Autonomous orbit determination of deep space probe based on the Sun line-of-sight vector

In this paper, two types of autonomous navigation method based on the Sun line-of-sight (LOS) vector are proposed for the problem of orbit determination of deep space probe. The radial velocity of the spacecraft relative to the Sun is measured by a spectrometer, and the LOS vector of the reference celestial body relative to the spacecraft is measured by the onboard camera. Then, two kinds of observation scheme, one is based on the Sun information and the other is based on the line-of-sight information, are constructed combined with the LOS vector from the spacecraft to the Sun. The fundamental of the observation schemes are analyzed and the observation equations are educed in detail. The orbit parameters of the spacecraft are estimated by utilizing extended Kalman filter. Finally, the autonomous navigation methods presented are verified by the practical data of Deep Impact mission.