Dynamics of small satellites with gravity gradient attitude control

Abstract: SWIM (Space Weather using Ion Spectrometers and Magnetometers) is a CubeSat to be launched with the purpose of studying interaction between the Sun and the Earth. A magnetometer will be placed in a boom which provides gravity gradient stabilization. SWIM will be inserted in a 600 km circular orbit and it is required to maintain a LVLH (Local Vertical Local Horizontal) position. This master thesis analyses the dynamical behavior of SWIM. For doing so an attitude simulator and a mass model have been developed. Mass model has been designed according to linear stability analysis. Simulations with the mass model have been carried out from the most ideal environment to realistic orbit. As a result it has been deduced that gravity gradient stabilization propagates initial conditions which are perturbed by aerodynamic and magnetic torques. Magnetic torques could lead to uncontrolled yaw spin. Additionally the deployment of two solar panels to guarantee passive stabilization for yaw axes has been studied. Three axes stabilization and LVLH pointing can be achieved in an orbit lower than 600 km.