Search NASA⌕ Search

SEARCH · Search NASA

Results for “solar energetic protons”

Search indexed NASA NTRS and DOE OSTI research on propulsion, heat transfer, battery materials and energy systems. Follow report and document links to the original sources.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 55 records · Page 3
All sourcesNASA NTRSDOE OSTI
NASA NTRS1994

Solar proton effects on austral ozone during the final months of 1989

Intense solar activity during 1989 prompted six major particle events. Four of these occurred between August and December. Energetic solar protons are a natural source of ozone depletion due to the nitric oxides they produce in the polar atmospheres. In particular, modelling (Reid et al., 1991) of an event that peaked on October 20 (with greater than 10 MeV proton flux of 73000 particles sq cm s(exp -1) ster(exp -1) yields 55 percent column density enhancements of NO over the southern polar cap. Total column ozone data from the total ozone ,mapping spectrometer (TOMS) instrument aboard the Nimbus 7 satellite used at times when solar illumination facilitates measurements by TOMS over the entire southern polar regions. The impact of odd nitrogen enhancements on the spatial extent of low total column ozone and of the total ozone mass, over a region August to December. Comparisons are made with previous years (1984 to 1988) of moderate solar activity. The effect, if any, of these events on ozone during times of heterogeneous chlorine chemistry and dynamic processes is discussed.

Stephenson, Judy A. E.↗
NASA NTRS1967

Particles and fields

Interplanetary magnetic field, magnetosphere, solar energetic protons, and galactic cosmic rays

MAGNETOSPHERE↗
NASA NTRS1975

Project SOLWIND: Space radiation exposure

A special orbital radiation study was conducted for the SOLWIND project to evaluate mission-encountered energetic particle fluxes. Magnetic field calculations were performed with a current field model, extrapolated to the tentative spacecraft launch epoch with linear time terms. Orbital flux integrations for circular flight paths were performed with the latest proton and electron environment models, using new improved computational methods. Temporal variations in the ambient electron environment are considered and partially accounted for. Estimates of average energetic solar proton fluences are given for a one year mission duration at selected integral energies ranging from E greater than 10 to E greater than 100 MeV; the predicted annual fluence is found to relate to the period of maximum solar activity during the next solar cycle. The results are presented in graphical and tabular form; they are analyzed, explained, and discussed.

Stassinopoulos, E. G.↗
NASA NTRS1973

Radiation hazards to synchronous satellites: The IUE (SAS-D) mission

The ambient trapped particle fluxes incident on the IUE (SAS-D) satellite were studied. Several synchronous elliptical and circular flight paths were evaluated and the effect of inclination, eccentricity, and parking longitude on vehicle encountered intensities was investigated. Temporal variations in the electron environment were considered and partially accounted for. Magnetic field calculations were performed with a current field model extrapolated to a later epoch with linear time terms. Orbital flux integrations were performed with the latest proton and electron environment models using new improved computational methods. The results are presented in graphical and tabular form; they are analyzed, explained, and discussed. Estimates of energetic solar proton fluxes are given for a one year mission at selected integral energies ranging from 10 to 100 MeV, calculated for a year of maximum solar activity during the next solar cycle.

Stassinopoulos, E. G.↗
NASA NTRS1974

Radiation environment for ATS-F

The ambient trapped particle fluxes incident on the ATS-F satellite were determined. Several synchronous circular flight paths were evaluated and the effect of parking longitude on vehicle encountered intensities was investigated. Temporal variations in the electron environment were considered and partially accounted for. Magnetic field calculations were performed with a current field model extrapolated to a later epoch with linear time terms. Orbital flux integrations were performed with the latest proton and electron environment models using new improved computational methods. The results are presented in graphical and tabular form; they are analyzed, explained, and discussed. Estimates of energetic solar proton fluxes are given for a one year mission at selected integral energies ranging from 10 to 100 Mev, calculated for a year of maximum solar activity during the next solar cycle.

Stassinopoulos, E. G.↗
NASA NTRS2014

Middle Atmospheric Changes Caused by the January and March 2012 Solar Proton Events

The recent 23-30 January and 7-11 March 2012 solar proton event (SPE) periods were substantial and caused significant impacts on the middle atmosphere. These were the two largest SPE periods of solar cycle 24 so far. The highly energetic solar protons produced considerable ionization of the neutral atmosphere as well as HOx (H, OH, HO2) and NOx (N, NO, NO2). We compute a NOx production of 1.9 and 2.1 Gigamoles due to these SPE periods in January and March 2012, respectively, which places these SPE periods among the 12 largest in the past 50 years. Aura Microwave Limb Sounder (MLS) observations of the peroxy radical, HO2, show significant enhancements of 0.9 ppbv in the northern polar mesosphere as a result of these SPE periods. Both MLS measurements and Goddard Space Flight Center (GSFC) two-dimensional (2D) model predictions indicated middle mesospheric ozone decreases of 20 percent for several days in the northern polar region with maximum depletions 60 percent as a result of the HOx produced in both the January and March 2012 SPE periods. The SCISAT-1 Atmospheric Chemistry Experiment Fourier Transform Spectrometer (ACE) and the Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIPAS) instruments measured NO and NO2 (NOx), which indicated enhancements of over 20 ppbv in most of the northern polar mesosphere for several days as a result of these SPE periods. The GSFC 2D model was used to predict the medium-term (months) influence and found that the polar Southern Hemisphere middle atmosphere ozone was most affected by these solar events due to the increased downward motion in the fall and early winter. The downward transport moved the SPE-produced NOy to lower altitudes and led to predicted modest destruction of ozone (5-9 percent) in the upper stratosphere days to weeks after the March 2012 event. Total ozone reductions were predicted to be a maximum of 1 percent in 2012 due to these SPEs.

ozone↗
DOE OSTI2024

The Impact of the 8–10 March 2012 Geomagnetic Storm on Inner Zone Protons as Measured by Van Allen Probes

The Relativistic Electron Proton Telescope (REPT) instrument on the Van Allen Probes observed a double-peaked inner zone proton population throughout the 7 year lifetime of the mission. M. Hudson et al. (2023) showed that a strong SEP event accompanied by a CME-shock in early March 2012 provided the Solar Energetic Proton (SEP) source for the higher L trapped proton population, which then diffused radially inward to be observed by REPT at L = 2. The study followed trajectories of SEP protons launched isotropically from a sphere at 7 Re for 2.5 hr in fields calculated by the LFM-RCM global MHD model, which includes electric fields needed to model the transport and trapping of the protons by the shock, and then a radial diffusion simulation was run for 2 years using the result from the test-particle simulation as the initial condition. The simulation result was compared with REPT measurement in November 2013 and showed reasonable agreement. However, the simulation overestimated the Phase Space Density by a factor of four due to lack of field line curvature scattering during the storm in the model. In this study, a test-particle simulation is performed for 2 days following the injection and trapping of protons in March 2012 using TS05 fields to simulate the field line curvature scattering of the trapped SEP due to the buildup of the ring current during the geomagnetic storm. The resulting sample distribution was then weighted using the flux at the end of the two-hour MHD-test particle simulation. A radial diffusion simulation is then run using the initial profile that included the loss effect, with improved comparison with REPT measurements after 2 years.

79 ASTRONOMY AND ASTROPHYSICS↗
NASA NTRS1972

Predicted trapped particle radiation levels for Tiros-N

Vehicle encountered electron and proton fluxes were calculated for a set of nominal TIROS-N trajectories with new computational methods and new electron environment models. Temporal variations in the electron data were considered and partially accounted for. Estimates of energetic solar proton fluxes are given for the lifetime of the satellite at selected integral energies from 10 to 100 MeV. Field strength calculations were performed with an extrapolated model on the basis of linear secular variation predictions. Orbital flux integration results are presented in graphical and tabular form.

Stassinopoulos, E. G.↗
NASA NTRS2016

Multidirectional Cosmic Ray Ion Detector for Deep Space CubeSats

Understanding the nature of anisotropy of solar energetic protons (SEPs) and galactic cosmic ray (GCR) fluxes in the interplanetary medium is crucial in characterizing time-dependent radiation exposure in interplanetary space for future exploration missions. NASA Glenn Research Center has proposed a CubeSat-based instrument to study solar and cosmic ray ions in lunar orbit or deep space. The objective of Solar Proton Anisotropy and Galactic cosmic ray High Energy Transport Instrument (SPAGHETI) is to provide multi-directional ion data to further understand anisotropies in SEP and GCR flux. The instrument is to be developed using large area detectors fabricated from high density, high purity silicon carbide (SiC) to measure linear energy transfer (LET) of ions. Stacks of these LET detectors are arranged in a CubeSat at orthogonal directions to provide multidirectional measurements. The low-noise, thermally-stable nature of silicon carbide and its radiation tolerance allows the multidirectional array of detector stacks to be packed in a 6U CubeSat without active cooling. A concept involving additional coincidence/anticoincidence detectors and a high energy Cherenkov detector is possible to further expand ion energy range and sensitivity.

Extraterrestrial Radiation↗
NASA NTRS1993

Simultaneous observations of solar MeV particles in a magnetic cloud and in the earth's northern tail lobe - Implications for the global field line topology of magnetic clouds and for the entry of solar particles into the magnetosphere during cloud passage

Simultaneous ISEE 3 and IMP 8 spacecraft observations of magnetic fields and flow anisotropies of solar energetic protons and electrons during the passage of an interplanetary magnetic cloud show various particle signature differences at the two spacecraft. These differences are interpretable in terms of the magnetic line topology of the cloud, the connectivity of the cloud field lines to the solar surface, and the interconnection between the magnetic fields of the magnetic clouds and of the earth. These observations are consistent with a magnetic cloud model in which these mesoscale configurations are curved magnetic flux ropes attached at both ends to the sun's surface, extending out to 1 AU.

Farrugia, C. J.↗
NASA NTRS2003

Proton-Induced Transients and Charge Collection Mechanisms in a LWlR HgCdTe Focal Plane Array

Low noise performance of IR detectors is required, even in the presence of charged particles. Galactic cosmic rays, trapped protons & solar energetic particles. Particle induced transients identified as an important source of noise on ESA's ISO satellite. Also observed on NICMOS Instrument on NASA% Hubble Space Telescope. Tools to analyse particle induced transients have been developed. To date, comparisons of model have been made to flight data for a HgCdTe array exposed to trapped protons, and to a Si array exposed to laboratory protons. We report ground based proton transient measurements in a modem LWlR HgCdTe array operating under cryogenic conditions. Demonstration of charge collection mechanisms. Provide benchmarks for modeling tools.

Marshall, Paul↗
NASA NTRS1990

Coronal mass ejections and the injection profiles of solar energetic particle events

Previous studies using Skylab and Solwind coronagraph observations have shown that almost all E greater than 10 MeV solar energetic proton (SEP) events are associated with the occurrence of a coronal mass ejection (CME). These earlier studies did not address the relationship between the position of the associated CME and the timing of the injection of particles into the interplanetary medium. Ten cases are selected in which a SEP event observed with the GSFC detectors on the IMP 8 or ISEE 3 spacecraft was correlated to a CME well observed by the Solwind coronagraph. The height of the leading edge of the CME is compared with the particle injection profiles for several energy ranges using the solar release times for the particles. The derived injection profiles are found to be increasing and sometimes reaching maximum while the associated CMEs are at heights of 2-10 Ro.

Kahler, S. W.↗
NASA NTRSDate not supplied

Lunar-surface UV Photometric Investigation of Exospheres (LUPINE): Thermal Modeling of Payload in a Relevant Daylit Environment

Direct upward remote sensing of the moon’s exosphere from a surface vantage can address production of water-related lunar volatiles as well as their exospheric loss, ballistic transport, and ultimate adsorption in permanently shadowed regions (PSRs). Far UV (FUV) dayside measurements of atomic oxygen, liberated from regolith by energetic solar protons and micrometeorite impact, can provide critical insight into the endogenic lunar water cycle by constraining total column density [O] at site of production. A notional Lunar-surface UV Photometric Investigation of Exospheres (LUPINE) instrument is designed to exploit solar-pumped atomic oxygen fluorescence at 130.4-nm, in a manner similar to the Apollo 17 UV Spectrometer (UVS) experiment [Fastie 1973; Feldman and Morrison, 1991] and the LRO Lyman-alpha Mapping Project (LAMP) spectrograph [Cook et al., 2013], by implementing a zenith-directed FUV photometer from the lunar surface at low (± 10°) selenographic latitude during the lunar day. Atomic oxygen production from solar energetic particle impact sources is thought to maximize in near solar noon [Sarantos et al., 2012], and the lander-embedded zenith-directed LUPINE photometer, in contrast to UVS and LAMP twilight measurements from orbit, can potentially capture the full column abundance of lunar regolith liberated oxygen. Herein we describe adaptation of FUV reflective optics, pulse-counting electronics, and scattered-light-suppression technologies developed for LEO FUV photometry for the challenging thermal environment of the daylit lunar surface. Preliminary thermal modeling and TVAC measurements of heritage FUV photometer components suggests that, if allowed to shed ~8W of waste heat into the bus of a reference Commercial Lunar Payload Services (CLPS) lander, the LUPINE photometer will be kept sufficiently cool to limit dark current to less than 20 counts/s. This level of dark signal enables an OI 130.4-nm 3-sigma detection threshold of ~1 mR for assumed 2-hour integrations.

Lunar UV Photometer↗
NASA NTRS2010

Polar Northern Hemisphere Middle Atmospheric Influence due to Energetic Particle Precipitation in January 2005

Solar eruptions and geomagnetic activity led to energetic particle precipitation in early 2005, primarily during the January 16-21 period. Production of OH and destruction of ozone have been documented due to the enhanced energetic solar proton flux in January 2005 [e.g., Verronen et al., Geophys. Res. Lett.,33,L24811,doi:10.1029/2006GL028115, 2006; Seppala et al., Geophys. Res. Lett.,33,L07804, doi:10.1029/2005GL025571,2006]. These solar protons as well as precipitating electrons also led to the production of NO(x) (NO, NO2). Our simulations with the Whole Atmosphere Community Climate Model (WACCM) show that NO(x) is enhanced by 20-50 ppbv in the polar Northern Hemisphere middle mesosphere (approx.60-70 km) by January 18. Both the SCISAT-1 Atmospheric Chemistry Experiment (ACE) NO(x) measurements and Envisat Michelson Interferometer for Passive Atmospheric Sounding (MIP AS) nighttime NO2 observations show large increases during this period, in reasonable agreement with WACCM predictions. Such enhancements are considerable for the mesosphere and led to simulated increases in polar Northern Hemisphere upper stratospheric odd nitrogen (NO(y)) of2-5 ppbv into February 2005. The largest ground level enhancement (GLE) of solar cycle 23 occurred on January 20, 2005 with a neutron monitor increase of about 270 percent [Gopalswamy et al., 29th International Cosmic Ray Conference, Pune,00,101-104,2005]. We found that protons of energies 300 to 20,000 MeV, not normally included in our computations, led to enhanced stratospheric NO(y) of less than 1 percent as a result of this GLE. The atmospheric impact of precipitating middle energy electrons (30-2,500 keV) during the January 16-21, 2005 period is also of interest, and an effort is ongoing to include these in WACCM computations. This presentation will show both short- and longer-term changes due to the January 2005 energetic particle precipitation.

Jackman, Charles H.↗
NASA NTRS2012

Size Distributions of Solar Flares and Solar Energetic Particle Events

We suggest that the flatter size distribution of solar energetic proton (SEP) events relative to that of flare soft X-ray (SXR) events is primarily due to the fact that SEP flares are an energetic subset of all flares. Flares associated with gradual SEP events are characteristically accompanied by fast (much > 1000 km/s) coronal mass ejections (CMEs) that drive coronal/interplanetary shock waves. For the 1996-2005 interval, the slopes (alpha values) of power-law size distributions of the peak 1-8 Angs fluxes of SXR flares associated with (a) >10 MeV SEP events (with peak fluxes much > 1 pr/sq cm/s/sr) and (b) fast CMEs were approx 1.3-1.4 compared to approx 1.2 for the peak proton fluxes of >10 MeV SEP events and approx 2 for the peak 1-8 Angs fluxes of all SXR flares. The difference of approx 0.15 between the slopes of the distributions of SEP events and SEP SXR flares is consistent with the observed variation of SEP event peak flux with SXR peak flux.

Solar Flares↗
NASA NTRS1974

Projects SOLRAD and TIMATION: Space radiation exposure

The charged particle fluxes to be encountered by spacecraft in circular orbits with inclinations of 125 and 65 degrees, and altitudes of 13890 and 11111 kilometers, respectively were investigated. For these conditions, two nominal trajectories were generated corresponding to missions SOLRAD and TIMATION. The orbits and geomagnetic geometry, spectral profiles, peaks per orbit, trajectory data, and energetic solar proton fluxes are discussed. The tabulated results are analyzed.

Stassinopoulos, E. G.↗