Space Modeling Space Radiation Radiation Environment Environment Modeling Efforts Efforts at JPL JPL Dr. Henry Garrett Jet Propulsion Laboratory 4800 Oak Grove Dr. Pasadena, CA 91109 Spacecraft Environmental Interactions, Envts (Garrett).ppt 2-1
SPACE RADIATION RADIATION ENVIRONMENTS ENVIRONMENTS SUN SEP Models EARTH POES SAA Models Geosynchronous Plasma PLANETS Jupiter Saturn MAN-MADE RPG/RHU 2-2
SOLAR PROTON EVENTS-SPACE RAIN 2-3
FREQUENCY OF MAJOR SOLAR PROTON EVENTS 2-4
JPL SPE Model Updates Purpose of new model is to develop statistical distributions of 3 quantities: -Event fluences: Log-normal distribution -Event durations: Poisson Distribution -Time Intervals between events: Poisson Distribution Event Fluence Can generate a virtual data set based on these three distributions. Spacecraft Environmental Interactions, Time interval between events Duration of events 2-year at 1 AU Envts (Garrett).ppt 2-5
JPL SPE Model Updates SPE Model Composition Fraction of missions with fluences > F. This particular example was obtained for a 60-day solar probe mission trajectory with a 1/r2 scaling factor. 2-6
JPL SPE Model Updates Publications: - Feynman, J, G. Spitale, J. Wang and S. Gabriel, Interplanetary proton fluence model : JPL 1991, J. Geophys. Res., 98, 13281, 1993. - Ruzmaikin, A., G. Li, G. Zank, J. Feynman, and I. Jun, The radial dependence of solar energetic particle fluxes, 11th Solar Wind/ SOHO 16: Connecting Sun and Heliosphere, June 11-17, 2005 - Swimm, R. T., I. Jun, A. Ruzmaikin, J. Feynman, A. J. Tylka, and W. F. Dietrich, Statistics of solar energetic particle events: fluences, durations, and time interval, 36th COSPAR Scientific Assembly, Beijing, China, July 16-23, 2006. 2-7
EARTH TRAPPED RADIATION MODELS Contour plots of > 1MeV electron and >10 MeV proton integral fluxes at Earth. Coordinate system used is geographic at the 0 meridian. Based on AP8 and AE8 solar maximum models. 2-8
Why is there a South Atlantic Anomaly? 2-9
Long-Term Observations of Trapped High-Energy Protons (L<4) by NOAA Polar Orbiting Environmental Satellites (POES) D. Evans (NOAA), H. Garrett (JPL), I. Jun (JPL), R. Evans (Gibbel Corp.), and J. Chow (Raytheon Corp. SPACECRAFT: ORBIT: PERIOD: NOAA-15, -16, -17 ~840 Km altitude, 98 Incl June 1, 1998 June 30, 2005 ~15 satellite-years INSTRUMENT: Space Environment Monitor (SEM)-2 Omni-directional H+ detectors ENERGY RANGE: >16 MeV, >36 MeV, >70 MeV, >140 MeV COVERAGE: 8-s intervals on 1 lat x 2 long grid. 65.5 N-72.5 S; 1-359 E 2-10 SEM-2 Omni-Directional Detectors
POES Observations of the South Atlantic Anomaly (SAA) P6: >16 MeV 50% P9: >140 MeV Contour Plots of Trapped Protons 95% High radiation region at high latitude, likely due to E>3MeV electrons 50% 95% 2-11
POES Observations of the SAA and Nearby Regions (L<4) Low L Region Normalized statistical (percentile) distribution of the particle fluxes at a given energy and at a specified B and L for P6. High L Region POES Model of the SAA and Nearby Regions (L<4) 2-12
Summary of POES Long-term Statistics for Low-Altitude, High-Energy Trapped H+ Environment SUMMARY: - Energetic H+ fluxes vary by only ~2 between 10% and 99% levels in SAA. - Little or no association between H+ intensities and SEP events in SAA. - Proton intensities at POES altitudes in SAA primarily governed by local pitch-angle extent over which trapped protons access satellite. - Highly variable secondary region of enhanced P6 responses at L>3.0 -~1000's between10%-99%. Sensor responses at 90% and above believed to be dominated by episodes of high intensity, >3 MeV electrons (2004-2005). - Data set forms extensive source of information for studying long-term near-earth trapped proton environment as a function of solar cycle and magnetic activity and for evaluating role of SEP events. 2-13
JPL Geosynchronous Plasma Models 2-14
Two Maxwellian Plasma Model Approach 2-15
THE GEOSYNCHRONOUS PLASMA ENVIRONMENT MODEL STATISTICAL DISTRIBUTIONS OF KEY GEOSYNCHRONOUS PARAMETERS LOCAL TIME/Kp VARIATIONS FOR KEY GEOYSNCHRONOUS PLASMA PARAMETERS 2-16
Jupiter 2-17
Jupiter 2-18
Jupiter s Magnetic Field X 104 = 2-19
JUPITER S LOW ENERGY PLASMA ENVIRONMENT 2-20
DIVINE/GIRE JOVIAN TRAPPED RADIATION MODELS Contour plots of >1 MeV electron and >10 MeV proton integral fluxes at Jupiter. Coordinate system used is jovi-centric. Models are based on Divine/GIRE models. Meridian is for System III 110 W. 2-21
DIVINE HIGH ENERGY ELECTRON MODEL 2-22
COMPARISONS BETWEEN JOVIAN AND TERRESTRIAL RADIATION SPECTRA 2-23 COURTESY A. JOHNSTON
Saturn 2-24
Saturn 2-25
HIGH ENERGY ELECTRON AND PROTON FLUXES AT SATURN (DIVINE/SATRAD) 2-26
DIVINE/SATRAD SATURN TRAPPED RADIATION MODELS o West Longitude = 0 14 12 10 8 6 4 2 0 2 4 6 8 10 12 14 R s Contour plots of >1 MeV electron and >10 MeV proton integral fluxes at Saturn. Coordinate system used is Saturn-centric. Models are based on Divine/SATRAD models. Meridian is for 0 W. 2-27
Earth TRAPPED RADIATION BELTS Jupiter o West Longitude = 0 Saturn 14 12 10 8 6 4 2 0 2 R s 4 6 8 10 12 14 2-28
MAN-MADE ENVIRONMENTS 2-29
GALILEO RADIOISOTOPE SOURCES General Purpose Heat Source Radioisotope Thermoelectric Generator Lightweight Radioisotope Heater Unit 2-30
GALILEO RTG NORMALIZED AND NEUTRON FLUXES 2-31
GALILEO RTG AND NEUTRON FLUXES VS DISTANCES 2-32
GALILEO RADIOISOTOPE THERMOELECTRIC GENERATOR ISODOSE-ISOFLUX CONTOURS 2-33