Quarter orbit maneuver using magnetorquer to maintain spacecraft angular momentum

Abstract

Abstract LAPAN-Tubsat, angular momentum is maintained by using magnetorquer in right ascension direction and gravity gradient in declination direction. Declination correction using gravity gradient in LAPAN-Tubsat only produce 1.5 °/day corrections for 5° gravity gradient. Must be noted that gravity gradient achieved by tilting the satellite, or require off-nadir attitude, this condition is not ideal for imaging mission. This paper introduces new method for angular momentum vector correction in declination direction by using magnetorquer. In this method certain coil current in y direction is set to produce magnetic torque. From previous research certain y coil current for one orbit will effectively change angular momentum’s right ascension. In this research y coil current is only set for a quarter orbits, hence torque resultant will only affect angular momentum’s declination. LAPAN-A3 satellite, 7° declination correction can be achieved by setting y coil current 30 mA for a quarter orbits or 23.5 minutes. Furthermore, by varying y coil current direction for each quarter orbit, 28° declination correction can be achieved in one full orbit. From this research can be seen that the new method is more efficient than the gravity gradient and also have advantage where the spacecraft will always in near nadir pointing.