Mission-level differential drag control for formation flying of 6U CubeSats through automated management of rule-based and power-budget modes.

The operational success of inter-satellite laser link (ISL) missions in CubeSat constellations depends on the strict management of conflicting requirements: energy harvesting, high-precision payload targeting, and orbital maintenance. This paper presents an automated onboard mission logic designed to manage the relative distance of a two-satellite 6U in formation flight (ranging from 100 km to 1000 km) using differential drag as the sole propellantless maneuvering mechanism.

The main contribution is a deterministic decision-making framework based on a finite state machine (FSM) that governs transitions between eight operating modes of the ADCS. These modes, including solar tracking with fixed panels, ground station tracking, and high-precision laser pointing, are prioritized to modulate the ballistic coefficient between minimum and maximum drag while respecting mission constraints. To ensure mission feasibility, the logic incorporates experimentally derived power and consumption profiles obtained from laboratory characterization of satellite subsystems, maintaining confidentiality with respect to specific hardware components.

The proposed logic is validated using Basilisk, an open source high-fidelity simulator, incorporating gravitational perturbations and a facet-based aerodynamic model. Results from a 30-day simulation demonstrate that this drag-based differential logic can achieve relative drift greater than 400 km per month while maintaining energy balance for the laser operation. Finally, we discuss the potential of parallel learning algorithms to augment the FSM, identifying environmental clusters and predicting energy trends to further optimize deterministic transitions under realistic operational constraints.