The effect of the March 1991 storm on accumulated dose for selected satellite orbits: CRRES dose models

Abstract

12a, DISTRIBUTION AVAILASILITY STATEMENT 12b. 0IS7RI3UI'I 1CZEtApproved for public release; Distribution unlimited ASTRAT lax,'rnmrn CO word~s)Thmt dose fodels ate constucted using direct measurmen of dose on the CRpES sa~tellite in a o-nIou gscsyncrouous-trensfer orbit. The Average Model -a duat July 19M to March 1991 The Actve Model -rn date from active partods is based on the 24 Muchi 1991 sOWartil = magnetosphere radiation populadoes. The dose models aue doss rate aveager in grids of L and 1111%. A software oPWam (cUERRFAD), developed for doe models, allows the f calculatin of doss behind 4 shielding &Waam-s for -Y setallite orbit. In the acm"v period, doese acquired -a circarw, low-inclination orbit in the '&oW rgiOU* it greate dun in the qmez Period by up to two Orders of magnitude, nakiug this region, heretofore thought to be relattvely be-So. comparable in radiazioe hershwa to the peak of do now radiation belt. The INtahility Of the CRIE &os mo0e" for evaluating dose in high inclination orbits is also discussed. Abstract measured in either the inner or the outer belts. The new beits were still in existence some 6-plus months after their formsThree dose models are constructed using direct measure-tion when CRRES ceased transmitting daft due to battery meats of dose on the CRRES satellite, in a low-inclination, failures. geosynchronous-transfer orbit. The Average Model uses data SUBJECT TERMS 1S. NUMBER OF PAGESThe dynamic nature of the inner magnetospher is not taken over the entire 14 months of the CRRES mission from included in any existing model, and presents a problem for July 1990 to October 1991. The Quiet Model uses data from orbit planning and satellite design when cost-effective mison July 1990 to March 1991. The Active Model uses data from ane imperative. A comparison of dose measurements on March 1991 to October 1991. The separation of the quiet and CRRES with NASA model predictions was previously reported active periods is based on the 24 March 1991 solar particle [6]. The comparison showed the extrem inadequacy of event and subsequent solar wind shock which rearranged the NASA AES [7] electron dose predictions for energies greater inner magnetosphere radiation pop-ulations. The dose models than 5 MeV following the March event. Here we use the are dose rate averages in grids of L and B/Bo. A software CRRES dose data to make statistical dose models for three program (CRRESRAD), developed for the models, allows the periods, before and after the March storm, separately, and Lf-ýýcalculation of dose behind 4 shielding thicknesses for any over the entire CRRES mission. We then use these models to satellite orbit. In the active period, dose acquired in a calculate the dose that would be received in various satellite circular, low-inclination orbit in the "slot region* is greater orbits behind four thicknesses of shielding. We show that, in than in the quiet period by up to two orders of magnitude, selected orbits, the dose can increase by more than two orders making this region, heretofore thought ...

Identification of an unexpected space radiation hazard

“…The dramatic increase in radiation dose is described by 10 Gussenhoven et al [4]. The injection event was completely unexpected and may have been a unique occurrence in magni-10 tude during 35 years of space research.…”

Demonstration and science experiment (DSX) space weather experiment (SWx)

“…In contrast, the AFRL model covers 1MeV to 100MeV range for protons in MEO region and covers 0.5 MeV to 6.6MeV for electrons in both MEO and GEO regions. Radiation doses rates were calculated from the NASA and AFRL models [9,10,11] to compare the range of differences. The dose rates, as seen behind 0.23 inches of an Al shielding layer, was calculated using the AFRL's CRRES and NASA's AE-8 and AP-9 models, noting that NASA models were run under quiet solar conditions.…”

The Radiation Environment Impacting DSX Orbit Options

“…To compare radiation doses for the study orbit the CRRESRAD model was used Kerns and Gussenhoven, 1992;Hilmer, 2001). CRRESRAD was constructed from dosimeter measurements made aboard the CRRES satellite (Jul 1990-Oct 1991 and, similar to the CRRESPRO model, is divided into quiet/active models representing data taken before/after the great geomagnetic storm of March 1991 which formed a new radiation belt within the slot region.…”