Using only two magnetorquers to de-tumble a 2U CubeSAT

A CubeSAT is a small satellite on the order of 10 cm along each axis. A 1U satellite is a small cube with 10 cm sides. A 2U CubeSAT has the volume of two single 1U satellites. The size of the satellite is 10 x 10 x 20 cm. These satellites are used for a variety of missions and created by a variety of different organizations. When deployed from a rocket, a CubeSAT may obtain a large angular velocity which must be reduced before most science missions or communications can take place. Maximizing solar energy charging also involves better pointing accuracy. To control the attitude of these small satellites, thrusters, reaction wheels or magnetorquers are used. On a standard CubeSAT, 3 reaction wheels are used as well as 3 magnetorquers. In the initial phase of the CubeSAT mission, the magnetorquers are used to reduce the angular velocity of the satellite down to a manageable level. Once the norm of the angular velocity is low enough, the reaction wheels can spin up reducing the angular velocity to zero. This paper derives a simple control scheme that allows the performance of the de-tumbling maneuver to decline while reducing the number magnetorquers by 1. Thus, the de-tumbling maneuver is completed using 2 magnetorquers rather than 3. This reduces complexity of the satellite, saves weight and reduces energy consumed by the satellite which can be used for other power hungry devices. Published by Elsevier Ltd on behalf of COSPAR.