Low-budget CubeSat star tracker calibration using Earth's rotation

Abstract

A low-budget calibration method for a star tracker using Earth's rotation is presented. The rotating Earth is one of the most accurate turntables in nature, as its rotation rate and axis are known precisely, thanks to astronomers. Using a precise model of the Earth's rotation and time tags, it is possible to set the attitude of a star tracker fixed on the ground so that all star measurements can be used in a fullstate estimation with only one attitude state. The proposed method needs only a GPS receiver that outputs pulse-per second signals for time synchronization, which is useful for low-budget star-tracker development in university-level CubeSat projects. The simulation results show that the proposed method outperforms the previous calibration method, which does not use the Earth's rotation, in terms of estimate covariance. An outdoor experiment demonstrated the accuracy of the star tracker calibration with low-cost hardware. (c) 2022 COSPAR. Published by Elsevier B.V. All rights reserved.