Abstract

This paper focuses on the trajectory planning that optical satellites approach the geostationary (GEO) spacecraft and the trajectory planning that the optical satellite flies around the GEO spacecraft for continuous surveillance of the GEO spacecraft The optical satellite approaches the GEO spacecraft with continuous thrust and flies around the GEO spacecraft without thrust. The observation angles of the optical satellite to the GEO spacecraft are less than 30 degrees throughout the entire fly-around mission. Two methods are used in fly-around trajectory planning: trajectory planning based on classical orbital elements and trajectory planning based on CW equations. The advantage of trajectory planning based on classical orbital elements is that the position of the optical satellite relative to the GEO spacecraft is clear in earthcentered-inertial frame and the calculation method of fly-around orbital elements is simple. If the orbital inclination of the GEO spacecraft is less than 0.02 degrees and the semi-major axis of the elliptical relative trajectory of the fly-around formation is greater than 60 km, fly-around trajectory planning based on classical orbital elements is more efficient and easier than that based on CW equations. Optimal control theory is used in the trajectory planning for optical satellites approaching GEO spacecraft and the trajectory optimization is a two-point boundary-value problem. Simulations have proved that this method is feasible, which is highly effective in engineering. This method can be used for space situational awareness and on-orbit servicing missions of GEO spacecraft.

Highlights

  • A large number of valuable spacecraft are in the geostationary (GEO) region due to the characteristics of GEO orbit

  • Two methods are used in the fly-around trajectory planning: trajectory planning based on classical orbital elements and trajectory planning based on CW equations

  • Because of the shortcoming of CW equations, the disadvantage of trajectory planning based on CW equations is that the precision is not high if the distance between the optical satellite and the GEO spacecraft is far

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Summary

INTRODUCTION

A large number of valuable spacecraft are in the geostationary (GEO) region due to the characteristics of GEO orbit. The advantage of trajectory planning based on classical orbital elements is that: firstly, the position of the optical satellite relative to the GEO spacecraft is clear in earthcentered-inertial (ECI) frame; secondly, the calculation method of fly-around orbital elements is simple. Considering the motion of the sun relative to the GEO spacecraft, the fly-around trajectory planning is based on classical orbital elements and CW equations, respectively, and the optical satellite can keep watching the spacecraft with observation angles less than 30◦ throughout the entire fly-around mission Section III describes the trajectory planning of the optical satellite approaching the GEO spacecraft. We can calculate the trajectory of the optical satellite relative to the GEO spacecraft based on classical orbital elements or CW equations, and calculate observation angles during fly-around missions, which are presented in B and C, respectively.

FLY-AROUND TRAJECTORY PLANNING BASED ON
FLY-AROUND TRAJECTORY PLANNING BASED ON CW
SIMULATION
FLY-AROUND TRAJECTORY PLANNING BASED ON CW EQUATIONS
TRAJECTORY PLANNING OF OPTICAL SATELLITES
CONCLUSION
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