Calculate equilibrium temperatures, evaluate hot/cold case scenarios, and analyze power balance for any orbit and surface configuration.
LEO
Inclined
Sun angle to orbital plane
Total outer surface area of spacecraft
Total waste heat from electronics and payloads
Cold-biased (emits more than absorbs)
Orbit-average heat inputs and radiation output
Paints and surface treatments to control alpha/epsilon ratios. White paints reflect solar energy; black coatings maximize radiation.
Multi-layer insulation using alternating reflective films and spacers. Reduces radiative and conductive heat transfer by 10-100x.
Sealed tubes with working fluid that transfers heat via evaporation/condensation. Effective over short to medium distances.
High-emissivity panels that reject waste heat to space via radiation. Sized based on worst-case hot dissipation.
Electric resistance heaters (patch, cartridge, or strip) to maintain minimum temperatures during eclipse or cold cases.
Bi-metallic or motor-driven blades that vary effective emissivity. Open to radiate heat, close to retain it. Turndown ratio 6:1.
Mechanically pumped fluid loops for high-power thermal transport. Used when heat pipes cannot reach radiator locations.
Mechanical refrigeration for IR detectors, focal planes, or superconducting devices. Pulse tube or Stirling cycle.
This calculator uses a simplified single-node thermal model assuming uniform temperature across the spacecraft. It models the spacecraft as a sphere for solar projection (A/4) and assumes nadir-facing geometry for Earth flux (A/2 with view factor). Real spacecraft have complex multi-node thermal networks with directional properties, transient responses, internal conduction paths, and time-varying attitudes. Results are suitable for preliminary design estimates and trade studies. For detailed thermal analysis, use specialized tools such as Thermal Desktop, ESATAN-TMS, or OpenThermal.