Week in Space Data, every Friday.
Design and validate satellite power systems: solar generation, load profiles, battery sizing, and power margins
Configure solar panel and orbit parameters
~500-800 km, dawn-dusk or noon-midnight
Total active cell area (both wings if applicable)
GaAs triple-junction: ~30%. Si cells: ~20%. Next-gen: ~35%
Size the battery for eclipse survival and cycle life
Total nameplate capacity of the battery pack
Max allowed DoD per cycle. Lower = longer life, less usable energy
Required operational lifetime for battery cycle calculation
Define power draw and duty cycle for each subsystem
Power system has positive margin. Satellite can sustain operations.
Power Generated (sunlit): P = A x eta x S x cos(theta), where A = panel area (m2), eta = cell efficiency, S = solar constant (1361 W/m2), theta = average sun incidence angle.
Orbit Average Power: P_avg = P_sunlit x (1 - eclipse_fraction). LEO satellites spend approximately 35% of each orbit in Earth's shadow. GEO satellites experience eclipse only near equinoxes (~1% annually).
Battery Energy Required: E = P_avg_load x t_eclipse. The battery must supply the average load for the full eclipse duration. Usable energy = Capacity x DoD.
Battery Cycle Life: Estimated using a simplified Li-ion degradation model. Lower depth of discharge significantly extends cycle life. At 40% DoD, typical space-grade Li-ion cells achieve 5,000-8,000 cycles.