Optimization for Solar Angle Free Attitude Motion Model by Solar Sail IKAROS

Abstract

The world's first solar sail IKAROS (Interplanetary Kite-craft Accelerated by Radiation of the Sun) was launched along with the Venus Climate Orbiter Akatsuki in May 2010. At the time of writing, IKAROS is still the only solar sail in deep space. IKAROS was full successful of missions that have been planned for first half year. After the Venus flyby in Dec 2010, it carried out an extended mission. IKAROS has succeeded many additional engineering and scientific missions. On the orbit determination, we obtained various skills. IKAROS has been almost 8 years from launch, we have been still maintaining operation that repeating the power generation period and hibernation period cycle for 10 months and more. Even though we cannot be obtained enough observation data for orbit determination that can withstand long-term propagation over several years. But we have been successful in four times search operation, at the wake-up from the hibernation in 2012-2015. As a similar success, Rosetta has been successfully wake-up from hibernation for 31-month form June 2011 to January 2014 due to a power shortage. In that operation, the antenna pointing accuracy was not a problem at all. However, IKAROS has an area to mass ratio which is 50 times that of Rosetta, and the solar distance of IKAROS's orbit is only a fraction of Rosetta's one. So, it has been received several hundred times of Rosetta's solar radiation pressure. Therefore, we needed high precision attitude dynamic model for predicting future position of IKAROS. We have been 3 years from when we got receiving the last observation data in 2015. We studied extension of attitude motion model and optimizations for model parameter. The base of attitude motion model, was constructed using nominal phase of data and modified for the first wake up from hibernation. Then, the attitude motion model was divided 3 sections, by spin rate for search operation after 2015. And the attitude motion model parameters were estimated using one of the devised optimization method. In this paper, we present modified attitude motion model for solar angle-free and the optimized attitude motion model parameter.