Line-of-sight pointing stability for "drifting" satellites

Explored here is the feasibility of a new attitude control approach for satellites in high altitude elliptic orbits, in order to compensate for the effect of longitudinal periodic drift relative to the ground station. A simple attitude control technique using tethers has been proposed for achieving the fixed apparent satellite orientation with respect to the ground segment of the space mission. Combining the proposed feedback tether length control law with the analytically developed open-loop control policy results in a significant improvement of the controller performance. To illustrate implementation of the proposed concept, the particular case of 24 h elliptic orbits has been considered. A high degree of satellite pointing along the drifting line-of-sight made possible even with modest tether lengths makes the concept particularly attractive.