Spacecraft Thermal Analysis
Calculate equilibrium temperatures, evaluate hot/cold case scenarios, and analyze power balance for any orbit and surface configuration.
Orbit Configuration
LEO
Inclined
Sun angle to orbital plane
Spacecraft Configuration
Total outer surface area of spacecraft
Total waste heat from electronics and payloads
Cold-biased (emits more than absorbs)
Key Constants
Power Balance Breakdown
Orbit-average heat inputs and radiation output
Heat Inputs
Heat Output
Temperature Limits Check
Thermal Control Techniques
Surface Coatings
Paints and surface treatments to control alpha/epsilon ratios. White paints reflect solar energy; black coatings maximize radiation.
MLI Blankets
Multi-layer insulation using alternating reflective films and spacers. Reduces radiative and conductive heat transfer by 10-100x.
Heat Pipes
Sealed tubes with working fluid that transfers heat via evaporation/condensation. Effective over short to medium distances.
Radiators
High-emissivity panels that reject waste heat to space via radiation. Sized based on worst-case hot dissipation.
Heaters
Electric resistance heaters (patch, cartridge, or strip) to maintain minimum temperatures during eclipse or cold cases.
Louvers
Bi-metallic or motor-driven blades that vary effective emissivity. Open to radiate heat, close to retain it. Turndown ratio 6:1.
Heat Pumps
Mechanically pumped fluid loops for high-power thermal transport. Used when heat pipes cannot reach radiator locations.
Cryocoolers
Mechanical refrigeration for IR detectors, focal planes, or superconducting devices. Pulse tube or Stirling cycle.
Design Guidance
- • If the cold case is too cold: add heaters, reduce radiator area, or use MLI to insulate
- • If the hot case is too hot: increase radiator area, use OSR/white paint coatings, or add louvers
- • Low α/ε ratio (e.g. OSR, white paint) keeps spacecraft cooler
- • High α/ε ratio (e.g. bare aluminum, gold) keeps spacecraft warmer
- • MLI minimizes both absorption and emission -- used to decouple surfaces from the thermal environment
Assumptions and Limitations
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.