Solar Particle Events in Aviation and Space Günther Reitz Insitute of Aerospace Medicine German Aerospace Center, DLR, Cologne, Germany
Radiation Field in the Heliosphere LEO orbit
Fluxes of primary space radiation components inner Van Allen belt protons
The Earth Magnetic Field
Deflection and trapping of charged particles by the geomagnetic field
Vertical Cut-Off Rigidities in GV
Atmospheric Shielding - Particle Cascade
Charged Particle Count rate in dependence of Altitude
The Solar Cycle
The Solar Cyle
Solar corona and sudden release of a huge clouds of particles
Sourcle: NASA Source: Charlton et al. Solar energetic particle events (Solar Particle Events (SPE), Coronal Mass Ejections (CME)) probability of occurrence is correlated with the solar cycle
Integral energy spectra of historical worstcase solar particle events
What are flares and CMEs? Solar sources of major space weather disturbances: Flares & coronal mass ejections (CMEs) CMEs are huge clouds of magnetized plasma expelled from the solar corona to interplanetary space with velocities of ~100 km/s up to 3000 km/s. Flares manifest themselves as enhanced radiation across the whole electromagnetic spectrum due to heating and interaction of high-energetic particles with the solar atmosphere. Both flares and CMEs are powered by a sudden release of magnetic energy in the corona previously stored in non-potential (stressed) fields. Both may be associated with solar energetic particles (SEPs) : cause e.g. surface and internal charging on satellites; radiation hazard to astronauts
Solar Energetic Particles (SEPs)
Solar Flares and Coronal Mass Ejections
Space Weather Impact Drivers of Space Weather Coronal Mass Ejections (CMEs): Arrive 1-4 Days later Last a day or two Produce Geomagnetic Storms at Earth Systems Affected Radio Communications Navigations Electric Power Grids Pipelines High-Speed Solar Wind: Common During Solar Minimum Enhances Radiation Belts Systems Affected Satellite Charging Astronouts Solar X-Rays and EUV: Arrive in 8 Minutes Last minutes to hours Increases ionosphere density Increases neutral density Systems Affected: Radio Communications Navigation Satellite Orbits Solar Energetic Particles: Arrive in 30 Minutes to 24 hours Last several days Systems Affected: Astronauts Spacecraft Airlines Radio Communications
Measurements
Navigation camera image showing the surface scour marks and rocks on the rover s deck and RAD! RAD NASA/JPL-Caltech
MSL Radiation Assessment Detector
Radiation Assessment Detector (Cruise Measurements) SPE Exposures msv 23-29 Jan 4 7-15 March 19.5 17-18 May 1.2 Daily GCR 1.84 msv
ISS Radiation measurements : Area Monitoring NASA ESA JAXA IMBP
1 / cm 2 s sr Count Rate (top panel) and Particle Fluxes on ISS GOES Satellite Measurements (bottom panel) 100 10 DOSTEL count rate 1 / s cm 2 1 0.1 104.50 104.75 105.00 105.25 105.50 105.75 106.00 106.25 106.50 10 3 10 2 10 1 10 0 10-1 10-2 15 th April GOES8 Proton Flux >= 100MeV DoY 2001 16 th April 104.50 104.75 105.00 105.25 105.50 105.75 106.00 106.25 106.50
Dose equivalent (µsv/day) Cummulative Dose Equivalent (msv) ISS TEPC During 2005 (Dose Equivalent Rate) 1000 250 900 800 700 200 150 600 500 400 300 100 50 0
Increase and decrease of radiation exposure in 12 km due to GLE 65 and the following Forbush decrease
Calculations
Solare Worst Case particle event Space suit (0.3 g/cm 2 ) Equipment room (5 g/cm 2 ) Radiation shelter (10 g/cm 2 ) Skin Lens BFO Skin Lens BFO Skin Lens BFO Free Space Lunar Surface Exposure [Sv] 295 81 4.2 6.5 5.5 1.9 2.6 2.4 1.3 148 40 2.1 3.2 2.7 1.0 1.3 1.2 0.6 Martian Surface 0.5 0.4 0.3 0.3 0.4 0.3 0.3 0.3 0.25
Determination of SEP spectrum Assume spectrum for Solar Energetic Particles at time t Calculate secondary particle fluences and Neutron- Monitor count rates related to GCR and SEP (PLANETOCOSMICS, GEANT4) ( stations Compare to measured count rates (~30 ( Minimization ) Adapt spectrum for SEP Calculate secondary particle fluences at aviation altitudes Conversion to radiation exposure
Neutron Monitor Network
GLE70: Primary proton spectra
Vortrag > Autor > Dokumentname > Datum Interplanetary space: GLE 70 on of Dec. 13, 2006 Organ dose equivalent H for 25 g/cm2 Al shielding Water sphere with NUNDO Water sphere with ICRPP NUNDO voxel (16-21 msv) ICRPP voxel (13-20 msv)
Vortrag > Autor > Dokumentname > Datum ISS orbit: GLE 70 on of December 13, 2006 Organ dose equivalent for 25 g/cm2 Al shielding Water sphere with NUNDO Water sphere with ICRPP NUNDO voxel (0.44 0.59 msv) ICRPP voxel (0.39 0.54 msv) Quality factor : 1.3 1.5 Benghin et al.: DB-8: 0.32 mgy 0.67 mgy
GLE70: Dose rates at 200g/cm 2 ( 12km, FL390) Along 25 E Peak values of 4.5 to 5 times GCR background
GLE70: Dose Rates in FL390 (12km, 200g/cm 2 ) Prior to event 3.05 UTC 3.35 UTC
GLE70: Dose rates in high latitudes g/cm 200, 12km )FL390 2 ) FRA-LAX: 140 μsv (GCR=93μSv) JFK-PEK: 153 μsv (GCR=107μSv) ~50% Increase compared to GCR 12km GCR GCR+SEP
GLE 60 Dose equivalent at 300 g cm -2 (~10,000m) CERCLe Lantos et al. 12,200m
Comparison of Calculation and Measurement GLE 60 Courtesy: J.-F. Bottollier
Maximum Dose Equivalent in µsv of large SPE s above latitudes of 60 for different Flight levels GLE No. Solar Particle Event Flight level 30 000 feet 40 000 feet 50 000 feet GLE 5 # Feb 23, 1956 330 1200 2200 GLE 42 Sept 29, 1989 33 120 220 GLE 43 Oct 19, 1989 5 19 39 GLE 44 Oct 22, 1989 1 2 5 GLE 45 Oct 24, 1989 11 38 80 GLE 60 April 15, 2001 49 GLE 68 Jan. 20, 2005 86 GLE 70 Dec 13, 2006 15 46 # estimated as 10 fold dose of the GLE42
Summary I SPE Exposures in Interplanetary Space AcuteExposures can exceed 1 Sv and are potentially life threatening, but risks are manageable by shielding measures Optimise shielding design, include storm shelters (material & thickness) Shielding should limit excessive exposure to prevent acute effects Optimise mission design duration timeline relative to solar activity cycle guarantied shelter accessibility Advance forecasting capabilities for solar particle events Exploration vehicles shielding should focus on SPE instead on GCR SPE Exposures in Low Earth Orbit Thanks to the high magnetic shielding of the ISS exposures higher than a couple of tenth of msv are not likely Astronauts are advised to move to higher shielding areas in case of a SPE Extravehicluar activities are prohibited
Summary II Civil airflight Altitudes Exposures are in the micosv range, nevertheless strong interest of air crew to monitor them accurately Only a few measurements available, next step: To equip more airplanes with monitor to optimize the coverage Calculations are necessary for an fast estimate of the exposure: Two models are available one using Models and one is based on Concorde measurements (SiGle) The combination of neutron monitor data analysis with the Geant4 applications MAGNETOCOSMICS and PLANETOCOSMICS is a suitable tool for dosage evaluations at aircraft altitudes during GLEs, in particular during highly anisotropic events (Univ. Bern; DLR) Additional fine-tuning is in progress, as well as the comparison action with the French SiGle
www.dlr.de Chart 42 > Vortrag > Autor Dokumentname > Datum SPARES
di x 0, 0,,, b dr 0 C Count rate of C c s i SEP GCR i GCR i x x x Primary SEP spectrum Background count rate of Neutron Monitor i GCR C x Ci Relative count rate increase SEP GCR i GCR Ci i x modeled measured c c 2 i Minimize s(x) by adapting x! i Neutron Monitor i
GLE 70: Calculated Neutron Monitor Count Rates
www.dlr.de Chart 45 > Vortrag > Autor Dokumentname > Datum GLE 68: Jan. 20, 2005 Courtesy: J.-F. Bottollier
Mission Doses from Galactic Cosmic Rays for Reference Scenarios
Exposures of Radiation workers 600000 300000 surveillance of personal dosimeters by GSF for 2001 persons per dose unit / msv -1 25000 20000 all workers medical 'industrial' source: http://awst.gsf.de/statiskik/stat2001/ 20001bk1_1, 2001bk2_1, 2001sum_1.gif 15000 range and average of aircrew exposure 10000 5000 0 0 1 2 3 4 5 6 7 60 80 annual equivalent dose / msv GSFannualexp2001.opj
www.dlr.de Chart 48 > Vortrag > Autor Dokumentname > Datum Solar Forecast 1) To predict when the next CME-flare event will occur - we are still far from that. Needs better understanding and modeling of the basic physics 2) Given the observation of an event occurring on the Sun: predict its arrival time and effect on Earth Needs good input data (observations) Needs good understanding and modeling of interplanetary propagation and magnetosphere response Time scales: - Flare radiation: immediate - if we see it, it s here - SEPs from flares and CMEs: some ten minutes to days - CMEs: ~1 5 days
Space Radiation Environment
Comparison of estimated probabilities for human radiation deaths from extreme solar particle events with common terrestrial risks.
The three major components of ionising space radiation, galactic cosmic rays (GCR), solar particle-, and geomagnetically trapped radiation