Distance-keeping strategies for SAMSON

Space Autonomous Mission for Swarming and Geolocation with Nano-satellites (SAMSON) is a new satellite mission, led by the Distributed Space Systems Lab at the Technion - Israel Institute of Technology. SAMSON will include three nanosatellites, built based on the CubeSat standard. The mission is planned for at least one year, and has two main goals: (i) Demonstrate long-term autonomous cluster flight of multiple satellites, and (ii) Determine the position of a radiating electromagnetic terrestrial source based on time difference of arrival and/or frequency difference of arrival. In this paper, the cluster flight control strategy for SAMSON is discussed. This strategy performs cooperative maneuvers upon necessity, when any inter-satellite distance reaches either the upper or lower bound. The maneuvers are conceived to avoid that the secular component of the inter-satellite distances exceed the prescribed distance bounds. To compute the maneuvers, a logic scheme is first applied, which establishes constraints on the differential mean semimajor axes to provide desired post-maneuver behavior. Then, a Lyapunov based control law steers the mean semimajor axis, eccentricity and inclination, to hold the aforementioned constraints. The considered actuators are constant-thrust-magnitude thrusters. Simulations for 1 year are shown, validating the potential implementability of the proposed algorithm on-board the SAMSON satellites.