Dose Measured On-Board INTEGRAL After More Than 12 Years in Space

The INTEGRAL satellite was launched on October 17, 2002 and all on-board instruments are still operating successfully after more than 12 years, which represents more than a full solar cycle. This paper deals with the dose measured by 8 RadFETs mounted in 2 electronic boxes, which control the detector plane of the IBIS/ISGRI camera. These measurements are compared to what could be predicted before the launch, by using the dose profile, as determined by common space environment software, and also a detailed sectorial analysis of shielding materials around the RadFETs by means of a Monte-Carlo based model of the whole spacecraft. In this study, the sectorial analysis relies on the accurate knowledge of the geometry, as determined from the qualification model of the electronic box still in the lab. In order to take into account the orbit evolution with time, the dose profile is determined with yearly-averaged orbital parameters for each of the 12 years of measurements. The aim of this analysis is to estimate the possibility of releasing some margins for future projects.