Lunarsat ADCS European orbiter to the moon attitude determination and control system

LunarSat, the Lunar Academic and Research Satellite, is a micro-spacecraft that will be sent into an orbit around the Moon to perform scientific investigations concerning the lunar environment and its characteristics. However, the prime objective of the LunarSat mission is to serve as an educational and outreach project. LunarSat is designed by young engineers, scientists, and students from around Europe, with support from numerous institutions and space industry. It shall be launched as an auxiliary payload on an Ariane 5 ASAP platform and will have a mass of 100 kg in GTO. LunarSat will orbit the Moon on a highly elliptical polar orbit with its perilune above the Lunar south pole area. This orbital strategy yields the possibility to obtain images of the Lunar south pole region with a resolution never achieved before. Further measurements shall provide further evidence regarding the existence of water ice in the lunar polar craters. This paper describes the Attitude Determination and Control System (ADCS) design of the LunarSat spacecraft. The ADCS baseline shows a 3-axis stabilized satellite during all the phases of the mission. During orbital insertions, the control is achieved by off-pulsing the 4 main engines accordingly. The actuators are reaction wheels, attitude thrusters, and main engine thrusters. The attitude determination is performed through sensors, including laser gyros, sun sensor, and star sensor.