Accession Number : ADA302779

Title :   New Solar Flare Particle Environment Models and Titan/Centaur INU Multiple-Bit Single Event Upset Rates.

Descriptive Note : Technical rept.,

Corporate Author : AEROSPACE CORP EL SEGUNDO CA TECHNOLOGY OPERATIONS

Personal Author(s) : Lie, T. J. ; Kolasinski, W. A.

PDF Url : ADA302779

Report Date : 01 DEC 1995

Pagination or Media Count : 39

Abstract : Recently acquired solar flare data have been used to revise particle environment models for the August 1972 and October 1989 events. The revised models are presented, together with their composite event model and the average flare model. These models are applied to calculate the rates of single and multiple bit single event upsets (SbSEUs and MbSEUs) during solar flares for the Titan/Centaur inertial navigation unit (INU) in an orbit of 26.6 deg inclination for a 6 hour geosynchronous orbit (GSO) transfer mission. Since shielding has been found to enhance immunity to solar flare SEU, the effect of the inherently present anisotropic shielding distributions was studied, including shielding by printed circuit board components. The INU's SEU requirement of a 25,000 hour mean time between failures (MTBF) is satisfied when the proton integral flux above 50 MeV falls below 30pfu (1 pfu (particle flux unit) is 1 proton/cm2/sec/steradian), which corresponds to the peak integral flux of a three times average flare. For the referred Titan/Centaur mission, we recommend that the current solar activity launch NO-GO criterion of 10 pfu be changed to 30 pfu. This change should reduce the average number of NO-GO days per year from 24 to 14.

Descriptors :   *FORECASTING, *SOLAR FLARES, *ELECTROMAGNETIC ENVIRONMENTS, PEAK VALUES, FLUX(RATE), PROTONS, ANISOTROPY, MISSIONS, PRINTED CIRCUIT BOARDS, ELECTROMAGNETIC SHIELDING, SYNCHRONOUS SATELLITES, PARTICLE FLUX, HIGH ORBIT TRAJECTORIES.

Subject Categories : Astronautics

Distribution Statement : APPROVED FOR PUBLIC RELEASE