Spacecraft Thermal Calculator

Temperature range from solar flux, albedo, and surface properties.

Orbital altitude (km)

Solar absorptance (alpha)

Thermal emittance (epsilon)

Solar projected area (m²)

Radiator area (m²)

Internal heat dissipation (W)

Eclipse fraction (0-0.5)

Tab to move between fields

Equilibrium temp (°C)

-19

Hot case temp (°C)

-1.9

Cold case temp (°C)

-75.5

Equilibrium temp (K)254.2

Total heat input (W)1,207.1

Solar heat (W)530.8

Albedo heat (W)134.9

Earth IR heat (W)341.4

Alpha/epsilon ratio0.35

Earth view factor0.85

T_fahrenheit-2.14

How to Use This Calculator

Enter orbital altitude (km) and the spacecraft's solar absorptance (α) and thermal emittance (ε) surface properties.
Set the projected solar area (m²), radiator area (m²), and internal heat dissipation (W).
Review equilibrium temperature (°C and K), hot case temperature, and cold case temperature.
Ensure all temperatures fall within the allowable operating ranges for electronics and propellant.
Adjust surface coatings (α/ε ratio) or radiator area to bring temperatures within acceptable limits.

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