attribute this to the expected increase in upper atmospheric densities. The electron flux above 1 MeV exhibits a systematic decay beyond 1979 to values well below the current NASA AE-8 model. This indicates that the natural background of high-energy electrons has previously been overestimated due to the long lasting presence of electrons produced by nuclear detonations in the upper atmosphere in the late 1950s and early 1960s.

  17. Accurately Characterizing the Importance of Wave-Particle Interactions in Radiation Belt Dynamics: The Pitfalls of Statistical Wave Representations

    NASA Technical Reports Server (NTRS)

    Murphy, Kyle R.; Mann, Ian R.; Rae, I. Jonathan; Sibeck, David G.; Watt, Clare E. J.

    2016-01-01

    Wave-particle interactions play a crucial role in energetic particle dynamics in the Earths radiation belts. However, the relative importance of different wave modes in these dynamics is poorly understood. Typically, this is assessed during geomagnetic storms using statistically averaged empirical wave models as a function of geomagnetic activity in advanced radiation belt simulations. However, statistical averages poorly characterize extreme events such as geomagnetic storms in that storm-time ultralow frequency wave power is typically larger than that derived over a solar cycle and Kp is a poor proxy for storm-time wave power.

  18. Characterization and modeling of radiation effects NASA/MSFC semiconductor devices

    NASA Technical Reports Server (NTRS)

    Kerns, D. V., Jr.; Cook, K. B., Jr.

    1978-01-01

    A literature review of the near-Earth trapped radiation of the Van Allen Belts, the radiation within the solar system resulting from the solar wind, and the cosmic radiation levels of deep space showed that a reasonable simulation of space radiation, particularly the Earth orbital environment, could be simulated in the laboratory by proton bombardment. A 3 MeV proton accelerator was used to irradiate CMOS integrated circuits fabricated from three different processes. The drain current and output voltage for three inverters was recorded as the input voltage was swept from zero to ten volts after each successive irradiation. Device parameters were extracted. Possible damage mechanisms are discussed and recommendations for improved radiation hardness are suggested.

  19. Imaging Jupiter's radiation belts down to 127 MHz with LOFAR

    NASA Astrophysics Data System (ADS)

    Girard, J. N.; Zarka, P.; Tasse, C.; Hess, S.; de Pater, I.; Santos-Costa, D.; Nenon, Q.; Sicard, A.; Bourdarie, S.; Anderson, J.; Asgekar, A.; Bell, M. E.; van Bemmel, I.; Bentum, M. J.; Bernardi, G.; Best, P.; Bonafede, A.; Breitling, F.; Breton, R. P.; Broderick, J. W.; Brouw, W. N.; Brüggen, M.; Ciardi, B.; Corbel, S.; Corstanje, A.; de Gasperin, F.; de Geus, E.; Deller, A.; Duscha, S.; Eislöffel, J.; Falcke, H.; Frieswijk, W.; Garrett, M. A.; Grießmeier, J.; Gunst, A. W.; Hessels, J. W. T.; Hoeft, M.; Hörandel, J.; Iacobelli, M.; Juette, E.; Kondratiev, V. I.; Kuniyoshi, M.; Kuper, G.; van Leeuwen, J.; Loose, M.; Maat, P.; Mann, G.; Markoff, S.; McFadden, R.; McKay-Bukowski, D.; Moldon, J.; Munk, H.; Nelles, A.; Norden, M. J.; Orru, E.; Paas, H.; Pandey-Pommier, M.; Pizzo, R.; Polatidis, A. G.; Reich, W.; Röttgering, H.; Rowlinson, A.; Schwarz, D.; Smirnov, O.; Steinmetz, M.; Swinbank, J.; Tagger, M.; Thoudam, S.; Toribio, M. C.; Vermeulen, R.; Vocks, C.; van Weeren, R. J.; Wijers, R. A. M. J.; Wucknitz, O.

    2016-03-01

    Context. With the limited amount of in situ particle data available for the innermost region of Jupiter's magnetosphere, Earth-based observations of the giant planets synchrotron emission remain the sole method today of scrutinizing the distribution and dynamical behavior of the ultra energetic electrons magnetically trapped around the planet. Radio observations ultimately provide key information about the origin and control parameters of the harsh radiation environment. Aims: We perform the first resolved and low-frequency imaging of the synchrotron emission with LOFAR. At a frequency as low as 127 MHz, the radiation from electrons with energies of ~1-30 MeV are expected, for the first time, to be measured and mapped over a broad region of Jupiter's inner magnetosphere. Methods: Measurements consist of interferometric visibilities taken during a single 10-hour rotation of the Jovian system. These visibilities were processed in a custom pipeline developed for planetary observations, combining flagging, calibration, wide-field imaging, direction-dependent calibration, and specific visibility correction for planetary targets. We produced spectral image cubes of Jupiter's radiation belts at the various angular, temporal, and spectral resolutions from which flux densities were measured. Results: The first resolved images of Jupiter's radiation belts at 127-172 MHz are obtained with a noise level ~20-25 mJy/beam, along with total integrated flux densities. They are compared with previous observations at higher frequencies. A greater extent of the synchrotron emission source (≥4 RJ) is measured in the LOFAR range, which is the signature - as at higher frequencies - of the superposition of a "pancake" and an isotropic electron distribution. Asymmetry of east-west emission peaks is measured, as well as the longitudinal dependence of the radial distance of the belts, and the presence of a hot spot at λIII = 230° ± 25°. Spectral flux density measurements are on the low

  20. Reproducing the observed energy-dependent structure of Earth's electron radiation belts during storm recovery with an event-specific diffusion model

    DOE PAGES

    Ripoll, J. -F.; Reeves, Geoffrey D.; Cunningham, Gregory Scott; ...

    2016-06-11

    Here, we present dynamic simulations of energy-dependent losses in the radiation belt “slot region” and the formation of the two-belt structure for the quiet days after the 1 March storm. The simulations combine radial diffusion with a realistic scattering model, based data-driven spatially and temporally resolved whistler-mode hiss wave observations from the Van Allen Probes satellites. The simulations reproduce Van Allen Probes observations for all energies and L shells (2–6) including (a) the strong energy dependence to the radiation belt dynamics (b) an energy-dependent outer boundary to the inner zone that extends to higher L shells at lower energies andmore » (c) an “S-shaped” energy-dependent inner boundary to the outer zone that results from the competition between diffusive radial transport and losses. We find that the characteristic energy-dependent structure of the radiation belts and slot region is dynamic and can be formed gradually in ~15 days, although the “S shape” can also be reproduced by assuming equilibrium conditions. The highest-energy electrons (E > 300 keV) of the inner region of the outer belt (L ~ 4–5) also constantly decay, demonstrating that hiss wave scattering affects the outer belt during times of extended plasmasphere. Through these simulations, we explain the full structure in energy and L shell of the belts and the slot formation by hiss scattering during storm recovery. We show the power and complexity of looking dynamically at the effects over all energies and L shells and the need for using data-driven and event-specific conditions.« less

  1. Energetic electrons observed in higher latitude regions of the plasma sheet near the outer radiation belt

    NASA Astrophysics Data System (ADS)

    Yoshizumi, M.; Shinohara, I.; Nagai, T.; Kanazawa, K.; Mitani, T.; Kasahara, S.; Kazama, Y.; Wang, B. J.; Wang, S. Y.; Tam, S. W. Y.; Higashio, N.; Matsuoka, A.; Asamura, K.; Yokota, S.; Takashima, T.

    2017-12-01

    The Arase satellite was successfully launched on Dec. 20, 2016, and it has started the regular mission observation since the end of March, 2017. The orbital inclination of Arase is about 31 degree, so that Arase is possible to observe higher L-value plasma sheet close to the plasma sheet boundary. During this summer, the local time of the apogee is located at near the midnight, and Arase observed the plasma sheet just outside of the outer radiation belt as expected. In these observations, we found that energetic electron bursts up to 500 keV frequently appear in the plasma sheet. Possible sources of these energetic electron bursts of a few hundreds keV near thein higher L-value region are (1) directly accelerated from magnetotail reconnection sites and (2) dispersion-less injections. It is interesting to distinguish the acceleration source of them and address each contribution of the energy input to the outer radiation belt for understanding the relation between magnetotail reconnection and the acceleration of MeV electrons in the radiation belts. We will present the initial results on the characteristics of the observed energetic electron bursts by using the wide-range electron distribution measurements from 10 eV to 20 MeV.

  2. FIREBIRD: A Dual Satellite Mission to Examine the Spatial and Energy Coherence Scales of Radiation Belt Electron Microbursts

    NASA Astrophysics Data System (ADS)

    Klumpar, D. M.; Spence, H. E.; Larsen, B. A.; Blake, J. B.; Springer, L.; Crew, A. B.; Mosleh, E.; Mashburn, K. W.

    2009-12-01

    FIREBIRD (Focused Investigations of Relativistic Electron Burst Intensity, Range, and Dynamics), a mission under NSF’s “CubeSat-based Science Missions for Space Weather and Atmospheric Research”, will address the broad scientific question: What is the role of microburst electron precipitation in radiation belt dynamics? There are four major candidate processes for losses of relativistic electrons from the outer radiation belt [Millan and Thorne, 2007]: wave-particle interactions with whistler-mode chorus, wave-particle interactions with electromagnetic ion-cyclotron (EMIC) waves, outward radial diffusion to the magnetopause, and loss of adiabaticity on stretched magnetic field lines. FIREBIRD will further investigate the role of whistler-mode chorus, by examining the microburst electron precipitation phenomenon attributed to chorus. Microbursts are thought to be a hallmark of rapid radiation belt losses, possibly removing the entire pre-storm outer zone in a single day [Lorentzen 2001b; O'Brien et al., 2004], yet they are also intimately tied to in-situ acceleration mechanisms. FIREBIRD’s two 1.5U (10 x 10 x 15 cm) CubeSats, each weighing up to 2 kg, will be placed into a common high-inclination bead-on-a-string orbit. The two satellites will remain within ~500 km of one another for six to twelve months, allowing characterization over the spatial scale regime from 10 - 500 km. Each satellite will carry an identical co-aligned pair of solid-state detectors sensitive to electrons from 30 keV to ~3 MeV with 100 msec time resolution. Simultaneous dual measurements provided by the twin FIREBIRD satellites will permit, for the first time, the determination of spatial scales of single microburst events. Along with energy-resolved spectra, these measurements will provide the critically needed answers on the radiation belt loss rate attributed to microbursts. There are three critical questions about relativistic electron microbursts that FIREBIRD can answer: 1) What

  3. New High Energy Electron Component of Earth Radiation Belt

    NASA Astrophysics Data System (ADS)

    Dmitrenko, V. V.; Galper, A. M.; Gratchev, V. M.; Kirillov-Ugryumov, V. G.; Ulin, S. E.; Voronov, S. A.

    The Earth Radiation Belt (ERB) was discovered in the course of the first flights of Russian and American satellites with conventional instruments (gas discharge and scintillation counters), which made it possible to investigate many characteristics of trapped particles and simulate adequate radiation belt models. However, the experimental and theoretical evidence accumulated over recent time, needs more elaborate measurements for its interpretation. These measurements became feasible after the development of devices based on more perfect detectors (solid and gas-filled Cherenkov detectors, magnetic spectrometer, scintillation time-of-flight systems). The evidence requiring new direct measurements in the ERB was obtained in the late 1960s in the course of balloon flights carried out by Cosmophysics Laboratory of the Moscow Engineering and Physics Institute. In these flights a correlation between the high energy electron flux in the upper atmosphere and perturbations ofthe Earth's magnetosphere was established. This phenomenon could be explained assuming there exist high energy electron fluxes in the ERB. High energy electron fluxes in the ERB were recorded for the first time in the direct experiments carried out on board orbital station 'Salyut-6' (orbit altitude - 350 km, inclination 51.6 deg). A scintillation-Cherenkov telescope 'Elena' controlled by cosmonauts was preset to different programmed positions. The measurements were made in the periphery of the ERB, namely, in the part which goes as low as several hundred km in the Brazil Anomaly Region (BRA). The flux of electrons with energies above 30 MeV was up to 104 (m2s sr)-1.

  4. New Radiation Zones on Jupiter

    NASA Image and Video Library

    2017-12-11

    This graphic shows a new radiation zone surrounding Jupiter, located just above the atmosphere near the equator, that has been discovered by NASA's Juno mission. The new radiation zone is depicted here as a glowing blue area around the planet's middle. This radiation zone includes energetic hydrogen, oxygen and sulfur ions moving at close to the speed of light (referred to as "relativistic" speeds). It resides inside Jupiter's previously known radiation belts. The zone was identified by the mission's Jupiter Energetic Particle Detector Instrument (JEDI), enabled by Juno's unique close approach to the planet during the spacecraft's science flybys (2,100 miles or 3,400 kilometers from the cloud tops). Juno scientists believe the particles creating this region of intense radiation are derived from energetic neutral atoms -- that is, fast-moving atoms without an electric charge -- coming from the tenuous gas around Jupiter's moons Io and Europa. The neutral atoms then become ions -- atoms with an electric charge -- as their electrons are stripped away by interaction with the planet's upper atmosphere. (This discovery is discussed further in an issue of the journal Geophysical Research Letters [Kollmann et al. (2017), Geophys. Res. Lett., 44, 5259-5268].) Juno also has detected signatures of a population of high-energy, heavy ions in the inner edges of Jupiter's relativistic electron radiation belt. This radiation belt was previously understood to contain mostly electrons moving at near light speed. The signatures of the heavy ions are observed at high latitude locations within the electron belt -- a region not previously explored by spacecraft. The origin and exact species of these heavy ions is not yet understood. Juno's Stellar Reference Unit (SRU-1) star camera detects the signatures of this population as extremely high noise in images collected as part of the mission's radiation monitoring investigation. The locations where the heavy ions were detected are

  5. Observation of Relativistic Electron Microbursts in Conjunction with Intense Radiation Belt Whistler-Mode Waves

    NASA Technical Reports Server (NTRS)

    Kersten, K.; Cattell, C. A.; Breneman, A.; Goetz, K.; Kellogg, P. J.; Wygant, J. R.; Wilson, L. B., III; Blake, J. B.; Looper, M. D.; Roth, I.

    2011-01-01

    We present multi-satellite observations of large amplitude radiation belt whistler-mode waves and relativistic electron precipitation. On separate occasions during the Wind petal orbits and STEREO phasing orbits, Wind and STEREO recorded intense whistler-mode waves in the outer nightside equatorial radiation belt with peak-to-peak amplitudes exceeding 300 mV/m. During these intervals of intense wave activity, SAMPEX recorded relativistic electron microbursts in near magnetic conjunction with Wind and STEREO. This evidence of microburst precipitation occurring at the same time and at nearly the same magnetic local time and L-shell with a bursty temporal structure similar to that of the observed large amplitude wave packets suggests a causal connection between the two phenomena. Simulation studies corroborate this idea, showing that nonlinear wave.particle interactions may result in rapid energization and scattering on timescales comparable to those of the impulsive relativistic electron precipitation.

  6. On the Effect of Geomagnetic Storms on Relativistic Electrons in the Outer Radiation Belt: Van Allen Probes Observations

    NASA Astrophysics Data System (ADS)

    Moya, Pablo S.; Pinto, Víctor A.; Sibeck, David G.; Kanekal, Shrikanth G.; Baker, Daniel N.

    2017-11-01

    Using Van Allen Probes Energetic Particle, Composition, and Thermal Plasma-Relativistic Electron-Proton Telescope (ECT-REPT) observations, we performed a statistical study on the effect of geomagnetic storms on relativistic electrons fluxes in the outer radiation belt for 78 storms between September 2012 and June 2016. We found that the probability of enhancement, depletion, and no change in flux values depends strongly on L and energy. Enhancement events are more common for ˜2 MeV electrons at L ˜ 5, and the number of enhancement events decreases with increasing energy at any given L shell. However, considering the percentage of occurrence of each kind of event, enhancements are more probable at higher energies, and the probability of enhancement tends to increases with increasing L shell. Depletion are more probable for 4-5 MeV electrons at the heart of the outer radiation belt, and no-change events are more frequent at L < 3.5 for E ˜ 3 MeV particles. Moreover, for L > 4.5 the probability of enhancement, depletion, or no-change response presents little variation for all energies. Because these probabilities remain relatively constant as a function of radial distance in the outer radiation belt, measurements obtained at geosynchronous orbit may be used as a proxy to monitor E≥1.8 MeV electrons in the outer belt.

  7. Kuiper Belt Objects Along the Pluto Express Path

    NASA Technical Reports Server (NTRS)

    Jewitt, David

    1999-01-01

    The objective of this proposal was to mount a ground-based search for Kuiper Belt objects near the trajectory of the NASA Pluto Express spacecraft. The high density of Kuiper Belt objects established from work on Mauna Kea makes it probable that one or more bodies can be visited by Pluto Express after its encounter with Pluto. The work was funded during its first year through NASA HQ. The second year was funded through Goddard. The third year was never funded.

  8. NASA Strategy to Safely Live and Work in the Space Radiation Environment

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis; Wu, Honglu; Corbin, Barbara; Sulzman, Frank; Kreneck, Sam

    2007-01-01

    This viewgraph document reviews the radiation environment that is a significant potential hazard to NASA's goals for space exploration, of living and working in space. NASA has initiated a Peer reviewed research program that is charged with arriving at an understanding of the space radiation problem. To this end NASA Space Radiation Laboratory (NSRL) was constructed to simulate the harsh cosmic and solar radiation found in space. Another piece of the work was to develop a risk modeling tool that integrates the results from research efforts into models of human risk to reduce uncertainties in predicting risk of carcinogenesis, central nervous system damage, degenerative tissue disease, and acute radiation effects acute radiation effects.

  9. VLF Wave Local Acceleration & ULF Wave Radial Diffusion: The Importance of K-Dependent PSD Analysis for Diagnosing the cause of Radiation Belt Acceleration.

    NASA Astrophysics Data System (ADS)

    Ozeke, L.; Mann, I. R.; Claudepierre, S. G.; Morley, S.; Henderson, M. G.; Baker, D. N.; Kletzing, C.; Spence, H. E.

    2017-12-01

    We present results showing the temporal evolution of electron Phase Space Density (PSD) in the outer radiation belt during the most intense geomagnetic storm of the last decade which occurred on March 17th 2015. Based on observations of growing local PSD peaks at fixed first and second adiabatic invariants of M=1000 MeV/G and K=0.18 G1/2Re respectively, previous studies argued that the outer radiation belt flux enhancement that occurred during this storm resulted from local acceleration driven by VLF waves. Here we show that the vast majority of the outer radiation belt consisted of electrons with much lower K-values than 0.18 G1/2Re, and that at these lower K-values there is no clear evidence of growing local PSD peaks consistent with that expected from local acceleration. Contrary to prior studies we show that the outer radiation belt flux enhancement is consistent with inward radial diffusion driven by ULF waves and present evidence that the growing local PSD peaks at K=0.18 G1/2Re and M=1000 MeV/G result from pitch-angle scattering of lower-K electrons to K=0.18 G1/2Re. In addition, we also show that the observed outer radiation belt flux enhancement during this geomagnetic storm can be reproduced using a radial diffusion model driven by measured ULF waves without including any local acceleration. These results highlight the importance of careful analysis of the electron PSD profiles as a function of L* over a range of fixed first, M and second K, adiabatic invariants to correctly determine the mechanism responsible for the electron flux enhancements observed in the outer radiation belt.

  10. Jupiter's magnetosphere and radiation belts

    NASA Technical Reports Server (NTRS)

    Kennel, C. F.; Coroniti, F. V.

    1979-01-01

    Radioastronomy and Pioneer data reveal the Jovian magnetosphere as a rotating magnetized source of relativistic particles and radio emission, comparable to astrophysical cosmic ray and radio sources, such as pulsars. According to Pioneer data, the magnetic field in the outer magnetosphere is radially extended into a highly time variable disk-shaped configuration which differs fundamentally from the earth's magnetosphere. The outer disk region, and the energetic particles confined in it, are modulated by Jupiter's 10 hr rotation period. The entire outer magnetosphere appears to change drastically on time scales of a few days to a week. In addition to its known modulation of the Jovian decametric radio bursts, Io was found to absorb some radiation belt particles and to accelerate others, and most importantly, to be a source of neutral atoms, and by inference, a heavy ion plasma which may significantly affect the hydrodynamic flow in the magnetosphere. Another important Pioneer finding is that the Jovian outer magnetosphere generates, or permits to escape, fluxes of relativistic electrons of such intensities that Jupiter may be regarded as the dominant source of 1 to 30 MeV cosmic ray electrons in the heliosphere.

  11. Vega: Two Belts and the Possibility of Planets

    NASA Image and Video Library

    2013-01-08

    In this diagram, the Vega system, which was already known to have a cooler outer belt of comets orange, is compared to our solar system with its asteroid and Kuiper belts. The ring of warm, rocky debris was detected using NASA Spitzer Space Telescope,

  12. Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models

    NASA Astrophysics Data System (ADS)

    Sakaguchi, Kaori; Nagatsuma, Tsutomu; Reeves, Geoffrey D.; Spence, Harlan E.

    2015-12-01

    The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary orbit (GEO) and medium Earth orbit. To provide alerts of electron flux enhancements, 16 prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omnidirectional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES 15 spacecraft were used as the predictors. Model explanatory parameters were selected from solar wind parameters, the electron log-flux at GEO, and geomagnetic indices. For the innermost region of the outer radiation belt, the electron flux is best predicted by using the Dst index as the sole input parameter. For the central to outermost regions, at L ≧ 4.8 and L ≧ 5.6, the electron flux is predicted most accurately by including also the solar wind velocity and then the dynamic pressure, respectively. The Dst index is the best overall single parameter for predicting at 3 ≦ L ≦ 6, while for the GEO flux prediction, the KP index is better than Dst. A test calculation demonstrates that the model successfully predicts the timing and location of the flux maximum as much as 2 days in advance and that the electron flux decreases faster with time at higher L values, both model features consistent with the actually observed behavior.

  13. Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sakaguchi, Kaori; Nagatsuma, Tsutomu; Reeves, Geoffrey D.

    The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary orbit (GEO) and medium Earth orbit. In order to provide alerts of electron flux enhancements, 16 prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omnidirectional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES 15 spacecraftmore » were used as the predictors. Furthermore, we selected model explanatory parameters from solar wind parameters, the electron log-flux at GEO, and geomagnetic indices. For the innermost region of the outer radiation belt, the electron flux is best predicted by using the Dst index as the sole input parameter. For the central to outermost regions, at L≥4.8 and L ≥5.6, the electron flux is predicted most accurately by including also the solar wind velocity and then the dynamic pressure, respectively. The Dst index is the best overall single parameter for predicting at 3 ≤ L ≤ 6, while for the GEO flux prediction, the K P index is better than Dst. Finally, a test calculation demonstrates that the model successfully predicts the timing and location of the flux maximum as much as 2 days in advance and that the electron flux decreases faster with time at higher L values, both model features consistent with the actually observed behavior.« less

  14. Prediction of MeV electron fluxes throughout the outer radiation belt using multivariate autoregressive models

    DOE PAGES

    Sakaguchi, Kaori; Nagatsuma, Tsutomu; Reeves, Geoffrey D.; ...

    2015-12-22

    The Van Allen radiation belts surrounding the Earth are filled with MeV-energy electrons. This region poses ionizing radiation risks for spacecraft that operate within it, including those in geostationary orbit (GEO) and medium Earth orbit. In order to provide alerts of electron flux enhancements, 16 prediction models of the electron log-flux variation throughout the equatorial outer radiation belt as a function of the McIlwain L parameter were developed using the multivariate autoregressive model and Kalman filter. Measurements of omnidirectional 2.3 MeV electron flux from the Van Allen Probes mission as well as >2 MeV electrons from the GOES 15 spacecraftmore » were used as the predictors. Furthermore, we selected model explanatory parameters from solar wind parameters, the electron log-flux at GEO, and geomagnetic indices. For the innermost region of the outer radiation belt, the electron flux is best predicted by using the Dst index as the sole input parameter. For the central to outermost regions, at L≥4.8 and L ≥5.6, the electron flux is predicted most accurately by including also the solar wind velocity and then the dynamic pressure, respectively. The Dst index is the best overall single parameter for predicting at 3 ≤ L ≤ 6, while for the GEO flux prediction, the K P index is better than Dst. Finally, a test calculation demonstrates that the model successfully predicts the timing and location of the flux maximum as much as 2 days in advance and that the electron flux decreases faster with time at higher L values, both model features consistent with the actually observed behavior.« less

  15. Quantifying the Precipitation Loss of Radiation Belt Electrons during a Rapid Dropout Event

    NASA Astrophysics Data System (ADS)

    Pham, K. H.; Tu, W.; Xiang, Z.

    2017-12-01

    Relativistic electron flux in the radiation belt can drop by orders of magnitude within the timespan of hours. In this study, we used the drift-diffusion model that includes azimuthal drift and pitch angle diffusion of electrons to simulate low-altitude electron distribution observed by POES/MetOp satellites for rapid radiation belt electron dropout event occurring on May 1, 2013. The event shows fast dropout of MeV energy electrons at L>4 over a few hours, observed by the Van Allen Probes mission. By simulating the electron distributions observed by multiple POES satellites, we resolve the precipitation loss with both high spatial and temporal resolution and a range of energies. We estimate the pitch angle diffusion coefficients as a function of energy, pitch angle, and L-shell, and calculate corresponding electron lifetimes during the event. The simulation results show fast electron precipitation loss at L>4 during the electron dropout, with estimated electron lifetimes on the order of half an hour for MeV energies. The electron loss rate show strong energy dependence with faster loss at higher energies, which suggest that this dropout event is dominated by quick and localized scattering process that prefers higher energy electrons. The estimated pitch angle diffusion rates from the model are then compared with in situ wave measurements from Van Allen Probes to uncover the underlying wave-particle-interaction mechanisms that are responsible for the fast electron precipitation. Comparing the resolved precipitation loss with the observed electron dropouts at high altitudes, our results will suggest the relative role of electron precipitation loss and outward radial diffusion to the radiation belt dropouts during storm and non-storm times, in addition to its energy and L dependence.

  16. Preliminary evaluation of a liquid belt radiator for space applications

    NASA Technical Reports Server (NTRS)

    Teagan, W. P.; Fitzgerald, K.

    1984-01-01

    The liquid belt radiator (LBR) is discussed. The LBR system operates either in the sensible heat mode or in the latent heat mode. Parametric analysis shows that the LBR may reduce the mass of heat pipe radiators by 70 to 90% when the LBR surface has a total emissivity in excess of 0.3. It is indicated that the diffusion pump oils easily meet this criteria with emissivities greater than 0.8. Measurements on gallium indicate that its emissivity is probably in excess of 0.3 in the solid state when small amounts of impurities are on the surface. The point design exhibits a characteristic mass of 3.1 kg/kW of power dissipation, a mass per unit prime radiating area of approximately 0.9 kg/sq ms and a total package volume of approximately 2.50 cubic m. This compares favorably with conventional technologies which have weights on the order of 4 kg/sq m.

  17. Controlled Studies of Whistler Wave Interactions with Energetic Particles in Radiation Belts

    DTIC Science & Technology

    2009-07-01

    the IGRF geomagnetic field and PIM ionosphere /plasmasphere models . Those simulations demonstrate that on this particular evening 28.5 kHz whistler...a simplified slab model of ionospheric plasmas, we can compute the transmission coefficient and, subsequently, estimate that -15% of the incident...with inner radiation belts as well as the ionospheric effects caused by precipitated energetic electrons. The whistler waves used in our experiments

  18. Wave-Particle Interactions in the Earth's Radiation Belts: Recent Advances and Unprecedented Future Opportunities

    NASA Astrophysics Data System (ADS)

    Li, W.

    2017-12-01

    In the collisionless heliospheric plasmas, wave-particle interaction is a fundamental physical process in transferring energy and momentum between particles with different species and energies. This presentation focuses on one of the important wave-particle interaction processes: interaction between whistler-mode waves and electrons. Whistler-mode waves have frequencies between proton and electron cyclotron frequency and are ubiquitously present in the heliospheric plasmas including solar wind and planetary magnetospheres. I use Earth's Van Allen radiation belt as "local space laboratory" to discuss the role of whistler-mode waves in energetic electron dynamics using multi-satellite observations, theory and modeling. I further discuss solar wind drivers leading to energetic electron dynamics in the Earth's radiation belts, which is critical in predicting space weather that has broad impacts on our technological systems and society. At last, I discuss the unprecedented future opportunities of exploring space science using multi-satellite observations and state-of-the-art theory and modeling.

  19. Some results on radiation belt electrons from observations of satellite-borne semiconductor electron detector

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cheng Doug-yuan; Wu Ji-ping

    1987-04-01

    This paper presents some results from observations of a Chinese satellite-borne semiconductor electron detector. Data analysis yields typical values of electron fluxes in the central region of the inner radiation belt. The omnidirectional fluxes of electrons having energies greater than 0.5 MeV and 1.0 MeV are 1.9 x 10/sup 8/ and 6.7 x 10/sup 7/ elec./s-cm/sup 2/, respectively. The electron-flux profile on a typical orbit as a function of time is also given. In addition, the omnidirectional fluxes at the synchronous altitude for the two electron-energy levels mentioned are 2.43 x 10/sup 6/ and 4.25 x 10/sup 5/ elec./s-cm/sup 2/.more » The diurnal variations of electrons in the outer radiation belt observed at the synchronous altitude are also given. The results agree with those observed abroad.« less

  20. THE OUTER RADIATION BELT OF THE EARTH AT THE ALTITUDE OF 320 KM

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vernov, S.N.; Savenko, I.A.; Shavrin, P.I.

    1962-11-01

    Scintillation and gas-discharge counters on the second Soviet spaceship allowed a detailed investigation of the outer radiation belt near the earth and established its boundaries in relation to longitude. The spaceship orbit was almost circular at an altitude of 306 to 339 km. The energy threshold of the counter channel was 25 kev. (W,D.M.)

  1. Direct comparison of transient radiation belt topology and dynamics in 1991 based on measurements onboard Mir space station and NOAA satellite.

    PubMed

    Shurshakov, V A; Huston, S L; Dachev TsP; Petrov, V M; Ivanov YuV; Semkova, J V

    1998-01-01

    In March 1991 the CRRES spacecraft measured a new transient radiation belt resulting from a solar proton event and subsequent geomagnetic disturbance. The presence of this belt was also noted by dosimeter-radiometers aboard the Mir space station (approx. 400 km, 51 degrees orbit) and by particle telescopes on the NOAA-10 spacecraft (850 km, 98 degrees). This event provides a unique opportunity to compare particle flux and dose measurements made by different instruments in different orbits under changing conditions. We present here a comparison of the measurements made by the different detectors. We discuss the topology and dynamics of the transient radiation belt over a period of more than one year.

  2. Effects of whistler mode hiss waves on the radiation belts structure during quiet times

    NASA Astrophysics Data System (ADS)

    Ripoll, J. F.; Santolik, O.; Reeves, G. D.; Kurth, W. S.; Denton, M.; Loridan, V.; Thaller, S. A.; Cunningham, G.; Kletzing, C.; Turner, D. L.; Henderson, M. G.; Ukhorskiy, S.; Drozdov, A.; Cervantes Villa, J. S.; Shprits, Y.

    2017-12-01

    We present dynamic Fokker-Planck simulations of the electron radiation belts and slot formation during the quiet days that can follow a storm. Simulations are made for all energies and L-shells between 2 and 6 in the view of recovering the observations of two particular events. Pitch angle diffusion is essential to energy structure of the belts and slot region. Pitch angle diffusion is computed from data-driven spatially and temporally-resolved whistler mode hiss wave and ambient plasma observations from the Van Allen Probes satellites. The simulations are performed either with a 3D formulation that uses pitch angle diffusion coefficients or with a simpler 1D Fokker-Planck equation based on losses computed from a lifetime. Validation is carried out globally against Magnetic Electron and Ion Spectrometer observations of the belts at all energy. Results are complemented with a sensitivity study involving different radial diffusion coefficients, electron lifetimes, and pitch angle diffusion coefficients. We discuss which models allow to recover the observed "S-shaped" energy-dependent inner boundary to the outer zone that results from the competition between diffusive radial transport and losses. Periods when the plasmasphere extends beyond L 5 favor long-lasting hiss losses from the outer belt. Through these simulations, we explain the full structure in energy and L-shell of the belts and the slot formation by hiss scattering during quiet storm recovery.

  3. Modeling radiation belt electron dynamics during GEM challenge intervals with the DREAM3D diffusion model

    NASA Astrophysics Data System (ADS)

    Tu, Weichao; Cunningham, G. S.; Chen, Y.; Henderson, M. G.; Camporeale, E.; Reeves, G. D.

    2013-10-01

    a response to the Geospace Environment Modeling (GEM) "Global Radiation Belt Modeling Challenge," a 3D diffusion model is used to simulate the radiation belt electron dynamics during two intervals of the Combined Release and Radiation Effects Satellite (CRRES) mission, 15 August to 15 October 1990 and 1 February to 31 July 1991. The 3D diffusion model, developed as part of the Dynamic Radiation Environment Assimilation Model (DREAM) project, includes radial, pitch angle, and momentum diffusion and mixed pitch angle-momentum diffusion, which are driven by dynamic wave databases from the statistical CRRES wave data, including plasmaspheric hiss, lower-band, and upper-band chorus. By comparing the DREAM3D model outputs to the CRRES electron phase space density (PSD) data, we find that, with a data-driven boundary condition at Lmax = 5.5, the electron enhancements can generally be explained by radial diffusion, though additional local heating from chorus waves is required. Because the PSD reductions are included in the boundary condition at Lmax = 5.5, our model captures the fast electron dropouts over a large L range, producing better model performance compared to previous published results. Plasmaspheric hiss produces electron losses inside the plasmasphere, but the model still sometimes overestimates the PSD there. Test simulations using reduced radial diffusion coefficients or increased pitch angle diffusion coefficients inside the plasmasphere suggest that better wave models and more realistic radial diffusion coefficients, both inside and outside the plasmasphere, are needed to improve the model performance. Statistically, the results show that, with the data-driven outer boundary condition, including radial diffusion and plasmaspheric hiss is sufficient to model the electrons during geomagnetically quiet times, but to best capture the radiation belt variations during active times, pitch angle and momentum diffusion from chorus waves are required.

  4. AN EXTERNAL RADIATION BELT AT A HEIGHT OF 320 KM ABOVE THE EARTH (in Russian)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vernov, S.N.; Savenko, I.A.; Shavrin, P.I.

    1961-10-01

    The orbit of the second Russian sputnik was almost circular with altitude extremes of 307 and 339 km. The count rate obtained from a scintillation counter (NaI (Tl) crystall on board the sputnik showed an increase from 4 to 11 disinteg/cm/sup 2/-sec on going from the equator to latitudes of plus or minus 40 to 50 deg due to the variation in cosmic ray count with latitude. Then, a sharp increase in count rate of 20-600 disinteg/cm/sup 2/-sec was observed at geometrical latitudes 50 to 65 deg . Conjugate points were determined, where a zone of increased activity in Siberiamore » was related with a region in the South Indian Ocean, and a zone in North America was related with a zone in the South Pacific Ocean. Thus, zones of increased radiation in the Northern Hemisphere were related to corresponding zones in the Southern Hemisphere by means of the force lines of the geomagnetic field which determines the external radiation belt. The limit of the radiation belt at small latitudes corresponds with the isocline delta = 70 deg in the Northern Hemisphere and with delta = 66 deg in the Southern Hemisphere. The radiation was found to be due to gamma rays having an energy of 100 to 300 kev which originated from the slow-down of electrons hitting the shell of the sputnik. It was estimated that the upper limit of the lifetime of the electrons in the belt was 10/sup 6/to 10/ sup 8/ seconds. Hence it is more likely that the electrons are captured by local acceleration of electrons within the limits of the geomagnetic field than in accordance with a neutron hypothesis (TTT)« less

  5. The effects of magnetospheric processes on relativistic electron dynamics in the Earth's outer radiation belt

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Tang, C. L.; Wang, Y. X.; Ni, B.

    Using the electron phase space density (PSD) data measured by Van Allen Probe A from January 2013 to April 2015, we investigate the effects of magnetospheric processes on relativistic electron dynamics in the Earth's outer radiation belt during 50 geomagnetic storms. A statistical study shows that the maximum electron PSDs for various μ (μ = 630, 1096, 2290, and 3311 MeV/G) at L*~4.0 after the storm peak have good correlations with storm intensity (cc~0.70). This suggests that the occurrence and magnitude of geomagnetic storms are necessary for relativistic electron enhancements at the inner edge of the outer radiation belt (L*more » = 4.0). For moderate or weak storm events (SYM–H min > ~–100 nT) with weak substorm activity (AE max < 800 nT) and strong storm events (SYM–H min ≤ ~–100 nT) with intense substorms (AE max ≥ 800 nT) during the recovery phase, the maximum electron PSDs for various μ at different L* values (L* = 4.0, 4.5, and 5.0) are well correlated with storm intensity (cc > 0.77). For storm events with intense substorms after the storm peak, relativistic electron enhancements at L* = 4.5 and 5.0 are observed. This shows that intense substorms during the storm recovery phase are crucial to relativistic electron enhancements in the heart of the outer radiation belt. In conclusion, our statistics study suggests that magnetospheric processes during geomagnetic storms have a significant effect on relativistic electron dynamics.« less

  6. The effects of magnetospheric processes on relativistic electron dynamics in the Earth's outer radiation belt

    DOE PAGES

    Tang, C. L.; Wang, Y. X.; Ni, B.; ...

    2017-08-11

    Using the electron phase space density (PSD) data measured by Van Allen Probe A from January 2013 to April 2015, we investigate the effects of magnetospheric processes on relativistic electron dynamics in the Earth's outer radiation belt during 50 geomagnetic storms. A statistical study shows that the maximum electron PSDs for various μ (μ = 630, 1096, 2290, and 3311 MeV/G) at L*~4.0 after the storm peak have good correlations with storm intensity (cc~0.70). This suggests that the occurrence and magnitude of geomagnetic storms are necessary for relativistic electron enhancements at the inner edge of the outer radiation belt (L*more » = 4.0). For moderate or weak storm events (SYM–H min > ~–100 nT) with weak substorm activity (AE max < 800 nT) and strong storm events (SYM–H min ≤ ~–100 nT) with intense substorms (AE max ≥ 800 nT) during the recovery phase, the maximum electron PSDs for various μ at different L* values (L* = 4.0, 4.5, and 5.0) are well correlated with storm intensity (cc > 0.77). For storm events with intense substorms after the storm peak, relativistic electron enhancements at L* = 4.5 and 5.0 are observed. This shows that intense substorms during the storm recovery phase are crucial to relativistic electron enhancements in the heart of the outer radiation belt. In conclusion, our statistics study suggests that magnetospheric processes during geomagnetic storms have a significant effect on relativistic electron dynamics.« less

  7. Electrons with E greater than 40 MeV in the earth's radiation belt

    NASA Astrophysics Data System (ADS)

    Galper, A. M.; Grachev, V. M.; Dmitrenko, V. V.; Kirillov-Ugriumov, V. G.; Polukhina, N. G.; Ulin, S. E.

    1983-10-01

    The spatial-angle characteristics of radiation-belt electrons with energies exceeding 40 MeV have been constructed on the basis of data from the Elena-F instrument on the Salyut 6-Soyuz-Progress complex. A sufficiently narrow pitch-angle distribution is found, which indicates that high-energy electrons observed in the region of the Brazilian magnetic anomaly are trapped by the geomagnetic field.

  8. Integration of the radiation belt environment model into the space weather modeling framework

    NASA Astrophysics Data System (ADS)

    Glocer, A.; Toth, G.; Fok, M.; Gombosi, T.; Liemohn, M.

    2009-11-01

    We have integrated the Fok radiation belt environment (RBE) model into the space weather modeling framework (SWMF). RBE is coupled to the global magnetohydrodynamics component (represented by the Block-Adaptive-Tree Solar-wind Roe-type Upwind Scheme, BATS-R-US, code) and the Ionosphere Electrodynamics component of the SWMF, following initial results using the Weimer empirical model for the ionospheric potential. The radiation belt (RB) model solves the convection-diffusion equation of the plasma in the energy range of 10 keV to a few MeV. In stand-alone mode RBE uses Tsyganenko's empirical models for the magnetic field, and Weimer's empirical model for the ionospheric potential. In the SWMF the BATS-R-US model provides the time dependent magnetic field by efficiently tracing the closed magnetic field-lines and passing the geometrical and field strength information to RBE at a regular cadence. The ionosphere electrodynamics component uses a two-dimensional vertical potential solver to provide new potential maps to the RBE model at regular intervals. We discuss the coupling algorithm and show some preliminary results with the coupled code. We run our newly coupled model for periods of steady solar wind conditions and compare our results to the RB model using an empirical magnetic field and potential model. We also simulate the RB for an active time period and find that there are substantial differences in the RB model results when changing either the magnetic field or the electric field, including the creation of an outer belt enhancement via rapid inward transport on the time scale of tens of minutes.

  9. Modeling of the Radiation Belt Dynamics During the Two Largest Geomagnetic Storms of Solar Cycle 24

    NASA Astrophysics Data System (ADS)

    Zheng, Y.; Rastaetter, L.; Kuznetsova, M. M.

    2016-12-01

    In this paper, radiation belt response to the two largest geomagnetic storms of Solar Cycle 24 (17 March 2015 and the 22 June 2015) is investigated in detail. Even though both storms are primarily CME driven, each has its own complexities [Liu et al., 2015, Kataoka et al., 2015]. Using the CCMC's run-on-request system, modeling results using the RBE (Radiation Belt Environment) model within the SWMF (Space Weather Modeling Framework) and the RBE model coupled with the SWMF and RCM (Rice Convection Model, which takes the ring current's contribution into consideration) will be examined. Comparative and comprehensive analyses of the same event from two different models and of two events from the same model/model suite will be provided. Focus will be specially given to impacts of different solar wind drivers on radiation belt dynamics and to the coupling and interactions of different plasma populations/physical processes within the region. Liu, Ying D., H. Hu, R. Wang, Z. Yang, B., Zhu, Y. A., Liu, J. G. Luhmann, J. D. Richardson (2015), Plasma and Magnetic Field Characteristics of Solar Coronal Mass Ejections in Relation to Geomagnetic Storm Intensity and Variability, The Astrophysical Journal Letters, Volume 809, Issue 2, article id. L34, 6 pp. doi:10.1088/2041-8205/809/2/L34. Kataoka, R., D. Shiota, E. Kilpua, and K. Keika (2015), Pileup accident hypothesis of magnetic storm on 17 March 2015, Geophys. Res. Lett., 42, 5155-5161, doi:10.1002/2015GL064816.

  10. Prompt Recovery and Enhancement of the Earth's Outer Radiation Belt due to Relativistic Electron Injections

    NASA Astrophysics Data System (ADS)

    Tang, C. L.; Zhang, J.; Reeves, G. D.; Baker, D. N.; Spence, H. E.; Funsten, H. O.; Blake, J. B.

    2015-12-01

    We present multipoint observations (RBSP, GEOS and THEMIS) of the substorm electron injections during the substorm event on 16 August 2013. RBSP-A detected the MeV electron phase space density increased by an order of magnitude in about one hour at L* > 5.0. At L* = 4.4, the injected MeV electrons were also detected. It is suggested that the magnetic field dipolarization associated with the substorm injections alone can explain that the prompt recovery and enhancements of the relativistic electron (~ MeV) fluxes in the outer radiation belt. The observations of THEMIS-A also first presented that the near-Earth magnetotail at substorm onset is important in the MeV electron injection event: the enhanced fluxes of ~200 keV electrons are the source population and intense electromagnetic pulses are the driving source of MeV injected electrons. The pulse model is used to explain the dispersionless MeV injected electrons in the outer radiation belt observed by GEOS-13 and RBSP-A.

  11. Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Baker, Daniel N.; Jaynes, A. N.; Kanekal, S. G.

    Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching –223 nT. On 22 June 2015 another strong storm (Dst reaching –204 nT) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed amore » rich variety of pitch angle features including strong “butterfly” distributions with deep minima in flux at α = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported “impenetrable barrier” at L ≈ 2.8 was pushed inward, but not significantly breached, and no E ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Altogether, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.« less

  12. Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015

    DOE PAGES

    Baker, Daniel N.; Jaynes, A. N.; Kanekal, S. G.; ...

    2016-07-01

    Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching –223 nT. On 22 June 2015 another strong storm (Dst reaching –204 nT) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed amore » rich variety of pitch angle features including strong “butterfly” distributions with deep minima in flux at α = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported “impenetrable barrier” at L ≈ 2.8 was pushed inward, but not significantly breached, and no E ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Altogether, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.« less

  13. Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015

    NASA Astrophysics Data System (ADS)

    Baker, D. N.; Jaynes, A. N.; Kanekal, S. G.; Foster, J. C.; Erickson, P. J.; Fennell, J. F.; Blake, J. B.; Zhao, H.; Li, X.; Elkington, S. R.; Henderson, M. G.; Reeves, G. D.; Spence, H. E.; Kletzing, C. A.; Wygant, J. R.

    2016-07-01

    Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (storm time ring current index) value reaching -223 nT. On 22 June 2015 another strong storm (Dst reaching -204 nT) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong "butterfly" distributions with deep minima in flux at α = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported "impenetrable barrier" at L ≈ 2.8 was pushed inward, but not significantly breached, and no E ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Overall, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.

  14. Automated Identification and Shape Analysis of Chorus Elements in the Van Allen Radiation Belts

    NASA Astrophysics Data System (ADS)

    Sen Gupta, Ananya; Kletzing, Craig; Howk, Robin; Kurth, William; Matheny, Morgan

    2017-12-01

    An important goal of the Van Allen Probes mission is to understand wave-particle interaction by chorus emissions in terrestrial Van Allen radiation belts. To test models, statistical characterization of chorus properties, such as amplitude variation and sweep rates, is an important scientific goal. The Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrumentation suite provides measurements of wave electric and magnetic fields as well as DC magnetic fields for the Van Allen Probes mission. However, manual inspection across terabytes of EMFISIS data is not feasible and as such introduces human confirmation bias. We present signal processing techniques for automated identification, shape analysis, and sweep rate characterization of high-amplitude whistler-mode chorus elements in the Van Allen radiation belts. Specifically, we develop signal processing techniques based on the radon transform that disambiguate chorus elements with a dominant sweep rate against hiss-like chorus. We present representative results validating our techniques and also provide statistical characterization of detected chorus elements across a case study of a 6 s epoch.

  15. Observational evidence of competing source, loss, and transport processes for relativistic electrons in Earth's outer radiation belt

    NASA Astrophysics Data System (ADS)

    Turner, Drew; Mann, Ian; Usanova, Maria; Rodriguez, Juan; Henderson, Mike; Angelopoulos, Vassilis; Morley, Steven; Claudepierre, Seth; Li, Wen; Kellerman, Adam; Boyd, Alexander; Kim, Kyung-Chan

    Earth’s outer electron radiation belt is a region of extreme variability, with relativistic electron intensities changing by orders of magnitude over time scales ranging from minutes to years. Extreme variations of outer belt electrons ultimately result from the relative impacts of various competing source (and acceleration), loss, and transport processes. Most of these processes involve wave-particle interactions between outer belt electrons and different types of plasma waves in the inner magnetosphere, and in turn, the activity of these waves depends on different solar wind and magnetospheric driving conditions and thus can vary drastically from event to event. Using multipoint analysis with data from NASA’s Van Allen Probes, THEMIS, and SAMPEX missions, NOAA’s GOES and POES constellations, and ground-based observatories, we present results from case studies revealing how different source/acceleration and loss mechanisms compete during active periods to result in drastically different distributions of outer belt electrons. By using a combination of low-Earth orbiting and high-altitude-equatorial orbiting satellites, we briefly review how it is possible to get a much more complete picture of certain wave activity and electron losses over the full range of MLTs and L-shells throughout the radiation belt. We then show example cases highlighting the importance of particular mechanisms, including: substorm injections and whistler-mode chorus waves for the source and acceleration of relativistic electrons; magnetopause shadowing and wave-particle interactions with EMIC waves for sudden losses; and ULF wave activity for driving radial transport, a process which is important for redistributing relativistic electrons, contributing both to acceleration and loss processes. We show how relativistic electron enhancement events involve local acceleration that is consistent with wave-particle interactions between a seed population of 10s to 100s of keV electrons, with a

  16. Multi-satellite simultaneous observations of magnetopause and atmospheric losses of radiation belt electrons during an intense solar wind dynamic pressure pulse

    DOE PAGES

    Xiang, Zheng; Ni, Binbin; Zhou, Chen; ...

    2016-05-03

    Radiation belt electron flux dropouts are a kind of drastic variation in the Earth's magnetosphere, understanding of which is of both scientific and societal importance. We report multi-satellite simultaneous observations of magnetopause and atmospheric losses of radiation belt electrons during an event of intense solar wind dynamic pressure pulse, using electron flux data from a group of 14 satellites. Moreover, when the pulse occurred, magnetopause and atmospheric loss could take effect concurrently contributing to the electron flux dropout. Losses through the magnetopause were observed to be efficient and significant at L ≳ 5, owing to the magnetopause intrusion into Lmore » ~6 and outward radial diffusion associated with sharp negative gradient in electron phase space density. Losses to the atmosphere were directly identified from the precipitating electron flux observations, for which pitch angle scattering by plasma waves could be mainly responsible. While the convection and substorm injections strongly enhanced the energetic electron fluxes up to hundreds of keV, they could delay other than avoid the occurrence of electron flux dropout at these energies. Finally, we demonstrate that the pulse-time radiation belt electron flux dropout depends strongly on the specific interplanetary and magnetospheric conditions and that losses through the magnetopause and to the atmosphere and enhancements of substorm injection play an essential role in combination, which should be incorporated as a whole into future simulations for comprehending the nature of radiation belt electron flux dropouts.« less

  17. On the possibility to use semiconductive hybrid pixel detectors for study of radiation belt of the Earth.

    NASA Astrophysics Data System (ADS)

    Guskov, A.; Shelkov, G.; Smolyanskiy, P.; Zhemchugov, A.

    2016-02-01

    The scientific apparatus GAMMA-400 designed for study of electromagnetic and hadron components of cosmic rays will be launched to an elliptic orbit with the apogee of about 300 000 km and the perigee of about 500 km. Such a configuration of the orbit allows it to cross periodically the radiation belt and the outer part of magnetosphere. We discuss the possibility to use hybrid pixel detecters based on the Timepix chip and semiconductive sensors on board the GAMMA-400 apparatus. Due to high granularity of the sensor (pixel size is 55 mum) and possibility to measure independently an energy deposition in each pixel, such compact and lightweight detector could be a unique instrument for study of spatial, energy and time structure of electron and proton components of the radiation belt.

  18. New insights about the structure and variability of Saturn's electron radiation belts from Cassini's Ring-Grazing and Proximal orbits

    NASA Astrophysics Data System (ADS)

    Roussos, E.; Kollmann, P.; Krupp, N.; Paranicas, C.; Dialynas, K.; Sergis, N.; Mitchell, D. G.; Krimigis, S. M.

    2017-12-01

    During 2008, Cassini performed a unique series of orbits with a period of about 7 days which allowed us to monitor the evolution of Saturn's radiation belts across time scales shorter than the 28-day solar rotation and to identify the role of Corotating Interaction Regions (CIRs) as a key driver of dynamics for the belts' MeV electron population. Cassini's "Grand Finale" included a new set of such short-period orbits (6.5 to 7.2 days long), executed continuously between November 20, 2016 until September 15, 2017. While the 2008 observations were typically limited up to the L-shell of the G-ring, the Grand Finale orbits probed the radiation belts deeper and for a longer duration, covering the sparsely sampled regions outside the F- and A-rings and the previously unexplored particle trapping region inside the main rings. Observations with Cassini's MIMI/LEMMS instrument reveal that the electron belt intensities are persistently asymmetric in local time all the way down to the exterior edge of the main rings. The strength of this asymmetry appears to correlate with the appearence of transient belt components and changes in the intensity of the main belts which may be triggered by solar-wind or magnetospheric driven storms. The intensity of transient components in the electron belts, that may also appear in the small gap between the A- and the F-rings, evolve over several weeks, indicating that convection may occasionally dominate diffusive electron transport, the time scales of which are longer. Detection of MeV electrons inside the main rings during the Proximal orbits is ambiguous, but if electrons are present, all the LEMMS channels that may contain their signal indicate that their distribution would be very stable in time and unaffected by convective fields that drive electron transport outside the main rings.

  19. On the time needed to reach an equilibrium structure of the radiation belts

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ripoll, J. -F.; Loran, V.; Cunningham, Gregory Scott

    In this paper, we complement the notion of equilibrium states of the radiation belts with a discussion on the dynamics and time needed to reach equilibrium. We solve for the equilibrium states obtained using 1D radial diffusion with recently developed hiss and chorus lifetimes at constant values of Kp = 1, 3 and 6. We find that the equilibrium states at moderately low Kp, when plotted vs L-shell (L) and energy (E), display the same interesting S-shape for the inner edge of the outer belt as recently observed by the Van Allen Probes. The S-shape is also produced as themore » radiation belts dynamically evolve toward the equilibrium state when initialized to simulate the buildup after a massive dropout or to simulate loss due to outward diffusion from a saturated state. Physically, this shape, intimately linked with the slot structure, is due to the dependence of electron loss rate (originating from wave-particle interactions) on both energy and L-shell. Equilibrium electron flux profiles are governed by the Biot number (τ Diffusion/τ loss), with large Biot number corresponding to low fluxes and low Biot number to large fluxes. The time it takes for the flux at a specific (L, E) to reach the value associated with the equilibrium state, starting from these different initial states, is governed by the initial state of the belts, the property of the dynamics (diffusion coefficients), and the size of the domain of computation. Its structure shows a rather complex scissor form in the (L, E) plane. The equilibrium value (phase space density or flux) is practically reachable only for selected regions in (L, E) and geomagnetic activity. Convergence to equilibrium requires hundreds of days in the inner belt for E > 300 keV and moderate Kp (≤3). It takes less time to reach equilibrium during disturbed geomagnetic conditions (Kp ≥ 3), when the system evolves faster. Restricting our interest to the slot region, below L = 4, we find that only small regions in (L, E) space

  20. On the time needed to reach an equilibrium structure of the radiation belts

    DOE PAGES

    Ripoll, J. -F.; Loran, V.; Cunningham, Gregory Scott; ...

    2016-08-01

    In this paper, we complement the notion of equilibrium states of the radiation belts with a discussion on the dynamics and time needed to reach equilibrium. We solve for the equilibrium states obtained using 1D radial diffusion with recently developed hiss and chorus lifetimes at constant values of Kp = 1, 3 and 6. We find that the equilibrium states at moderately low Kp, when plotted vs L-shell (L) and energy (E), display the same interesting S-shape for the inner edge of the outer belt as recently observed by the Van Allen Probes. The S-shape is also produced as themore » radiation belts dynamically evolve toward the equilibrium state when initialized to simulate the buildup after a massive dropout or to simulate loss due to outward diffusion from a saturated state. Physically, this shape, intimately linked with the slot structure, is due to the dependence of electron loss rate (originating from wave-particle interactions) on both energy and L-shell. Equilibrium electron flux profiles are governed by the Biot number (τ Diffusion/τ loss), with large Biot number corresponding to low fluxes and low Biot number to large fluxes. The time it takes for the flux at a specific (L, E) to reach the value associated with the equilibrium state, starting from these different initial states, is governed by the initial state of the belts, the property of the dynamics (diffusion coefficients), and the size of the domain of computation. Its structure shows a rather complex scissor form in the (L, E) plane. The equilibrium value (phase space density or flux) is practically reachable only for selected regions in (L, E) and geomagnetic activity. Convergence to equilibrium requires hundreds of days in the inner belt for E > 300 keV and moderate Kp (≤3). It takes less time to reach equilibrium during disturbed geomagnetic conditions (Kp ≥ 3), when the system evolves faster. Restricting our interest to the slot region, below L = 4, we find that only small regions in (L, E) space

  1. Electrons in the Inner Van Allen Belt

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Reeves, Geoff

    A recent study shows that the inner Van Allen belt has less radiation than previously believed. Observations from NASA’s Van Allen probes show the fastest, most energetic electrons in the inner radiation belt are actually much rarer and harder to find than scientists expected. This is good news for spacecraft that are orbiting in the region and can be damaged by high levels of radiation. The results will also help scientists better understand—and detect—effects from high-altitude nuclear explosions.

  2. Liquid droplet radiator program at the NASA Lewis Research Center

    NASA Technical Reports Server (NTRS)

    Presler, A. F.; Coles, C. E.; Diem-Kirsop, P. S.; White, K. A., III

    1985-01-01

    The NASA Lewis Research Center and the Air Force Rocket Propulsion Laboratory (AFRPL) are jointly engaged in a program for technical assessment of the Liquid Droplet Radiator (LDR) concept as an advanced high performance heat ejection component for future space missions. NASA Lewis has responsibility for the technology needed for the droplet generator, for working fluid qualification, and for investigating the physics of droplets in space; NASA Lewis is also conducting systems/mission analyses for potential LDR applications with candidate space power systems. For the droplet generator technology task, both micro-orifice fabrication techniques and droplet stream formation processes have been experimentally investigated. High quality micro-orifices (to 50 micron diameter) are routinely fabricated with automated equipment. Droplet formation studies have established operating boundaries for the generation of controlled and uniform droplet streams. A test rig is currently being installed for the experimental verification, under simulated space conditions, of droplet radiation heat transfer performance analyses and the determination of the effect radiative emissivity of multiple droplet streams. Initial testing has begun in the NASA Lewis Zero-Gravity Facility for investigating droplet stream behavior in microgravity conditions. This includes the effect of orifice wetting on jet dynamics and droplet formation. Results for both Brayton and Stirling power cycles have identified favorable mass and size comparisons of the LDR with conventional radiator concepts.

  3. Energetic electrons response to ULF waves induced by interplanetary shocks in the outer radiation belt

    NASA Astrophysics Data System (ADS)

    Zong, Qiugang

    Strong interplanetary shocks interaction with the Earth's magnetosphere would have great impacts on the Earth's magnetosphere. Cluster and Double Star constellation provides an ex-cellent opportunity to study the inner magnetospheric response to a powerful interplanetary solar wind forcing. An interplanetary shock on Nov.7 2004 with the solar wind dynamic pres-sure ˜ 70 nPa (Maximum) induced a large bipolar electric field in the plasmasphere boundary layer as observed by Cluster fleet, the peak-to-peak ∆Ey is more than 60 mV/m. Energetic elec-trons in the outer radiation belt are accelerated almost simultaneously when the interplanetary shock impinges upon the Earth's magnetosphere. Energetic electron bursts are coincident with the induced large electric field, energetic electrons (30 to 500 keV) with 900 pitch angles are accelerated first whereas those electrons are decelerated when the shock-induced electric field turns to positive value. Both toroidal and poloidal mode waves are found to be important but interacting with energetic electron at a different L-shell and a different period. At the Cluster's position (L = 4.4,), poloidal is predominant wave mode whereas at the geosynchronous orbits (L = 6.6), the ULF waves observed by the GOES -10 and -12 satellites are mostly toroidal. For comparison, a rather weak interplanetary shock on Aug. 30, 2001 (dynamic pressure ˜ 2.7 nPa) is also investigated in this paper. It is found that interplanetary shocks or solar wind pressure pulses with even small dynamic pressure change would have non-ignorable role in the radiation belt dynamic. Further, in this paper, our results also reveal the excitation of ULF waves re-sponses on the passing interplanetary shock, especially the importance of difference ULF wave modes when interacting with the energetic electrons in the radiation belt. The damping of the shock induced ULF waves could be separated into two terms: one term corresponds to the generalized Landau damping, the

  4. Prompt Disappearance and Emergence of Radiation Belt Magnetosonic Waves Induced by Solar Wind Dynamic Pressure Variations

    NASA Astrophysics Data System (ADS)

    Liu, Nigang; Su, Zhenpeng; Zheng, Huinan; Wang, Yuming; Wang, Shui

    2018-01-01

    Magnetosonic waves are highly oblique whistler mode emissions transferring energy from the ring current protons to the radiation belt electrons in the inner magnetosphere. Here we present the first report of prompt disappearance and emergence of magnetosonic waves induced by the solar wind dynamic pressure variations. The solar wind dynamic pressure reduction caused the magnetosphere expansion, adiabatically decelerated the ring current protons for the Bernstein mode instability, and produced the prompt disappearance of magnetosonic waves. On the contrary, because of the adiabatic acceleration of the ring current protons by the solar wind dynamic pressure enhancement, magnetosonic waves emerged suddenly. In the absence of impulsive injections of hot protons, magnetosonic waves were observable even only during the time period with the enhanced solar wind dynamic pressure. Our results demonstrate that the solar wind dynamic pressure is an essential parameter for modeling of magnetosonic waves and their effect on the radiation belt electrons.

  5. Galactic Cosmic Ray Simulator at the NASA Space Radiation Laboratory

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Slaba, Tony C.; Rusek, Adam

    2015-01-01

    The external Galactic Cosmic Ray (GCR) spectrum is significantly modified when it passes through spacecraft shielding and astronauts. One approach for simulating the GCR space radiation environment is to attempt to reproduce the unmodified, external GCR spectrum at a ground based accelerator. A possibly better approach would use the modified, shielded tissue spectrum, to select accelerator beams impinging on biological targets. NASA plans for implementation of a GCR simulator at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory will be discussed.

  6. One ring to rule them all: storm time ring current and its influence on radiation belts, plasmasphere and global magnetosphere electrodynamics

    NASA Astrophysics Data System (ADS)

    Buzulukova, Natalia; Fok, Mei-Ching; Glocer, Alex; Moore, Thomas E.

    2013-04-01

    We report studies of the storm time ring current and its influence on the radiation belts, plasmasphere and global magnetospheric dynamics. The near-Earth space environment is described by multiscale physics that reflects a variety of processes and conditions that occur in magnetospheric plasma. For a successful description of such a plasma, a complex solution is needed which allows multiple physics domains to be described using multiple physical models. A key population of the inner magnetosphere is ring current plasma. Ring current dynamics affects magnetic and electric fields in the entire magnetosphere, the distribution of cold ionospheric plasma (plasmasphere), and radiation belts particles. To study electrodynamics of the inner magnetosphere, we present a MHD model (BATSRUS code) coupled with ionospheric solver for electric field and with ring current-radiation belt model (CIMI code). The model will be used as a tool to reveal details of coupling between different regions of the Earth's magnetosphere. A model validation will be also presented based on comparison with data from THEMIS, POLAR, GOES, and TWINS missions. INVITED TALK

  7. Genesis of the NASA Space Radiation Laboratory.

    PubMed

    Schimmerling, Walter

    2016-06-01

    A personal recollection of events leading up to the construction and commissioning of NSRL, including reference to precursor facilities and the development of the NASA Space Radiation Program. Copyright © 2016 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  8. Highly Relativistic Radiation Belt Electron Acceleration, Transport, and Loss: Large Solar Storm Events of March and June 2015

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Jaynes, A. N.; Kanekal, S. G.; Foster, J.C.; Erickson, P. J.; Fennell, Joseph; Blake, J. B.; Zhao, H.; Li, X.; Elkington, S. R.; hide

    2016-01-01

    Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection-driven event occurred with a Dst (Disturbance Storm Time Ring Current Index) value reaching 223 nanoteslas. On 22 June 2015 another strong storm (Dst reaching 204 nanoteslas) was recorded. These two storms each produced almost total loss of radiation belt high-energy (E (Energy) greater than or approximately equal to 1 millielectronvolt) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 millielectronvolts in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong butterfly distributions with deep minima in flux at alpha equals 90 degrees. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported impenetrable barrier at L (L-shell magnetic field line value) approximately equal to 2.8 was pushed inward, but not significantly breached, and no E (Energy) greater than or approximately equal to 2.0 millielectronvolts electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Overall, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis.

  9. Highly relativistic radiation belt electron acceleration, transport, and loss: Large solar storm events of March and June 2015

    PubMed Central

    Jaynes, A. N.; Kanekal, S. G.; Foster, J. C.; Erickson, P. J.; Fennell, J. F.; Blake, J. B.; Zhao, H.; Li, X.; Elkington, S. R.; Henderson, M. G.; Reeves, G. D.; Spence, H. E.; Kletzing, C. A.; Wygant, J. R.

    2016-01-01

    Abstract Two of the largest geomagnetic storms of the last decade were witnessed in 2015. On 17 March 2015, a coronal mass ejection‐driven event occurred with a Dst (storm time ring current index) value reaching −223 nT. On 22 June 2015 another strong storm (Dst reaching −204 nT) was recorded. These two storms each produced almost total loss of radiation belt high‐energy (E ≳ 1 MeV) electron fluxes. Following the dropouts of radiation belt fluxes there were complex and rather remarkable recoveries of the electrons extending up to nearly 10 MeV in kinetic energy. The energized outer zone electrons showed a rich variety of pitch angle features including strong “butterfly” distributions with deep minima in flux at α = 90°. However, despite strong driving of outer zone earthward radial diffusion in these storms, the previously reported “impenetrable barrier” at L ≈ 2.8 was pushed inward, but not significantly breached, and no E ≳ 2.0 MeV electrons were seen to pass through the radiation belt slot region to reach the inner Van Allen zone. Overall, these intense storms show a wealth of novel features of acceleration, transport, and loss that are demonstrated in the present detailed analysis. PMID:27867796

  10. Observing the Edge of the Inner Radiation Belt: the South Atlantic Anomaly Seen with Photometers in Low Earth Orbit

    NASA Astrophysics Data System (ADS)

    Schaefer, R. K.; Wolven, B. C.; Paxton, L.; Romeo, G.; Selby, C.; Hsieh, S. W.

    2013-12-01

    The South Atlantic Anomaly (SAA) is a region where the Earth's inner radiation belt dips down and bathes low earth orbit satellites with energetic charged particles sometimes causing problems for satellite operations. We will describe data from a series of UV spectrographic imagers (DMSP/SSUSI) that remain on through 4 daily SAA passages. Using spectrographic information, we are able to separate, study, and remove the detector counts due to energetic (~ 1 MeV and above) particle hits. We have made a model of the SAA at Defense Meteorological Satellite Program altitudes (~850 km), and we are able to monitor the intensity of the SAA over the long term (> a decade). Using this window into the inner radiation belt, we are able to see seasonal and solar cycle variations in intensity. In this talk we will describe the techniques, the model, and show results of our study, and and indicate directions for future development and usefulness of using SSUSI as an inner radiation belt particle intensity monitor. Nighttime 427 nm Photometer count rates as seen by SSUSI binned onto a 3 x 3 degree grid and accumulated over the year 2006. The classic shape of the South Atlantic Anomaly is clearly traced by the data.

  11. Twenty years of space radiation physics at the BNL AGS and NASA Space Radiation Laboratory.

    PubMed

    Miller, J; Zeitlin, C

    2016-06-01

    Highly ionizing atomic nuclei HZE in the GCR will be a significant source of radiation exposure for humans on extended missions outside low Earth orbit. Accelerators such as the LBNL Bevalac and the BNL AGS, designed decades ago for fundamental nuclear and particle physics research, subsequently found use as sources of GCR-like particles for ground-based physics and biology research relevant to space flight. The NASA Space Radiation Laboratory at BNL was constructed specifically for space radiation research. Here we review some of the space-related physics results obtained over the first 20 years of NASA-sponsored research at Brookhaven. Copyright © 2016 The Committee on Space Research (COSPAR). Published by Elsevier Ltd. All rights reserved.

  12. NASA Human Research Program Space Radiation Program Element

    NASA Technical Reports Server (NTRS)

    Chappell, Lori; Huff, Janice; Patel, Janapriya; Wang, Minli; Hu, Shaowwen; Kidane, Yared; Myung-Hee, Kim; Li, Yongfeng; Nounu, Hatem; Plante, Ianik; hide

    2013-01-01

    The goal of the NASA Human Research Program's Space Radiation Program Element is to ensure that crews can safely live and work in the space radiation environment. Current work is focused on developing the knowledge base and tools required for accurate assessment of health risks resulting from space radiation exposure including cancer and circulatory and central nervous system diseases, as well as acute risks from solar particle events. Division of Space Life Sciences (DSLS) Space Radiation Team scientists work at multiple levels to advance this goal, with major projects in biological risk research; epidemiology; and physical, biophysical, and biological modeling.

  13. Quantification of the Precipitation Loss of Radiation Belt Electrons Observed by SAMPEX (Invited)

    NASA Astrophysics Data System (ADS)

    Tu, W.; Li, X.; Selesnick, R. S.; Looper, M. D.

    2010-12-01

    Based on SAMPEX/PET observations, the fluxes and the spatial and temporal variations of electron loss to the atmosphere in the Earth’s radiation belt were quantified using a drift-diffusion model that includes the effects of azimuthal drift and pitch angle diffusion. The measured electrons by SAMPEX can be distinguished as trapped, quasi-trapped (in the drift loss cone), or precipitating (in the bounce loss cone), and the model simulates the low-altitude electron distribution from SAMPEX. After fitting the model results to the data, the magnitudes and variations of the electron loss rate can be estimated based on the optimum model parameter values. In this presentation we give an overview of our method and published results, followed by some recent improvements we made on the model, including updating the quantified electron lifetimes more frequently (e.g., every two hours instead of half a day) to achieve smoother variations, estimating the adiabatic effects at SAMPEX’s orbit and their influence on our model results, and calculating the error bar associated with each quantified electron lifetime. This method combining a model with low-altitude observations provides direct quantification of the electron loss rate, as required for any accurate modeling of the radiation belt electron dynamics.

  14. Statistical analysis of low-energy electron fluxes in the radiation belt: ERG LEP-e measurements

    NASA Astrophysics Data System (ADS)

    Chang, T. F.; Chiang, C. Y.; Tam, S. W. Y.; Syugu, W. J.; Kazama, Y.; Wang, B. J.; Wang, S. Y.; Hori, T.; Yoshizumi, M.; Shinohara, I.

    2017-12-01

    The Exploration of energization and Radiation in Geospace (ERG) satellite, which is led by Institute of Space and Astronautical Science (ISAS), Japan Aerospace Exploration Agency (JAXA), has observed the Earth's radiation belts for several months. Through years of efforts, Taiwan team successfully delivered the low-energy particle experiments - electron analyzer (LEP-e) for deployment on the ERG satellite. In Taiwan, the project is led by Academia Sinica Institute of Astronomy and Astrophysics (ASIAA) in partnership with National Cheng Kung University (NCKU). The LEP-e instrument measures a 3-D velocity distribution function of low energy electrons ranging from 20 eV to 19 keV. We provide an overview of electron fluxes within the radiation belts using the LEP-e instrument data obtained in the past months. The L-shell plots are made upon 100 eV, 1 keV and 10 keV, respectively, to display the electron flux in various L-shells measured by the ERG satellite. The enhancement of the electron fluxes is found to show correspondence with the increase of ring current intensity. These electrons are found to migrate inwards as the ring current increases. We also investigate the 3-D distribution of the electron fluxes and discuss the contribution of the energetic electrons to the ring current.

  15. Role of dust direct radiative effect on the tropical rain belt over Middle East and North Africa: A high-resolution AGCM study

    NASA Astrophysics Data System (ADS)

    Bangalath, Hamza Kunhu; Stenchikov, Georgiy

    2015-05-01

    To investigate the influence of direct radiative effect of dust on the tropical summer rain belt across the Middle East and North Africa (MENA), the present study utilizes the high-resolution capability of an Atmospheric General Circulation Model, the High-Resolution Atmospheric Model. Ensembles of Atmospheric Model Intercomparison Project style simulations have been conducted with and without dust radiative impacts, to differentiate the influence of dust on the tropical rain belt. The analysis focuses on summer season. The results highlight the role of dust-induced responses in global- and regional-scale circulations in determining the strength and the latitudinal extent of the tropical rain belt. A significant response in the strength and position of the local Hadley circulation is predicted in response to meridionally asymmetric distribution of dust and the corresponding radiative effects. Significant responses are also found in regional circulation features such as African Easterly Jet and West African Monsoon circulation. Consistent with these dynamic responses at various scales, the tropical rain belt across MENA strengthens and shifts northward. Importantly, the summer precipitation over the semiarid strip south of Sahara, including Sahel, increases up to 20%. As this region is characterized by the "Sahel drought," the predicted precipitation sensitivity to the dust loading over this region has a wide range of socioeconomic implications. Overall, the study demonstrates the extreme importance of incorporating dust radiative effects and the corresponding circulation responses at various scales, in the simulations and future projections of this region's climate.

  16. Empirical radiation belt models: Comparison with in situ data and implications for environment definition

    NASA Astrophysics Data System (ADS)

    de Soria-Santacruz Pich, Maria; Jun, Insoo; Evans, Robin

    2017-09-01

    The empirical AP8/AE8 model has been the de facto Earth's radiation belts engineering reference for decades. The need from the community for a better model incubated the development of AP9/AE9/SPM, which addresses several shortcomings of the old model. We provide additional validation of AP9/AE9 by comparing in situ electron and proton data from Jason-2, Polar Orbiting Environmental Satellites (POES), and the Van Allen Probes spacecraft with the 5th, 50th, and 95th percentiles from AE9/AP9 and with the model outputs from AE8/AP8. The relatively short duration of Van Allen Probes and Jason-2 missions means that their measurements are most certainly the result of specific climatological conditions. In low Earth orbit (LEO), the Jason-2 proton flux is better reproduced by AP8 compared to AP9, while the POES electron data are well enveloped by AE9 5th and 95th percentiles. The shape of the South Atlantic anomaly (SAA) from Jason-2 data is better captured by AP9 compared to AP8, while the peak SAA flux is better reproduced by AP8. The <1.5 MeV inner belt electrons from Magnetic Electron Ion Spectrometer (MagEIS) are well enveloped by AE9 5th and 95th percentiles, while AE8 overpredicts the measurements. In the outer radiation belt, MagEIS and Relativistic Electron and Proton Telescope (REPT) electrons closely follow the median estimate from AE9, while AP9 5th and 95th percentiles generally envelope REPT proton measurements in the inner belt and slot regions. While AE9/AP9 offer the flexibility to specify the environment with different confidence levels, the dose and trapped proton peak flux for POES and Jason-2 trajectories from the AE9/AP9 50th percentile and above are larger than the estimates from the AE8/AP8 models.

  17. NASA Space Radiation Risk Project: Overview and Recent Results

    NASA Technical Reports Server (NTRS)

    Blattnig, Steve R.; Chappell, Lori J.; George, Kerry A.; Hada, Megumi; Hu, Shaowen; Kidane, Yared H.; Kim, Myung-Hee Y.; Kovyrshina, Tatiana; Norman, Ryan B.; Nounu, Hatem N.; hide

    2015-01-01

    The NASA Space Radiation Risk project is responsible for integrating new experimental and computational results into models to predict risk of cancer and acute radiation syndrome (ARS) for use in mission planning and systems design, as well as current space operations. The project has several parallel efforts focused on proving NASA's radiation risk projection capability in both the near and long term. This presentation will give an overview, with select results from these efforts including the following topics: verification, validation, and streamlining the transition of models to use in decision making; relative biological effectiveness and dose rate effect estimation using a combination of stochastic track structure simulations, DNA damage model calculations and experimental data; ARS model improvements; pathway analysis from gene expression data sets; solar particle event probabilistic exposure calculation including correlated uncertainties for use in design optimization.

  18. Earthward penetration of Pc 4-5 waves and radiation belt electron enhancements during geospace magnetic storms

    NASA Astrophysics Data System (ADS)

    Daglis, I. A.; Georgiou, M.; Zesta, E.; Balasis, G.; Tsinganos, K.

    2013-12-01

    This paper addresses the question whether radiation belt electron enhancements are associated with ultra-low frequency (ULF) wave power penetrating to lower L-shells during intense geospace magnetic storms. We have examined the variation of relativistic electron fluxes in the inner magnetosphere during small, moderate, and intense storms and have compared them with concurrent variations of the power of Pc 4-5 waves, using multi-point wave observations from the IMAGE and CARISMA ground-based magnetometer arrays. We discuss the excitation, growth and decay characteristics of Pc 4-5 waves during the different phases of the three classes of magnetic storms, with particular emphasis on the distribution of wave power over a range of L shells. The work leading to this paper has received funding from the European Union's Seventh Framework Programme (FP7-SPACE-2011-1) under grant agreement no. 284520 for the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Energization and Loss) collaborative research project.

  19. Very Oblique Whistler Mode Propagation in the Radiation Belts: Effects of Hot Plasma and Landau Damping

    DOE PAGES

    Ma, Q.; Artemyev, A. V.; Mourenas, D.; ...

    2017-11-30

    We present that satellite observations of a significant population of very oblique chorus waves in the outer radiation belt have fueled considerable interest in the effects of these waves on energetic electron scattering and acceleration. However, corresponding diffusion rates are extremely sensitive to the refractive index N, controlled by hot plasma effects including Landau damping and wave dispersion modifications by suprathermal (15–100 eV) electrons. A combined investigation of wave and electron distribution characteristics obtained from the Van Allen Probes shows that peculiarities of the measured electron distribution significantly reduce Landau damping, allowing wave propagation with high N ~ 100–200. Furthermore » comparing measured refractive indexes with theoretical estimates incorporating hot plasma corrections to the wave dispersion, we provide the first experimental demonstration that suprathermal electrons indeed control the upper limit of the refractive index of highly oblique whistler mode waves. In conclusion, such results further support the importance of incorporating very oblique waves into radiation belt models.« less

  20. Very Oblique Whistler Mode Propagation in the Radiation Belts: Effects of Hot Plasma and Landau Damping

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ma, Q.; Artemyev, A. V.; Mourenas, D.

    We present that satellite observations of a significant population of very oblique chorus waves in the outer radiation belt have fueled considerable interest in the effects of these waves on energetic electron scattering and acceleration. However, corresponding diffusion rates are extremely sensitive to the refractive index N, controlled by hot plasma effects including Landau damping and wave dispersion modifications by suprathermal (15–100 eV) electrons. A combined investigation of wave and electron distribution characteristics obtained from the Van Allen Probes shows that peculiarities of the measured electron distribution significantly reduce Landau damping, allowing wave propagation with high N ~ 100–200. Furthermore » comparing measured refractive indexes with theoretical estimates incorporating hot plasma corrections to the wave dispersion, we provide the first experimental demonstration that suprathermal electrons indeed control the upper limit of the refractive index of highly oblique whistler mode waves. In conclusion, such results further support the importance of incorporating very oblique waves into radiation belt models.« less

  1. Inner Magnetosphere Modeling at the CCMC: Ring Current, Radiation Belt and Magnetic Field Mapping

    NASA Astrophysics Data System (ADS)

    Rastaetter, L.; Mendoza, A. M.; Chulaki, A.; Kuznetsova, M. M.; Zheng, Y.

    2013-12-01

    Modeling of the inner magnetosphere has entered center stage with the launch of the Van Allen Probes (RBSP) in 2012. The Community Coordinated Modeling Center (CCMC) has drastically improved its offerings of inner magnetosphere models that cover energetic particles in the Earth's ring current and radiation belts. Models added to the CCMC include the stand-alone Comprehensive Inner Magnetosphere-Ionosphere (CIMI) model by M.C. Fok, the Rice Convection Model (RCM) by R. Wolf and S. Sazykin and numerous versions of the Tsyganenko magnetic field model (T89, T96, T01quiet, TS05). These models join the LANL* model by Y. Yu hat was offered for instant run earlier in the year. In addition to these stand-alone models, the Comprehensive Ring Current Model (CRCM) by M.C. Fok and N. Buzulukova joined as a component of the Space Weather Modeling Framework (SWMF) in the magnetosphere model run-on-request category. We present modeling results of the ring current and radiation belt models and demonstrate tracking of satellites such as RBSP. Calculations using the magnetic field models include mappings to the magnetic equator or to minimum-B positions and the determination of foot points in the ionosphere.

  2. Nonlinear VLF Wave Physics in the Radiation Belts

    NASA Astrophysics Data System (ADS)

    Crabtree, C. E.; Tejero, E. M.; Ganguli, G.; Mithaiwala, M.; Rudakov, L.; Hospodarsky, G. B.; Kletzing, C.

    2014-12-01

    Electromagnetic VLF waves, such as whistler mode waves, both control the lifetime of trapped electrons in the radiation belts by pitch-angle scattering and are responsible for the energization of electrons during storms. Traditional approaches to understanding the influence of waves on trapped electrons have assumed that the wave characteristics (frequency spectrum, wave-normal angle distribution, etc.) were both stationary in time and amplitude independent from event to event. In situ data from modern satellite missions, such as the Van Allen probes, are showing that this assumption may not be justified. In addition, recent theoretical results [Crabtree et al. 2012] show that the threshold for nonlinear wave scattering can often be met by naturally occurring VLF waves in the magnetosphere, with wave magnetic fields of the order of 50-100 pT inside the plasmapause. Nonlinear wave scattering (Nonlinear Landau Damping) is an amplitude dependent mechanism that can strongly alter VLF wave propagation [Ganguli et al. 2010], primarily by altering the direction of propagation. Laboratory results have confirmed the dramatic change in propagation direction when the pump wave has sufficient amplitude to exceed the nonlinear threshold [Tejero et al. 2014]. Nonlinear scattering can alter the macroscopic dynamics of waves in the radiation belts leading to the formation of a long-lasting wave-cavity [Crabtree et al. 2012] and, when amplification is present, a multi-pass amplifier [Ganguli et al., 2012]. Such nonlinear wave effects can dramatically reduce electron lifetimes. Nonlinear wave dynamics such as these occur when there are more than one wave present, such a condition necessarily violates the assumption of traditional wave-normal analysis [Santolik et al., 2003] which rely on the plane wave assumption. To investigate nonlinear wave dynamics using modern in situ data we apply the maximum entropy method [Skilling and Bryan, 1984] to solve for the wave distribution function

  3. Origins and Asteroid Main-Belt Stratigraphy for H-, L-, LL-Chondrite Meteorites

    NASA Astrophysics Data System (ADS)

    Binzel, Richard; DeMeo, Francesca; Burbine, Thomas; Polishook, David; Birlan, Mirel

    2016-10-01

    We trace the origins of ordinary chondrite meteorites to their main-belt sources using their (presumably) larger counterparts observable as near-Earth asteroids (NEAs). We find the ordinary chondrite stratigraphy in the main belt to be LL, H, L (increasing distance from the Sun). We derive this result using spectral information from more than 1000 near-Earth asteroids [1]. Our methodology is to correlate each NEA's main-belt source region [2] with its modeled mineralogy [3]. We find LL chondrites predominantly originate from the inner edge of the asteroid belt (nu6 region at 2.1 AU), H chondrites from the 3:1 resonance region (2.5 AU), and the L chondrites from the outer belt 5:2 resonance region (2.8 AU). Each of these source regions has been cited by previous researchers [e.g. 4, 5, 6], but this work uses an independent methodology that simultaneously solves for the LL, H, L stratigraphy. We seek feedback from the planetary origins and meteoritical communities on the viability or implications of this stratrigraphy.Methodology: Spectroscopic and taxonomic data are from the NASA IRTF MIT-Hawaii Near-Earth Object Spectroscopic Survey (MITHNEOS) [1]. For each near-Earth asteroid, we use the Bottke source model [2] to assign a probability that the object is derived from five different main-belt source regions. For each spectrum, we apply the Shkuratov model [3] for radiative transfer within compositional mixing to derive estimates for the ol / (ol+px) ratio (and its uncertainty). The Bottke source region model [2] and the Shkuratov mineralogic model [3] each deliver a probability distribution. For each NEA, we convolve its source region probability distribution with its meteorite class distribution to yield a likelihood for where that class originates. Acknowledgements: This work supported by the National Science Foundation Grant 0907766 and NASA Grant NNX10AG27G.References: [1] Binzel et al. (2005), LPSC XXXVI, 36.1817. [2] Bottke et al. (2002). Icarus 156, 399. [3

  4. Review of NASA approach to space radiation risk assessments for Mars exploration.

    PubMed

    Cucinotta, Francis A

    2015-02-01

    Long duration space missions present unique radiation protection challenges due to the complexity of the space radiation environment, which includes high charge and energy particles and other highly ionizing radiation such as neutrons. Based on a recommendation by the National Council on Radiation Protection and Measurements, a 3% lifetime risk of exposure-induced death for cancer has been used as a basis for risk limitation by the National Aeronautics and Space Administration (NASA) for low-Earth orbit missions. NASA has developed a risk-based approach to radiation exposure limits that accounts for individual factors (age, gender, and smoking history) and assesses the uncertainties in risk estimates. New radiation quality factors with associated probability distribution functions to represent the quality factor's uncertainty have been developed based on track structure models and recent radiobiology data for high charge and energy particles. The current radiation dose limits are reviewed for spaceflight and the various qualitative and quantitative uncertainties that impact the risk of exposure-induced death estimates using the NASA Space Cancer Risk (NSCR) model. NSCR estimates of the number of "safe days" in deep space to be within exposure limits and risk estimates for a Mars exploration mission are described.

  5. On the source location of radiation belt relativistic electrons

    NASA Astrophysics Data System (ADS)

    Selesnick, R. S.; Blake, J. B.

    2000-02-01

    Observations from the High Sensitivity Telescope (HIST) on Polar made around Janurary and May 1998 are used to constrain the source location of outer radiation belt relativistic electrons. Phase space densities calculated as a function of the three adiabatic invariants show positive radial gradients for L<4, suggestive of no source in that region. In particular, the peak intensity near L=3 of a large enhancement beginning on May 4, 1998, appears to have been formed by inward transport over a period of several days. For L>4, peaks in the radial dependence of the phase space density are suggestive of a local electron source that may be nonadiabatic acceleration or pitch angle scattering. However, discrepancies in the results obtained with different magnetic field models and at different local times make this a tentative conclusion.

  6. Penetration of Solar Wind Driven ULF Waves into the Earth's Inner Magnetosphere: Role in Radiation Belt and Ring Current Dynamics

    NASA Astrophysics Data System (ADS)

    Mann, Ian; Murphy, Kyle; Rae, Jonathan; Ozeke, Louis; Milling, David

    2013-04-01

    combination of data from ground arrays such as CARISMA and the contemporaneous operation of the NASA Van Allen Probes (VAP) mission offers an excellent basis for understanding this cross-energy plasma coupling which spans more than 6 orders of magnitude in energy. Explaining the casual connections between plasmas in the plasmasphere (eV), ring current (keV), and radiation belt (MeV), via the intermediaries of plasma waves, is key to understanding inner magnetosphere dynamics. This work has received funding from the European Union under the Seventh Framework Programme (FP7-Space) under grant agreement n 284520 for the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Energization and Loss) collaborative research project.

  7. Van Allen Probes Science Gateway: Single-Point Access to Long-Term Radiation Belt Measurements and Space Weather Nowcasting

    NASA Astrophysics Data System (ADS)

    Romeo, G.; Barnes, R. J.; Ukhorskiy, A. Y.; Sotirelis, T.; Stephens, G.

    2017-12-01

    The Science Gateway gives single-point access to over 4.5 years of comprehensive wave and particle measurements from the Van Allen Probes NASA twin-spacecraft mission. The Gateway provides a set of visualization and data analysis tools including: HTML5-based interactive visualization of high-level data products from all instrument teams in the form of: line plots, orbital content plots, dynamical energy spectra, L-shell context plots (including two-spacecraft plotting), FFT spectra of wave data, solar wind and geomagnetic indices data, etc.; download custom multi-instrument CDF data files of selected data products; publication quality plots of digital data; combined orbit predicts for mission planning and coordination including: Van Allen Probes, MMS, THEMIS, Arase (ERG), Cluster, GOES, Geotail, FIREBIRD; magnetic footpoint calculator for coordination with LEO and ground-based assets; real-time computation and processing of empirical magnetic field models - computation of magnetic ephemeris, computation of adiabatic invariants. Van Allen Probes is the first spacecraft mission to provide a nowcast of the radiation environment in the heart of the radiation belts, where the radiation levels are the highest and most dangerous for spacecraft operations. For this purpose, all instruments continuously broadcast a subset of their science data in real time. Van Allen Probes partners with four foreign institutions who operate ground stations that receive the broadcast: Korea (KASI), the Czech republic (CAS), Argentina (CONAE), and Brazil (INPE). The SpWx broadcast is then collected at APL and delivered to the community via the Science Gateway.

  8. Galactic Cosmic Ray Simulation at the NASA Space Radiation Laboratory

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Slaba, Tony C.; Rusek, Adam

    2015-01-01

    The external Galactic Cosmic Ray (GCR) spectrum is significantly modified when it passes through spacecraft shielding and astronauts. One approach for simulating the GCR space radiation environment at ground based accelerators would use the modified spectrum, rather than the external spectrum, in the accelerator beams impinging on biological targets. Two recent workshops have studied such GCR simulation. The first workshop was held at NASA Langley Research Center in October 2014. The second workshop was held at the NASA Space Radiation Investigators' workshop in Galveston, Texas in January 2015. The results of these workshops will be discussed in this paper.

  9. A quiescent state of 3 to 8 MeV radiation belt electrons

    NASA Astrophysics Data System (ADS)

    Selesnick, R. S.; Blake, J. B.; Kolasinski, W. A.; Fritz, T. A.

    During a ∼3 month period in mid-1996 outer radiation belt electrons in the energy range from ∼ 3 to 8 MeV were diffusing inward and decaying in intensity with no internal or external source. Measurements from the HIST instrument on POLAR are used to constrain a model for time dependent lossy radial diffusion of these electrons, and to obtain estimates of a parameterized radial diffusion coefficient and lifetime. For lower energy electrons, of ∼ 1 to 3 MeV, a source at L > 6 is apparent throughout most of the same period.

  10. NASA Future Forum

    NASA Image and Video Library

    2011-08-11

    Asher Gendelman, a director of technology at Zephyr Technology, holds up chest belt as he speaks about technology investments and their benefits during a panel discussion at the 2011 NASA Future Forum held at the Riggs Alumni Center on the campus of the University of Maryland, Thursday, Aug. 11, 2011, in College Park, Md. Photo Credit: (NASA/Paul E. Alers)

  11. A Review of NASA's Radiation-Hardened Electronics for Space Environments Project

    NASA Technical Reports Server (NTRS)

    Keys, Andrew S.; Adams, James H.; Patrick, Marshall C.; Johnson, Michael A.; Cressler, John D.

    2008-01-01

    NASA's Radiation Hardened Electronics for Space Exploration (RHESE) project develops the advanced technologies required to produce radiation hardened electronics, processors, and devices in support of the requirements of NASA's Constellation program. Over the past year, multiple advancements have been made within each of the RHESE technology development tasks that will facilitate the success of the Constellation program elements. This paper provides a brief review of these advancements, discusses their application to Constellation projects, and addresses the plans for the coming year.

  12. Plasmasphere-Ring Current-Radiation Belts Interactions: Review of 16 Years of Cluster Observations

    NASA Astrophysics Data System (ADS)

    Dandouras, I. S.

    2016-12-01

    The Cluster mission is based on four identical spacecraft launched in 2000 on similar elliptical polar orbits with an initial perigee at about 4 RE and an apogee at 19.6 RE. This allows Cluster to cross the outer plasmasphere, the ring current region and the radiation belts, from south to north, during every perigee pass and to obtain their latitudinal profile following almost the same flux tube. Due to various perturbations the perigee geocentric distance decreased during 2007-2010 to about 2 RE, whereas actually it is again up to about 5 RE, allowing in this way to study, during the mission, the inner magnetosphere populations and their interactions at a wide range of L-shells and under different solar activity conditions. The CIS experiment, on board these spacecraft, provides the ion distribution functions from 1 eV (plasmasphere populations) up to 40 keV (ring current), whereas the MeV penetrating particles allow to monitor the position and dynamics of the radiation belts. The FGM experiment on board these four spacecraft allowed for the first time an instantaneous calculation of the magnetic field gradients and thus a direct measurement of the local current density using the curlometer technique. Earlier and more recent results, based on Cluster data acquired during the passes in inner magnetosphere, will be reviewed and analysed.

  13. Pitch-angle diffusion of electrons through growing and propagating along a magnetic field electromagnetic wave in Earth's radiation belts

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Choi, C.-R., E-mail: crchoi@kaist.ac.kr; Dokgo, K.; Min, K.-W.

    The diffusion of electrons via a linearly polarized, growing electromagnetic (EM) wave propagating along a uniform magnetic field is investigated. The diffusion of electrons that interact with the growing EM wave is investigated through the autocorrelation function of the parallel electron acceleration in several tens of electron gyration timescales, which is a relatively short time compared with the bounce time of electrons between two mirror points in Earth's radiation belts. Furthermore, the pitch-angle diffusion coefficient is derived for the resonant and non-resonant electrons, and the effect of the wave growth on the electron diffusion is discussed. The results can bemore » applied to other problems related to local acceleration or the heating of electrons in space plasmas, such as in the radiation belts.« less

  14. National Radiation Hardness Assurance (RHA) Planning For NASA Missions: Updated Guidance

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.; Pellish, Jonathan Allen

    2014-01-01

    Radiation Hardness Assurance (RHA) is the process of ensuring space system performance in the presence of a space radiation environment. Herein, we present an updated NASA methodology for RHA focusing on content, deliverables and timeframes.

  15. Notional Radiation Hardness Assurance (RHA) Planning For NASA Missions: Updated Guidance

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.; Pellish, Jonathan A.

    2014-01-01

    Radiation Hardness Assurance (RHA) is the process of ensuring space system performance in the presence of a space radiation environment. Herein, we present an updated NASA methodology for RHA focusing on content, deliverables and timeframes.

  16. Resonant scattering of energetic electrons in the outer radiation belt by HAARP-induced ELF/VLF waves

    NASA Astrophysics Data System (ADS)

    Chang, Shanshan; Zhu, Zhengping; Ni, Binbin; Cao, Xing; Luo, Weihua

    2016-10-01

    Several extremely low-frequency (ELF)/very low-frequency (VLF) wave generation experiments have been performed successfully at High-Frequency Active Auroral Research Program (HAARP) heating facility and the artificial ELF/VLF signals can leak into the outer radiation belt and contribute to resonant interactions with energetic electrons. Based on the artificial wave properties revealed by many of in situ observations, we implement test particle simulations to evaluate the effects of energetic electron resonant scattering driven by the HAARP-induced ELF/VLF waves. The results indicate that for both single-frequency/monotonic wave and multi-frequency/broadband waves, the behavior of each electron is stochastic while the averaged diffusion effect exhibits temporal linearity in the wave-particle interaction process. The computed local diffusion coefficients show that, the local pitch-angle scattering due to HARRP-induced single-frequency ELF/VLF whistlers with an amplitude of ∼10 pT can be intense near the loss cone with a rate of ∼10-2 rad2 s-1, suggesting the feasibility of HAARP-induced ELF/VLF waves for removal of outer radiation belt energetic electrons. In contrast, the energy diffusion of energetic electrons is relatively weak, which confirms that pitch-angle scattering by artificial ELF/VLF waves can dominantly lead to the precipitation of energetic electrons. Moreover, diffusion rates of the discrete, broadband waves, with the same amplitude of each discrete frequency as the monotonic waves, can be much larger, which suggests that it is feasible to trigger a reasonable broadband wave instead of the monotonic wave to achieve better performance of controlled precipitation of energetic electrons. Moreover, our test particle scattering simulation show good agreement with the predictions of the quasi-linear theory, confirming that both methods are applied to evaluate the effects of resonant interactions between radiation belt electrons and artificially generated

  17. Van Allen Probes observations of outer radiation belt evolution during CME and CIR storms

    NASA Astrophysics Data System (ADS)

    Hudson, M. K.; Shen, X.; Jaynes, A. N.; Shi, Q.; Tian, A.; Claudepierre, S. G.; Qin, M.; Zong, Q.; Sun, W.

    2017-12-01

    Storm time outer radiation belt evolutes dramatically. It is still an stuff problem to model and predict the evolutions. The MeV electron flux can loss, no change or increase during different storms. Most of the previous statistical results were made by low altitude polar orbiting satellites, such as SAMPEX and NOAA POES, or geosynchronous orbiting satellites, such as GOES. Although part of the electron flux observed by polar orbiting satellites can be treated as trapped electrons, they are already close to the ionosphere with pitch angles apart from 90 degrees. Geosynchronous orbiting satellites are limited to r=6.6 RE (geocentric radial distance in Earth radii). The Van Allen Probes twin spacecraft, launched on 30 August 2012 with orbit near the equatorial plane, apogee at 5.8 RE and perigee at 620 km, give us a good oppurtuinity to study the storm-time outer radiation belt evolutions. During the time period from the begining of 2013 to the end of 2016, 31 CMEs and 28 CIRs are identified from OMNI-2 dataset. Superposed epoch analysis shows that CIR-storms which increased flux closer to geosynchronous orbit consistent with earlier studies, while CME-storms likely produce deeper penetration of enhanced flux and local heating which is greater at higher energies at lower L*.

  18. Summary of types of radiation belt electron precipitation observed by BARREL

    NASA Astrophysics Data System (ADS)

    Halford, Alexa

    2016-07-01

    The Balloon Array for Relativistic Radiation belt Electron Loss (BARREL) was able to infer precipitation of radiation belt electrons on multiple time scales and due to multiple loss mechanisms. One storm will be specifically highlighted which occurred on 26 January 2013 when a solar wind shock hit the Earth. Although MeV electrons were observed to be lost due to an EMIC wave event [Zhang et al in prep], and multiple periods of electron loss during substorms were observed [Rae et al submitted JGR, Mann et al in prep], we will consider an event period where loss associated with multiple time scales, and thus possibly different loss mechanisms was observed from 1000 - 1200 UT on 26 January 2013. At about 1005 UT on 26 January 2013 an injection of radiation belt electrons followed by drift echoes for energies of ˜80 - 400 keV. BARREL observed X-rays with energies less than 180 keV associated with multiple temporal structures during the drift echo event period. The Van Allen Probes were at similar L-values but upwards of 2 hours away in MLT. Upper band chorus and ULF waves were observed during the event period. Throughout the beginning of the event period, microbursts were clearly observed. During this time lower band chorus waves as well as time domain structures were observed at Van Allen Probe A located upwards of 2 hours away in MLT. This large difference in MLT meant that neither potential loss mechanism was able to be clearly associated with the microbursts. As the lower band chorus and time domain structures were observed to recede, the microbursts were also observed to subside. ULF time scale modulation of the X-rays was also observed throughout most of the event period. We will examine if the ULF waves are the cause of the precipitation themselves, or are modulating the loss of particles from a secondary loss mechanism [Brito et al 2015 JGR, Rae et al Submitted JGR]. Although the 100s ms and ULF time scales are clearly observed, there is an ˜20 minute

  19. Kuiper Belt Objects Along the Pluto-Express Path

    NASA Technical Reports Server (NTRS)

    Jewitt, David (Principal Investigator)

    1997-01-01

    The science objective of this work is to identify objects in the Kuiper Belt which will, in the 5 years following Pluto encounter, be close to the flight path of NASA's Pluto Express. Our hope is that we will find a Kuiper Belt object or objects close enough that a spacecraft flyby will be possible. If we find a suitable object, the science yield of Pluto Express will be substantially enhanced. The density of objects in the Kuiper Belt is such that we are reasonably likely to find an object close enough to the flight path that on-board gas thrusters can effect a close encounter.

  20. On the Role of Last Closed Drift Shell Dynamics in Driving Fast Losses and Van Allen Radiation Belt Extinction

    NASA Astrophysics Data System (ADS)

    Olifer, L.; Mann, I. R.; Morley, S. K.; Ozeke, L. G.; Choi, D.

    2018-05-01

    We present observations of very fast radiation belt loss as resolved using high time resolution electron flux data from the constellation of Global Positioning System (GPS) satellites. The time scale of these losses is revealed to be as short as ˜0.5-2 hr during intense magnetic storms, with some storms demonstrating almost total loss on these time scales and which we characterize as radiation belt extinction. The intense March 2013 and March 2015 storms both show such fast extinction, with a rapid recovery, while the September 2014 storm shows fast extinction but no recovery for around 2 weeks. By contrast, the moderate September 2012 storm which generated a three radiation belt morphology shows more gradual loss. We compute the last closed drift shell (LCDS) for each of these four storms and show a very strong correspondence between the LCDS and the loss patterns of trapped electrons in each storm. Most significantly, the location of the LCDS closely mirrors the high time resolution losses observed in GPS flux. The fast losses occur on a time scale shorter than the Van Allen Probes orbital period, are explained by proximity to the LCDS, and progress inward, consistent with outward transport to the LCDS by fast ultralow frequency wave radial diffusion. Expressing the location of the LCDS in L*, and not model magnetopause standoff distance in units of RE, clearly reveals magnetopause shadowing as the cause of the fast loss observed by the GPS satellites.

  1. Radiation Environment Modeling for Spacecraft Design: New Model Developments

    NASA Technical Reports Server (NTRS)

    Barth, Janet; Xapsos, Mike; Lauenstein, Jean-Marie; Ladbury, Ray

    2006-01-01

    A viewgraph presentation on various new space radiation environment models for spacecraft design is described. The topics include: 1) The Space Radiatio Environment; 2) Effects of Space Environments on Systems; 3) Space Radiatio Environment Model Use During Space Mission Development and Operations; 4) Space Radiation Hazards for Humans; 5) "Standard" Space Radiation Environment Models; 6) Concerns about Standard Models; 7) Inadequacies of Current Models; 8) Development of New Models; 9) New Model Developments: Proton Belt Models; 10) Coverage of New Proton Models; 11) Comparison of TPM-1, PSB97, AP-8; 12) New Model Developments: Electron Belt Models; 13) Coverage of New Electron Models; 14) Comparison of "Worst Case" POLE, CRESELE, and FLUMIC Models with the AE-8 Model; 15) New Model Developments: Galactic Cosmic Ray Model; 16) Comparison of NASA, MSU, CIT Models with ACE Instrument Data; 17) New Model Developmemts: Solar Proton Model; 18) Comparison of ESP, JPL91, KIng/Stassinopoulos, and PSYCHIC Models; 19) New Model Developments: Solar Heavy Ion Model; 20) Comparison of CREME96 to CREDO Measurements During 2000 and 2002; 21) PSYCHIC Heavy ion Model; 22) Model Standardization; 23) Working Group Meeting on New Standard Radiation Belt and Space Plasma Models; and 24) Summary.

  2. Forecasting of Radiation Belts: Results From the PROGRESS Project.

    NASA Astrophysics Data System (ADS)

    Balikhin, M. A.; Arber, T. D.; Ganushkina, N. Y.; Walker, S. N.

    2017-12-01

    Forecasting of Radiation Belts: Results from the PROGRESS Project. The overall goal of the PROGRESS project, funded in frame of EU Horizon2020 programme, is to combine first principles based models with the systems science methodologies to achieve reliable forecasts of the geo-space particle radiation environment.The PROGRESS incorporates three themes : The propagation of the solar wind to L1, Forecast of geomagnetic indices, and forecast of fluxes of energetic electrons within the magnetosphere. One of the important aspects of the PROGRESS project is the development of statistical wave models for magnetospheric waves that affect the dynamics of energetic electrons such as lower band chorus, hiss and equatorial noise. The error reduction ratio (ERR) concept has been used to optimise the set of solar wind and geomagnetic parameters for organisation of statistical wave models for these emissions. The resulting sets of parameters and statistical wave models will be presented and discussed. However the ERR analysis also indicates that the combination of solar wind and geomagnetic parameters accounts for only part of the variance of the emissions under investigation (lower band chorus, hiss and equatorial noise). In addition, advances in the forecast of fluxes of energetic electrons, exploiting empirical models and the first principles IMPTAM model achieved by the PROGRESS project is presented.

  3. Accaleration of Electrons of the Outer Electron Radiation Belt and Auroral Oval Dynamics

    NASA Astrophysics Data System (ADS)

    Antonova, Elizaveta; Ovchinnikov, Ilya; Riazantseva, Maria; Znatkova, Svetlana; Pulinets, Maria; Vorobjev, Viachislav; Yagodkina, Oksana; Stepanova, Marina

    2016-07-01

    We summarize the results of experimental observations demonstrating the role of auroral processes in the formation of the outer electron radiation belt and magnetic field distortion during magnetic storms. We show that the auroral oval does not mapped to the plasma sheet proper (region with magnetic field lines stretched in the tailward direction). It is mapped to the surrounding the Earth plasma ring in which transverse currents are closed inside the magnetosphere. Such currents constitute the high latitude continuation of the ordinary ring current. Mapping of the auroral oval to the region of high latitude continuation of the ordinary ring current explains the ring like shape of the auroral oval with finite thickness near noon and auroral oval dynamics during magnetic storms. The auroral oval shift to low latitudes during storms. The development of the ring current produce great distortion of the Earth's magnetic field and corresponding adiabatic variations of relativistic electron fluxes. Development of the asymmetric ring current produce the dawn-dusk asymmetry of such fluxes. We analyze main features of the observed processes including formation of sharp plasma pressure profiles during storms. The nature of observed pressure peak is analyzed. It is shown that the observed sharp pressure peak is directly connected with the creation of the seed population of relativistic electrons. The possibility to predict the position of new radiation belt during recovery phase of the magnetic storm using data of low orbiting and ground based observations is demonstrated.

  4. NASA Strategy to Safely Live and Work in the Space Radiation Environment

    NASA Technical Reports Server (NTRS)

    Cucinotta, Francis A.; Wu, Honglu; Corbin, Barbara J.; Sulzman, Frank M.; Krenek, Sam

    2007-01-01

    In space, astronauts are constantly bombarded with energetic particles. The goal of the National Aeronautics and Space Agency and the NASA Space Radiation Project is to ensure that astronauts can safely live and work in the space radiation environment. The space radiation environment poses both acute and chronic risks to crew health and safety, but unlike some other aspects of space travel, space radiation exposure has clinically relevant implications for the lifetime of the crew. Among the identified radiation risks are cancer, acute and late CNS damage, chronic and degenerative tissue decease, and acute radiation syndrome. The term "safely" means that risks are sufficiently understood such that acceptable limits on mission, post-mission and multi-mission consequences can be defined. The NASA Space Radiation Project strategy has several elements. The first element is to use a peer-reviewed research program to increase our mechanistic knowledge and genetic capabilities to develop tools for individual risk projection, thereby reducing our dependency on epidemiological data and population-based risk assessment. The second element is to use the NASA Space Radiation Laboratory to provide a ground-based facility to study the health effects/mechanisms of damage from space radiation exposure and the development and validation of biological models of risk, as well as methods for extrapolation to human risk. The third element is a risk modeling effort that integrates the results from research efforts into models of human risk to reduce uncertainties in predicting the identified radiation risks. To understand the biological basis for risk, we must also understand the physical aspects of the crew environment. Thus, the fourth element develops computer algorithms to predict radiation transport properties, evaluate integrated shielding technologies and provide design optimization recommendations for the design of human space systems. Understanding the risks and determining

  5. Modeling the Proton Radiation Belt With Van Allen Probes Relativistic Electron-Proton Telescope Data

    NASA Technical Reports Server (NTRS)

    Kanekal, S. G.; Li, X.; Baker, D. N.; Selesnick, R. S.; Hoxie, V. C.

    2018-01-01

    An empirical model of the proton radiation belt is constructed from data taken during 2013-2017 by the Relativistic Electron-Proton Telescopes on the Van Allen Probes satellites. The model intensity is a function of time, kinetic energy in the range 18-600 megaelectronvolts, equatorial pitch angle, and L shell of proton guiding centers. Data are selected, on the basis of energy deposits in each of the nine silicon detectors, to reduce background caused by hard proton energy spectra at low L. Instrument response functions are computed by Monte Carlo integration, using simulated proton paths through a simplified structural model, to account for energy loss in shielding material for protons outside the nominal field of view. Overlap of energy channels, their wide angular response, and changing satellite orientation require the model dependencies on all three independent variables be determined simultaneously. This is done by least squares minimization with a customized steepest descent algorithm. Model uncertainty accounts for statistical data error and systematic error in the simulated instrument response. A proton energy spectrum is also computed from data taken during the 8 January 2014 solar event, to illustrate methods for the simpler case of an isotropic and homogeneous model distribution. Radiation belt and solar proton results are compared to intensities computed with a simplified, on-axis response that can provide a good approximation under limited circumstances.

  6. Modeling the Proton Radiation Belt With Van Allen Probes Relativistic Electron-Proton Telescope Data

    NASA Astrophysics Data System (ADS)

    Selesnick, R. S.; Baker, D. N.; Kanekal, S. G.; Hoxie, V. C.; Li, X.

    2018-01-01

    An empirical model of the proton radiation belt is constructed from data taken during 2013-2017 by the Relativistic Electron-Proton Telescopes on the Van Allen Probes satellites. The model intensity is a function of time, kinetic energy in the range 18-600 MeV, equatorial pitch angle, and L shell of proton guiding centers. Data are selected, on the basis of energy deposits in each of the nine silicon detectors, to reduce background caused by hard proton energy spectra at low L. Instrument response functions are computed by Monte Carlo integration, using simulated proton paths through a simplified structural model, to account for energy loss in shielding material for protons outside the nominal field of view. Overlap of energy channels, their wide angular response, and changing satellite orientation require the model dependencies on all three independent variables be determined simultaneously. This is done by least squares minimization with a customized steepest descent algorithm. Model uncertainty accounts for statistical data error and systematic error in the simulated instrument response. A proton energy spectrum is also computed from data taken during the 8 January 2014 solar event, to illustrate methods for the simpler case of an isotropic and homogeneous model distribution. Radiation belt and solar proton results are compared to intensities computed with a simplified, on-axis response that can provide a good approximation under limited circumstances.

  7. A non-storm time enhancement of outer radiation belt electrons

    NASA Astrophysics Data System (ADS)

    Schiller, Q.; Li, X.; Blum, L. W.; Jaynes, A. N.; Malaspina, D.; Tu, W.; Turner, D. L.; Blake, J. B.

    2013-12-01

    On January 13th, 2013, a high-speed solar wind stream impacted Earth's magnetosphere, resulting in low geomagnetic activity (Real-Time Dst minimum of -30 nT). However, the relativistic electron population was enhanced by over two orders of magnitude in the outer radiation belt. Fortunately, during the event, the outer belt was well sampled by a variety of missions, including the Van Allen Probes, THEMIS, GOES, and the Colorado Student Space Weather Experiment (CSSWE). The energetic electrons are measured in-situ using flux and phase space density observations from the Magnetic Electron Ion Spectrometer (MagEIS) onboard the Van Allen Probes, the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) onboard CSSWE, and SST onboard THEMIS. These measured electron populations are the net result of the balance between concurrent loss and acceleration processes. Precipitation loss is quantified using REPTile measurements at low altitudes, while the energization mechanisms, namely interactions with whistler-mode chorus and Pc5 ULF waves, are investigated using Van Allen Probes' MagEIS and Electric Fields and Waves Suite (EFW), THEMIS' EFI and SCM instrument suites, and GOES magnetometers. The quantity and quality of measurements during this event provide a rare opportunity to address outstanding science questions; such as, whether the energetic electrons originate from inward injections associated with substorms or are accelerated via local heating, as well as what the energy dependence of the enhancement is during a period of such low geomagnetic activity.

  8. Drift-resonant, relativistic electron acceleration at the outer planets: Insights from the response of Saturn's radiation belts to magnetospheric storms

    NASA Astrophysics Data System (ADS)

    Roussos, E.; Kollmann, P.; Krupp, N.; Paranicas, C.; Dialynas, K.; Sergis, N.; Mitchell, D. G.; Hamilton, D. C.; Krimigis, S. M.

    2018-05-01

    The short, 7.2-day orbital period of Cassini's Ring Grazing Orbits (RGO) provided an opportunity to monitor how fast the effects of an intense magnetospheric storm-time period (days 336-343/2016) propagated into Saturn's electron radiation belts. Following the storms, Cassini's MIMI/LEMMS instrument detected a transient extension of the electron radiation belts that in subsequent orbits moved towards the inner belts, intensifying them in the process. This intensification was followed by an equally fast decay, possibly due to the rapid absorption of MeV electrons by the planet's main rings. Surprisingly, all this cycle was completed within four RGOs, effectively in less than a month. That is considerably faster than the year-long time scales of Saturn's proton radiation belt evolution. In order to explain this difference, we propose that electron radial transport is partly controlled by the variability of global scale electric fields which have a fixed local time pointing. Such electric fields may distort significantly the orbits of a particular class of energetic electrons that cancel out magnetospheric corotation due to their westward gradient and curvature drifts (termed "corotation-resonant" or "local-time stationary" electrons) and transport them radially between the ring current and the radiation belts within several days and few weeks. The significance of the proposed process is highlighted by the fact that corotation resonance at Saturn occurs for electrons of few hundred keV to several MeV. These are the characteristic energies of seed electrons from the ring current that sustain the radiation belts of the planet. Our model's feasibility is demonstrated through the use of a simple test-particle simulation, where we estimate that uniform but variable electric fields with magnitudes lower that 1.0 mV/m can lead to a very efficient transport of corotation resonant electrons. Such electric fields have been consistently measured in the magnetosphere, and here we

  9. Technical Evaluation of the NASA Model for Cancer Risk to Astronauts Due to Space Radiation

    NASA Technical Reports Server (NTRS)

    2012-01-01

    At the request of NASA, the National Research Council's (NRC's) Committee for Evaluation of Space Radiation Cancer Risk Model reviewed a number of changes that NASA proposes to make to its model for estimating the risk of radiation-induced cancer in astronauts. The NASA model in current use was last updated in 2005, and the proposed model would incorporate recent research directed at improving the quantification and understanding of the health risks posed by the space radiation environment. NASA's proposed model is defined by the 2011 NASA report Space Radiation Cancer Risk Projections and Uncertainties 2010 (Cucinotta et al., 2011). The committee's evaluation is based primarily on this source, which is referred to hereafter as the 2011 NASA report, with mention of specific sections or tables cited more formally as Cucinotta et al. (2011). The overall process for estimating cancer risks due to low linear energy transfer (LET) radiation exposure has been fully described in reports by a number of organizations. They include, more recently: (1) The "BEIR VII Phase 2" report from the NRC's Committee on Biological Effects of Ionizing Radiation (BEIR) (NRC, 2006); (2) Studies of Radiation and Cancer from the United Nations Scientific Committee on the Effects of Atomic Radiation (UNSCEAR, 2006), (3) The 2007 Recommendations of the International Commission on Radiological Protection (ICRP), ICRP Publication 103 (ICRP, 2007); and (4) The Environmental Protection Agency s (EPA s) report EPA Radiogenic Cancer Risk Models and Projections for the U.S. Population (EPA, 2011). The approaches described in the reports from all of these expert groups are quite similar. NASA's proposed space radiation cancer risk assessment model calculates, as its main output, age- and gender-specific risk of exposure-induced death (REID) for use in the estimation of mission and astronaut-specific cancer risk. The model also calculates the associated uncertainties in REID. The general approach for

  10. Application of New Chorus Wave Model from Van Allen Probe Observations in Earth's Radiation Belt Modeling

    NASA Astrophysics Data System (ADS)

    Wang, D.; Shprits, Y.; Spasojevic, M.; Zhu, H.; Aseev, N.; Drozdov, A.; Kellerman, A. C.

    2017-12-01

    In situ satellite observations, theoretical studies and model simulations suggested that chorus waves play a significant role in the dynamic evolution of relativistic electrons in the Earth's radiation belts. In this study, we developed new wave frequency and amplitude models that depend on Magnetic Local Time (MLT)-, L-shell, latitude- and geomagnetic conditions indexed by Kp for upper-band and lower-band chorus waves using measurements from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) instrument onboard the Van Allen Probes. Utilizing the quasi-linear full diffusion code, we calculated corresponding diffusion coefficients in each MLT sector (1 hour resolution) for upper-band and lower-band chorus waves according to the new developed wave models. Compared with former parameterizations of chorus waves, the new parameterizations result in differences in diffusion coefficients that depend on energy and pitch angle. Utilizing obtained diffusion coefficients, lifetime of energetic electrons is parameterized accordingly. In addition, to investigate effects of obtained diffusion coefficients in different MLT sectors and under different geomagnetic conditions, we performed simulations using four-dimensional Versatile Electron Radiation Belt simulations and validated results against observations.

  11. Aircraft radial-belted tire evaluation

    NASA Technical Reports Server (NTRS)

    Yager, Thomas J.; Stubbs, Sandy M.; Davis, Pamela A.

    1990-01-01

    An overview is given of the ongoing joint NASA/FAA/Industry Surface Traction And Radial Tire (START) Program being conducted at NASA Langley's Aircraft Landing Dynamics Facility (ALDF). The START Program involves tests using three different tire sizes to evaluate tire rolling resistance, braking, and cornering performance throughout the aircraft ground operational speed range for both dry and wet runway surfaces. Preliminary results from recent 40 x 14 size bias-ply, radial-belted, and H-type aircraft tire tests are discussed. The paper concludes with a summary of the current program status and planned ALDF test schedule.

  12. A statistical approach to determining energetic outer radiation belt electron precipitation fluxes

    NASA Astrophysics Data System (ADS)

    Simon Wedlund, Mea; Clilverd, Mark A.; Rodger, Craig J.; Cresswell-Moorcock, Kathy; Cobbett, Neil; Breen, Paul; Danskin, Donald; Spanswick, Emma; Rodriguez, Juan V.

    2014-05-01

    Subionospheric radio wave data from an Antarctic-Arctic Radiation-Belt (Dynamic) Deposition VLF Atmospheric Research Konsortia (AARDDVARK) receiver located in Churchill, Canada, is analyzed to determine the characteristics of electron precipitation into the atmosphere over the range 3 < L < 7. The study advances previous work by combining signals from two U.S. transmitters from 20 July to 20 August 2010, allowing error estimates of derived electron precipitation fluxes to be calculated, including the application of time-varying electron energy spectral gradients. Electron precipitation observations from the NOAA POES satellites and a ground-based riometer provide intercomparison and context for the AARDDVARK measurements. AARDDVARK radiowave propagation data showed responses suggesting energetic electron precipitation from the outer radiation belt starting 27 July 2010 and lasting ~20 days. The uncertainty in >30 keV precipitation flux determined by the AARDDVARK technique was found to be ±10%. Peak >30 keV precipitation fluxes of AARDDVARK-derived precipitation flux during the main and recovery phase of the largest geomagnetic storm, which started on 4 August 2010, were >105 el cm-2 s-1 sr-1. The largest fluxes observed by AARDDVARK occurred on the dayside and were delayed by several days from the start of the geomagnetic disturbance. During the main phase of the disturbances, nightside fluxes were dominant. Significant differences in flux estimates between POES, AARDDVARK, and the riometer were found after the main phase of the largest disturbance, with evidence provided to suggest that >700 keV electron precipitation was occurring. Currently the presence of such relativistic electron precipitation introduces some uncertainty in the analysis of AARDDVARK data, given the assumption of a power law electron precipitation spectrum.

  13. Risk Management of New Microelectronics for NASA: Radiation Knowledge-base

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.

    2004-01-01

    Contents include the following: NASA Missions - implications to reliability and radiation constraints. Approach to Insertion of New Technologies Technology Knowledge-base development. Technology model/tool development and validation. Summary comments.

  14. KSC-2012-3130

    NASA Image and Video Library

    2012-05-30

    CAPE CANAVERAL, Fla. – At the Astrotech payload processing facility near NASA's Kennedy Space Center in Florida, a technician performs a black light inspection on one of the Radiation Belt Storm Probes. Black light inspection uses UVA fluorescence to detect possible microcontamination, small cracks or fluid leaks. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  15. KSC-2012-3131

    NASA Image and Video Library

    2012-05-30

    CAPE CANAVERAL, Fla. – A technician performs a black light inspection on one of NASA's Radiation Belt Storm Probes inside the clean room high bay at Astrotech payload processing facility. Black light inspection uses UVA fluorescence to detect possible microcontamination, small cracks or fluid leaks. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  16. KSC-2012-3135

    NASA Image and Video Library

    2012-05-30

    CAPE CANAVERAL, Fla. – Using a black light, a technician closely inspects one of NASA's twin Radiation Belt Storm Probes inside the clean room high bay at Astrotech payload processing facility. Black light inspection uses UVA fluorescence to detect possible microcontamination, small cracks or fluid leaks. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  17. On the role of last closed drift shell dynamics in driving fast losses and Van Allen radiation belt extinction

    DOE PAGES

    Olifer, Leonid; Mann, Ian R.; Morley, Steven Karl; ...

    2018-04-20

    We present observations of very fast radiation belt loss as resolved using high time resolution electron flux data from the constellation of Global Positioning System (GPS) satellites. The time scale of these losses is revealed to be as short as ~0.5–2 hr during intense magnetic storms, with some storms demonstrating almost total loss on these time scales and which we characterize as radiation belt extinction. The intense March 2013 and March 2015 storms both show such fast extinction, with a rapid recovery, while the September 2014 storm shows fast extinction but no recovery for around 2 weeks. By contrast, themore » moderate September 2012 storm which generated a three radiation belt morphology shows more gradual loss. Here, we compute the last closed drift shell (LCDS) for each of these four storms and show a very strong correspondence between the LCDS and the loss patterns of trapped electrons in each storm. Most significantly, the location of the LCDS closely mirrors the high time resolution losses observed in GPS flux. The fast losses occur on a time scale shorter than the Van Allen Probes orbital period, are explained by proximity to the LCDS, and progress inward, consistent with outward transport to the LCDS by fast ultralow frequency wave radial diffusion. Expressing the location of the LCDS in L*, and not model magnetopause standoff distance in units of RE, clearly reveals magnetopause shadowing as the cause of the fast loss observed by the GPS satellites.« less

  18. On the role of last closed drift shell dynamics in driving fast losses and Van Allen radiation belt extinction

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Olifer, Leonid; Mann, Ian R.; Morley, Steven Karl

    We present observations of very fast radiation belt loss as resolved using high time resolution electron flux data from the constellation of Global Positioning System (GPS) satellites. The time scale of these losses is revealed to be as short as ~0.5–2 hr during intense magnetic storms, with some storms demonstrating almost total loss on these time scales and which we characterize as radiation belt extinction. The intense March 2013 and March 2015 storms both show such fast extinction, with a rapid recovery, while the September 2014 storm shows fast extinction but no recovery for around 2 weeks. By contrast, themore » moderate September 2012 storm which generated a three radiation belt morphology shows more gradual loss. Here, we compute the last closed drift shell (LCDS) for each of these four storms and show a very strong correspondence between the LCDS and the loss patterns of trapped electrons in each storm. Most significantly, the location of the LCDS closely mirrors the high time resolution losses observed in GPS flux. The fast losses occur on a time scale shorter than the Van Allen Probes orbital period, are explained by proximity to the LCDS, and progress inward, consistent with outward transport to the LCDS by fast ultralow frequency wave radial diffusion. Expressing the location of the LCDS in L*, and not model magnetopause standoff distance in units of RE, clearly reveals magnetopause shadowing as the cause of the fast loss observed by the GPS satellites.« less

  19. Mapping lightning discharges on Earth with lightning-generated whistlers wave emission in space and their effects on radiation belt electrons

    NASA Astrophysics Data System (ADS)

    Farges, T.; Ripoll, J. F.; Santolik, O.; Kolmasova, I.; Kurth, W. S.; Hospodarsky, G. B.; Kletzing, C.

    2017-12-01

    It is widely accepted that the slot region of the Van Allen radiation belts is sculpted by the presence of whistler mode waves especially by plasmaspheric hiss emissions. In this work, we investigate the role of lightning-generated whistler waves (LGW), which also contribute to scatter electrons trapped in the plasmaphere but, in general, to a lesser extent due to their low mean amplitude and occurrence rate. Our goal is to revisit the characterization of LGW occurrence in the Earth's atmosphere and in space as well as the computation of LGW effects by looking at a series of particular events, among which intense events, in order to characterize maximal scattering effects. We use multicomponent measurements of whistler mode waves by the Waves instrument of Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) onboard the Van Allen Probes spacecraft as our primary data source. We combine this data set with local measurements of the plasma density. We also use the data of the World Wide Lightning Location Network in order to localize the source of lightning discharges on Earth and their radiated energy, both locally at the footprint of the spacecraft and, globally, along the drift path. We discuss how to relate the signal measured in space with the estimation of the power emitted in the atmosphere and the associated complexity. Using these unique data sets we model the coefficients of quasi-linear pitch angle diffusion and we estimate effects of these waves on radiation belt electrons. We show evidence that lightning generated whistlers can, at least in some cases, influence the radiation belt dynamics.

  20. Improvements to the Ionizing Radiation Risk Assessment Program for NASA Astronauts

    NASA Technical Reports Server (NTRS)

    Semones, E. J.; Bahadori, A. A.; Picco, C. E.; Shavers, M. R.; Flores-McLaughlin, J.

    2011-01-01

    To perform dosimetry and risk assessment, NASA collects astronaut ionizing radiation exposure data from space flight, medical imaging and therapy, aviation training activities and prior occupational exposure histories. Career risk of exposure induced death (REID) from radiation is limited to 3 percent at a 95 percent confidence level. The Radiation Health Office at Johnson Space Center (JSC) is implementing a program to integrate the gathering, storage, analysis and reporting of astronaut ionizing radiation dose and risk data and records. This work has several motivations, including more efficient analyses and greater flexibility in testing and adopting new methods for evaluating risks. The foundation for these improvements is a set of software tools called the Astronaut Radiation Exposure Analysis System (AREAS). AREAS is a series of MATLAB(Registered TradeMark)-based dose and risk analysis modules that interface with an enterprise level SQL Server database by means of a secure web service. It communicates with other JSC medical and space weather databases to maintain data integrity and consistency across systems. AREAS is part of a larger NASA Space Medicine effort, the Mission Medical Integration Strategy, with the goal of collecting accurate, high-quality and detailed astronaut health data, and then securely, timely and reliably presenting it to medical support personnel. The modular approach to the AREAS design accommodates past, current, and future sources of data from active and passive detectors, space radiation transport algorithms, computational phantoms and cancer risk models. Revisions of the cancer risk model, new radiation detection equipment and improved anthropomorphic computational phantoms can be incorporated. Notable hardware updates include the Radiation Environment Monitor (which uses Medipix technology to report real-time, on-board dosimetry measurements), an updated Tissue-Equivalent Proportional Counter, and the Southwest Research Institute

  1. Technical Evaluation of the NASA Model for Cancer Risk to Astronauts Due to Space Radiation

    NASA Technical Reports Server (NTRS)

    2012-01-01

    At the request of NASA, the National Research Council's (NRC's) Committee for Evaluation of Space Radiation Cancer Risk Model1 reviewed a number of changes that NASA proposes to make to its model for estimating the risk of radiation-induced cancer in astronauts. The NASA model in current use was last updated in 2005, and the proposed model would incorporate recent research directed at improving the quantification and understanding of the health risks posed by the space radiation environment. NASA's proposed model is defined by the 2011 NASA report Space Radiation Cancer Risk Projections and Uncertainties--2010 . The committee's evaluation is based primarily on this source, which is referred to hereafter as the 2011 NASA report, with mention of specific sections or tables. The overall process for estimating cancer risks due to low linear energy transfer (LET) radiation exposure has been fully described in reports by a number of organizations. The approaches described in the reports from all of these expert groups are quite similar. NASA's proposed space radiation cancer risk assessment model calculates, as its main output, age- and gender-specific risk of exposure-induced death (REID) for use in the estimation of mission and astronaut-specific cancer risk. The model also calculates the associated uncertainties in REID. The general approach for estimating risk and uncertainty in the proposed model is broadly similar to that used for the current (2005) NASA model and is based on recommendations by the National Council on Radiation Protection and Measurements. However, NASA's proposed model has significant changes with respect to the following: the integration of new findings and methods into its components by taking into account newer epidemiological data and analyses, new radiobiological data indicating that quality factors differ for leukemia and solid cancers, an improved method for specifying quality factors in terms of radiation track structure concepts as

  2. ULF Waves in the Earth's Inner Magnetosphere: Role in Radiation Belt and Ring Current Dynamics

    NASA Astrophysics Data System (ADS)

    Mann, I. R.; Murphy, K. R.; Rae, J.; Claudepierre, S. G.; Fennell, J. F.; Baker, D. N.; Reeves, G. D.; Spence, H. E.; Ozeke, L.; Milling, D. K.

    2013-05-01

    . Finally, the combination of data from ground arrays such as CARISMA and the contemporaneous operation of the NASA Van Allen Probes mission offers an excellent basis for understanding this cross-energy plasma coupling which spans more than 6 orders of magnitude in energy; we present an initial example of ULF-wave particle interaction using early mission data. This work has received funding from the European Union under the Seventh Framework Programme (FP7-Space) under grant agreement n 284520 for the MAARBLE (Monitoring, Analyzing and Assessing Radiation Belt Energization and Loss) collaborative research project.

  3. Transport, charge exchange and loss of energetic heavy ions in the earth's radiation belts - Applicability and limitations of theory

    NASA Technical Reports Server (NTRS)

    Spjeldvik, W. N.

    1981-01-01

    Computer simulations of processes which control the relative abundances of ions in the trapping regions of geospace are compared with observations from discriminating ion detectors. Energy losses due to Coulomb collisions between ions and exospheric neutrals are considered, along with charge exchange losses and internal charge exchanges. The time evolution of energetic ion fluxes of equatorially mirroring ions under radial diffusion is modelled to include geomagnetic and geoelectric fluctutations. Limits to the validity of diffusion transport theory are discussed, and the simulation is noted to contain provisions for six ionic charge states and the source effect on the radiation belt oxygen ion distributions. Comparisons are made with ion flux data gathered on Explorer 45 and ISEE-1 spacecraft and results indicate that internal charge exchanges cause the radiation belt ion charge state to be independent of source charge rate characteristics, and relative charge state distribution is independent of the radially diffusive transport rate below the charge state redistribution zone.

  4. Investigating Stimulated Wave-Particle Interaction of Radiation Belt Particles with Space-Borne Whistler Mode Transmitters

    DTIC Science & Technology

    2009-03-30

    presented. ii Figure 12. Arrival time of electrons during the positive phase of charge on the antenna. ........ 15 The distances...relativistic electrons in the radiation belt. The target electrons are in the energy range of 0.5~3.0 MeV in the region between L = 1.7~2.2, where L is the...waves to pitch-angle diffuse the electrons into the loss-cone, i.e., to precipitate the relativistic electrons into the neutral atmosphere. There are

  5. The Propeller Belts in Saturn A Ring

    NASA Image and Video Library

    2017-01-30

    This image from NASA's Cassini mission shows a region in Saturn's A ring. The level of detail is twice as high as this part of the rings has ever been seen before. The view contains many small, bright blemishes due to cosmic rays and charged particle radiation near the planet. The view shows a section of the A ring known to researchers for hosting belts of propellers -- bright, narrow, propeller-shaped disturbances in the ring produced by the gravity of unseen embedded moonlets. Several small propellers are visible in this view. These are on the order of 10 times smaller than the large, bright propellers whose orbits scientists have routinely tracked (and which are given nicknames for famous aviators). This image is a lightly processed version, with minimal enhancement, preserving all original details present in the image. he image was taken in visible light with the Cassini spacecraft wide-angle camera on Dec. 18, 2016. The view was obtained at a distance of approximately 33,000 miles (54,000 kilometers) from the rings and looks toward the unilluminated side of the rings. Image scale is about a quarter-mile (330 meters) per pixel. http://photojournal.jpl.nasa.gov/catalog/PIA21059

  6. New Horizons Corrects Its Course in the Kuiper Belt

    NASA Image and Video Library

    2017-12-11

    The New Horizons spacecraft is about 300 million miles (483 million kilometers) from 2014 MU69, the Kuiper Belt object it will encounter on Jan. 1, 2019. https://photojournal.jpl.nasa.gov/catalog/PIA22188

  7. The statistics of relativistic electron pitch angle distribution in the Earth's radiation belt based on the Van Allen Probes measurements

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Freidel, R. H. W.; Chen, Y.; Henderson, M. G.; Kanekal, S. G.; Baker, D. N.; Spence, H. E.; Reeves, G. D.

    2015-12-01

    The relativistic electron pitch angle distribution (PAD) is an important characteristic of radiation belt electrons, which can give information on source or loss processes in a specific region. Using data from MagEIS and REPT instruments onboard the Van Allen Probes, a statistical survey of relativistic electron pitch angle distribution (PAD) is performed. By fitting relativistic electron PADs to Legendre polynomials, an empirical model of PADs as a function of L (from 1.4 to 6), MLT, electron energy (~100 keV - 5 MeV), and geomagnetic activity is developed and many intriguing features are found. In the outer radiation belt, an unexpected dawn/dusk asymmetry of ultra-relativistic electrons is found during quiet times, with the asymmetry becoming stronger at higher energies and at higher L shells. This may indicate the existence of physical processes acting on the relativistic electrons on the order of drift period, or be a signature of the partial ring current. In the inner belt and slot region, 100s of keV pitch angle distributions with minima at 90° are shown to be persistent in the inner belt and appears in the slot region during storm times. The model also shows clear energy dependence and L shell dependence of 90°-minimum pitch angle distribution. On the other hand, the head-and-shoulder pitch angle distributions are found during quiet times in the slot region, and the energy, L shell and geomagnetic activity dependence of those PADs are consistent with the wave-particle interaction caused by hiss waves.

  8. KSC-2012-3132

    NASA Image and Video Library

    2012-05-30

    CAPE CANAVERAL, Fla. – Barely visible behind equipment, a technician uses a black light to inspect one of NASA's twin Radiation Belt Storm Probes inside the clean room high bay at Astrotech payload processing facility. Black light inspection uses UVA fluorescence to detect possible microcontamination, small cracks or fluid leaks. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  9. KSC-2012-3134

    NASA Image and Video Library

    2012-05-30

    CAPE CANAVERAL, Fla. – Working in near-darkness inside the high bay clean room at the Astrotech payload processing facility, two technicians use black lights to inspect of one of NASA's twin Radiation Belt Storm Probes. Black light inspection uses UVA fluorescence to detect possible microcontamination, small cracks or fluid leaks. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  10. Dynamics of the outer radiation belts in relation to polar substorms and hot plasma injections at geostationary altitude

    NASA Technical Reports Server (NTRS)

    Sauvaud, J. A.; Winckler, J. R.

    1981-01-01

    Geostationary satellite and ground measurements of dynamic variations of the outer radiation belts and their relations with the development of auroral structures during magnetospheric substorms are analyzed. A comparison of measurements of the H or X geomagnetic field components made by seven auroral stations with ATS-6 low-energy and high-energy particle measurements during the multiple-onset substorm of Aug. 16, 1974 is presented which demonstrates that while the decrease in energetic particle fluxed ends only at the time of a strong substorm onset, rapid motions of the outer radiation belts may occur during the flux decrease. All-sky photographs of auroral phenomena taken at Fort Yukon and College, Alaska are then compared with ATS-1 energetic particle flux measurements in order to demonstrate the relation between flux decreases and increases and distinct substorm phases. Results support the hypothesis of a magnetospheric substorm precursor which appears to be an instability growing at the inner boundary of the plasma layer and approaching the earth, and underline the importance of current and magnetic field variations in charged particle dynamics.

  11. Modeling Resonant Structure in the Kuiper Belt

    NASA Astrophysics Data System (ADS)

    Holmes, E. K.; Dermott, S. F.; Grogan, K.

    1999-12-01

    There is a possible connection between structure in circumstellar disks and the presence of planets, our own zodiacal cloud being the prime example. Asymmetries in such a disk could be diagnostic of planets which would be otherwise undetectable. At least three different types of asymmetries can serve to indicate bodies orbiting a star in a disk: (1) a warp in the plane of symmetry of the disk, (2) an offset in the center of symmetry of the disk with respect to the central star, and (3) density anomalies in the plane of the disk due to resonant trapping of dust particles. In the asteroid belt, collisions between asteroids supply dust particles to the zodiacal cloud. By comparison, it has been postulated that collisions between KBOs could initiate a collisional cascade which would produce a Kuiper dust disk. In fact, the Kuiper Belt is the region of our solar system that is most analogous to the planetary debris disks we see around other stars such as Vega, β Pic, Fomalhaut, and ɛ Eridani (Backman and Paresce 1993). A Kuiper Disk would most likely have a resonant structure, with two concentrations in brightness along the ecliptic longitude. This large scale structure arises because many of the KBOs, the Plutinos, are in the 2:3 mean motion resonance with Neptune. By running numerical integrations of particles in Pluto-like orbits, the resonant structure of the Kuiper belt can be studied by determining the percentage of particles trapped in the resonance as a function of their initial velocity and beta, where β = Frad}/F{grav. The dynamical evolution of the particles is followed from source to sink with Poynting Robertson light drag, solar wind drag, radiation pressure, and the effects of planetary gravitational perturbations included. This research was funded in part by a NASA GSRP grant.

  12. Modeling Resonant Structure in the Kuiper Belt

    NASA Astrophysics Data System (ADS)

    Holmes, E. K.; Dermott, S. F.; Grogan, K.

    1999-09-01

    There is a possible connection between structure in circumstellar disks and the presence of planets, our own zodiacal cloud being the prime example. Asymmetries in such a disk could be diagnostic of planets which would be otherwise undetectable. At least three different types of asymmetries can serve to indicate bodies orbiting a star in a disk: (1) a warp in the plane of symmetry of the disk, (2) an offset in the center of symmetry of the disk with respect to the central star, and (3) density anomalies in the plane of the disk due to resonant trapping of dust particles. In the asteroid belt, collisions between asteroids supply dust particles to the zodiacal cloud. By comparison, it has been postulated that collisions between KBOs could initiate a collisional cascade which would produce a Kuiper dust disk. In fact, the Kuiper Belt is the region of our solar system that is most analogous to the planetary debris disks we see around other stars such as Vega, beta Pic, Fomalhaut, and epsilon Eridani (Backman and Paresce 1993). A Kuiper Disk would most likely have a resonant structure, with two concentrations in brightness along the ecliptic longitude. This large scale structure arises because many of the KBOs, the Plutinos, are in the 2:3 mean motion resonance with Neptune. By running numerical integrations of particles in Pluto-like orbits, the resonant structure of the Kuiper belt can be studied by determining the percentage of particles trapped in the resonance as a function of their initial velocity and beta, where beta = Frad/Fgrav. The dynamical evolution of the particles is followed from source to sink with Poynting Robertson light drag, solar wind drag, radiation pressure, and the effects of planetary gravitational perturbations included. This research was funded in part by a NASA GSRP grant.

  13. Automated bow shock and radiation belt edge identification methods and their application for Cluster, THEMIS/ARTEMIS and Van Allen Probes data

    NASA Astrophysics Data System (ADS)

    Facsko, Gabor; Sibeck, David; Balogh, Tamas; Kis, Arpad; Wesztergom, Viktor

    2017-04-01

    The bow shock and the outer rim of the outer radiation belt are detected automatically by our algorithm developed as a part of the Boundary Layer Identification Code Cluster Active Archive project. The radiation belt positions are determined from energized electron measurements working properly onboard all Cluster spacecraft. For bow shock identification we use magnetometer data and, when available, ion plasma instrument data. In addition, electrostatic wave instrument electron density, spacecraft potential measurements and wake indicator auxiliary data are also used so the events can be identified by all Cluster probes in highly redundant way, as the magnetometer and these instruments are still operational in all spacecraft. The capability and performance of the bow shock identification algorithm were tested using known bow shock crossing determined manually from January 29, 2002 to February 3,. The verification enabled 70% of the bow shock crossings to be identified automatically. The method shows high flexibility and it can be applied to observations from various spacecraft. Now these tools have been applied to Time History of Events and Macroscale Interactions during Substorms (THEMIS)/Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon's Interaction with the Sun (ARTEMIS) magnetic field, plasma and spacecraft potential observations to identify bow shock crossings; and to Van Allen Probes supra-thermal electron observations to identify the edges of the radiation belt. The outcomes of the algorithms are checked manually and the parameters used to search for bow shock identification are refined.

  14. International Collaboration for Galactic Cosmic Ray Simulation at the NASA Space Radiation Laboratory

    NASA Technical Reports Server (NTRS)

    Norbury, John W.; Slaba, Tony C.; Rusek, Adam; Durante, Marco; Reitz, Guenther

    2015-01-01

    An international collaboration on Galactic Cosmic Ray (GCR) simulation is being formed to make recommendations on how to best simulate the GCR spectrum at ground based accelerators. The external GCR spectrum is significantly modified when it passes through spacecraft shielding and astronauts. One approach for simulating the GCR space radiation environment at ground based accelerators would use the modified spectrum, rather than the external spectrum, in the accelerator beams impinging on biological targets. Two recent workshops have studied such GCR simulation. The first workshop was held at NASA Langley Research Center in October 2014. The second workshop was held at the NASA Space Radiation Investigators' workshop in Galveston, Texas in January 2015. The anticipated outcome of these and other studies may be a report or journal article, written by an international collaboration, making accelerator beam recommendations for GCR simulation. This poster describes the status of GCR simulation at the NASA Space Radiation Laboratory and encourages others to join the collaboration.

  15. Ambient magnetic field weakness during chorus event and their implication on the outer radiation belt dynamic

    NASA Astrophysics Data System (ADS)

    Alves, L. R.; Jauer, P. R.; Souza, V. M. C. E. S.; Da Silva, L. A.; Marchezi, J. P.; Medeiros, C.; Rockenbach, M.; Kanekal, S. G.; Baker, D. N.; Wygant, J. R.; Sibeck, D. G.

    2017-12-01

    The Earth's magnetosphere is continuously disturbed by the solar wind plasma incident upon it, and such a disturbance in association with internal (to the magnetosphere) physical processes may engender both the generation and amplification of Very Low Frequency (VLF) range whistler-mode chorus waves in the inner magnetosphere. Chorus waves are known to interact with particles in the outer Van Allen radiation belt resulting in both acceleration and pitch angle scattering into the loss cone, which in turn leads to flux dropouts. The first two years of operational Van Allen Probes magnetometer data were analyzed regarding the local magnetic field variation during periods of relativistic electron flux dropouts. It was observed that the ambient magnetic field at the spacecraft's apogee can vary from 180 nT to as low as 30 nT. Also, the high time resolution magnetic field data show that the whistler-mode chorus waves can often occur throughout the periods in which the ambient magnetic field is weakened, i.e. less than about 70 nT. We investigate the likelihood of the weakness of the ambient magnetic field to be an additional parameter related to outer radiation belt electron flux dropouts during periods when only chorus waves are present.

  16. False Color Mosaic of Jupiter Belt-Zone Boundary

    NASA Image and Video Library

    1997-12-18

    This false color mosaic shows a belt-zone boundary near Jupiter equator. The images that make up the four quadrants of this mosaic were taken within a few minutes of each other. These images were taken on Nov. 5, 1996 by NASA Galileo orbiter.

  17. On the Role of Solar Wind Discontinuities in the ULF Power Spectral Density at the Earth's Outer Radiation Belt: a Case Study

    NASA Astrophysics Data System (ADS)

    Lago, A.; Alves, L. R.; Braga, C. R.; Mendonca, R. R. S.; Jauer, P. R.; Medeiros, C.; Souza, V. M. C. E. S.; Mendes, O., Jr.; Marchezi, J.; da Silva, L.; Vieira, L.; Rockenbach, M.; Sibeck, D. G.; Kanekal, S. G.; Baker, D. N.; Wygant, J. R.; Kletzing, C.

    2016-12-01

    The solar wind incident upon the Earth's magnetosphere can produce either enhancement, depletion or no change in the flux of relativistic electrons at the outer radiation belt. During geomagnetic storms progress, solar wind parameters may change significantly, and occasionally relativistic electron fluxes at the outer radiation belt show dropouts in a range of energy and L-shells. Wave-particle interactions observed within the Van Allen belts have been claimed to play a significant role in energetic particle flux changes. The relation between changes on the solar wind parameters and the radiation belt is still a hot topic nowadays, particularly the role played by the solar wind on sudden electron flux decreases. The twin satellite Van Allen Probes measured a relativistic electron flux dropout concurrent to broad band Ultra-low frequency (ULF) waves, i.e. from 1 mHz to 10 Hz, on October 2, 2013. Magnetic field and plasma data from both ACE and WIND satellites allowed the characterization of this event as being an interplanetary coronal mass ejection in conjunction with shock. The interaction of this event with the Earth's magnetosphere was modeled using a global magnetohydrodynamic simulation and the magnetic field perturbation deep in magnetosphere could be analyzed from the model outputs. Results show the contribution of time-varying solar wind parameters to the generation of ULF waves. The power spectral densities, as a function of L-shell, were evaluated considering changes in the input parameters, e.g. magnitude and duration of dynamic pressure and magnetic field. The modeled power spectral densities are compared with Van Allen Probes data. The results provide us a clue on the solar wind characteristics that might be able to drive ULF waves in the inner magnetosphere, and also which wave modes are expected to be excited under a specific solar wind driving.

  18. NASA GeneLab Project: Bridging Space Radiation Omics with Ground Studies.

    PubMed

    Beheshti, Afshin; Miller, Jack; Kidane, Yared; Berrios, Daniel; Gebre, Samrawit G; Costes, Sylvain V

    2018-06-01

    Accurate assessment of risks of long-term space missions is critical for human space exploration. It is essential to have a detailed understanding of the biological effects on humans living and working in deep space. Ionizing radiation from galactic cosmic rays (GCR) is a major health risk factor for astronauts on extended missions outside the protective effects of the Earth's magnetic field. Currently, there are gaps in our knowledge of the health risks associated with chronic low-dose, low-dose-rate ionizing radiation, specifically ions associated with high (H) atomic number (Z) and energy (E). The NASA GeneLab project ( https://genelab.nasa.gov/ ) aims to provide a detailed library of omics datasets associated with biological samples exposed to HZE. The GeneLab Data System (GLDS) includes datasets from both spaceflight and ground-based studies, a majority of which involve exposure to ionizing radiation. In addition to detailed information on radiation exposure for ground-based studies, GeneLab is adding detailed, curated dosimetry information for spaceflight experiments. GeneLab is the first comprehensive omics database for space-related research from which an investigator can generate hypotheses to direct future experiments, utilizing both ground and space biological radiation data. The GLDS is continually expanding as omics-related data are generated by the space life sciences community. Here we provide a brief summary of the space radiation-related data available at GeneLab.

  19. Forecast and Specification of Radiation Belt Electrons Based on Solar Wind Measurements

    NASA Astrophysics Data System (ADS)

    Li, X.; Barker, A.; Burin Des Roziers, E.

    2003-12-01

    Relativistic electrons in the Earth's magnetosphere are of considerable practical importance because of their effect on spacecraft and because of their radiation hazard to astronauts who perform extravehicular activity. The good correlation between solar wind velocity and MeV electron fluxes at geosynchronous orbit has long been established. We have developed a radial diffusion model, using solar wind parameters as the only input, to reproduce the variation of the MeV electrons at geosynchronous orbit. Based on this model, we have constructed a real-time model that forecasts one to two days in advance the daily averaged >2 MeV electron flux at geosynchronous orbit using real-time solar wind data from ACE. The forecasts from this model are available on the web in real time. A natural extension of our current model is to create a system for making quantitative forecasts and specifications of radiation belt electrons at different radial distances and different local times based on the solar wind conditions. The successes and obstacles associated with this extension will be discussed in this presentation.

  20. Wave energy budget analysis in the Earth's radiation belts uncovers a missing energy.

    PubMed

    Artemyev, A V; Agapitov, O V; Mourenas, D; Krasnoselskikh, V V; Mozer, F S

    2015-05-15

    Whistler-mode emissions are important electromagnetic waves pervasive in the Earth's magnetosphere, where they continuously remove or energize electrons trapped by the geomagnetic field, controlling radiation hazards to satellites and astronauts and the upper-atmosphere ionization or chemical composition. Here, we report an analysis of 10-year Cluster data, statistically evaluating the full wave energy budget in the Earth's magnetosphere, revealing that a significant fraction of the energy corresponds to hitherto generally neglected very oblique waves. Such waves, with 10 times smaller magnetic power than parallel waves, typically have similar total energy. Moreover, they carry up to 80% of the wave energy involved in wave-particle resonant interactions. It implies that electron heating and precipitation into the atmosphere may have been significantly under/over-valued in past studies considering only conventional quasi-parallel waves. Very oblique waves may turn out to be a crucial agent of energy redistribution in the Earth's radiation belts, controlled by solar activity.

  1. Radiation belt electron acceleration during the 17 March 2015 geomagnetic storm: Observations and simulations

    DOE PAGES

    Li, W.; Ma, Q.; Thorne, R. M.; ...

    2016-06-10

    Various physical processes are known to cause acceleration, loss, and transport of energetic electrons in the Earth's radiation belts, but their quantitative roles in different time and space need further investigation. During the largest storm over the past decade (17 March 2015), relativistic electrons experienced fairly rapid acceleration up to ~7 MeV within 2 days after an initial substantial dropout, as observed by Van Allen Probes. In the present paper, we evaluate the relative roles of various physical processes during the recovery phase of this large storm using a 3-D diffusion simulation. By quantitatively comparing the observed and simulated electronmore » evolution, we found that chorus plays a critical role in accelerating electrons up to several MeV near the developing peak location and produces characteristic flat-top pitch angle distributions. By only including radial diffusion, the simulation underestimates the observed electron acceleration, while radial diffusion plays an important role in redistributing electrons and potentially accelerates them to even higher energies. Moreover, plasmaspheric hiss is found to provide efficient pitch angle scattering losses for hundreds of keV electrons, while its scattering effect on > 1 MeV electrons is relatively slow. Although an additional loss process is required to fully explain the overestimated electron fluxes at multi-MeV, the combined physical processes of radial diffusion and pitch angle and energy diffusion by chorus and hiss reproduce the observed electron dynamics remarkably well, suggesting that quasi-linear diffusion theory is reasonable to evaluate radiation belt electron dynamics during this big storm.« less

  2. Megavolt parallel potentials arising from double-layer streams in the Earth's outer radiation belt.

    PubMed

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

    2013-12-06

    Huge numbers of double layers carrying electric fields parallel to the local magnetic field line have been observed on the Van Allen probes in connection with in situ relativistic electron acceleration in the Earth's outer radiation belt. For one case with adequate high time resolution data, 7000 double layers were observed in an interval of 1 min to produce a 230,000 V net parallel potential drop crossing the spacecraft. Lower resolution data show that this event lasted for 6 min and that more than 1,000,000 volts of net parallel potential crossed the spacecraft during this time. A double layer traverses the length of a magnetic field line in about 15 s and the orbital motion of the spacecraft perpendicular to the magnetic field was about 700 km during this 6 min interval. Thus, the instantaneous parallel potential along a single magnetic field line was the order of tens of kilovolts. Electrons on the field line might experience many such potential steps in their lifetimes to accelerate them to energies where they serve as the seed population for relativistic acceleration by coherent, large amplitude whistler mode waves. Because the double-layer speed of 3100  km/s is the order of the electron acoustic speed (and not the ion acoustic speed) of a 25 eV plasma, the double layers may result from a new electron acoustic mode. Acceleration mechanisms involving double layers may also be important in planetary radiation belts such as Jupiter, Saturn, Uranus, and Neptune, in the solar corona during flares, and in astrophysical objects.

  3. Radiation belt electron acceleration during the 17 March 2015 geomagnetic storm: Observations and simulations

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, W.; Ma, Q.; Thorne, R. M.

    Various physical processes are known to cause acceleration, loss, and transport of energetic electrons in the Earth's radiation belts, but their quantitative roles in different time and space need further investigation. During the largest storm over the past decade (17 March 2015), relativistic electrons experienced fairly rapid acceleration up to ~7 MeV within 2 days after an initial substantial dropout, as observed by Van Allen Probes. In the present paper, we evaluate the relative roles of various physical processes during the recovery phase of this large storm using a 3-D diffusion simulation. By quantitatively comparing the observed and simulated electronmore » evolution, we found that chorus plays a critical role in accelerating electrons up to several MeV near the developing peak location and produces characteristic flat-top pitch angle distributions. By only including radial diffusion, the simulation underestimates the observed electron acceleration, while radial diffusion plays an important role in redistributing electrons and potentially accelerates them to even higher energies. Moreover, plasmaspheric hiss is found to provide efficient pitch angle scattering losses for hundreds of keV electrons, while its scattering effect on > 1 MeV electrons is relatively slow. Although an additional loss process is required to fully explain the overestimated electron fluxes at multi-MeV, the combined physical processes of radial diffusion and pitch angle and energy diffusion by chorus and hiss reproduce the observed electron dynamics remarkably well, suggesting that quasi-linear diffusion theory is reasonable to evaluate radiation belt electron dynamics during this big storm.« less

  4. Braking, steering, and wear performance of radial-belted and bias-ply aircraft tires

    NASA Technical Reports Server (NTRS)

    Yager, Thomas J.; Davis, Pamela A.; Stubbs, Sandy M.; Martinson, Veloria J.

    1992-01-01

    Preliminary steering, braking, and tread wear performance results from testing of radial-belted and bias-ply aircraft tires at NASA Langley are described. An overview of the joint NASA/FAA/industry START program is presented. Attention is given to the Langley Test Facility, equipment and future activities.

  5. Large Amplitude Whistler Waves and Electron Acceleration in the Earth's Radiation Belts: A Review of STEREO and Wind Observations

    NASA Technical Reports Server (NTRS)

    Cattell, Cynthia; Breneman, A.; Goetz, K.; Kellogg, P.; Kersten, K.; Wygant, J.; Wilson, L. B., III; Looper, Mark D.; Blake, J. Bernard; Roth, I.

    2012-01-01

    One of the critical problems for understanding the dynamics of Earth's radiation belts is determining the physical processes that energize and scatter relativistic electrons. We review measurements from the Wind/Waves and STEREO S/Waves waveform capture instruments of large amplitude whistler-mode waves. These observations have provided strong evidence that large amplitude (100s mV/m) whistler-mode waves are common during magnetically active periods. The large amplitude whistlers have characteristics that are different from typical chorus. They are usually nondispersive and obliquely propagating, with a large longitudinal electric field and significant parallel electric field. We will also review comparisons of STEREO and Wind wave observations with SAMPEX observations of electron microbursts. Simulations show that the waves can result in energization by many MeV and/or scattering by large angles during a single wave packet encounter due to coherent, nonlinear processes including trapping. The experimental observations combined with simulations suggest that quasilinear theoretical models of electron energization and scattering via small-amplitude waves, with timescales of hours to days, may be inadequate for understanding radiation belt dynamics.

  6. Solar Rotational Periodicities and the Semiannual Variation in the Solar Wind, Radiation Belt, and Aurora

    NASA Technical Reports Server (NTRS)

    Emery, Barbara A.; Richardson, Ian G.; Evans, David S.; Rich, Frederick J.; Wilson, Gordon R.

    2011-01-01

    The behavior of a number of solar wind, radiation belt, auroral and geomagnetic parameters is examined during the recent extended solar minimum and previous solar cycles, covering the period from January 1972 to July 2010. This period includes most of the solar minimum between Cycles 23 and 24, which was more extended than recent solar minima, with historically low values of most of these parameters in 2009. Solar rotational periodicities from S to 27 days were found from daily averages over 81 days for the parameters. There were very strong 9-day periodicities in many variables in 2005 -2008, triggered by recurring corotating high-speed streams (HSS). All rotational amplitudes were relatively large in the descending and early minimum phases of the solar cycle, when HSS are the predominant solar wind structures. There were minima in the amplitudes of all solar rotational periodicities near the end of each solar minimum, as well as at the start of the reversal of the solar magnetic field polarity at solar maximum (approx.1980, approx.1990, and approx. 2001) when the occurrence frequency of HSS is relatively low. Semiannual equinoctial periodicities, which were relatively strong in the 1995-1997 solar minimum, were found to be primarily the result of the changing amplitudes of the 13.5- and 27-day periodicities, where 13.5-day amplitudes were better correlated with heliospheric daily observations and 27-day amplitudes correlated better with Earth-based daily observations. The equinoctial rotational amplitudes of the Earth-based parameters were probably enhanced by a combination of the Russell-McPherron effect and a reduction in the solar wind-magnetosphere coupling efficiency during solstices. The rotational amplitudes were cross-correlated with each other, where the 27 -day amplitudes showed some of the weakest cross-correlations. The rotational amplitudes of the > 2 MeV radiation belt electron number fluxes were progressively weaker from 27- to 5-day periods

  7. Chorus Waves Modulation of Langmuir Waves in the Radiation Belts

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Jinxing; Bortnik, Jacob; An, Xin

    Using high-resolution waveforms measured by the Van Allen Probes, we report a novel observation in the radiation belts. Namely, we show that multiband, discrete, rising-tone whistler-mode chorus emissions exhibit a one-to-one correlation with Langmuir wave bursts. Moreover, the periodic Langmuir wave bursts are generally observed at the phase location where the chorus wave E || component is oriented opposite to its propagation direction. The electron measurements show a beam in phase space density at the particle velocity that matches the parallel phase velocity of the chorus waves. Based on this evidence, we conclude that the chorus waves accelerate the suprathermalmore » electrons via Landau resonance, and generate a localized electron beam in phase space density. Consequently, the Langmuir waves are excited locally and are modulated by the chorus wave phase. As a result, this microscale interaction between chorus waves and high frequency electrostatic waves provides a new insight into the nonlinear wave-particle interaction process.« less

  8. Chorus Waves Modulation of Langmuir Waves in the Radiation Belts

    DOE PAGES

    Li, Jinxing; Bortnik, Jacob; An, Xin; ...

    2017-11-20

    Using high-resolution waveforms measured by the Van Allen Probes, we report a novel observation in the radiation belts. Namely, we show that multiband, discrete, rising-tone whistler-mode chorus emissions exhibit a one-to-one correlation with Langmuir wave bursts. Moreover, the periodic Langmuir wave bursts are generally observed at the phase location where the chorus wave E || component is oriented opposite to its propagation direction. The electron measurements show a beam in phase space density at the particle velocity that matches the parallel phase velocity of the chorus waves. Based on this evidence, we conclude that the chorus waves accelerate the suprathermalmore » electrons via Landau resonance, and generate a localized electron beam in phase space density. Consequently, the Langmuir waves are excited locally and are modulated by the chorus wave phase. As a result, this microscale interaction between chorus waves and high frequency electrostatic waves provides a new insight into the nonlinear wave-particle interaction process.« less

  9. Observation of relativistic electron loss induced by EMIC waves in the outer radiation belt: Arase and PWING induction magnetometer array collaboration

    NASA Astrophysics Data System (ADS)

    Kurita, S.; Yoshizumi, M.; Kazuo, S.; Higashio, N.; Mitani, T.; Takashima, T.; Matsuoka, A.; Teramoto, M.; Shinohara, I.

    2017-12-01

    EMIC waves are generated by temperature anisotropy of energetic ions near the magnetic equator and satellite observations show that the waves tend to be observed on the dusk side and noon side magnetosphere. EMIC waves can propagate from the magnetosphere to the ground and they are observed by ground-based magnetometers as Pc1 pulsation. It has been pointed out that EMIC waves can resonate with relativistic electrons through anomalous cyclotron resonance, and cause strong pitch angle scattering of radiation belt electrons. It has been considered that precipitation loss of relativistic electrons by pitch angle scattering induced by EMIC waves is an important loss mechanism of radiation belt electrons. We report on the observation of relativistic electron loss observed by the Arase satellite on the dawn side magnetosphere during a geomagnetic disturbance, which is likely to be related to an EMIC wave activity. During the event, the EMIC wave activity in conjunction with the relativistic electron loss is identified from observation by the ground-based induction magnetometer array deployed by the PWING project. The magnetometer array observation reveals that EMIC waves are distributed in the wide magnetic local time range from the dusk to midnight sector. It is suggested that drifting relativistic electrons are scattered into the loss cone by the EMIC waves on the dusk to midnight sector before they arrive at the Arase satellite located on the dawn side. We will discuss the impact of loss caused by EMIC wave-induced precipitation loss on the overall flux variation of radiation belt electrons during the geomagnetic disturbance.

  10. Review of advanced radiator technologies for spacecraft power systems and space thermal control

    NASA Technical Reports Server (NTRS)

    Juhasz, Albert J.; Peterson, George P.

    1994-01-01

    A two-part overview of progress in space radiator technologies is presented. The first part reviews and compares the innovative heat-rejection system concepts proposed during the past decade, some of which have been developed to the breadboard demonstration stage. Included are space-constructable radiators with heat pipes, variable-surface-area radiators, rotating solid radiators, moving-belt radiators, rotating film radiators, liquid droplet radiators, Curie point radiators, and rotating bubble-membrane radiators. The second part summarizes a multielement project including focused hardware development under the Civil Space Technology Initiative (CSTI) High Capacity Power program carried out by the NASA Lewis Research Center and its contractors to develop lightweight space radiators in support of Space Exploration Initiative (SEI) power systems technology.

  11. HEPD on NEXTSat-1: A High Energy Particle Detector for Measurements of Precipitating Radiation Belt Electrons

    NASA Astrophysics Data System (ADS)

    Sohn, Jongdae; Lee, Jaejin; Min, Kyoungwook; Lee, Junchan; Lee, Seunguk; Lee, Daeyoung; Jo, Gyeongbok; Yi, Yu; Na, Gowoon; Kang, Kyung-In; Shin, Goo-Hwan

    2018-05-01

    Radiation belt particles of the inner magnetosphere precipitate into the atmosphere in the subauroral regions when they are pitch-angle scattered into the loss cone by wave-particle interactions. Such particle precipitations are known to be especially enhanced during space storms, though they can also occur during quiet times. The observed characteristics of precipitating electrons can be distinctively different, in their time series as well as in their spectra, depending on the waves involved. The present paper describes the High Energy Particle Detector (HEPD) on board the Next Generation Small Satellite-1 (NEXTSat-1), which will measure these radiation belt electrons from a low-Earth polar orbit satellite to study the mechanisms related to electron precipitation in the sub-auroral regions. The HEPD is based on silicon barrier detectors and consists of three telescopes that are mounted on the satellite to have angles of 0°. 45°, and 90°, respectively with the local geomagnetic field during observations. With a high time resolution of 32 Hz and a high spectral resolution of 11 channels over the energy range from 350 keV to 2 MeV, together with the pitch angle information provided by the three telescopes, HEPD is capable of identifying physical processes, such as microbursts and dust-side relativistic electron precipitation (DREP) events associated with electron precipitations. NextSat-1 is scheduled for launch in early 2018.

  12. Alternatives to accuracy and bias metrics based on percentage errors for radiation belt modeling applications

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Morley, Steven Karl

    This report reviews existing literature describing forecast accuracy metrics, concentrating on those based on relative errors and percentage errors. We then review how the most common of these metrics, the mean absolute percentage error (MAPE), has been applied in recent radiation belt modeling literature. Finally, we describe metrics based on the ratios of predicted to observed values (the accuracy ratio) that address the drawbacks inherent in using MAPE. Specifically, we define and recommend the median log accuracy ratio as a measure of bias and the median symmetric accuracy as a measure of accuracy.

  13. New observations of the low energy proton inner belt

    NASA Astrophysics Data System (ADS)

    Guild, T. B.; Mazur, J. E.; Looper, M. D.; Blake, J. B.

    2013-12-01

    We present preliminary results of the trapped low energy (6-32 MeV) proton population in the inner radiation belt (L>1.8) from May, 2008 through present. These observations were made by the High Linear Energy Transfer (HiLET) proton telescope, part of the TWIN-ES instrument suite on the TWINS-2 spacecraft. This collimated telescope measures pitch-angle-resolved proton fluxes as it rises through the inner radiation belt twice per day. We present pitch angle distributions of low energy protons as a function of L, and show how the flux and pitch angle distributions change from the deep solar minimum of 2009 through the rising phase of solar cycle 24. Particular emphasis will be given to inner belt dynamics throughout this interval, both gradual and abrupt, and a discussion of the candidate processes responsible for these changes will be given.

  14. Van Allen Probes Observations of Radiation Belt Acceleration associated with Solar Wind Shocks

    NASA Astrophysics Data System (ADS)

    Foster, J. C.; Wygant, J. R.; Baker, D. N.

    2017-12-01

    During a moderate solar wind shock event on 8 October 2013 the twin Van Allen Probes spacecraft observed the shock-induced electric field in the dayside magnetosphere and the response of the electron populations across a broad range of energies. Whereas other mechanisms populating the radiation belts close to Earth (L 3-5) take place on time scales of months (diffusion) or hours (storm and substorm effects), acceleration during shock events occurs on a much faster ( 1 minute) time scale. During this event the dayside equatorial magnetosphere experienced a strong dusk-dawn/azimuthal component of the electric field of 1 min duration. This shock-induced pulse accelerates radiation belt electrons for the length of time they are exposed to it creating "quasi-periodic pulse-like" enhancements in the relativistic (2 - 6 MeV) electron flux. Electron acceleration occurs on a time scale that is a fraction of their orbital drift period around the Earth. Those electrons whose drift velocity closely matches the azimuthal phase velocity of the shock-induced pulse stay in the accelerating wave as it propagates tailward and receive the largest increase in energy. Relativistic electron gradient drift velocities are energy-dependent, selecting a preferred range of energies (3-4 MeV) for the strongest enhancement. The time scale for shock acceleration is short with respect to the electron drift period ( 5 min), but long with respect to bounce and gyro periodicities. As a result, the third invariant is broken and the affected electron populations are displaced earthward experiencing an adiabatic energy gain. At radial distances tailward of the peak in phase space density, the impulsive inward displacement of the electron population produces a decrease in electron flux and a sequence of gradient drifting "negative holes".Dual spacecraft coverage of the 8 October 2013 event provided a before/after time sequence documenting shock effects.

  15. NASA Galactic Cosmic Radiation Environment Model: Badhwar - O'Neill (2014)

    NASA Technical Reports Server (NTRS)

    Golge, S.; O'Neill, P. M.; Slaba, T. C.

    2015-01-01

    The Badhwar-O'Neill (BON) Galactic Cosmic Ray (GCR) flux model has been used by NASA to certify microelectronic systems and in the analysis of radiation health risks for human space flight missions. Of special interest to NASA is the kinetic energy region below 4.0 GeV/n due to the fact that exposure from GCR behind shielding (e.g., inside a space vehicle) is heavily influenced by the GCR particles from this energy domain. The BON model numerically solves the Fokker-Planck differential equation to account for particle transport in the heliosphere due to diffusion, convection, and adiabatic deceleration under the assumption of a spherically symmetric heliosphere. The model utilizes a comprehensive database of GCR measurements from various particle detectors to determine boundary conditions. By using an updated GCR database and improved model fit parameters, the new BON model (BON14) is significantly improved over the previous BON models for describing the GCR radiation environment of interest to human space flight.

  16. NASA Galactic Cosmic Radiation Environment Model: Badhwar-O'Neill (2014)

    NASA Technical Reports Server (NTRS)

    O'Neill, P. M.; Golge, S.; Slaba, T. C.

    2015-01-01

    The Badhwar-O'Neill (BON) Galactic Cosmic Ray (GCR) flux model is used by NASA to certify microelectronic systems and in the analysis of radiation health risks for human space flight missions. Of special interest to NASA is the kinetic energy region below 4.0 GeV/n due to the fact that exposure from GCR behind shielding (e.g., inside a space vehicle) is heavily influenced by the GCR particles from this energy domain. The BON model numerically solves the Fokker-Planck differential equation to account for particle transport in the heliosphere due to diffusion, convection, and adiabatic deceleration under the assumption of a spherically symmetric heliosphere. The model utilizes a GCR measurements database from various particle detectors to determine the boundary conditions. By using an updated GCR database and improved model fit parameters, the new BON model (BON14) is significantly improved over the previous BON models for describing the GCR radiation environment of interest to human space flight.

  17. KSC-2012-4610

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, Barbara Giles, director of NASA's Science Mission Directorate Heliophysics Division, talks to agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  18. KSC-2012-4621

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, NASA Administrator Charlie Bolden talks to agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. At left is performer Beth Nielson Chapman. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  19. KSC-2012-4616

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, astronaut Leland Melvin, associate administrator of NASA Education, talks to agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  20. KSC-2012-4614

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, Aly Mendoza-Hill, NASA Launch Services Program mission manager, talks to agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  1. KSC-2012-4617

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, astronaut Leland Melvin, associate administrator of NASA Education, introduces performer Beth Nielson Chapman to agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  2. KSC-2012-4615

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, astronaut Leland Melvin, associate administrator of NASA Education, talks to agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  3. KSC-2012-4611

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, David Sibeck, NASA Living with a Star mission scientist from Goddard Space Flight Center, talks to agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  4. KSC-2012-4622

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, NASA Administrator Charlie Bolden talks to agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. At left is performer Beth Nielson Chapman. At right is astronaut Leland Melvin, associate administrator of NASA Education. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  5. KSC-2012-4620

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, NASA Administrator Charlie Bolden talks to agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. At left is performer Beth Nielson Chapman. At right is astronaut Leland Melvin, associate administrator of NASA Education. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  6. KSC-2012-4612

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, Nicky Fox, deputy project scientist of NASA's Radiation Belt Storm Probes, or RBSP, mission talks to agency social media followers during the second day of NASA Social activities. The probes are set to launch aboard a United Launch Alliance ULA Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  7. KSC-2012-4619

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, Beth Nielson Chapman performs "The Mighty Night Sky" for agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  8. KSC-2012-4618

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, Beth Nielson Chapman performs "The Mighty Night Sky" for agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  9. Radiation Belt Electron Dynamics: Modeling Atmospheric Losses

    NASA Technical Reports Server (NTRS)

    Selesnick, R. S.

    2003-01-01

    The first year of work on this project has been completed. This report provides a summary of the progress made and the plan for the coming year. Also included with this report is a preprint of an article that was accepted for publication in Journal of Geophysical Research and describes in detail most of the results from the first year of effort. The goal for the first year was to develop a radiation belt electron model for fitting to data from the SAMPEX and Polar satellites that would provide an empirical description of the electron losses into the upper atmosphere. This was largely accomplished according to the original plan (with one exception being that, for reasons described below, the inclusion of the loss cone electrons in the model was deferred). The main concerns at the start were to accurately represent the balance between pitch angle diffusion and eastward drift that determines the dominant features of the low altitude data, and then to accurately convert the model into simulated data based on the characteristics of the particular electron detectors. Considerable effort was devoted to achieving these ends. Once the model was providing accurate results it was applied to data sets selected from appropriate periods in 1997, 1998, and 1999. For each interval of -30 to 60 days, the model parameters were calculated daily, thus providing good short and long term temporal resolution, and for a range of radial locations from L = 2.7 to 3.9. .

  10. The Impenetrable Barrier Revisited - Anthroprogenic Effects on Earth's Radiation Belts

    NASA Astrophysics Data System (ADS)

    Foster, J. C.; Baker, D. N.; Erickson, P. J.; Albert, J.; Fennell, J. F.; Mishin, E. V.; Starks, M. J.; Jaynes, A. N.; Li, X.; Kanekal, S. G.; Kletzing, C.

    2015-12-01

    The Van Allen Probes are contributing significantly to the understanding of processes effecting Earth's radiation belts. It has been noted that the earthward extent of the outer zone highly-relativistic electrons encounters a nearly impenetrable barrier at a radial distance (L) near 2.8 RE inside of which they are not observed. Modeling suggests that this is the result of a balance between slow inward diffusion and hiss-induced precipitation. The large storm of 17 March 2015 afforded an excellent opportunity to investigate the impenetrable barrier using the full complement of sensors carried by the Van Allen Probes. The storm was marked by the rapid reappearance of strong fluxes of MeV electrons directly outside the barrier with the formation of very steep MeV flux gradients. In spite of the strong rapid recovery of MeV electron fluxes immediately outside the barrier, the sharpness and constancy of the gradient at the barrier is strongly suggestive of a previously unrecognized fast-acting and spatially localized mechanism responsible for the formation of such a well-defined feature during these dramatic circumstances. The Van Allen Probes regularly observe a magnetically confined bubble of VLF emissions of terrestrial origin filling the inner magnetosphere. Strongest signals are from US Navy VLF transmitters used for one-way communication to submarines. These signals largely are confined to the region of L space where their frequency is < ½ fce. The strong signal from station NAA at 24 kHz is confined to L < 2.8 where it encounters the ½ fce limit. During the event, the flux of MeV electrons decreased by 1000x across 0.5 RE outside L = 2.8 simultaneous with a 6 order of magnitude increase in the VLF wave intensity as the Probes entered the VLF bubble. The VLF transmitter frequencies are amplified at the point where they overlap natural chorus band near ½ fce suggestive of transmitter-induced triggered emissions. MeV radiation belt electrons encounter this

  11. Quantification of the precipitation loss of radiation belt electrons observed by SAMPEX

    NASA Astrophysics Data System (ADS)

    Tu, Weichao; Selesnick, Richard; Li, Xinlin; Looper, Mark

    2010-07-01

    Based on SAMPEX/PET observations, the rates and the spatial and temporal variations of electron loss to the atmosphere in the Earth's radiation belt were quantified using a drift diffusion model that includes the effects of azimuthal drift and pitch angle diffusion. The measured electrons by SAMPEX can be distinguished as trapped, quasi-trapped (in the drift loss cone), and precipitating (in the bounce loss cone). The drift diffusion model simulates the low-altitude electron distribution from SAMPEX. After fitting the model results to the data, the magnitudes and variations of the electron lifetime can be quantitatively determined based on the optimum model parameter values. Three magnetic storms of different magnitudes were selected to estimate the various loss rates of ˜0.5-3 MeV electrons during different phases of the storms and at L shells ranging from L = 3.5 to L = 6.5 (L represents the radial distance in the equatorial plane under a dipole field approximation). The storms represent a small storm, a moderate storm from the current solar minimum, and an intense storm right after the previous solar maximum. Model results for the three individual events showed that fast precipitation losses of relativistic electrons, as short as hours, persistently occurred in the storm main phases and with more efficient loss at higher energies over wide range of L regions and over all the SAMPEX-covered local times. In addition to this newly discovered common feature of the main phase electron loss for all the storm events and at all L locations, some other properties of the electron loss rates, such as the local time and energy dependence that vary with time or locations, were also estimated and discussed. This method combining model with the low-altitude observations provides direct quantification of the electron loss rate, a prerequisite for any comprehensive modeling of the radiation belt electron dynamics.

  12. From Present Surveying to Future Prospecting of the Asteroid Belt

    NASA Astrophysics Data System (ADS)

    Clark, P. E.; Curtis, S. A.; Rilee, M.; Cheung, C.

    2004-03-01

    Requirements are analyzed for application of future mission architecture, the Autonomous Nano-Technology Swarm (ANTS), to proposed in situ prospecting, of the asteroid belt, the Prospecting Asteroid Mission (PAM) as part of a NASA 2003 Revolutionary Aerospace Concept (RASC) study.

  13. A radiation belt monitor for the High Energy Transient Experiment Satellite

    NASA Technical Reports Server (NTRS)

    Lo, D. H.; Wenzel, K. W.; Petrasso, R. D.; Prigozhin, G. Y.; Doty, J.; Ricker, G.

    1993-01-01

    A Radiation Belt Monitor (RBM) sensitive to protons and electrons with energy approximately greater than 0.5 MeV has been designed for the High Energy Transient Experiment (HETE) satellite in order to: first, control the on-off configuration of the experiments (i.e. those susceptible to proton damage); and second, to indicate the presence of proton and/or electron events that could masquerade as legitimate high energy photon events. One of the two RBM channels has an enhanced sensitivity to electrons. Each channel of the RBM, based on a PIN silicon diode, requires a typical power of 6 milliwatts. Tests have been performed with protons with energies from approximately 0.1 to 2.5 MeV (generated by a Cockcroft-Walton linear accelerator via the d(d,p)t reaction), and with electrons with energies up to 1 MeV (from a 1.0 microcurie Bi-207 source).

  14. Overview of NASARTI (NASA Radiation Track Image) Program: Highlights of the Model Improvement and the New Results

    NASA Technical Reports Server (NTRS)

    Ponomarev, Artem L.; Plante, I.; George, Kerry; Cornforth, M. N.; Loucas, B. D.; Wu, Honglu

    2014-01-01

    This presentation summarizes several years of research done by the co-authors developing the NASARTI (NASA Radiation Track Image) program and supporting it with scientific data. The goal of the program is to support NASA mission to achieve a safe space travel for humans despite the perils of space radiation. The program focuses on selected topics in radiation biology that were deemed important throughout this period of time, both for the NASA human space flight program and to academic radiation research. Besides scientific support to develop strategies protecting humans against an exposure to deep space radiation during space missions, and understanding health effects from space radiation on astronauts, other important ramifications of the ionizing radiation were studied with the applicability to greater human needs: understanding the origins of cancer, the impact on human genome, and the application of computer technology to biological research addressing the health of general population. The models under NASARTI project include: the general properties of ionizing radiation, such as particular track structure, the effects of radiation on human DNA, visualization and the statistical properties of DSBs (DNA double-strand breaks), DNA damage and repair pathways models and cell phenotypes, chromosomal aberrations, microscopy data analysis and the application to human tissue damage and cancer models. The development of the GUI and the interactive website, as deliverables to NASA operations teams and tools for a broader research community, is discussed. Most recent findings in the area of chromosomal aberrations and the application of the stochastic track structure are also presented.

  15. Comment on ``Unraveling the Causes of Radiation Belt Enhancements''

    NASA Astrophysics Data System (ADS)

    Campbell, Wallace H.

    2008-09-01

    The excellent article by M. W. Liemohn and A. A. Chan on the radiation belts (see Eos, 88(42), 16 October 2007) is misleading in its implication that the disturbance storm-time (Dst) index is an indicator of a magnetospheric ring current. That index is formed from an average of magnetic data from three or four low-latitude stations that have been fallaciously ``adjusted'' to a magnetic equatorial location under the 1960's assumption [Sugiura, 1964] that the fields arrive from the growth and decay of a giant ring of current in the magnetosphere. In truth, the index has a negative lognormal form [Campbell, 1996; Yago and Kamide, 2003] as a result of its composition from numerous negative ionospheric and magnetospheric disturbance field sources, each having normal field amplitude distributions [Campbell, 2004]. Some partial ring currents [Lui et al., 1987] and their associated field-aligned currents, as well as major ionospheric currents flowing from the auroral zone to equatorial latitudes, are the main contributors to the Dst index. No full magnetospheric ring of currents is involved, despite its false name (``Equatorial Dst Ring Current Index'') given by the index suppliers, the Geomagnetism Laboratory at Kyoto University, Japan.

  16. Radiation Exposure and Mortality from Cardiovascular Disease and Cancer in Early NASA Astronauts: Space for Exploration

    NASA Technical Reports Server (NTRS)

    Elgart, S. R.; Little, M. P.; Campbell, L. J.; Milder, C. M.; Shavers, M. R.; Huff, J. L.; Patel, Z. S.

    2018-01-01

    Of the many possible health challenges posed during extended exploratory missions to space, the effects of space radiation on cardiovascular disease and cancer are of particular concern. There are unique challenges to estimating those radiation risks; care and appropriate and rigorous methodology should be applied when considering small cohorts such as the NASA astronaut population. The objective of this work was to establish whether there is evidence for excess cardiovascular disease or cancer mortality in an early NASA astronaut cohort and determine if a correlation exists between space radiation exposure and mortality.

  17. Loss and source mechanisms of Jupiter's radiation belts near the inner boundary of trapping regions

    NASA Astrophysics Data System (ADS)

    Santos-Costa, Daniel; Bolton, Scott J.; Becker, Heidi N.; Clark, George; Kollmann, Peter; Paranicas, Chris; Mauk, Barry; Joergensen, John L.; Adriani, Alberto; Thorne, Richard M.; Bagenal, Fran; Janssen, Mike A.; Levin, Steve M.; Oyafuso, Fabiano A.; Williamson, Ross; Adumitroaie, Virgil; Ingersoll, Andrew P.; Kurth, Bill; Connerney, John E. P.

    2017-04-01

    We have merged a set of physics-based and empirical models to investigate the energy and spatial distributions of Jupiter's electron and proton populations in the inner and middle magnetospheric regions. Beyond the main source of plasma (> 5 Rj) where interchange instability is believed to drive the radial transport of charged particles, the method originally developed by Divine and Garrett [J. Geophys. Res., 88, 6889-6903, 1983] has been adapted. Closer to the planet where field fluctuations control the radial transport, a diffusion theory approach is used. Our results for the equatorial and mid-latitude regions are compared with Pioneer and Galileo Probe measurements. Data collected along Juno's polar orbit allow us to examine the features of Jupiter's radiation environment near the inner boundary of trapping regions. Significant discrepancies between Juno (JEDI keV energy particles and high energy radiation environment measurements made by Juno's SRU and ASC star cameras and the JIRAM infrared imager) and Galileo Probe data sets and models are observed close to the planet. Our simulations of Juno MWR observations of Jupiter's electron-belt emission confirm the limitation of our model to realistically depict the energy and spatial distributions of the ultra-energetic electrons. In this paper, we present our modeling approach, the data sets and resulting data-model comparisons for Juno's first science orbits. We describe our effort to improve our models of electron and proton belts. To gain a physical understanding of the dissimilarities with observations, we revisit the magnetic environment and the mechanisms of loss and source in our models.

  18. Wave energy budget analysis in the Earth’s radiation belts uncovers a missing energy

    PubMed Central

    Artemyev, A.V.; Agapitov, O.V.; Mourenas, D.; Krasnoselskikh, V.V.; Mozer, F.S.

    2015-01-01

    Whistler-mode emissions are important electromagnetic waves pervasive in the Earth’s magnetosphere, where they continuously remove or energize electrons trapped by the geomagnetic field, controlling radiation hazards to satellites and astronauts and the upper-atmosphere ionization or chemical composition. Here, we report an analysis of 10-year Cluster data, statistically evaluating the full wave energy budget in the Earth’s magnetosphere, revealing that a significant fraction of the energy corresponds to hitherto generally neglected very oblique waves. Such waves, with 10 times smaller magnetic power than parallel waves, typically have similar total energy. Moreover, they carry up to 80% of the wave energy involved in wave–particle resonant interactions. It implies that electron heating and precipitation into the atmosphere may have been significantly under/over-valued in past studies considering only conventional quasi-parallel waves. Very oblique waves may turn out to be a crucial agent of energy redistribution in the Earth’s radiation belts, controlled by solar activity. PMID:25975615

  19. KSC-2012-3223

    NASA Image and Video Library

    2012-06-07

    CAPE CANAVERAL, Fla. – Using a black light, technicians closely inspect a solar panel on one of NASA's twin Radiation Belt Storm Probes inside the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida. The technicians are dressed in clean-room attire known as “bunny suits.” Black-light inspection uses UVA fluorescence to detect possible microcontamination, small cracks or fluid leaks. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  20. KSC-2012-3220

    NASA Image and Video Library

    2012-06-07

    CAPE CANAVERAL, Fla. – Working in near-darkness inside the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, technicians use black lights to inspect a solar panel on one of NASA's twin Radiation Belt Storm Probes. The technicians are dressed in clean-room attire known as “bunny suits.” Black-light inspection uses UVA fluorescence to detect possible microcontamination, small cracks or fluid leaks. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  1. KSC-2012-3221

    NASA Image and Video Library

    2012-06-07

    CAPE CANAVERAL, Fla. – Using a black light, technicians closely inspect a solar panel on one of NASA's twin Radiation Belt Storm Probes inside the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida. The technicians are dressed in clean-room attire known as “bunny suits.” Black-light inspection uses UVA fluorescence to detect possible microcontamination, small cracks or fluid leaks. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  2. KSC-2012-3219

    NASA Image and Video Library

    2012-06-07

    CAPE CANAVERAL, Fla. – Using a black light, technicians closely inspect a solar panel on one of NASA's twin Radiation Belt Storm Probes inside the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida. The technicians are dressed in clean-room attire known as “bunny suits.” Black-light inspection uses UVA fluorescence to detect possible microcontamination, small cracks or fluid leaks. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  3. KSC-2012-3222

    NASA Image and Video Library

    2012-06-07

    CAPE CANAVERAL, Fla. – Working in near-darkness inside the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, technicians use black lights to inspect a solar panel on one of NASA's twin Radiation Belt Storm Probes. The technicians are dressed in clean-room attire known as “bunny suits.” Black-light inspection uses UVA fluorescence to detect possible microcontamination, small cracks or fluid leaks. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  4. KSC-2012-4608

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, NASA Administrator Charlie Bolden talks to agency social media followers during the second day of NASA Social activities revolving around the agency's Radiation Belt Storm Probes, or RBSP, mission. At left is performer Beth Nielson Chapman. At right is astronaut Leland Melvin, associate administrator of NASA Education. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  5. Direct detection of albedo neutron decay electrons at the inner edge of the radiation belt and experimental determination of neutron density in near-Earth space

    NASA Astrophysics Data System (ADS)

    Li, X.; Selesnick, R.; Schiller, Q. A.; Zhang, K.; Zhao, H.; Baker, D. N.; Temerin, M. A.

    2017-12-01

    The galaxy is filled with cosmic ray particles, mostly protons with kinetic energy above hundreds of mega-electron volts (MeV). Soon after the discovery of Earth's Van Allen radiation belts almost six decades ago, it was recognized that the main source of inner belt protons, with kinetic energies of tens to hundreds of MeV, is Cosmic Ray Albedo Neutron Decay (CRAND). In this process, cosmic rays reaching the upper atmosphere from throughout the galaxy interact with neutral atoms to produce albedo neutrons which, being unstable to 𝛽 decay, are a potential source of geomagnetically trapped protons and electrons. Protons retain most of the neutrons' kinetic energy while the electrons have lower energies, mostly below 1 MeV. The viability of the electron source was, however, uncertain because measurements showed that electron intensity can vary greatly while the neutron decay rate should be almost constant. Recent measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) onboard the Colorado Student Space Weather Experiment (CSSWE) CubeSat now show that CRAND is the main electron source for the radiation belt near its inner edge, and also contributes to the inner belt elsewhere. Furthermore, measurement of the CRAND electron intensity provides the first experimental determination of the neutron density in near-Earth space, 2x10-9/cm3, confirming earlier theoretical estimates.

  6. Genesis Radiation Environment

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Altstatt, Richard L.; Skipworth, William C.

    2007-01-01

    The Genesis spacecraft launched on 8 August 2001 sampled solar wind environments at L1 from 2001 to 2004. After the Science Capsule door was opened, numerous foils and samples were exposed to the various solar wind environments during periods including slow solar wind from the streamer belts, fast solar wind flows from coronal holes, and coronal mass ejections. The Survey and Examination of Eroded Returned Surfaces (SEERS) program led by NASA's Space Environments and Effects program had initiated access for the space materials community to the remaining Science Capsule hardware after the science samples had been removed for evaluation of materials exposure to the space environment. This presentation will describe the process used to generate a reference radiation Genesis Radiation Environment developed for the SEERS program for use by the materials science community in their analyses of the Genesis hardware.

  7. KSC-2012-4613

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, Dave "Kouch" Kusnierkiewicz, Space Department chief engineer from Johns Hopkins University's Applied Physics Laboratory, talks to agency social media followers during the second day of NASA Social activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  8. KSC-2012-4609

    NASA Image and Video Library

    2012-08-23

    CAPE CANAVERAL, Fla. – At NASA's Kennedy Space Center in Florida, Jason Townsend of NASA's Social Media Team welcomes agency social media followers to the second day of activities revolving around NASA's Radiation Belt Storm Probes, or RBSP, mission. The probes are set to launch aboard a United Launch Alliance, or ULA, Atlas V rocket from nearby Cape Canaveral Air Force Station. About 40 followers were selected to participate in RBSP's prelaunch and launch activities and share them with their own fan base. The RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Frankie Martin

  9. Solar, interplanetary, and magnetospheric parameters for the radiation belt energetic electron flux

    NASA Astrophysics Data System (ADS)

    Vassiliadis, D.; Fung, S. F.; Klimas, A. J.

    2005-04-01

    In developing models of the radiation belt energetic electron flux, it is important to include the states of the interplanetary medium and the magnetosphere, as well as the solar activity. In this study we choose the log flux je(t;L;E) at 2-6 MeV, as measured by the Proton-Electron Telescope (PET) on SAMPEX in the period 1993-2002, as a representative flux variable and evaluate the usefulness of 17 interplanetary and magnetospheric (IP/MS) parameters in its specification. The reference parameter is the solar wind velocity, chosen because of its known high geoeffectiveness. We use finite impulse response filters to represent the effective coupling of the individual parameters to the log flux. We measure the temporal and spatial scales of the coupling using the impulse response function and the input's geoeffectiveness using the data-model correlation. The correlation profile as a function of L is complex, and we identify its peaks in reference to the radial regions P0 (L = 3.1-4.0, inner edge of the outer belt), P1 (4.1-7.5, main outer belt), and P2 (>7.5, quasi-trapped population), whose boundaries are determined from a radial correlative analysis (Vassiliadis et al., 2003b). Using the profiles, we classify the IP/MS parameters in four categories: (1) For the solar wind velocity and pressure the correlation is high and largely independent of L across P0 and P1, reaching its maximum in L = 4.8-6.1, or the central part of P1. (2) The IMF BSouth component and related IP/MS parameters have a bimodal correlation function, with peaks in region P0 (L = 3.0-4.1) and the geosynchronous orbit region within P1. (3) The IMF BNorth and four other interplanetary or solar irradiance parameters have a minimum correlation in P1, while the highest correlation is in the slot-outer belt boundary (L = 2.5). (4) Finally, the solar wind density has a unique correlation profile, which is anticorrelated with that of the solar wind velocity for certain L shells. We verify this

  10. Characteristics of pitch angle distributions of hundreds of keV electrons in the slot region and inner radiation belt

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Li, X.; Blake, J. B.; Fennell, J. F.; Claudepierre, S. G.; Baker, D. N.; Jaynes, A. N.; Malaspina, D. M.

    2014-12-01

    The pitch angle distribution (PAD) of energetic electrons in the slot region and inner radiation belt received little attention in the past decades due to the lack of quality measurements. Using the state-of-the-art pitch angle-resolved data from the Magnetic Electron Ion Spectrometer instrument onboard the Van Allen Probes, a detailed analysis of hundreds of keV electron PADs below L = 4 is performed, in which the PADs are categorized into three types: normal (flux peaking at 90°), cap (exceedingly peaking narrowly around 90°), and 90° minimum (lower flux at 90°) PADs. By examining the characteristics of the PADs of ˜460 keV electrons for over a year, we find that the 90° minimum PADs are generally present in the inner belt (L<2), while normal PADs dominate at L˜3.5-4. In the region between, 90° minimum PADs dominate during injection times and normal PADs dominate during quiet times. Cap PADs appear mostly at the decay phase of storms in the slot region and are likely caused by the pitch angle scattering of hiss waves. Fitting the normal PADs into sinnα form, the parameter n is much higher below L = 3 than that in the outer belt and relatively constant in the inner belt but changes significantly in the slot region (2 < L < 3) during injection times. As for the 90° minimum PADs, by performing a detailed case study, we find in the slot region this type of PAD is likely caused by chorus wave heating, but this mechanism can hardly explain the formation of 90° minimum PADs at the center of inner belt.

  11. Generation of extremely low frequency chorus in Van Allen radiation belts

    NASA Astrophysics Data System (ADS)

    Xiao, Fuliang; Liu, Si; Tao, Xin; Su, Zhenpeng; Zhou, Qinghua; Yang, Chang; He, Zhaoguo; He, Yihua; Gao, Zhonglei; Baker, D. N.; Spence, H. E.; Reeves, G. D.; Funsten, H. O.; Blake, J. B.

    2017-03-01

    Recent studies have shown that chorus can efficiently accelerate the outer radiation belt electrons to relativistic energies. Chorus, previously often observed above 0.1 equatorial electron gyrofrequency fce, was generated by energetic electrons originating from Earth's plasma sheet. Chorus below 0.1 fce has seldom been reported until the recent data from Van Allen Probes, but its origin has not been revealed so far. Because electron resonant energy can approach the relativistic level at extremely low frequency, relativistic effects should be considered in the formula for whistler mode wave growth rate. Here we report high-resolution observations during the 14 October 2014 small storm and firstly demonstrate, using a fully relativistic simulation, that electrons with the high-energy tail population and relativistic pitch angle anisotropy can provide free energy sufficient for generating chorus below 0.1 fce. The simulated wave growth displays a very similar pattern to the observations. The current results can be applied to Jupiter, Saturn, and other magnetized planets.

  12. Radial transport of radiation belt electrons in kinetic field-line resonances

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chaston, Christopher C.; Bonnell, J. W.; Wygant, J. R.

    A representative case study from the Van Allen Probes during a geomagnetic storm recovery phase reveals enhanced electron fluxes at intermediate pitch angles over energies from ~100 keV to 5 MeV coincident with broadband low-frequency electromagnetic waves. The statistical properties of these waves are used to build a model for radial diffusion via drift-bounce resonances in kinetic Alfvén eigenmodes/kinetic field-line resonances. Estimated diffusion coefficients indicate timescales for radial transport on the order of hours in storm time events at energies from <100 keV to MeVs over equatorial pitch angles from the edge of the loss cone to nearly perpendicular tomore » the geomagnetic field. In conclusion, the correlation of kinetic resonances with electron depletions and enhancements during storm main phase and recovery, and the rapid diffusion these waves drive, suggests that they may modulate the outer radiation belt.« less

  13. The turbulent plasmasphere boundary layer and the outer radiation belt boundary

    NASA Astrophysics Data System (ADS)

    Mishin, Evgeny; Sotnikov, Vladimir

    2017-12-01

    We report on observations of enhanced plasma turbulence and hot particle distributions in the plasmasphere boundary layer formed by reconnection-injected hot plasma jets entering the plasmasphere. The data confirm that the electron pressure peak is formed just outward of the plasmapause in the premidnight sector. Free energy for plasma wave excitation comes from diamagnetic ion currents near the inner edge of the boundary layer due to the ion pressure gradient, electron diamagnetic currents in the entry layer near the electron plasma sheet boundary, and anisotropic (sometimes ring-like) ion distributions revealed inside, and further inward of, the inner boundary. We also show that nonlinear parametric coupling between lower oblique resonance and fast magnetosonic waves significantly contributes to the VLF whistler wave spectrum in the plasmasphere boundary layer. These emissions represent a distinctive subset of substorm/storm-related VLF activity in the region devoid of substorm injected tens keV electrons and could be responsible for the alteration of the outer radiation belt boundary during (sub)storms.

  14. Radial transport of radiation belt electrons in kinetic field-line resonances

    DOE PAGES

    Chaston, Christopher C.; Bonnell, J. W.; Wygant, J. R.; ...

    2017-07-25

    A representative case study from the Van Allen Probes during a geomagnetic storm recovery phase reveals enhanced electron fluxes at intermediate pitch angles over energies from ~100 keV to 5 MeV coincident with broadband low-frequency electromagnetic waves. The statistical properties of these waves are used to build a model for radial diffusion via drift-bounce resonances in kinetic Alfvén eigenmodes/kinetic field-line resonances. Estimated diffusion coefficients indicate timescales for radial transport on the order of hours in storm time events at energies from <100 keV to MeVs over equatorial pitch angles from the edge of the loss cone to nearly perpendicular tomore » the geomagnetic field. In conclusion, the correlation of kinetic resonances with electron depletions and enhancements during storm main phase and recovery, and the rapid diffusion these waves drive, suggests that they may modulate the outer radiation belt.« less

  15. Memories and NASA Spacecraft: A Description of Memories, Radiation Failure Modes, and System Design Considerations

    NASA Technical Reports Server (NTRS)

    LaBel, Kenneth A.; Ladbury, Ray; Oldhamm, Timothy

    2010-01-01

    As NASA has evolved it's usage of spaceflight computing, memory applications have followed as well. In this slide presentation, the history of NASA's memories from magnetic core and tape recorders to current semiconductor approaches is discussed. There is a brief description of current functional memory usage in NASA space systems followed by a description of potential radiation-induced failure modes along with considerations for reliable system design.

  16. Van Allen Probe Observations of Chorus Wave Activity, Source and Seed electrons, and the Radiation Belt Response During ICME and CIR Storms

    NASA Astrophysics Data System (ADS)

    Bingham, S.; Mouikis, C.; Kistler, L. M.; Farrugia, C. J.; Paulson, K. W.; Huang, C. L.; Boyd, A. J.; Spence, H. E.; Kletzing, C.

    2017-12-01

    Whistler mode chorus waves are electromagnetic waves that have been shown to be a major contributor to enhancements in the outer radiation belt during geomagnetic storms. The temperature anisotropy of source electrons (10s of keV) provides the free energy for chorus waves, which can accelerate sub-relativistic seed electrons (100s of keV) to relativistic energies. This study uses Van Allen Probe observations to examine the excitation and plasma conditions associated with chorus wave observations, the development of the seed population, and the outer radiation belt response in the inner magnetosphere, for 25 ICME and 35 CIR storms. Plasma data from the Helium Oxygen Proton Electron (HOPE) instrument and magnetic field measurements from the Electric and Magnetic Field Instrument Suite and Integrated Science (EMFISIS) are used to identify chorus wave activity and to model a linear theory based proxy for chorus wave growth. A superposed epoch analysis shows a peak of chorus wave power on the dawnside during the storm main phase that spreads towards noon during the storm recovery phase. According to the linear theory results, this wave activity is driven by the enhanced convection driving plasma sheet electrons across the dayside. Both ICME and CIR storms show comparable levels of wave growth. Plasma data from the Magnetic Electron Ion Spectrometer (MagEIS) and the Relativistic Electron Proton Telescope (REPT) are used to observe the seed and relativistic electrons. A superposed epoch analysis of seed and relativistic electrons vs. L shows radiation belt enhancements with much greater frequency in the ICME storms, coinciding with a much stronger and earlier seed electron enhancement in the ICME storms.

  17. Earth Radiation Budget Research at the NASA Langley Research Center

    NASA Technical Reports Server (NTRS)

    Smith, G. Louis; Harrison, Edwin F.; Gibson, Gary G.

    2014-01-01

    In the 1970s research studies concentrating on satellite measurements of Earth's radiation budget started at the NASA Langley Research Center. Since that beginning, considerable effort has been devoted to developing measurement techniques, data analysis methods, and time-space sampling strategies to meet the radiation budget science requirements for climate studies. Implementation and success of the Earth Radiation Budget Experiment (ERBE) and the Clouds and the Earth's Radiant Energy System (CERES) was due to the remarkable teamwork of many engineers, scientists, and data analysts. Data from ERBE have provided a new understanding of the effects of clouds, aerosols, and El Nino/La Nina oscillation on the Earth's radiation. CERES spacecraft instruments have extended the time coverage with high quality climate data records for over a decade. Using ERBE and CERES measurements these teams have created information about radiation at the top of the atmosphere, at the surface, and throughout the atmosphere for a better understanding of our climate. They have also generated surface radiation products for designers of solar power plants and buildings and numerous other applications

  18. Prediction of high-energy radiation belt electron fluxes using a combined VERB-NARMAX model

    NASA Astrophysics Data System (ADS)

    Pakhotin, I. P.; Balikhin, M. A.; Shprits, Y.; Subbotin, D.; Boynton, R.

    2013-12-01

    This study is concerned with the modelling and forecasting of energetic electron fluxes that endanger satellites in space. By combining data-driven predictions from the NARMAX methodology with the physics-based VERB code, it becomes possible to predict electron fluxes with a high level of accuracy and across a radial distance from inside the local acceleration region to out beyond geosynchronous orbit. The model coupling also makes is possible to avoid accounting for seed electron variations at the outer boundary. Conversely, combining a convection code with the VERB and NARMAX models has the potential to provide even greater accuracy in forecasting that is not limited to geostationary orbit but makes predictions across the entire outer radiation belt region.

  19. ICME-driven sheath regions deplete the outer radiation belt electrons

    NASA Astrophysics Data System (ADS)

    Hietala, H.; Kilpua, E. K.; Turner, D. L.

    2013-12-01

    It is an outstanding question in space weather and solar wind-magnetosphere interaction studies, why some storms result in an increase of the outer radiation belt electron fluxes, while others deplete them or produce no change. One approach to this problem is to look at differences in the storm drivers. Traditionally drivers have been classified to Stream Interaction Regions (SIRs) and Interplanetary Coronal Mass Ejections (ICMEs). However, an 'ICME event' is a complex structure: The core is a magnetic cloud (MC; a clear flux rope structure). If the mass ejection is fast enough, it can drive a shock in front of it. This leads to the formation of a sheath region between the interplanetary shock and the leading edge of the MC. While both the sheath and the MC feature elevated solar wind speed, their other properties are very different. For instance, the sheath region has typically a much higher dynamic pressure than the magnetic cloud. Moreover, the sheath region has a high power in magnetic field and dynamic pressure Ultra Low Frequency (ULF) range fluctuations, while the MC is characterised by an extremely smooth magnetic field. Magnetic clouds have been recognised as important drivers magnetospheric activity since they can comprise long periods of very large southward Interplanetary Magnetic Field (IMF). Nevertheless, previous studies have shown that sheath regions can also act as storm drivers. In this study, we analyse the effects of ICME-driven sheath regions on the relativistic electron fluxes observed by GOES satellites on the geostationary orbit. We perform a superposed epoch analysis of 31 sheath regions from solar cycle 23. Our results show that the sheaths cause an approximately one order of magnitude decrease in the 24h-averaged electron fluxes. Typically the fluxes also stay below the pre-event level for more than two days. Further analysis reveals that the decrease does not depend on, e.g., whether the sheath interval contains predominantly northward

  20. New Horizons High-Phase Observations of Distant Kuiper Belt Objects

    NASA Astrophysics Data System (ADS)

    Verbiscer, A.; Porter, S.; Spencer, J. R.; Buie, M. W.; Benecchi, S.; Weaver, H. A., Jr.; Buratti, B. J.; Ennico Smith, K.; Olkin, C.; Stern, S. A.; Young, L. A.; Cheng, A. F.

    2017-12-01

    From its unique vantage point far from the Sun, NASA's New Horizons spacecraft has observed Kuiper Belt Objects at separations ranging from 0.1 to 70 AU, and at solar phase angles far larger than those attainable from Earth. We have constructed the first KBO solar phase curves with substantial phase angle coverage for targets including Haumea, Makemake, Quaoar, Arawn (Porter et al. 2016, Astrophys. J. Lett. 828, L15), and 2002 MS4. We compare the phase functions of these KBOs with those of objects in the Pluto system and other Solar System bodies such as comets, asteroids, and icy satellites. For KBOs with known geometric albedos, these measurements enable calculation of the phase integral, an important photometric property that characterizes the energy balance on a distant KBO surface. During its approach to 2014 MU69, and following its close encounter on 1 January 2019, New Horizons will continue to exploit its capabilities as NASA's only observatory within the Kuiper Belt itself.

  1. Modeling the Impenetrable Barrier to Inward Transport of Ultra-relativistic Radiation Belt Electrons

    NASA Astrophysics Data System (ADS)

    Tu, W.; Cunningham, G.; Chen, Y.; Baker, D. N.; Henderson, M. G.; Reeves, G. D.

    2014-12-01

    It has long been considered that the inner edge of the Earth's outer radiation belt is closely correlated with the minimum plasmapause location. However, recent discoveries by Baker et al. [1] show that it is not the case for ultra-relativistic electrons (2-10 MeV) in the radiation belt. Based on almost two years of Van Allen Probes/REPT data, they find that the inner edge of highly relativistic electrons is rarely collocated with the plasmapause; and more interestingly, there is a clear, persistent, and nearly impenetrable barrier to inward transport of high energy electrons, observed to locate at L~2.8. The presence of such an impenetrable barrier at this very specific location poses a significant puzzle. Using our DREAM3D diffusion model, which includes radial, pitch angle, and momentum diffusion, we are able to simulate the observed impenetrable barrier of ultra-relativistic electrons. The simulation demonstrates that during strong geomagnetic storms the plasmapause can be compressed to very low L region (sometimes as low as L~3), then strong chorus waves just outside the plasmapause can locally accelerate electrons up to multiple-MeV; when storm recovers, plasmapause moves back to large L, while the highly-relativistic electrons generated at low L continue to diffuse inward and slow decay by pitch angle diffusion from plasmaspheric hiss. The delicate balance between slow inward radial diffusion and weak pitch angle scattering creates a fixed inner boundary or barrier for ultra-relativistic electrons. The barrier is found to locate at a fixed L location, independent of the initial penetration depth of electrons that is correlated with the plasmapause location. Our simulation results quantitatively reproduce the evolution of the flux versus L profile, the L location of the barrier, and the decay rate of highly energetic electrons right outside the barrier. 1Baker, D. N., et al. (2014), Nearly Impenetrable Barrier to Inward Ultra-relativistic Magnetospheric

  2. Terrestrial Sources of X-Ray Radiation and Their Effects on NASA Flight Hardware

    NASA Technical Reports Server (NTRS)

    Kniffin, Scott

    2016-01-01

    X-rays are an energetic and penetrating form of ionizing electromagnetic radiation, which can degrade NASA flight hardware. The main concern posed by such radiation is degradation of active electronic devices and, in some cases, diodes. Non-electronic components are only damaged at doses that far exceed the point where any electronic device would be destroyed. For the purposes of this document, flight hardware can be taken to mean an entire instrument, the flight electronics within the instrument or the individual microelectronic devices in the flight electronics. This document will discuss and describe the ways in which NASA flight hardware might be exposed to x-rays, what is and isn't a concern, and how to tell the difference. First, we must understand what components in flight hardware may be vulnerable to degradation or failure as a result of being exposed to ionizing radiation, such as x-rays. As stated above, bulk materials (structural metals, plastics, etc.) are generally only affected by ionizing radiation at very high dose levels. Likewise, passive electronic components (e.g. resistors, capacitors, most diodes) are strongly resistant to exposure to x-rays, except at very high doses. The main concerns arise when active components, that is, components like discrete transistors and microelectronic devices, are exposed to ionizing radiation. Active components are designed to respond to minute changes in currents and voltages in the circuit. As such, it is not surprising that exposure to ionizing radiation, which creates ionized and therefore electrically active particles, may degrade the way the hardware performs. For the most part, the mechanism for this degradation is trapping of the charges generated by ionizing radiation by defects in dielectric materials in the hardware. As such, the degree of damage is a function of both the quantity of ionizing radiation exposure and the physical characteristics of the hardware itself. The metric that describes the

  3. Heliospheric Physics and NASA's Vision for Space Exploration

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.

    2007-01-01

    The Vision for Space Exploration outlines NASA's development of a new generation of human-rated launch vehicles to replace the Space Shuttle and an architecture for exploring the Moon and Mars. The system--developed by the Constellation Program--includes a near term (approx. 2014) capability to provide crew and cargo service to the International Space Station after the Shuttle is retired in 2010 and a human return to the Moon no later than 2020. Constellation vehicles and systems will necessarily be required to operate efficiently, safely, and reliably in the space plasma and radiation environments of low Earth orbit, the Earth's magnetosphere, interplanetary space, and on the lunar surface. This presentation will provide an overview of the characteristics of space radiation and plasma environments relevant to lunar programs including the trans-lunar injection and trans-Earth injection trajectories through the Earth's radiation belts, solar wind surface dose and plasma wake charging environments in near lunar space, energetic solar particle events, and galactic cosmic rays and discusses the design and operational environments being developed for lunar program requirements to assure that systems operate successfully in the space environment.

  4. Van Allen Probes Mission Space Academy: Educating middle school students about Earth's mysterious radiation belts

    NASA Astrophysics Data System (ADS)

    Butler, L.; Turney, D.; Matiella Novak, A.; Smith, D.; Simon, M.

    2013-12-01

    How's the weather in space? Why on Earth did NASA send two satellites above Earth to study radiation belts and space weather? To learn the answer to questions about NASA's Van Allen Probes mission, 450 students and their teachers from Maryland middle schools attended Space Academy events highlighting the Van Allen Probes mission. Sponsored by the Applied Physics Laboratory (APL) and Discovery Education, the events are held at the APL campus in Laurel, MD. Space Academies take students and teachers on behind-the-scenes exploration of how spacecraft are built, what they are designed to study, and introduces them to the many professionals that work together to create some of NASA's most exciting projects. Moderated by a public relations representative in the format of an official NASA press conference, the daylong event includes a student press conference with students as reporters and mission experts as panelists. Lunch with mission team members gives students a chance to ask more questions. After lunch, students don souvenir clean room suits, enjoy interactive science demonstrations, and tour APL facilities where the Van Allen Probes were built and tested before launch. Students may even have an opportunity to peek inside a clean room to view spacecraft being assembled. Prior to the event, teachers are provided with classroom activities, lesson plans, and videos developed by APL and Discovery Education to help prepare students for the featured mission. The activities are aligned to National Science Education Standards and appropriate for use in the classroom. Following their visit, student journalists are encouraged to write a short article about their field trip; selections are posted on the Space Academy web site. Designed to engage, inspire, and influence attitudes about space science and STEM careers, Space Academies provide an opportunity to attract underserved populations and emphasize that space science is for everyone. Exposing students to a diverse group of

  5. Planetary Migration and Kuiper Belt Dynamics

    NASA Astrophysics Data System (ADS)

    Malhotra, Renu

    The Kuiper belt holds memory of the dynamical processes that shaped the architecture of the solar system, including the orbital migration history of the giant planets. We propose studies of the orbital dynamics of the Kuiper Belt in order to understand the origin of its complex dynamical structure and its link to the orbital migration history of the giant planets. By means of numerical simulations, statistical tests, as well as analytical calculations we will (1) investigate the origin of resonant Kuiper belt objects to test alternative scenarios of Neptune's migration history, (2) investigate the long term dynamical evolution of the Haumea family of Kuiper Belt objects in order to improve the age estimate of this family, and (3) investigate resonance-sticking behavior and the Kozai-Lidov mechanism and its role in the origin of the extended scattered disk. These studies directly support the goals of the NASA-OSS program by improving our understanding of the origin of the solar system's architecture. Our results will provide constraints on the nature and timing of the dynamical excitation event that is thought to have occurred in early solar system history and to have determined the architecture of the present-day solar system; our results will also provide deeper theoretical understanding of sticky mean motion resonances which contribute greatly to the longevity of many small bodies, improve our understanding of dynamical transport of planetesimals in planetary systems, and help interpret observations of other planetary systems.

  6. Effect of Thermospheric Neutral Density upon Inner Trapped-belt Proton Flux

    NASA Technical Reports Server (NTRS)

    Wilson, Thomas L.; Lodhi, M. A. K.; Diaz, Abel B.

    2007-01-01

    We wish to point out that a secular change in the Earth's atmospheric neutral density alters charged-particle lifetime in the inner trapped radiation belts, in addition to the changes recently reported as produced by greenhouse gases. Heretofore, changes in neutral density have been of interest primarily because of their effect on the orbital drag of satellites. We extend this to include the orbital lifetime of charged particles in the lower radiation belts. It is known that the charged-belt population is coupled to the neutral density of the atmosphere through changes induced by solar activity, an effect produced by multiple scattering off neutral and ionized atoms along with ionization loss in the thermosphere where charged and neutral populations interact. It will be shown here that trapped-belt flux J is bivariant in energy E and thermospheric neutral density , as J(E,rho). One can conclude that proton lifetimes in these belts are also directly affected by secular changes in the neutral species populating the Earth s thermosphere. This result is a consequence of an intrinsic property of charged-particle flux, that flux is not merely a function of E but is dependent upon density rho when a background of neutrals is present.

  7. Kak Amerikantsy iskali vetra v pole, a nashli radiatsionnyj poyas i kak Russkie iskali radiatsionnyj poyas, a nashli solnechnyj veter Chast' I %t How Americans looked for "a wind in a field" but found a radiation belt, and how Russians looked for a radiation belt but found a solar wind or physical experiments on the first artificial Earth's satellites and a discovery of radiation belts

    NASA Astrophysics Data System (ADS)

    Zavidonov, I. V.

    The history of the most important scientific discovery of the early space era - the discovery of the inner and outer radiation belts of the Earth in 1958 is reconstructed. The paper uses archival records to bring to light the relative contributions of Soviet and American reseachers to the complex process of discovery. It also shows how misuses of science in mass-media political propaganda led to misrepresentations of the real historical portrayal of early space research.

  8. Radiation Environment Inside Spacecraft

    NASA Technical Reports Server (NTRS)

    O'Neill, Patrick

    2015-01-01

    Dr. Patrick O'Neill, NASA Johnson Space Center, will present a detailed description of the radiation environment inside spacecraft. The free space (outside) solar and galactic cosmic ray and trapped Van Allen belt proton spectra are significantly modified as these ions propagate through various thicknesses of spacecraft structure and shielding material. In addition to energy loss, secondary ions are created as the ions interact with the structure materials. Nuclear interaction codes (FLUKA, GEANT4, HZTRAN, MCNPX, CEM03, and PHITS) transport free space spectra through different thicknesses of various materials. These "inside" energy spectra are then converted to Linear Energy Transfer (LET) spectra and dose rate - that's what's needed by electronics systems designers. Model predictions are compared to radiation measurements made by instruments such as the Intra-Vehicular Charged Particle Directional Spectrometer (IV-CPDS) used inside the Space Station, Orion, and Space Shuttle.

  9. Managing Radiation Degradation of CCDs on the Chandra X-ray Observatory

    NASA Technical Reports Server (NTRS)

    ODell, Stephen L.; Blackwell, William C.; Minow, Joseph I.; Cameron, Robert A.; Morris, David C.; Virani, Shanil N.; Six, N. Frank (Technical Monitor)

    2002-01-01

    The CCDs on the Chandra X ray Observatory are sensitive to radiation damage particularly from low-energy protons scattering off the telescope's mirrors onto the focal plane. In its highly elliptical orbit, Chandra passes through a spatially and temporally varying radiation environment, ranging from the radiation belts to the solar wind. Translating thc Advanced CCD Imaging Spectrometer (ACIS) out of the focal position during radiation-belt passages has prevented loss of scientific utility and eventually functionality. However, carefully managing the radiation damage during the remainder of the orbit, without unnecessarily sacrificing observing time, is essential to optimizing the scientific value of this exceptional observatory throughout its planned 10-year mission. In working toward this optimization, the Chandra team developed aid applied radiation-management strategies. These strategies include autonomous instrument safing triggered by the on-board radiation monitor, as well as monitoring, alerts, and intervention based upon real-time space-environment data from NOAA and NASA spacecraft. Furthermore, because Chandra often spends much of its orbit out of the solar wind (in the Earth's outer magnetosphere and magnetosheath), the team developed the Chandra Radiation Model to describe the complete low-energy-proton environment. Management of the radiation damage has thus far succeeded in limiting degradation of the charge-transfer inefficiency (CTI) to less than 4.4*10^-6 and 1.4*10^-6 per year for the front-illuminated and back-illuminated CCDs, respectively.

  10. Layered Model for Radiation-Induced Chemical Evolution of Icy Surface Composition on Kuiper Belt and Oort Cloud Bodies

    NASA Technical Reports Server (NTRS)

    Cooper, John F.; Hill, Matthew E.; Richardson, John D.; Sturner, Steven J.

    2010-01-01

    The diversity of albedos and surface colors on observed Kuiper Belt and Inner Oort Cloud objects remains to be explained in terms of competition between primordial intrinsic versus exogenic drivers of surface and near-surface evolution. Earlier models have attempted without success to attribute this diversity to the relations between surface radiolysis from cosmic ray irradiation and gardening by meteoritic impacts. A more flexible approach considers the different depth-dependent radiation profiles produced by low-energy plasma, suprathermal, and maximally penetrating charged particles of the heliospheric and local interstellar radiation environments. Generally red objects of the dynamically cold (low inclination, circular orbit) Classical Kuiper Belt might be accounted for from erosive effects of plasma ions and reddening effects of high energy cosmic ray ions, while suprathermal keV-MeV ions could alternatively produce more color neutral surfaces. The deepest layer of more pristine ice can be brought to the surface from meter to kilometer depths by larger impact events and potentially by cryovolcanic activity. The bright surfaces of some larger objects, e.g. Eris, suggest ongoing resurfacing activity. Interactions of surface irradiation, resultant chemical oxidation, and near-surface cryogenic fluid reservoirs have been proposed to account for Enceladus cryovolcanism and may have further applications to other icy irradiated bodies. The diversity of causative processes must be understood to account for observationally apparent diversities of the object surfaces.

  11. Spatial characterization of relativistic electron enhancements in the Earth's outer radiation belt during the Van Allen Probes era

    NASA Astrophysics Data System (ADS)

    Pinto, V. A.; Bortnik, J.; Moya, P. S.; Lyons, L. R.; Sibeck, D. G.; Kanekal, S. G.

    2017-12-01

    Using Van Allen Probes Relativistic Electron-Proton Telescope (REPT) instrument we have identified 73 relativistic electron enhancement events in the outer radiation belt that occurred at different L values between L = 2.5 and L = 6.0. To determine an enhancement, we have used three different identification methods. We then determine the radial location, MLT location, timing and strength of those enhancements. We discuss the differences of each of the methods and test them to pinpoint the origin and spatial propagation of each enhancement. We have classified the events based on the radial propagation, speed of enhancement and intensity of fluxes and response for energy channels ranging from 1.8 MeV to 6.3 MeV. In addition, we have used OMNI data to study the statistical properties of the solar wind during each event and have classified similarities and differences that might be relevant for each group of enhancements and help us determine the physical process responsible for different types of enhancements. Additionally, we have used >2 MeV electron fluxes at geostationary orbit as measured by the GOES 13 and 15 Energetic Particle Sensor (EPS) instrument to compare our results with the geostationary orbit. Our results suggest that under certain conditions GOES data can be used to predict fluxes at the core of the radiation belt and vice-versa.

  12. Kuiper Belt Object Orbiter Using Advanced Radioisotope Power Sources and Electric Propulsion

    NASA Technical Reports Server (NTRS)

    Oleson, Steven R.; McGuire, Melissa L.; Dankanich, John; Colozza, Anthony; Schmitz, Paul; Khan, Omair; Drexler, Jon; Fittje, James

    2011-01-01

    A joint NASA GRC/JPL design study was performed for the NASA Radioisotope Power Systems Office to explore the use of radioisotope electric propulsion for flagship class missions. The Kuiper Belt Object Orbiter is a flagship class mission concept projected for launch in the 2030 timeframe. Due to the large size of a flagship class science mission larger radioisotope power system building blocks were conceptualized to provide the roughly 4 kW of power needed by the NEXT ion propulsion system and the spacecraft. Using REP the spacecraft is able to rendezvous with and orbit a Kuiper Belt object in 16 years using either eleven (no spare) 420 W advanced RTGs or nine (with a spare) 550 W advanced Stirling Radioisotope systems. The design study evaluated integrating either system and estimated impacts on cost as well as required General Purpose Heat Source requirements.

  13. KSC-2012-2669

    NASA Image and Video Library

    2012-05-03

    CAPE CANAVERAL, Fla. – In the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, Applied Physics Laboratory technicians remove the protective shroud from around NASA's Radiation Belt Storm Probe B. Its twin, Radiation Belt Storm Probe A, in the background, has already been uncovered. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP instruments will provide the measurements needed to characterize and quantify the plasma processes that produce very energetic ions and relativistic electrons. The mission is part of NASA’s broader Living With a Star Program that was conceived to explore fundamental processes that operate throughout the solar system, particularly those that generate hazardous space weather effects in the vicinity of Earth and phenomena that could impact solar system exploration. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after launch. Launch aboard a United Launch Alliance Atlas V rocket is scheduled for August 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  14. Reverberation Chamber Uniformity Validation and Radiated Susceptibility Test Procedures for the NASA High Intensity Radiated Fields Laboratory

    NASA Technical Reports Server (NTRS)

    Koppen, Sandra V.; Nguyen, Truong X.; Mielnik, John J.

    2010-01-01

    The NASA Langley Research Center's High Intensity Radiated Fields Laboratory has developed a capability based on the RTCA/DO-160F Section 20 guidelines for radiated electromagnetic susceptibility testing in reverberation chambers. Phase 1 of the test procedure utilizes mode-tuned stirrer techniques and E-field probe measurements to validate chamber uniformity, determines chamber loading effects, and defines a radiated susceptibility test process. The test procedure is segmented into numbered operations that are largely software controlled. This document is intended as a laboratory test reference and includes diagrams of test setups, equipment lists, as well as test results and analysis. Phase 2 of development is discussed.

  15. Galactic cosmic ray simulation at the NASA Space Radiation Laboratory

    PubMed Central

    Norbury, John W.; Schimmerling, Walter; Slaba, Tony C.; Azzam, Edouard I.; Badavi, Francis F.; Baiocco, Giorgio; Benton, Eric; Bindi, Veronica; Blakely, Eleanor A.; Blattnig, Steve R.; Boothman, David A.; Borak, Thomas B.; Britten, Richard A.; Curtis, Stan; Dingfelder, Michael; Durante, Marco; Dynan, William S.; Eisch, Amelia J.; Elgart, S. Robin; Goodhead, Dudley T.; Guida, Peter M.; Heilbronn, Lawrence H.; Hellweg, Christine E.; Huff, Janice L.; Kronenberg, Amy; La Tessa, Chiara; Lowenstein, Derek I.; Miller, Jack; Morita, Takashi; Narici, Livio; Nelson, Gregory A.; Norman, Ryan B.; Ottolenghi, Andrea; Patel, Zarana S.; Reitz, Guenther; Rusek, Adam; Schreurs, Ann-Sofie; Scott-Carnell, Lisa A.; Semones, Edward; Shay, Jerry W.; Shurshakov, Vyacheslav A.; Sihver, Lembit; Simonsen, Lisa C.; Story, Michael D.; Turker, Mitchell S.; Uchihori, Yukio; Williams, Jacqueline; Zeitlin, Cary J.

    2017-01-01

    Most accelerator-based space radiation experiments have been performed with single ion beams at fixed energies. However, the space radiation environment consists of a wide variety of ion species with a continuous range of energies. Due to recent developments in beam switching technology implemented at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL), it is now possible to rapidly switch ion species and energies, allowing for the possibility to more realistically simulate the actual radiation environment found in space. The present paper discusses a variety of issues related to implementation of galactic cosmic ray (GCR) simulation at NSRL, especially for experiments in radiobiology. Advantages and disadvantages of different approaches to developing a GCR simulator are presented. In addition, issues common to both GCR simulation and single beam experiments are compared to issues unique to GCR simulation studies. A set of conclusions is presented as well as a discussion of the technical implementation of GCR simulation. PMID:26948012

  16. Galactic cosmic ray simulation at the NASA Space Radiation Laboratory.

    PubMed

    Norbury, John W; Schimmerling, Walter; Slaba, Tony C; Azzam, Edouard I; Badavi, Francis F; Baiocco, Giorgio; Benton, Eric; Bindi, Veronica; Blakely, Eleanor A; Blattnig, Steve R; Boothman, David A; Borak, Thomas B; Britten, Richard A; Curtis, Stan; Dingfelder, Michael; Durante, Marco; Dynan, William S; Eisch, Amelia J; Robin Elgart, S; Goodhead, Dudley T; Guida, Peter M; Heilbronn, Lawrence H; Hellweg, Christine E; Huff, Janice L; Kronenberg, Amy; La Tessa, Chiara; Lowenstein, Derek I; Miller, Jack; Morita, Takashi; Narici, Livio; Nelson, Gregory A; Norman, Ryan B; Ottolenghi, Andrea; Patel, Zarana S; Reitz, Guenther; Rusek, Adam; Schreurs, Ann-Sofie; Scott-Carnell, Lisa A; Semones, Edward; Shay, Jerry W; Shurshakov, Vyacheslav A; Sihver, Lembit; Simonsen, Lisa C; Story, Michael D; Turker, Mitchell S; Uchihori, Yukio; Williams, Jacqueline; Zeitlin, Cary J

    2016-02-01

    Most accelerator-based space radiation experiments have been performed with single ion beams at fixed energies. However, the space radiation environment consists of a wide variety of ion species with a continuous range of energies. Due to recent developments in beam switching technology implemented at the NASA Space Radiation Laboratory (NSRL) at Brookhaven National Laboratory (BNL), it is now possible to rapidly switch ion species and energies, allowing for the possibility to more realistically simulate the actual radiation environment found in space. The present paper discusses a variety of issues related to implementation of galactic cosmic ray (GCR) simulation at NSRL, especially for experiments in radiobiology. Advantages and disadvantages of different approaches to developing a GCR simulator are presented. In addition, issues common to both GCR simulation and single beam experiments are compared to issues unique to GCR simulation studies. A set of conclusions is presented as well as a discussion of the technical implementation of GCR simulation. Published by Elsevier Ltd.

  17. Stormtime transport of ring current and radiation belt ions

    NASA Technical Reports Server (NTRS)

    Chen, Margaret W.; Schulz, Michael; Lyons, L. R.; Gorney, David J.

    1993-01-01

    This is an investigation of stormtime particle transport that leads to formation of the ring current. Our method is to trace the guiding-center motion of representative ions (having selected first adiabatic invariants mu) in response to model substorm-associated impulses in the convection electric field. We compare our simulation results qualitatively with existing analytically tractable idealizations of particle transport (direct convective access and radial diffusion) in order to assess the limits of validity of these approximations. For mu approximately less than 10 MeV/G (E approximately less than 10 keV at L equivalent to 3) the ion drift period on the final (ring-current) drift shell of interest (L equivalent to 3) exceeds the duration of the main phase of our model storm, and we find that the transport of ions to this drift shell is appropriately idealized as direct convective access, typically from open drift paths. Ion transport to a final closed drift path from an open (plasma-sheet) drift trajectory is possible for those portions of that drift path that lie outside the mean stormtime separatrix between closed and open drift trajectories, For mu approximately 10-25 MeV/G (110 keV approximately less than E approximately less than 280 keV at L equivalent to 3) the drift period at L equivalent to 3 is comparable to the postulated 3-hr duration of the storm, and the mode of transport is transitional between direct convective access and transport that resembles radial diffusion. (This particle population is transitional between the ring current and radiation belt). For mu approximately greater than 25 MeV/G (radiation-belt ions having E approximately greater than 280 keV at L equivalent to 3) the ion drift period is considerably shorter than the main phase of a typical storm, and ions gain access to the ring-current region essentially via radial diffusion. By computing the mean and mean-square cumulative changes in 1/L among (in this case) 12 representative

  18. NASA Conference on Thermal Radiation Problems in Space Technology: a Compilation of Summaries of the Papers Presented

    NASA Technical Reports Server (NTRS)

    1960-01-01

    This document contains summaries of the talks presented at a small NASA Conference on Thermal Radiation Problems in Space Technology held at the Langley Research Center on September 12 and 13, 1960. The conferees were NASA members and NASA contractors directly concerned with radiation characteristics of materials and with thermal problems of spacecraft. The purpose of the conference was not only to present significant research information but also to provide an opportunity for the conferees to become aware of each other's fields of interest, activities, techniques, and problems. As arranged herein, the first set of talks, mostly by the contractors, is concerned with surfaces and surface coatings, and with the determination of their pertinent characteristics. The second set of talks, mostly by NASA personnel, is concerned with spacecraft and their thermal problems.

  19. Mathematical model of solar radiation based on climatological data from NASA SSE

    NASA Astrophysics Data System (ADS)

    Obukhov, S. G.; Plotnikov, I. A.; Masolov, V. G.

    2018-05-01

    An original model of solar radiation arriving at the arbitrarily oriented surface has been developed. The peculiarity of the model is that it uses numerical values of the atmospheric transparency index and the surface albedo from the NASA SSE database as initial data. The model is developed in the MatLab/Simulink environment to predict the main characteristics of solar radiation for any geographical point in Russia, including those for territories with no regular actinometric observations.

  20. Variation of Radiation Belt Content Indices and total electron energy During Magnetic Storms Based On Van Allen Probe Observations

    NASA Astrophysics Data System (ADS)

    Xiong, Y.; Xie, L.; Chen, L.; Pu, Z.

    2017-12-01

    We investigate the variability of the RBC indices and total electron energy for varying energies within outer belt during 42 isolate magnetic storms based on the electron flux data from MagEIS and REPT onboard Van Allen Probe-A spacecraft. Van Allan Probes travel throughout the entire radiation belt twice during each orbit, providing an excellent opportunity to measure the electron's pitch angle distributions near the magnetic equatorial plane which is essential to calculate the RBC index accurately. Instead of assuming an isotropic electron pitch angle distribution which is widely used in previous studies, we develop a new and reliable technique to infer the equatorial pitch angle distributions based on the off-equator measurements. The statistic results show that the total electron energy in outer belt increase in 80% storms and has a positive correlation with median value of AE during recovery phase and minimum -Dst. The possibility of observing RBC depletion increase at high energies. The upper limit energy of RBC enhancement has a positive correlation with median value of AE and Vsw during recovery phase and a negative correlation with median value of Nsw during storm, which is consist of the balance of acceleration by chorus waves and loss by EMIC waves.

  1. Three-dimensional stochastic modeling of radiation belts in adiabatic invariant coordinates

    NASA Astrophysics Data System (ADS)

    Zheng, Liheng; Chan, Anthony A.; Albert, Jay M.; Elkington, Scot R.; Koller, Josef; Horne, Richard B.; Glauert, Sarah A.; Meredith, Nigel P.

    2014-09-01

    A 3-D model for solving the radiation belt diffusion equation in adiabatic invariant coordinates has been developed and tested. The model, named Radbelt Electron Model, obtains a probabilistic solution by solving a set of Itô stochastic differential equations that are mathematically equivalent to the diffusion equation. This method is capable of solving diffusion equations with a full 3-D diffusion tensor, including the radial-local cross diffusion components. The correct form of the boundary condition at equatorial pitch angle α0=90° is also derived. The model is applied to a simulation of the October 2002 storm event. At α0 near 90°, our results are quantitatively consistent with GPS observations of phase space density (PSD) increases, suggesting dominance of radial diffusion; at smaller α0, the observed PSD increases are overestimated by the model, possibly due to the α0-independent radial diffusion coefficients, or to insufficient electron loss in the model, or both. Statistical analysis of the stochastic processes provides further insights into the diffusion processes, showing distinctive electron source distributions with and without local acceleration.

  2. Effects of Drift-Shell Splitting by Chorus Waves on Radiation Belt Electrons

    NASA Astrophysics Data System (ADS)

    Chan, A. A.; Zheng, L.; O'Brien, T. P., III; Tu, W.; Cunningham, G.; Elkington, S. R.; Albert, J.

    2015-12-01

    Drift shell splitting in the radiation belts breaks all three adiabatic invariants of charged particle motion via pitch angle scattering, and produces new diffusion terms that fully populate the diffusion tensor in the Fokker-Planck equation. Based on the stochastic differential equation method, the Radbelt Electron Model (REM) simulation code allows us to solve such a fully three-dimensional Fokker-Planck equation, and to elucidate the sources and transport mechanisms behind the phase space density variations. REM has been used to perform simulations with an empirical initial phase space density followed by a seed electron injection, with a Tsyganenko 1989 magnetic field model, and with chorus wave and ULF wave diffusion models. Our simulation results show that adding drift shell splitting changes the phase space location of the source to smaller L shells, which typically reduces local electron energization (compared to neglecting drift-shell splitting effects). Simulation results with and without drift-shell splitting effects are compared with Van Allen Probe measurements.

  3. Layered Model for Radiation-Induced Chemical Evolution of Icy Surface Composition and Dynamics on Kuiper Belt and Oort Cloud Bodies

    NASA Technical Reports Server (NTRS)

    Cooper, John F.; Richardson, John D.

    2010-01-01

    The diversity of albedos and surface colors on observed Kuiper Belt and Inner Oort Cloud objects remains to be explained in terms of competition between primordial intrinsic versus exogenic drivers of surface and near-surface evolution. Earlier models have attempted without success to attribute this diversity to the relations between surface radiolysis from cosmic ray irradiation and gardening by meteoritic impacts. A more flexible approach considers the different depth-dependent radiation profiles produced by low-energy plasma, suprathermal, and maximally penetrating charged particles of the heliospheric and local interstellar radiation environment. Generally red objects of the dynamically cold (low inclination, circular orbit) Classical Kuiper Belt might be accounted for from erosive effects of plasma ions and reddening effects of high energy cosmic ray ions, while suprathermal keV-MeV ions could alternatively produce more color neutral surfaces. The deepest layer of more pristine ice can be brought to the surface from meter to kilometer depths by larger impact events and potentially by cryovolcanic activity. The bright surfaces of some larger objects, e.g. Eris, suggest ongoing resurfacing activity. Cycles of atmospheric formation and surface freezeout can further account for temporal variation as observed on Pluto. The diversity of causative processes must therefore be understood to account for observationally apparent diversities of the object surfaces.

  4. Does Magnetosphere-Ionosphere Coupling, and the Associated Energetic Field Aligned Electron Beams Created Outside 12 RS, Populate Saturn's Radiation Belts?

    NASA Astrophysics Data System (ADS)

    Rymer, A. M.; Mauk, B.; Carbary, J. F.; Kollmann, P.; Clark, G. B.; Mitchell, D. G.; Coates, A. J.

    2016-12-01

    Carbary et al., 2010 showed that the majority (> 70 %) of energetic electron distributions observed beyond 12 Rs (Rs = one Saturn radius 60330 km) have a bi-directional (smile) shaped pitch angle distribution, that is they have peaks along the magnetically field aligned directions at 0 and 180 degree pitch angle with a minima in between. These beams are likely a consequence of magnetosphere-ionosphere electric current coupling resulting in the low altitude acceleration of electrons away from the planet. Since the source of the electron radiation belt is not well understood at Saturn (or elsewhere) we are motivated to explore to what extent energetic field aligned beams can populate the inner magnetosphere and explain the radiation belt intensities there. Using Cassini electron data from the Cassini Plasma Spectrometer (CAPS) electron sensor (ELS) [Young et al., 2004] and the Magnetospheric Imaging Instrument (MIMI) Low-Energy Magnetospheric Measurement System (LEMMS) [Krimigis et al., 2004] we fit electron pitch angle distributions with a commonly used sin^k(pitch angle) and a hyperbolic cosine form developed by Mauk et al. 2007. To estimate the maximum flux that these particles could potentially provide to the inner magnetosphere we compute the phase space density of the populations assuming adiabatic transport to Saturn's inner magnetosphere and compare it with the measurements.

  5. KSC-2012-4547

    NASA Image and Video Library

    2012-08-20

    CAPE CANAVERAL, Fla. - At NASA Kennedy Space Center’s Press Site in Florida, Kathy Winters, launch weather officer with the 45th Weather Squadron at Cape Canaveral Air Force Station, answers a question during a prelaunch news conference held for the Radiation Belt Storm Probes, or RBSP, mission. To her left, are Vernon Thorp, United Launch Alliance program manager, NASA missions, and Richard Fitzgerald, RBSP project manager at Johns Hopkins Applied Physics Laboratory in Laurel, Md. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard an Atlas V rocket. Launch is targeted for Aug. 24. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Glenn Benson

  6. An Empirical Model of Radiation Belt Electron Pitch Angle Distributions Based On Van Allen Probes Measurements

    NASA Astrophysics Data System (ADS)

    Zhao, H.; Friedel, R. H. W.; Chen, Y.; Reeves, G. D.; Baker, D. N.; Li, X.; Jaynes, A. N.; Kanekal, S. G.; Claudepierre, S. G.; Fennell, J. F.; Blake, J. B.; Spence, H. E.

    2018-05-01

    Based on over 4 years of Van Allen Probes measurements, an empirical model of radiation belt electron equatorial pitch angle distribution (PAD) is constructed. The model, developed by fitting electron PADs with Legendre polynomials, provides the statistical PADs as a function of L-shell (L = 1-6), magnetic local time, electron energy ( 30 keV to 5.2 MeV), and geomagnetic activity (represented by the Dst index) and is also the first empirical PAD model in the inner belt and slot region. For megaelectron volt electrons, model results show more significant day-night PAD asymmetry of electrons with higher energies and during disturbed times, which is caused by geomagnetic field configuration and flux radial gradient changes. Steeper PADs with higher fluxes around 90° pitch angle and lower fluxes at lower pitch angles for higher-energy electrons and during active times are also present, which could be due to electromagnetic ion cyclotron wave scattering. For hundreds of kiloelectron volt electrons, cap PADs are generally present in the slot region during quiet times and their energy-dependent features are consistent with hiss wave scattering, while during active times, cap PADs are less significant especially at outer part of slot region, which could be due to the complex energizing and transport processes. The 90°-minimum PADs are persistently present in the inner belt and appear in the slot region during active times, and minima at 90° pitch angle are more significant for electrons with higher energies, which could be a critical evidence in identifying the underlying physical processes responsible for the formation of 90°-minimum PADs.

  7. ULF waves and radiation belts: earthward penetration of Pc 4-5 waves and energetic electron flux enhancements during geospace magnetic storms

    NASA Astrophysics Data System (ADS)

    Georgiou, Marina; Daglis, Ioannis; Zesta, Eftyhia; Balasis, George; Tsinganos, Kanaris

    2013-04-01

    Energetic particle fluxes in the outer radiation belt can vary over orders of magnitude on time scales ranging from minutes, to days and years. Geospace magnetic storms when sufficiently strong to exceed key thresholds of the Dst index may either increase or decrease the fluxes of energetic electrons. We examine the responses of energetic electrons to nine moderate, intense and weak magnetic storms, which occurred at different phases of the solar cycle, and compare these with concurrent variations of ULF wave power. Pc 4-5 waves with frequencies in the range of a few mHz may be generated internally in the magnetosphere by low frequency instabilities of ring current ions and externally by shear instabilities at the magnetopause flanks, or compressive variations in the solar wind. Here, we present multipoint observations from ground-based magnetometer arrays collocated with electron drift orbits, which are complemented and measurements by conjugate multi-point satellites, such as CHAMP, Cluster, GOES and THEMIS. We discuss the excitation, growth and decay characteristics of Pc 4-5 waves during the different phases of the magnetic storms with particular emphasis on the distribution of Pc 4-5 wave power over a variety of L shells. We investigate whether Pc 4-5 wave power penetrates to lower L shell values during periods of relatively intense geomagnetic activity as compared to weak magnetic storms. Structural changes of the magnetosphere during intense geomagnetic storms can play an important role in the generation and penetration of Pc 4-5 waves deep into the inner magnetosphere, which in turn is of significance for the wave-particle interactions contributing to the acceleration, transport and loss of electrons in the outer radiation belt. We present preliminary statistics of Pc 4-5 waves observed during magnetic storms of varying intensity, which occurred over the course of the previous solar cycle. This work is supported by the European Community's Seventh Framework

  8. Roles of whistler mode waves and magnetosonic waves in changing the outer radiation belt and the slot region

    NASA Astrophysics Data System (ADS)

    Li, L. Y.; Yu, J.; Cao, J. B.; Yang, J. Y.; Li, X.; Baker, D. N.; Reeves, G. D.; Spence, H.

    2017-05-01

    Using the Van Allen Probe long-term (2013-2015) observations and quasi-linear simulations of wave-particle interactions, we examine the combined or competing effects of whistler mode waves (chorus or hiss) and magnetosonic (MS) waves on energetic (<0.5 MeV) and relativistic (>0.5 MeV) electrons inside and outside the plasmasphere. Although whistler mode chorus waves and MS waves can singly or jointly accelerate electrons from the hundreds of keV energy to the MeV energy in the low-density trough, most of the relativistic electron enhancement events are best correlated with the chorus wave emissions outside the plasmapause. Inside the plasmasphere, intense plasmaspheric hiss can cause the net loss of relativistic electrons via persistent pitch angle scattering, regardless of whether MS waves were present or not. The intense hiss waves not only create the energy-dependent electron slot region but also remove a lot of the outer radiation belt electrons when the expanding dayside plasmasphere frequently covers the outer zone. Since whistler mode waves (chorus or hiss) can resonate with more electrons than MS waves, they play dominant roles in changing the outer radiation belt and the slot region. However, MS waves can accelerate the energetic electrons below 400 keV and weaken their loss inside the plasmapause. Thus, MS waves and plasmaspheric hiss generate different competing effects on energetic and relativistic electrons in the high-density plasmasphere.

  9. Ballooning in the constant sun of the South Pole summer

    NASA Image and Video Library

    2014-04-24

    A BARREL balloon launches up into the sky, destined to float on the circumpolar winds around the South Pole for up to three weeks while measuring Earth's magnetic field and energetic particles from the radiation belts. Credit: NASA/Goddard/BARREL/Brett Anderson Read more: www.nasa.gov/content/goddard/nasas-barrel-returns-success... -- Three months, 20 balloons, and one very successful campaign. The team for NASA's BARREL – short for Balloon Array for Radiation belt Relativistic Electron Losses -- mission returned from Antarctica in March 2014. BARREL's job is to help unravel the mysterious Van Allen belts, two gigantic donuts of radiation that surround Earth, which can shrink and swell in response to incoming energy and particles from the sun and sometimes expose satellites to harsh radiation. While in Antarctica, the team launched 20 balloons carrying instruments that sense charged particles that are scattered into the atmosphere from the belts, spiraling down the magnetic fields near the South Pole. Each balloon traveled around the pole for up to three weeks. The team will coordinate the BARREL data with observations from NASA's two Van Allen Probes to better understand how occurrences in the belts relate to bursts of particles funneling down toward Earth. BARREL team members will be on hand at the USA Science and Engineering Festival in DC on April 26 and 27, 2014 for the exhibit Space Balloons: Exploring the Extremes of Space Weather. NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  10. KSC-2012-4546

    NASA Image and Video Library

    2012-08-20

    CAPE CANAVERAL, Fla. -- A prelaunch news conference is held at NASA Kennedy Space Center’s Press Site in Florida for the Radiation Belt Storm Probes, or RBSP, mission. From left are Michael Luther, deputy associate administrator for programs in NASA’s Science Mission Directorate, Tim Dunn, NASA launch director at Kennedy, Vernon Thorp, program manager, NASA missions, United Launch Alliance, Richard Fitzgerald, RBSP project manager at Johns Hopkins Applied Physics Laboratory in Laurel, Md., and Kathy Winters, launch weather officer with the 45th Weather Squadron at Cape Canaveral Air Force Station in Florida. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard an Atlas V rocket. Launch is targeted for Aug. 24. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Glenn Benson

  11. KSC-2012-4545

    NASA Image and Video Library

    2012-08-20

    CAPE CANAVERAL, Fla. - A prelaunch news conference was held at NASA Kennedy Space Center’s Press Site in Florida for the Radiation Belt Storm Probes, or RBSP, mission. From left, are George Diller, public affairs specialist and news conference moderator, Michael Luther, deputy associate administrator for programs in NASA’s Science Mission Directorate, Tim Dunn, NASA launch director at Kennedy, Vernon Thorp, program manager, NASA missions, United Launch Alliance, Richard Fitzgerald, RBSP project manager at Johns Hopkins Applied Physics Laboratory in Laurel, Md., and Kathy Winters, launch weather officer with the 45th Weather Squadron at Cape Canaveral Air Force Station in Florida. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard an Atlas V rocket. Launch is targeted for Aug. 24. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Glenn Benson

  12. Evidence for solar wind origin of energetic heavy ions in the earth's radiation belt

    NASA Technical Reports Server (NTRS)

    Hovestadt, D.; Klecker, B.; Scholer, M.; Gloeckler, G.; Ipavich, F. M.; Fan, C. Y.; Fisk, L. A.; Ogallagher, J. J.

    1978-01-01

    Analysis of data from our energetic ion composition experiment on ISEE-1 has revealed the presence of substantial fluxes of carbon, oxygen, and heavier ions above 400 keV/nucleon at L values between approximately 2.5 and 4 earth radii. The measured C/O ratio varies systematically from 1.3 at 450 keV/nucleon to 4.1 at 1.3 MeV/nucleon, and no iron is observed above 200 keV/nucleon. These results provide strong evidence for a solar wind origin for energetic ions in the outer radiation belt. The absence of iron and the increase of the carbon-to-oxygen ratio with energy suggest that the condition for the validity of the first adiabatic invariant may have a strong influence on the trapping of these particles.

  13. Modeling challenges and approaches in simulating the Jovian synchrotron radiation belts from an in-situ perspective

    NASA Astrophysics Data System (ADS)

    Adumitroaie, V.; Oyafuso, F. A.; Levin, S.; Gulkis, S.; Janssen, M. A.; Santos-Costa, D.; Bolton, S. J.

    2017-12-01

    In order to obtain credible atmospheric composition retrieval values from Jupiter's observed radiative signature via Juno's MWR instrument, it is necessary to separate as robustly as possible the contributions from three emission sources: CMB, planet and synchrotron radiation belts. The numerical separation requires a refinement, based on the in-situ data, of a higher fidelity model for the synchrotron emission, namely the multi-parameter, multi-zonal model of Levin at al. (2001). This model employs an empirical electron energy distribution, which prior to the Juno mission, has been adjusted exclusively from VLA observations. At minimum 8 sets of perijove observations (i.e. by PJ9) have to be delivered to an inverse model for retrieval of the electron distribution parameters with the goal of matching the synchrotron emission observed along MWR's lines of sight. The challenges and approaches taken to perform this task are discussed here. The model will be continuously improved with the availability of additional information, both from the MWR and magnetometer instruments.

  14. KSC-2012-3436

    NASA Image and Video Library

    2012-06-21

    CAPE CANAVERAL, Fla. – Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, a technician installs protective thermal blankets around the Radiation Belt Storm Probes, or RBSP, spacecraft A. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  15. KSC-2012-3437

    NASA Image and Video Library

    2012-06-21

    CAPE CANAVERAL, Fla. – Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, a technician installs protective thermal blankets around the Radiation Belt Storm Probes, or RBSP, spacecraft A. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  16. KSC-2012-3430

    NASA Image and Video Library

    2012-06-21

    CAPE CANAVERAL, Fla. – Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, technicians prepare to install protective thermal blankets around the Radiation Belt Storm Probes, or RBSP, spacecraft A. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  17. KSC-2012-3439

    NASA Image and Video Library

    2012-06-21

    CAPE CANAVERAL, Fla. – Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, a technician installs protective thermal blankets around the Radiation Belt Storm Probes, or RBSP, spacecraft A. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  18. KSC-2012-3435

    NASA Image and Video Library

    2012-06-21

    CAPE CANAVERAL, Fla. – Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, a technician installs protective thermal blankets around the Radiation Belt Storm Probes, or RBSP, spacecraft A. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  19. KSC-2012-3433

    NASA Image and Video Library

    2012-06-21

    CAPE CANAVERAL, Fla. – Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, a technician installs protective thermal blankets around the Radiation Belt Storm Probes, or RBSP, spacecraft A. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  20. KSC-2012-3432

    NASA Image and Video Library

    2012-06-21

    CAPE CANAVERAL, Fla. – Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, a technician installs protective thermal blankets around the Radiation Belt Storm Probes, or RBSP, spacecraft A. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  1. KSC-2012-3431

    NASA Image and Video Library

    2012-06-21

    CAPE CANAVERAL, Fla. – Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, technicians install protective thermal blankets around the Radiation Belt Storm Probes, or RBSP, spacecraft A. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  2. KSC-2012-3438

    NASA Image and Video Library

    2012-06-21

    CAPE CANAVERAL, Fla. – Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, technicians install protective thermal blankets around the Radiation Belt Storm Probes, or RBSP, spacecraft A. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  3. KSC-2012-3434

    NASA Image and Video Library

    2012-06-21

    CAPE CANAVERAL, Fla. – Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, a technician installs protective thermal blankets around the Radiation Belt Storm Probes, or RBSP, spacecraft A. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  4. Survival of bacterial isolates exposed to simulated Jovian trapped radiation belt electrons and solar wind protons

    NASA Technical Reports Server (NTRS)

    Taylor, D. M.; Hagen, C. A.; Renninger, G. M.; Simko, G. J.; Smith, C. D.; Yelinek, J. A.

    1972-01-01

    With missions to Jupiter, the spacecraft will be exposed for extended duration to solar wind radiation and the Jovian trapped radiation belt. This study is designed to determine the effect of these radiation environments on spacecraft bacterial isolates. The information can be used in the probability of contamination analysis for these missions. A bacterial subpopulation from Mariner Mars 1971 spacecraft (nine sporeforming and three nonsporeforming isolates) plus two comparative organisms, Staphylococcus epidermidis ATCC 17917 and a strain of Bacillus subtilis var. niger, were exposed to 2-, 12-, and 25-MeV electrons at different doses with simultaneous exposure to a vacuum of 0.0013 N/sqm at 20 and -20 C. The radioresistance of the subpopulation was dependent on the isolate, dose, and energy of electrons. Temperature affected the radioresistance of only the sporeforming isolates. Survival data indicated that spores were reduced approximately 1 log/1500 J/kg, while nonsporeforming isolates (micrococci) were reduced 1.5 to 2 logs/1500 J/kg with the exception of an apparent radioresistant isolate whose resistance approached that of the spores. The subpopulation was found to be less resistant to lower energy than to higher energy electrons.

  5. KSC-2012-4196

    NASA Image and Video Library

    2012-08-02

    CAPE CANAVERAL, Fla. - Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, NASA Administrator Charlie Bolden, at left, talks to technicians about the Radiation Belt Storm Probes, or RBSP, spacecraft. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. As the spacecraft orbits Earth, the four solar panels will continuously face the sun to provide constant power to its instruments. The boom will provide data of the electric fields that energize radiation particles and modify the structure of the inner magnetosphere. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  6. KSC-2012-4195

    NASA Image and Video Library

    2012-08-02

    CAPE CANAVERAL, Fla. - Inside the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, NASA Administrator Charlie Bolden, center, talks to technicians about the Radiation Belt Storm Probes, or RBSP, spacecraft. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. As the spacecraft orbits Earth, the four solar panels will continuously face the sun to provide constant power to its instruments. The boom will provide data of the electric fields that energize radiation particles and modify the structure of the inner magnetosphere. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard a United Launch Alliance Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Kim Shiflett

  7. Determination of the Risk of Radiation-Associated Circulatory and Cancer Disease Mortality in a NASA Early Astronaut Cohort

    NASA Technical Reports Server (NTRS)

    Elgart, S. R.; Chappell, L.; Milder, C. M.; Shavers, M. R.; Huff, J. L.; Little, M.; Patel, Z. S.

    2017-01-01

    Of the many possible health challenges posed during extended exploratory missions to space, the effects of space radiation on cardiovascular disease and cancer are of particular concern. There are unique challenges to estimating those radiation risks; care and appropriate and rigorous methodology should be applied when considering small cohorts such as the NASA astronaut population. The objective of this work was to determine if there was sufficient evidence for excess risk of cardiovascular disease and cancer in early NASA astronaut cohorts. NASA astronauts in selection groups 1-7 were chosen; this relatively homogeneous cohort consists of 73 white males, who unlike today's astronauts, maintained similar smoking and drinking habits to the general US population, and have published radiation doses. The participants flew in space on missions Mercury through Shuttle and received space radiation doses between 0-74.1 milligrays. Cause of death information was obtained from the Lifetime Surveillance of Astronaut Health (LSAH) program at NASA Johnson Space Center. Mortality was compared with the US male population. Trends of mortality with dose were assessed using a logistic model, fitted by maximum likelihood. Only 32 (43.84 percent) of the 73 early astronauts have died. Standard mortality ratios (SMRs) for cancer (n=7, SMR=43.4, 95 percent CI 17.8, 84.9), all circulatory disease (n=7, SMR=33.2, 95 percent CI 13.7, 65.0), and ischemic heart disease (IHD) (n=5, SMR=40.1, 95 percent CI 13.2, 89.4) were significantly lower than for the US white male population. For cerebrovascular disease, the upper confidence interval for SMR included 100, indicating it was not significantly different from the US population (n=2, SMR = 77.0, 95 percent CI 9.4, 268.2). The power of the study is low and remains below 10 percent even when risks 10 times those reported in the literature are assumed. Due to small sample size, there is currently insufficient statistical power to evaluate space

  8. Laterally bendable belt conveyor

    DOEpatents

    Peterson, William J.

    1985-01-01

    An endless, laterally flexible and bendable belt conveyor particularly adapted for coal mining applications in facilitating the transport of the extracted coal up- or downslope and around corners in a continuous manner is disclosed. The conveying means includes a flat rubber belt reinforced along the middle portion thereof along which the major portion of the belt tension is directed so as to cause rotation of the tubular shaped belt when trammed around lateral turns thus preventing excessive belt bulging distortion between adjacent belt supports which would inhibit belt transport. Pretension induced into the fabric reinforced flat rubber belt by conventional belt take-up means supports the load conveyed when the belt conveyor is making lateral turns. The carrying and return portions of the belt are supported and formed into a tubular shape by a plurality of shapers positioned along its length. Each shaper is supported from above by a monorail and includes clusters of idler rollers which support the belt. Additional cluster rollers in each shaper permit the belt supporting roller clusters to rotate in response to the belt's operating tension imposed upon the cluster rollers by induced lateral belt friction forces. The freely rotating roller clusters thus permit the belt to twist on lateral curves without damage to itself while precluding escape of the conveyed material by effectively enclosing it in the tube-shaped, inner belt transport length.

  9. The radiation-belt electron phase-space-density response to stream-interaction regions: A study combining multi-point observations, data-assimilation, and physics-based modeling

    NASA Astrophysics Data System (ADS)

    Kellerman, A. C.; Shprits, Y.; McPherron, R. L.; Kondrashov, D. A.; Weygand, J. M.; Zhu, H.; Drozdov, A.

    2017-12-01

    Presented is an analysis of the phase-space density (PSD) response to the stream-interaction region (SIR), which utilizes a reanalysis dataset principally comprised of the data-assimilative Versatile Electron Radiation Belt (VERB) code, Van Allen Probe and GOES observations. The dataset spans the period 2012-2017, and includes several SIR (and CIR) storms. The PSD is examined for evidence of injections, transport, acceleration, and loss by considering the instantaneous and time-averaged change at adiabatic invariant values that correspond to ring-current, relativistic, and ultra-relativistic energies. In the solar wind, the following variables in the slow and fast wind on either side of the stream interface (SI) are considered in each case: the coronal hole polarity, IMF, solar wind speed, density, pressure, and SI tilt angle. In the magnetosphere, the Dst, AE, and past PSD state are considered. Presented is an analysis of the dominant mechanisms, both external and internal to the magnetosphere, that cause radiation-belt electron non-adiabatic changes during the passage of these fascinating solar wind structures.

  10. KSC-2012-4058

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians checkout the two Radiation Belt Storm Probes, or RBSP, spacecraft prior to vertical stacking. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  11. KSC-2012-3935

    NASA Image and Video Library

    2012-07-16

    CAPE CANAVERAL, Fla. – At Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla., the Centaur stage has just been mated with the Atlas V rocket, which will launch the Radiation Belt Storm Probes, or RBSP, spacecraft. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Cape Canaveral. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  12. KSC-2012-4079

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, the Radiation Belt Storm Probes, or RBSP, spacecraft A has been placed atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  13. The Main-belt Asteroid and NEO Tour with Imaging and Spectroscopy (MANTIS)

    NASA Astrophysics Data System (ADS)

    Rivkin, A.; Cohen, B. A.; Barnouin, O. S.; Chabot, N. L.; Ernst, C. M.; Klima, R. L.; Helbert, J.; Sternovsky, Z.

    2015-12-01

    The asteroids preserve information from the earliest times in solar system history, with compositions in the population reflecting the material in the solar nebula and experiencing a wide range of temperatures. Today they experience ongoing processes, some of which are shared with larger bodies but some of which are unique to their size regime. They are critical to humanity's future as potential threats, resource sites, and targets for human visitation. However, over twenty years since the first spacecraft encounters with asteroids, they remain poorly understood. The mission we propose here, the Main-belt Asteroid and NEO Tour with Imaging and Spectroscopy (MANTIS), explores the diversity of asteroids to understand our solar system's past history, its present processes, and future opportunities and hazards. MANTIS addresses many of NASA's highest priorities as laid out in its 2014 Science Plan and provides additional benefit to the Planetary Defense and Human Exploration communities via a low-risk, cost-effective tour of the near-Earth and inner asteroid belt. MANTIS visits the materials that witnessed solar system formation and its earliest history, addressing the NASA goal of exploring and observing the objects in the solar system to understand how they formed and evolve. MANTIS measures OH, water, and organic materials via several complementary techniques, visiting and sampling objects known to have hydrated minerals and addressing the NASA goal of improving our understanding of the origin and evolution of life on Earth. MANTIS studies the geology and geophysics of nine diverse asteroids, with compositions ranging from water-rich to metallic, representatives of both binary and non-binary asteroids, and sizes covering over two orders of magnitude, providing unique information about the chemical and physical processes shaping the asteroids, addressing the NASA goal of advancing the understanding of how the chemical and physical processes in our solar system

  14. 26 x 6.6 radial-belted aircraft tire performance

    NASA Technical Reports Server (NTRS)

    Davis, Pamela A.; Martinson, Veloria J.; Yager, Thomas J.; Stubbs, Sandy M.

    1991-01-01

    Preliminary results from testing of 26 x 6.6 radial-belted and bias-ply aircraft tires at NASA Langley's Aircraft Landing Dynamics Facility (ALDF) are reviewed. The 26 x 6.6 tire size evaluation includes cornering performance tests throughout the aircraft ground operational speed range for both dry and wet runway surfaces. Static test results to define 26 x 6.6 tire vertical stiffness properties are also presented and discussed.

  15. Technical developments at the NASA Space Radiation Laboratory.

    PubMed

    Lowenstein, D I; Rusek, A

    2007-06-01

    The NASA Space Radiation Laboratory (NSRL) located at Brookhaven National Laboratory (BNL) is a center for space radiation research in both the life and physical sciences. BNL is a multidisciplinary research facility operated for the Office of Science of the US Department of Energy (DOE). The BNL scientific research portfolio supports a large and diverse science and technology program including research in nuclear and high-energy physics, material science, chemistry, biology, medial science, and nuclear safeguards and security. NSRL, in operation since July 2003, is an accelerator-based facility which provides particle beams for radiobiology and physics studies (Lowenstein in Phys Med 17(supplement 1):26-29 2001). The program focus is to measure the risks and to ameliorate the effects of radiation encountered in space, both in low earth orbit and extended missions beyond the earth. The particle beams are produced by the Booster synchrotron, an accelerator that makes up part of the injector sequence of the DOE nuclear physics program's Relativistic Heavy Ion Collider. Ion species from protons to gold are presently available, at energies ranging from <100 to >1,000 MeV/n. The NSRL facility has recently brought into operation the ability to rapidly switch species and beam energy to supply a varied spectrum onto a given specimen. A summary of past operation performance, plans for future operations and recent and planned hardware upgrades will be described.

  16. Occurrence features of simultaneous H+- and He+-band EMIC emissions in the outer radiation belt

    NASA Astrophysics Data System (ADS)

    Fu, Song; He, Fengming; Gu, Xudong; Ni, Binbin; Xiang, Zheng; Liu, Jiang

    2018-04-01

    As an important loss mechanism of radiation belt electrons, electromagnetic ion cyclotron (EMIC) waves show up as three distinct frequency bands below the hydrogen (H+), helium (He+), and oxygen (O+) ion gyrofrequencies. Compared to O+-band EMIC waves, H+- and He+-band emissions generally occur more frequently and result in more efficient scattering removal of <∼5 MeV relativistic electrons. Therefore, knowledge about the occurrence of these two bands is important for understanding the evolution of the relativistic electron population. To evaluate the occurrence pattern and wave properties of H+- and He+-band EMIC waves when they occur concurrently, we investigate 64 events of multi-band EMIC emissions identified from high quality Van Allen Probes wave data. Our quantitative results demonstrate a strong occurrence dependence of the multi-band EMIC emissions on magnetic local time (MLT) and L-shell to mainly concentrate on the dayside region of L = ∼4-6. We also find that the average magnetic field amplitude of H+-band waves is larger than that of He+-band waves only when L < 4.5 and AE∗ < 300 nT, and He+-band emissions are more intense under all other conditions. In contrast to 5 events that have average H+-band amplitude over 2 nT, 19 events exhibit >2 nT He+-band amplitude, indicating that the He+-band waves can be more easily amplified than the H+-band waves under the same circumstances. For simultaneous occurrences of the two EMIC wave bands, their frequencies vary with L-shell and geomagnetic activity: the peak wave frequency of H+-band emissions varies between 0.25 and 0.8 fcp with the average between 0.25 and 0.6 fcp, while that of He+-band emissions varies between 0.03 and 0.23 fcp with the average between 0.05 and 0.15 fcp. These newly observed occurrence features of simultaneous H+- and He+-band EMIC emissions provide improved information to quantify the overall contribution of multi-band EMIC waves to the loss processes of radiation belt electrons.

  17. GEO Collisional Risk Assessment Based on Analysis of NASA-WISE Data and Modeling

    DTIC Science & Technology

    2015-10-18

    GEO Collisional Risk Assessment Based on Analysis of NASA -WISE Data and Modeling Jeremy Murray Krezan1, Samantha Howard1, Phan D. Dao1, Derek...Surka2 1AFRL Space Vehicles Directorate,2Applied Technology Associates Incorporated From December 2009 through 2011 the NASA Wide-Field Infrared...of known debris. The NASA -WISE GEO belt debris population adds potentially thousands previously uncataloged objects. This paper describes

  18. Diverse Studies in the Reactivated NASA/Ames Radiation Facility: From Shock Layer Spectroscopy to Thermal Protection System Impact

    NASA Technical Reports Server (NTRS)

    Miller, Robert J.; Hartman, G. Joseph (Technical Monitor)

    1994-01-01

    NASA/Ames' Hypervelocity Free-Flight Radiation Facility has been reactivated after having been decommissioned for some 15 years, first tests beginning in early 1994. This paper discusses two widely different studies from the first series, one involving spectroscopic analysis of model shock-layer radiation, and the other the production of representative impact damage in space shuttle thermal protection tiles for testing in the Ames arc-jet facilities. These studies emphasize the interorganizational and interdisciplinary value of the facility in the newly-developing structure of NASA.

  19. 30 CFR 75.1731 - Maintenance of belt conveyors and belt conveyor entries.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... 30 Mineral Resources 1 2010-07-01 2010-07-01 false Maintenance of belt conveyors and belt conveyor....1731 Maintenance of belt conveyors and belt conveyor entries. (a) Damaged rollers, or other damaged belt conveyor components, which pose a fire hazard must be immediately repaired or replaced. All other...

  20. KSC-2012-4551

    NASA Image and Video Library

    2012-08-20

    CAPE CANAVERAL, Fla. - A mission science briefing was held at NASA Kennedy Space Center’s Press Site in Florida for the Radiation Belt Storm Probes, or RBSP, mission. From left, are George Diller, public affairs specialist and news conference moderator, Mona Kessel, RBSP program scientist from NASA Headquarters in Washington, Nicola Fox, RBSP deputy project scientist at Johns Hopkins Applied Physics Laboratory in Laurel, Md., Craig Kletzing, principal investigator from the University of Iowa, Harlan Spence, principal investigator from the University of New Hampshire, and Lou Lanzerotti, principal investigator from the New Jersey Institute of Technology. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard an Atlas V rocket. Launch is targeted for Aug. 24. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Glenn Benson

  1. KSC-2012-4548

    NASA Image and Video Library

    2012-08-20

    CAPE CANAVERAL, Fla. - A mission science briefing was held at NASA Kennedy Space Center’s Press Site in Florida for the Radiation Belt Storm Probes, or RBSP, mission. From left, are George Diller, public affairs specialist and news conference moderator, Mona Kessel, RBSP program scientist from NASA Headquarters in Washington, Nicola Fox, RBSP deputy project scientist at Johns Hopkins Applied Physics Laboratory in Laurel, Md., Craig Kletzing, principal investigator from the University of Iowa, Harlan Spence, principal investigator from the University of New Hampshire, and Lou Lanzerotti, principal investigator from the New Jersey Institute of Technology. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard an Atlas V rocket. Launch is targeted for Aug. 24. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Glenn Benson

  2. KSC-2012-4549

    NASA Image and Video Library

    2012-08-20

    CAPE CANAVERAL, Fla. - A mission science briefing was held at NASA Kennedy Space Center’s Press Site in Florida for the Radiation Belt Storm Probes, or RBSP, mission. From left, are George Diller, public affairs specialist and news conference moderator, Mona Kessel, RBSP program scientist from NASA Headquarters in Washington, Nicola Fox, RBSP deputy project scientist at Johns Hopkins Applied Physics Laboratory in Laurel, Md., Craig Kletzing, principal investigator from the University of Iowa, Harlan Spence, principal investigator from the University of New Hampshire, and Lou Lanzerotti, principal investigator from the New Jersey Institute of Technology. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard an Atlas V rocket. Launch is targeted for Aug. 24. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Glenn Benson

  3. Passive radiation shielding considerations for the proposed space elevator

    NASA Astrophysics Data System (ADS)

    Jorgensen, A. M.; Patamia, S. E.; Gassend, B.

    2007-02-01

    The Earth's natural van Allen radiation belts present a serious hazard to space travel in general, and to travel on the space elevator in particular. The average radiation level is sufficiently high that it can cause radiation sickness, and perhaps death, for humans spending more than a brief period of time in the belts without shielding. The exact dose and the level of the related hazard depends on the type or radiation, the intensity of the radiation, the length of exposure, and on any shielding introduced. For the space elevator the radiation concern is particularly critical since it passes through the most intense regions of the radiation belts. The only humans who have ever traveled through the radiation belts have been the Apollo astronauts. They received radiation doses up to approximately 1 rem over a time interval less than an hour. A vehicle climbing the space elevator travels approximately 200 times slower than the moon rockets did, which would result in an extremely high dose up to approximately 200 rem under similar conditions, in a timespan of a few days. Technological systems on the space elevator, which spend prolonged periods of time in the radiation belts, may also be affected by the high radiation levels. In this paper we will give an overview of the radiation belts in terms relevant to space elevator studies. We will then compute the expected radiation doses, and evaluate the required level of shielding. We concentrate on passive shielding using aluminum, but also look briefly at active shielding using magnetic fields. We also look at the effect of moving the space elevator anchor point and increasing the speed of the climber. Each of these mitigation mechanisms will result in a performance decrease, cost increase, and technical complications for the space elevator.

  4. Effectiveness of Ford's belt reminder system in increasing seat belt use

    PubMed Central

    Williams, A; Wells, J; Farmer, C

    2002-01-01

    Objectives: The study investigated the effectiveness in increasing seat belt use of Ford's belt reminder system, a supplementary system that provides intermittent flashing lights and chimes for five minutes if drivers are not belted. Methods: Seat belt use of drivers in relatively new cars with and without the reminder system was unobtrusively observed as vehicles were brought to dealerships for service. Results: Overall use rates were estimated at 71% for drivers in vehicles without the reminder system and 76% for drivers in vehicles with belt reminders (p<0.01). Conclusions: Seat belt use is relatively low in the United States. The present study showed that vehicle based reminder systems can be at least modestly effective in increasing belt use, which may encourage further development of such systems. PMID:12460965

  5. NASA's Hubble Sees Asteroid Spout Six Comet-like Tails

    NASA Image and Video Library

    2013-11-13

    This NASA Hubble Space Telescope set of images reveals a never-before-seen set of six comet-like tails radiating from a body in the asteroid belt, designated P/2013 P5. The asteroid was discovered as an unusually fuzzy-looking object with the Panoramic Survey Telescope and Rapid Response System (Pan-STARRS) survey telescope in Hawaii. The multiple tails were discovered in Hubble images taken on Sept. 10, 2013. When Hubble returned to the asteroid on Sept. 23, the asteroid's appearance had totally changed. It looked as if the entire structure had swung around. One interpretation is that the asteroid's rotation rate has been increased to the point where dust is falling off the surface and escaping into space where the pressure of sunlight sweeps out fingerlike tails. According to this theory, the asteroid's spin has been accelerated by the gentle push of sunlight. The object, estimated to be no more than 1,400 feet across, has ejected dust for at least five months, based on analysis of the tail structure. These visible-light, false-color images were taken with Hubble's Wide Field Camera 3. Object Name: P/2013 P5 Image Type: Astronomical/Annotated Credit: NASA, ESA, and D. Jewitt (UCLA) NASA image use policy. NASA Goddard Space Flight Center enables NASA’s mission through four scientific endeavors: Earth Science, Heliophysics, Solar System Exploration, and Astrophysics. Goddard plays a leading role in NASA’s accomplishments by contributing compelling scientific knowledge to advance the Agency’s mission. Follow us on Twitter Like us on Facebook Find us on Instagram

  6. The 2016 outbreak on Jupiter's North Temperate Belt and jet from ground-based and Juno imaging

    NASA Astrophysics Data System (ADS)

    Rogers, J. H.; Orton, G. S.; Eichstädt, G.; Vedovato, M.; Caplinger, M.; Momary, T. W.; Hansen, C. J.

    2017-09-01

    A new outbreak of convective plumes on the peak of Jupiter's fastest jet, which had been predicted the previous year, began in autumn, 2016. It was observed just after solar conjunction by the NASA Infrared Telescope Facility, by JunoCam, and by amateur astronomers. It unfolded in essentially the same way as previous such outbreaks, leading to revival of the North Temperate Belt with a notably red component. The maturation of this belt was monitored at high resolution by JunoCam.

  7. KSC-2012-4550

    NASA Image and Video Library

    2012-08-20

    CAPE CANAVERAL, Fla. - During a mission science briefing for the Radiation Belt Storm Probes, or RBSP, mission at NASA Kennedy Space Center’s Press Site in Florida, Craig Kletzing, a principal investigator from the University of Iowa, answers questions and displays a scale model of the twin probes. To the left, is Harlan Spence, principal investigator with the University of New Hampshire. To the right, is Lou Lanzerotti, principal investigator with the New Jersey Institute of Technology. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard an Atlas V rocket. Launch is targeted for Aug. 24. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Glenn Benson

  8. Call for NASA Mission Supporting Observations

    NASA Astrophysics Data System (ADS)

    Binzel, Richard P.

    2018-04-01

    Lightcurve observations are requested to support NASA missions planned for launch to study main-belt and Trojan asteroids. In some cases, the rotations of the target asteroids are unknown. In other cases, the periods are well established and ongoing measurements will deliver the precision needed to deduce the rotation phase at the time of encounter more than a decade away.

  9. Condition-Based Conveyor Belt Replacement Strategy in Lignite Mines with Random Belt Deterioration

    NASA Astrophysics Data System (ADS)

    Blazej, Ryszard; Jurdziak, Leszek

    2017-12-01

    In Polish lignite surface mines, condition-based belt replacement strategies are applied in order to assure profitable refurbishment of worn out belts performed by external firms specializing in belt maintenance. In two of three lignite mines, staff asses belt condition subjectively during visual inspections. Only one mine applies specialized diagnostic device (HRDS) allowing objective magnetic evaluation of belt core condition in order to choose the most profitable moment for the dismantling of worn out belt segments from conveyors and sending them to the maintenance firm which provides their refurbishment. This article describes the advantages of a new diagnostic device called DiagBelt. It was developed at the Faculty of Geoengineering, Mining and Geology, Wroclaw University of Science and Technology. Economic gains from its application are calculated for the lignite mine and for the belt maintenance firm, taking into account random life (durability) of new and reconditioned belts (after the 1st and the 2nd refurbishment). Recursive calculations for following years allow the estimation of the length and costs of replaced, reconditioned and purchased belts on an annual basis, while the use of the Monte Carlo method allows the estimation of their variability caused by random deterioration of belts. Savings are obtained due to better selection of moments (times) for the replacement of belt segments and die to the possibility to qualify worn out belts for refurbishment without the need to remove their covers. In effect, increased belt durability and lowered share of waste belts (which were not qualified for reconditioning) create savings which can quickly cover expenditures on new diagnostic tools and regular belt inspections in the mine.

  10. Simultaneous event-specific estimates of transport, loss, and source rates for relativistic outer radiation belt electrons: Event-Specific 1-D Modeling

    DOE PAGES

    Schiller, Q.; Tu, W.; Ali, A. F.; ...

    2017-03-11

    The most significant unknown regarding relativistic electrons in Earth’s outer Van Allen radiation belt is the relative contribution of loss, transport, and acceleration processes within the inner magnetosphere. Detangling each individual process is critical to improve the understanding of radiation belt dynamics, but determining a single component is challenging due to sparse measurements in diverse spatial and temporal regimes. However, there are currently an unprecedented number of spacecraft taking measurements that sample different regions of the inner magnetosphere. With the increasing number of varied observational platforms, system dynamics can begin to be unraveled. In this work, we employ in-situ measurementsmore » during the 13-14 January 2013 enhancement event to isolate transport, loss, and source dynamics in a one dimensional radial diffusion model. We then validate the results by comparing them to Van Allen Probes and THEMIS observations, indicating that the three terms have been accurately and individually quantified for the event. Finally, a direct comparison is performed between the model containing event-specific terms and various models containing terms parameterized by geomagnetic index. Models using a simple 3/Kp loss timescale show deviation from the event specific model of nearly two orders of magnitude within 72 hours of the enhancement event. However, models using alternative loss timescales closely resemble the event specific model.« less

  11. Simultaneous event-specific estimates of transport, loss, and source rates for relativistic outer radiation belt electrons: Event-Specific 1-D Modeling

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schiller, Q.; Tu, W.; Ali, A. F.

    The most significant unknown regarding relativistic electrons in Earth’s outer Van Allen radiation belt is the relative contribution of loss, transport, and acceleration processes within the inner magnetosphere. Detangling each individual process is critical to improve the understanding of radiation belt dynamics, but determining a single component is challenging due to sparse measurements in diverse spatial and temporal regimes. However, there are currently an unprecedented number of spacecraft taking measurements that sample different regions of the inner magnetosphere. With the increasing number of varied observational platforms, system dynamics can begin to be unraveled. In this work, we employ in-situ measurementsmore » during the 13-14 January 2013 enhancement event to isolate transport, loss, and source dynamics in a one dimensional radial diffusion model. We then validate the results by comparing them to Van Allen Probes and THEMIS observations, indicating that the three terms have been accurately and individually quantified for the event. Finally, a direct comparison is performed between the model containing event-specific terms and various models containing terms parameterized by geomagnetic index. Models using a simple 3/Kp loss timescale show deviation from the event specific model of nearly two orders of magnitude within 72 hours of the enhancement event. However, models using alternative loss timescales closely resemble the event specific model.« less

  12. Space weather effects measured in atmospheric radiation on aircraft

    NASA Astrophysics Data System (ADS)

    Tobiska, W. K.; Bouwer, D.; Bailey, J. J.; Didkovsky, L. V.; Judge, K.; Wieman, S. R.; Atwell, W.; Gersey, B.; Wilkins, R.; Rice, D.; Schunk, R. W.; Bell, L. D.; Mertens, C. J.; Xu, X.; Wiltberger, M. J.; Wiley, S.; Teets, E.; Shea, M. A.; Smart, D. F.; Jones, J. B. L.; Crowley, G.; Azeem, S. I.; Halford, A. J.

    2016-12-01

    Space weather's effects upon the near-Earth environment are due to dynamic changes in the energy transfer processes from the Sun's photons, particles, and fields. Of the domains that are affected by space weather, the coupling between the solar and galactic high-energy particles, the magnetosphere, and atmospheric regions can significantly affect humans and our technology as a result of radiation exposure. Since 2013 Space Environment Technologies (SET) has been conducting observations of the atmospheric radiation environment at aviation altitudes using a small fleet of six instruments. The objective of this work is to improve radiation risk management in air traffic operations. Under the auspices of the Automated Radiation Measurements for Aerospace Safety (ARMAS) and Upper-atmospheric Space and Earth Weather eXperiment (USEWX) projects our team is making dose rate measurements on multiple aircraft flying global routes. Over 174 ARMAS and USEWX flights have successfully demonstrated the operation of a micro dosimeter on commercial aviation altitude aircraft that captures the radiation environment resulting from Galactic Cosmic Rays (GCRs), Solar Energetic Protons (SEPs), and outer radiation belt energetic electrons. The real-time radiation exposure is measured as an absorbed dose rate in silicon and then computed as an ambient dose equivalent rate for reporting dose relevant to radiative-sensitive organs and tissue in units of microsieverts per hour. ARMAS total ionizing absorbed dose is captured on the aircraft, downlinked in real-time, processed on the ground into ambient dose equivalent rates, compared with NASA's Langley Research Center (LaRC) most recent Nowcast of Atmospheric Ionizing Radiation System (NAIRAS) global radiation climatology model runs, and then made available to end users. Dose rates from flight altitudes up to 56,700 ft. are shown for flights across the planet under a variety of space weather conditions. We discuss several space weather

  13. KSC-2012-2666

    NASA Image and Video Library

    2012-05-03

    CAPE CANAVERAL, Fla. – In the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, Applied Physics Laboratory technicians lower NASA's Radiation Belt Storm Probe B, wrapped in a protective shroud, onto a test stand. Prelaunch preparations and spacecraft testing will follow. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP instruments will provide the measurements needed to characterize and quantify the plasma processes that produce very energetic ions and relativistic electrons. The mission is part of NASA’s broader Living With a Star Program that was conceived to explore fundamental processes that operate throughout the solar system, particularly those that generate hazardous space weather effects in the vicinity of Earth and phenomena that could impact solar system exploration. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after launch. Launch aboard a United Launch Alliance Atlas V rocket is scheduled for August 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  14. KSC-2012-2668

    NASA Image and Video Library

    2012-05-03

    CAPE CANAVERAL, Fla. – In the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, Applied Physics Laboratory technicians remove the protective shroud from around NASA's Radiation Belt Storm Probe B. Prelaunch preparations and spacecraft testing will follow. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP instruments will provide the measurements needed to characterize and quantify the plasma processes that produce very energetic ions and relativistic electrons. The mission is part of NASA’s broader Living With a Star Program that was conceived to explore fundamental processes that operate throughout the solar system, particularly those that generate hazardous space weather effects in the vicinity of Earth and phenomena that could impact solar system exploration. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after launch. Launch aboard a United Launch Alliance Atlas V rocket is scheduled for August 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  15. KSC-2012-2650

    NASA Image and Video Library

    2012-05-02

    CAPE CANAVERAL, Fla. – In the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, Applied Physics Laboratory technicians lift the shipping container from around NASA's Radiation Belt Storm Probe A, wrapped in a protective shroud. Prelaunch preparations and spacecraft testing will follow. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP instruments will provide the measurements needed to characterize and quantify the plasma processes that produce very energetic ions and relativistic electrons. The mission is part of NASA’s broader Living With a Star Program that was conceived to explore fundamental processes that operate throughout the solar system, particularly those that generate hazardous space weather effects in the vicinity of Earth and phenomena that could impact solar system exploration. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after launch. Launch aboard a United Launch Alliance Atlas V rocket is scheduled for August 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  16. KSC-2012-2664

    NASA Image and Video Library

    2012-05-03

    CAPE CANAVERAL, Fla. – In the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, Applied Physics Laboratory technicians lift NASA's Radiation Belt Storm Probe B, wrapped in a protective shroud, from the bottom of its shipping container. Prelaunch preparations and spacecraft testing will follow. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP instruments will provide the measurements needed to characterize and quantify the plasma processes that produce very energetic ions and relativistic electrons. The mission is part of NASA’s broader Living With a Star Program that was conceived to explore fundamental processes that operate throughout the solar system, particularly those that generate hazardous space weather effects in the vicinity of Earth and phenomena that could impact solar system exploration. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after launch. Launch aboard a United Launch Alliance Atlas V rocket is scheduled for August 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  17. KSC-2012-2663

    NASA Image and Video Library

    2012-05-03

    CAPE CANAVERAL, Fla. – In the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, Applied Physics Laboratory technicians prepare to lift NASA's Radiation Belt Storm Probe B, wrapped in a protective shroud, from the bottom of its shipping container. Prelaunch preparations and spacecraft testing will follow. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP instruments will provide the measurements needed to characterize and quantify the plasma processes that produce very energetic ions and relativistic electrons. The mission is part of NASA’s broader Living With a Star Program that was conceived to explore fundamental processes that operate throughout the solar system, particularly those that generate hazardous space weather effects in the vicinity of Earth and phenomena that could impact solar system exploration. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after launch. Launch aboard a United Launch Alliance Atlas V rocket is scheduled for August 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  18. KSC-2012-2652

    NASA Image and Video Library

    2012-05-02

    CAPE CANAVERAL, Fla. – In the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, Applied Physics Laboratory technicians lift NASA's Radiation Belt Storm Probe A, wrapped in a protective shroud, onto a test stand. Prelaunch preparations and spacecraft testing will follow. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP instruments will provide the measurements needed to characterize and quantify the plasma processes that produce very energetic ions and relativistic electrons. The mission is part of NASA’s broader Living With a Star Program that was conceived to explore fundamental processes that operate throughout the solar system, particularly those that generate hazardous space weather effects in the vicinity of Earth and phenomena that could impact solar system exploration. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after launch. Launch aboard a United Launch Alliance Atlas V rocket is scheduled for August 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  19. KSC-2012-2662

    NASA Image and Video Library

    2012-05-03

    CAPE CANAVERAL, Fla. – In the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, Applied Physics Laboratory technicians prepare NASA's Radiation Belt Storm Probe B, wrapped in a protective shroud, to be lifted from the bottom of its shipping container. Prelaunch preparations and spacecraft testing will follow. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP instruments will provide the measurements needed to characterize and quantify the plasma processes that produce very energetic ions and relativistic electrons. The mission is part of NASA’s broader Living With a Star Program that was conceived to explore fundamental processes that operate throughout the solar system, particularly those that generate hazardous space weather effects in the vicinity of Earth and phenomena that could impact solar system exploration. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after launch. Launch aboard a United Launch Alliance Atlas V rocket is scheduled for August 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  20. KSC-2012-2653

    NASA Image and Video Library

    2012-05-02

    CAPE CANAVERAL, Fla. – In the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, Applied Physics Laboratory technicians secure NASA's Radiation Belt Storm Probe A, wrapped in a protective shroud, on a test stand. Prelaunch preparations and spacecraft testing will follow. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP instruments will provide the measurements needed to characterize and quantify the plasma processes that produce very energetic ions and relativistic electrons. The mission is part of NASA’s broader Living With a Star Program that was conceived to explore fundamental processes that operate throughout the solar system, particularly those that generate hazardous space weather effects in the vicinity of Earth and phenomena that could impact solar system exploration. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after launch. Launch aboard a United Launch Alliance Atlas V rocket is scheduled for August 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  1. KSC-2012-2667

    NASA Image and Video Library

    2012-05-03

    CAPE CANAVERAL, Fla. – In the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, Applied Physics Laboratory technicians position NASA's Radiation Belt Storm Probe B, wrapped in a protective shroud, on a test stand. Prelaunch preparations and spacecraft testing will follow. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP instruments will provide the measurements needed to characterize and quantify the plasma processes that produce very energetic ions and relativistic electrons. The mission is part of NASA’s broader Living With a Star Program that was conceived to explore fundamental processes that operate throughout the solar system, particularly those that generate hazardous space weather effects in the vicinity of Earth and phenomena that could impact solar system exploration. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after launch. Launch aboard a United Launch Alliance Atlas V rocket is scheduled for August 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  2. KSC-2012-2651

    NASA Image and Video Library

    2012-05-02

    CAPE CANAVERAL, Fla. – In the clean room high bay at the Astrotech payload processing facility near NASA’s Kennedy Space Center in Florida, Applied Physics Laboratory technicians prepare to lift NASA's Radiation Belt Storm Probe A, wrapped in a protective shroud, from the bottom of its shipping container. Prelaunch preparations and spacecraft testing will follow. The Radiation Belt Storm Probes, or RBSP, mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP instruments will provide the measurements needed to characterize and quantify the plasma processes that produce very energetic ions and relativistic electrons. The mission is part of NASA’s broader Living With a Star Program that was conceived to explore fundamental processes that operate throughout the solar system, particularly those that generate hazardous space weather effects in the vicinity of Earth and phenomena that could impact solar system exploration. RBSP will begin its mission of exploration of Earth's Van Allen radiation belts and the extremes of space weather after launch. Launch aboard a United Launch Alliance Atlas V rocket is scheduled for August 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  3. KSC-2012-4066

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to move the Radiation Belt Storm Probes, or RBSP, spacecraft A into position for stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  4. KSC-2012-4069

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to move the Radiation Belt Storm Probes, or RBSP, spacecraft A into position for stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  5. KSC-2012-4070

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to position the Radiation Belt Storm Probes, or RBSP, spacecraft A for stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  6. KSC-2012-4077

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, a technician carefully checks the Radiation Belt Storm Probes, or RBSP, spacecraft A as it is being placed atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  7. KSC-2012-4071

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to position the Radiation Belt Storm Probes, or RBSP, spacecraft A for stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  8. KSC-2012-4063

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians prepare the Radiation Belt Storm Probes, or RBSP, spacecraft A prior to vertical stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  9. KSC-2012-4075

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to position the Radiation Belt Storm Probes, or RBSP, spacecraft A atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  10. KSC-2012-4062

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians prepare the Radiation Belt Storm Probes, or RBSP, spacecraft A prior to vertical stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  11. KSC-2012-4072

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to position the Radiation Belt Storm Probes, or RBSP, spacecraft A for stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  12. KSC-2012-4068

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to move the Radiation Belt Storm Probes, or RBSP, spacecraft A into position for stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  13. KSC-2012-4076

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to position the Radiation Belt Storm Probes, or RBSP, spacecraft A atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  14. KSC-2012-4067

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to move the Radiation Belt Storm Probes, or RBSP, spacecraft A into position for stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  15. KSC-2012-4059

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians attach a crane to the Radiation Belt Storm Probes, or RBSP, spacecraft A prior to vertical stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  16. KSC-2012-4073

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to position the Radiation Belt Storm Probes, or RBSP, spacecraft A atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  17. KSC-2012-4065

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to lift the Radiation Belt Storm Probes, or RBSP, spacecraft A for stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  18. KSC-2012-4074

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to position the Radiation Belt Storm Probes, or RBSP, spacecraft A atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  19. KSC-2012-4064

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, technicians use a crane to lift the Radiation Belt Storm Probes, or RBSP, spacecraft A for stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  20. KSC-2012-3883

    NASA Image and Video Library

    2012-07-13

    CAPE CANAVERAL, Fla. - At Launch Complex 41 at Cape Canaveral Air Force Station in Florida, the first stage of the United Launch Alliance Atlas V rocket has been moved into the Vertical Integration Facility. The Atlas V is being prepared for the Radiation Belt Storm Probes, or RBSP, mission. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard an Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Cory Huston

  1. KSC-2012-4060

    NASA Image and Video Library

    2012-07-27

    TITUSVILLE, Fla. - Inside the Astrotech payload processing facility in Titusville, Fla. near NASA’s Kennedy Space Center, a crane has been attached to the Radiation Belt Storm Probes, or RBSP, spacecraft A prior to vertical stacking atop RBSP B. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its liftoff aboard a United Launch Alliance Atlas V from Space Launch Complex 41 at Cape Canaveral Air Force Station, Fla. Liftoff is targeted for Aug. 23, 2012. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Jim Grossmann

  2. KSC-2012-3884

    NASA Image and Video Library

    2012-07-13

    CAPE CANAVERAL, Fla. - At Launch Complex 41 at Cape Canaveral Air Force Station in Florida, the first stage of the United Launch Alliance Atlas V rocket has been moved into the Vertical Integration Facility. The Atlas V is being prepared for the Radiation Belt Storm Probes, or RBSP, mission. NASA’s RBSP mission will help us understand the sun’s influence on Earth and near-Earth space by studying the Earth’s radiation belts on various scales of space and time. RBSP will begin its mission of exploration of Earth’s Van Allen radiation belts and the extremes of space weather after its launch aboard an Atlas V rocket. Launch is targeted for Aug. 23. For more information, visit http://www.nasa.gov/rbsp. Photo credit: NASA/Cory Huston

  3. Neoclassical Diffusion of Radiation-Belt Electrons Across Very Low L -shells

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cunningham, Gregory S.; Loridan, Vivien; Ripoll, Jean-Francois

    In the presence of drift-shell splitting intrinsic to the IGRF magnetic field model, pitch-angle scattering from Coulomb collisions experienced by radiation-belt electrons in the upper atmosphere and ionosphere produces extra radial diffusion, a form of neoclassical diffusion. The strength of the neoclassical radial diffusion at L < 1.2 exceeds that expected there from radial-diffusion mechanisms traditionally considered, and decreases with increasing L-shell. In this study we construct a numerical model for this coupled (radial and pitch-angle) collisional diffusion process and apply it to simulate raw count-rate data observed aboard the Gemini spacecraft for several years after the 1962 Starfish nuclearmore » detonation. The data show apparent lifetimes 10-100 times as long as would have been expected from collisional pitch-angle diffusion and Coulomb drag alone. Our model reproduces apparent lifetimes for >0.5-MeV electrons in the region 1.14 < L < 1.26 to within a factor of two (comparable to the uncertainty quoted for the observations). We conclude that neoclassical radial diffusion (resulting from drift-shell splitting intrinsic to IGRF's azimuthal asymmetries) mitigates the decay expected from collisional pitch-angle diffusion and inelastic energy loss alone and thus contributes importantly to the long apparent lifetimes observed at these low L-shells.« less

  4. Neoclassical Diffusion of Radiation-Belt Electrons Across Very Low L -shells

    DOE PAGES

    Cunningham, Gregory S.; Loridan, Vivien; Ripoll, Jean-Francois; ...

    2018-03-30

    In the presence of drift-shell splitting intrinsic to the IGRF magnetic field model, pitch-angle scattering from Coulomb collisions experienced by radiation-belt electrons in the upper atmosphere and ionosphere produces extra radial diffusion, a form of neoclassical diffusion. The strength of the neoclassical radial diffusion at L < 1.2 exceeds that expected there from radial-diffusion mechanisms traditionally considered, and decreases with increasing L-shell. In this study we construct a numerical model for this coupled (radial and pitch-angle) collisional diffusion process and apply it to simulate raw count-rate data observed aboard the Gemini spacecraft for several years after the 1962 Starfish nuclearmore » detonation. The data show apparent lifetimes 10-100 times as long as would have been expected from collisional pitch-angle diffusion and Coulomb drag alone. Our model reproduces apparent lifetimes for >0.5-MeV electrons in the region 1.14 < L < 1.26 to within a factor of two (comparable to the uncertainty quoted for the observations). We conclude that neoclassical radial diffusion (resulting from drift-shell splitting intrinsic to IGRF's azimuthal asymmetries) mitigates the decay expected from collisional pitch-angle diffusion and inelastic energy loss alone and thus contributes importantly to the long apparent lifetimes observed at these low L-shells.« less

  5. Evaluation of Radiation Belt Space Weather Forecasts for Internal Charging Analyses

    NASA Technical Reports Server (NTRS)

    Minow, Joseph I.; Coffey, Victoria N.; Jun, Insoo; Garrett, Henry B.

    2007-01-01

    A variety of static electron radiation belt models, space weather prediction tools, and energetic electron datasets are used by spacecraft designers and operations support personnel as internal charging code inputs to evaluate electrostatic discharge risks in space systems due to exposure to relativistic electron environments. Evaluating the environment inputs is often accomplished by comparing whether the data set or forecast tool reliability predicts measured electron flux (or fluence over a given period) for some chosen period. While this technique is useful as a model metric, it does not provide the information necessary to evaluate whether short term deviances of the predicted flux is important in the charging evaluations. In this paper, we use a 1-D internal charging model to compute electric fields generated in insulating materials as a function of time when exposed to relativistic electrons in the Earth's magnetosphere. The resulting fields are assumed to represent the "true" electric fields and are compared with electric field values computed from relativistic electron environments derived from a variety of space environment and forecast tools. Deviances in predicted fields compared to the "true" fields which depend on insulator charging time constants will be evaluated as a potential metric for determining the importance of predicted and measured relativistic electron flux deviations over a range of time scales.

  6. Environmental Impact Specification for Direct Space Weathering of Kuiper Belt and Oort Cloud Objects

    NASA Technical Reports Server (NTRS)

    Cooper, John F.

    2010-01-01

    The Direct Space Weathering Project of NASA's Outer Planets Research Program addresses specification of the plasma and energetic particle environments for irradiation and surface chemical processing of icy bodies in the outer solar system and the local interstellar medium. Knowledge of the radiation environments is being expanded by ongoing penetration of the twin Voyager spacecraft into the heliosheath boundary region of the outer heliosphere and expected emergence within the next decade into the very local interstellar medium. The Voyager measurements are being supplemented by remote sensing from Earth orbit of energetic neutral atom emission from this boundary region by NASA's Interstellar Boundary Explorer (IBEX). Although the Voyagers long ago passed the region of the Classical Kuiper Belt, the New Horizons spacecraft will encounter Pluto in 2015 and thereafter explore one or more KBOs, meanwhile providing updated measurements of the heliospheric radiation environment in this region. Modeling of ion transport within the heliosphere allows specification of time-integrated irradiation effects while the combination of Voyager and IBEX data supports projection of the in-situ measurements into interstellar space beyond the heliosheath. Transformation of model ion flux distributions into surface sputtering and volume ionization profiles provides a multi-layer perspective for space weathering impact on the affected icy bodies and may account for some aspects of color and compositional diversity. Other important related factors may include surface erosion and gardening by meteoritic impacts and surface renewal by cryovolcanism. Chemical products of space weathering may contribute to energy resources for the latter.

  7. Two Step Acceleration Process of Electrons in the Outer Van Allen Radiation Belt by Time Domain Electric Field Bursts and Large Amplitude Chorus Waves

    NASA Astrophysics Data System (ADS)

    Agapitov, O. V.; Mozer, F.; Artemyev, A.; Krasnoselskikh, V.; Lejosne, S.

    2014-12-01

    A huge number of different non-linear structures (double layers, electron holes, non-linear whistlers, etc) have been observed by the electric field experiment on the Van Allen Probes in conjunction with relativistic electron acceleration in the Earth's outer radiation belt. These structures, found as short duration (~0.1 msec) quasi-periodic bursts of electric field in the high time resolution electric field waveform, have been called Time Domain Structures (TDS). They can quite effectively interact with radiation belt electrons. Due to the trapping of electrons into these non-linear structures, they are accelerated up to ~10 keV and their pitch angles are changed, especially for low energies (˜1 keV). Large amplitude electric field perturbations cause non-linear resonant trapping of electrons into the effective potential of the TDS and these electrons are then accelerated in the non-homogeneous magnetic field. These locally accelerated electrons create the "seed population" of several keV electrons that can be accelerated by coherent, large amplitude, upper band whistler waves to MeV energies in this two step acceleration process. All the elements of this chain acceleration mechanism have been observed by the Van Allen Probes.

  8. A Kuiper Belt Pair? Artist's Concept of 2014 MU69 as a Binary Object

    NASA Image and Video Library

    2017-08-03

    This is one artist's concept of Kuiper Belt object 2014 MU69, the next flyby target for NASA's New Horizons mission. This binary concept is based on telescope observations made at Patagonia, Argentina, on July 17, 2017, when MU69 passed in front of a star. New Horizons scientists theorize that it could be a single body with a large chunk taken out of it, or two bodies that are close together or even touching. https://photojournal.jpl.nasa.gov/catalog/PIA21867

  9. NASA's Discovery Mission to (16) Psyche: Visiting a Metal World

    NASA Astrophysics Data System (ADS)

    Elkins-Tanton, L. T.; Bell, J. F., III

    2017-09-01

    The Psyche mission is one of NASA's most recent Discovery mission selections. It is designed to explore the large metallic Main Belt asteroid (16) Psyche and test the hypothesis that it is the exposed core of an ancient differentiated planetesimal.

  10. Recent Advances in Understanding Radiation Belt Dynamics in the Earth's Inner Zone and Slot Region

    NASA Astrophysics Data System (ADS)

    Li, X.

    2015-12-01

    Comprehensive measurements of the inner belt protons from the Relativistic Electron and Proton Telescope (REPT) onboard Van Allen Probes, in a geo-transfer-like orbit, revealed new features of inner belt protons in terms of their spectrum distribution, spatial distribution, pitch angle distribution, and their different source populations. Concurrent measurements from the Relativistic Electron and Proton Telescope integrated little experiment (REPTile) on board Colorado Student Space Weather Experiment (CSSWE) CubeSat, in a highly inclined low Earth orbit, and REPT demonstrated that there exist sub-MeV electrons in the inner belt and their flux level is orders of magnitude higher than the background associated with the inner belt protons, while higher energy electron (>1.6 MeV) measurements cannot be distinguished from the background. Analysis on sub-MeV electrons data in the inner belt and slot region from the Magnetic Electron Ion Spectrometer (MagEIS) on board Van Allen Probes revealed rather complicated pitch angle distribution of these energetic electrons, with the 90 deg-minimum (butterfly) pitch angle distribution dominating near the magnetic equator. Furthermore, it is clearly shown from MagEIS measurements that 10s - 100s keV electrons are commonly seen penetrating into the inner belt region during geomagnetic active times while protons of similar energies are hardly seen there. These are part of a summary of the most recent measurements and understanding of the dynamics of energetic particles in the inner zone and slot region to be exhibited and discussed in this presentation.

  11. Near-infrared Spectroscopy Of Outer Main Belt Asteroids

    NASA Astrophysics Data System (ADS)

    Takir, Driss; Emery, J.

    2009-09-01

    We have recently begun a spectral survey of the outer Main Belt population (3.2 AU < a < 4.6 AU), using near-infrared spectroscopy (0.8-2.5 μm). The objective of this survey is to search for signatures of H2O, organics, hydrated silicates, and/or anhydrous silicates on this group of asteroids. Studying the outer Main Belt asteroids will allow us to better understand the dynamical evolution of the Solar System and provide crucial constrains on nebular composition. Our first observing run, using the SpeX spectrograph/imager at the NASA IRTF, took place remotely form the University of Tennessee Knoxville on the nights of April 15, 16, and 17, 2009 (UT). More observing runs will be conducted this year and the beginning of next year. The initial data reduction process reveals that some of these asteroids exhibit weak and strong absorption features. We will present some of these initial spectra and results.

  12. Lognormal Kalman filter for assimilating phase space density data in the radiation belts

    NASA Astrophysics Data System (ADS)

    Kondrashov, D.; Ghil, M.; Shprits, Y.

    2011-11-01

    Data assimilation combines a physical model with sparse observations and has become an increasingly important tool for scientists and engineers in the design, operation, and use of satellites and other high-technology systems in the near-Earth space environment. Of particular importance is predicting fluxes of high-energy particles in the Van Allen radiation belts, since these fluxes can damage spaceborne platforms and instruments during strong geomagnetic storms. In transiting from a research setting to operational prediction of these fluxes, improved data assimilation is of the essence. The present study is motivated by the fact that phase space densities (PSDs) of high-energy electrons in the outer radiation belt—both simulated and observed—are subject to spatiotemporal variations that span several orders of magnitude. Standard data assimilation methods that are based on least squares minimization of normally distributed errors may not be adequate for handling the range of these variations. We propose herein a modification of Kalman filtering that uses a log-transformed, one-dimensional radial diffusion model for the PSDs and includes parameterized losses. The proposed methodology is first verified on model-simulated, synthetic data and then applied to actual satellite measurements. When the model errors are sufficiently smaller then observational errors, our methodology can significantly improve analysis and prediction skill for the PSDs compared to those of the standard Kalman filter formulation. This improvement is documented by monitoring the variance of the innovation sequence.

  13. The Chemical Composition of an Extrasolar Kuiper-Belt-Object

    NASA Astrophysics Data System (ADS)

    Xu, S.; Zuckerman, B.; Dufour, P.; Young, E. D.; Klein, B.; Jura, M.

    2017-02-01

    The Kuiper Belt of our solar system is a source of short-period comets that may have delivered water and other volatiles to Earth and the other terrestrial planets. However, the distribution of water and other volatiles in extrasolar planetary systems is largely unknown. We report the discovery of an accretion of a Kuiper-Belt-Object analog onto the atmosphere of the white dwarf WD 1425+540. The heavy elements C, N, O, Mg, Si, S, Ca, Fe, and Ni are detected, with nitrogen observed for the first time in extrasolar planetary debris. The nitrogen mass fraction is ∼2%, comparable to that in comet Halley and higher than in any other known solar system object. The lower limit to the accreted mass is ∼1022 g, which is about one hundred thousand times the typical mass of a short-period comet. In addition, WD 1425+540 has a wide binary companion, which could facilitate perturbing a Kuiper-Belt-Object analog into the white dwarf’s tidal radius. This finding shows that analogs to objects in our Kuiper Belt exist around other stars and could be responsible for the delivery of volatiles to terrestrial planets beyond the solar system. Part of the data presented herein were obtained at the W.M. Keck Observatory, which is operated as a scientific partnership among Caltech, the University of California and NASA. The Observatory was made possible by the generous financial support of the W.M. Keck Foundation.

  14. Outer Radiation Belt Dropout Dynamics Following the Arrival of Two Interplanetary Coronal Mass Ejections

    NASA Technical Reports Server (NTRS)

    Alves, L. R.; Da Silva, L. A.; Souza, V. M.; Sibeck, D. G.; Jauer, P. R.; Vieira, L. E. A.; Walsh, B. M.; Silveira, M. V. D.; Marchezi, J. P.; Rockenbach, M.; hide

    2016-01-01

    Magnetopause shadowing and wave-particle interactions are recognized as the two primary mechanisms for losses of electrons from the outer radiation belt. We investigate these mechanisms, sing satellite observations both in interplanetary space and within the magnetosphere and particle drift modeling. Two interplanetary shocks sheaths impinged upon the magnetopause causing a relativistic electron flux dropout. The magnetic cloud (C) and interplanetary structure sunward of the MC had primarily northward magnetic field, perhaps leading to a concomitant lack of substorm activity and a 10 day long quiescent period. The arrival of two shocks caused an unusual electron flux dropout. Test-particle simulations have shown 2 to 5 MeV energy, equatorially mirroring electrons with initial values of L 5.5can be lost to the magnetosheath via magnetopause shadowing alone. For electron losses at lower L-shells, coherent chorus wave-driven pitch angle scattering and ULF wave-driven radial transport have been shownto be viable mechanisms.

  15. NASA EEE Parts and NASA Electronic Parts and Packaging (NEPP) Program Update 2018

    NASA Technical Reports Server (NTRS)

    Label, Kenneth A.; Sampson, Michael J.; Pellish, Jonathan A.; Majewicz, Peter J.

    2018-01-01

    NASA Electronic Parts and Packaging (NEPP) Program and NASA Electronic Parts Assurance Group (NEPAG) are NASAs point-of-contacts for reliability and radiation tolerance of EEE parts and their packages. This presentation includes an FY18 program overview.

  16. An Overview of NASA's Risk of Cardiovascular Disease from Radiation Exposure

    NASA Technical Reports Server (NTRS)

    Patel, Zarana S.; Huff, Janice L.; Simonsen, Lisa C.

    2015-01-01

    The association between high doses of radiation exposure and cardiovascular damage is well established. Patients that have undergone radiotherapy for primary cancers of the head and neck and mediastinal regions have shown increased risk of heart and vascular damage and long-term development of radiation-induced heart disease [1]. In addition, recent meta-analyses of epidemiological data from atomic bomb survivors and nuclear industry workers has also shown that acute and chronic radiation exposures is strongly correlated with an increased risk of circulatory disease at doses above 0.5 Sv [2]. However, these analyses are confounded for lower doses by lifestyle factors, such as drinking, smoking, and obesity. The types of radiation found in the space environment are significantly more damaging than those found on Earth and include galactic cosmic radiation (GCR), solar particle events (SPEs), and trapped protons and electrons. In addition to the low-LET data, only a few studies have examined the effects of heavy ion radiation on atherosclerosis, and at lower, space-relevant doses, the association between exposure and cardiovascular pathology is more varied and unclear. Understanding the qualitative differences in biological responses produced by GCR compared to Earth-based radiation is a major focus of space radiation research and is imperative for accurate risk assessment for long duration space missions. Other knowledge gaps for the risk of radiation-induced cardiovascular disease include the existence of a dose threshold, low dose rate effects, and potential synergies with other spaceflight stressors. The Space Radiation Program Element within NASA's Human Research Program (HRP) is managing the research and risk mitigation strategies for these knowledge gaps. In this presentation, we will review the evidence and present an overview of the HRP Risk of Cardiovascular Disease and Other Degenerative Tissue Effects from Radiation Exposure.

  17. Belt attachment and system

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schneider, Abraham D.; Davidson, Erick M.

    Disclosed herein is a belt assembly including a flexible belt with an improved belt attachment. The belt attachment includes two crossbars spaced along the length of the belt. The crossbars retain bearings that allow predetermined movement in six degrees of freedom. The crossbars are connected by a rigid body that attaches to the bearings. Implements that are attached to the rigid body are simply supported but restrained in pitching rotation.

  18. Belt attachment and system

    DOEpatents

    Schneider, Abraham D.; Davidson, Erick M.

    2016-02-02

    Disclosed herein is a belt assembly including a flexible belt with an improved belt attachment. The belt attachment includes two crossbars spaced along the length of the belt. The crossbars retain bearings that allow predetermined movement in six degrees of freedom. The crossbars are connected by a rigid body that attaches to the bearings. Implements that are attached to the rigid body are simply supported but restrained in pitching rotation.

  19. Explorer 1 60th Anniversary

    NASA Image and Video Library

    2018-01-31

    Alexander Moiseev, a research scientist at NASA's Goddard Spaceflight Center, speaks during an event celebrating the 60th Anniversary of the Explorer 1 mission and the discovery of Earth's radiation belts, Wednesday, Jan. 31, 2018, at the National Academy of Sciences in Washington. The first U.S. satellite, Explorer 1, was launched from Cape Canaveral on January 31, 1958. The 30-pound satellite would yield a major scientific discovery, the Van Allen radiation belts circling our planet, and begin six decades of groundbreaking space science and human exploration. (NASA/Joel Kowsky)

  20. Explorer 1 60th Anniversary

    NASA Image and Video Library

    2018-01-31

    Michael Freilich, Director of the Earth Science Division of NASA's Science Mission Directorate, speaks during an event celebrating the 60th Anniversary of the Explorer 1 mission and the discovery of Earth's radiation belts, Wednesday, Jan. 31, 2018, at the National Academy of Sciences in Washington. The first U.S. satellite, Explorer 1, was launched from Cape Canaveral on January 31, 1958. The 30-pound satellite would yield a major scientific discovery, the Van Allen radiation belts circling our planet, and begin six decades of groundbreaking space science and human exploration. (NASA/Joel Kowsky)