New Solar Flare Particle Environment Models and Titan/Centaur INU Multiple-Bit Single Event Upset Rates.
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.
Document Details
- Document Type
- Technical Report
- Publication Date
- Dec 01, 1995
- Accession Number
- ADA302779
Entities
People
- T. J. Lie
- W. A. Kolasinski
Organizations
- The Aerospace Corporation