Passive Solar Tracking for Space Applications Using Shape Memory Alloy-Based Thermal Actuation

Efficient solar energy capture is critical for spacecraft constrained by limited mass, power, and volume. Conventional solar tracking systems improve panel alignment but rely on gimbals, motors, and control electronics, which add weight, consume power continuously, and reduce reliability through mechanical complexity. This work presents a passive solar tracking system that employs Shape Memory Alloy (SMA) actuators to autonomously reorient spacecraft solar panels without electrical input or feedback control. The proposed design embeds Nitinol springs within the panel support structure, where selective solar heating induces thermally driven actuation. This temperature-responsive mechanism dynamically adjusts panel orientation to maximize incident solar flux, offering a lightweight, low-power, and mechanically robust alternative to motorized trackers. Prototype testing demonstrates meaningful angular displacement under simulated orbital heating, highlighting the potential of SMA-based systems to extend spacecraft lifetime and improve energy efficiency.