Lightweight Thermal Control of Spaceborne Focal Plane Arrays via a Flexible Graphite Thermal Strap Integrated with Phase Change Material

For the thermal stabilization of spaceborne focal plane arrays (FPAs) under high‐power pulsed loads, a phase change material‐integrated graphite thermal strap (PCM–GTS) is proposed as a lightweight passive thermal‐control solution. The design combines flexible pyrolytic graphite sheets (PGSs) with a graphitized carbon foam‐supported PCM composite encapsulated in a thin‐walled aluminum shell. Microstructural characterization indicates favorable infiltration and interfacial contact between n‐hexadecane and the porous carbon skeleton, resulting in a high composite latent heat of 157 kJ kg −1 and enhanced effective heat‐spreading capability. Thermal performance was evaluated through coupled finite‐element simulations and system‐level thermal‐vacuum (TVAC) testing under a deep‐space‐like radiative sink below 100 K. The findings indicate that under a 35 W pulsed load applied for 600 s, the PCM–GTS effectively suppresses transient temperature rise near the PCM phase‐transition range (approximately 18 °C) and reduces the peak temperature rise by 39.2% relative to an isovolumetric copper baseline. The simulations agreed well with the experimental data, with a root mean square error (RMSE) of 0.68 °C. In addition, the proposed architecture achieves an 81.4% mass reduction (0.384 vs. 2.065 kg), demonstrating its potential as a lightweight thermal‐management solution for precision instruments subject to strict mass and volume constraints.