Precision formation delta-v requirments for distributed platforms in Earth orbit

Distributed spacecraft flying in formation can overcome the resolution limitations of monolithic, Earth-sensing systems. However, formation spacecraft must now expend fuel to counteract disturbances and the gravity gradients between spacecraft. We consider three different formation architectures and determine the delta-v required to maintain relative positions at accuracies ranging from 0.1 to 10 m (1 sigma). The three architectures considered are: (i) Leader/Follower, in which individual spacecraft controllers track with respect to a passive, leader spacecraft, (ii) Center of Formation, in which individual spacecraft controllers track with respect to the geometric center of the formation, and (iii) Iterated Virtual Structure, in which a formation template is fit each timestep and individual spacecraft controllers track with respect to the fitted template. We show that in the presence of relative and inertial sensor noise and disturbances (e.g., Earth oblateness and aerodynamic drag) relative positions can be maintained to the 10 m level for 4 mm/s/orbit.