Mission pointing optimisation of twin satellite system for all-sky burst monitoring

Abstract

Currently, with the continuous enrichment of astronomical observation means (Ligo/Virgo for GW, Parkes, Arecibo and Green Bank Telescope for FRB, IceCube for neutrino observatory, etc…), multi-messenger observation has become one of the hot spots in current astronomical research. X /γ ray observation is one of the important means of multi-messenger observation. Considering the scarcity and preciseness of multi-messenger sources, a special all-sky x/γ-ray monitor is needed to monitor high-energy electromagnetic counterparts in real time. Considering the launch cost, it is an economical and efficient solution that launch low-orbit twin satellites to realize all day monitoring. Due to the constraints of x/γ-ray payload, high-energy payloads generally need to work in low attitude and low inclination orbit (to reduce the interference caused by high-energy particles, and in order to achieve all-day monitoring, the satellite attitude needs to ensure that payload pointing outside earth in real time. The satellite pointing should take into account both the payload pointing constrains and energy acquisition, as well as the operation of thermal control and STR. Different from the sun-synchronous orbit satellite, the satellite attitude needs to be specially designed. This paper presents a satellite pointing law suitable for all-sky monitor low orbit satellite. And the advantages of this pointing law are compared from the perspectives of constrains satisfaction, energy acquisition and economy. Then on this basis, implementation method, error analysis and on-orbit performance are given.