Autonomous Guidance and Control of VLEO Satellite Swarms

Very Low Earth Orbits are gaining momentum due to convenient launch options and to the trend to smaller platforms to be designed, manufactured and flown in a shorter time. The exploitation of VLEO often calls for missions performed by systems of platforms. The number of platforms could be large, and the swarm concept, with many similar agents acting in a cooperative way and without pre-defined roles is a valuable option. From the engineering point of view these systems shall be completely autonomous to limit at the maximum extent the need for assistance from the ground segment. This paper aims to present a tool for investigate possible autonomous guidance and control schemes for these swarms. The lifetime of the system, limited by the disrupting action of the atmospheric drag, dominant in VLEO, the number and frequency of the passages above selected target at the ground (for Earth observation missions) and the capability to collect data of interest (for scientific missions devoted to in situ measurements) are goals to be considered. A specific advantage of a swarm architecture is the limited role of each single agent, leading eventually to accept its anticipated dismissal from the system. As a preliminary step, the paper motivates the interest for VLEOs. Then, the tool is presented and qualitatively validated, and the first analyses carried on are discussed with respect to relevant findings. The aspects investigated till now deal with the effect of the poor knowledge of the atmospheric density and with the role of the navigation accuracy to feed the GNC loop. Overall, this introductory work paves the way for more advanced and detailed studies, especially with respect to the different suitable control techniques