Solar and planetary heating

Discussion

Solar and planetary heating play a critical role in determining the thermal environment of spacecraft throughout a mission. These external heat sources vary with orbit, altitude, orientation, and environmental conditions and must be accurately modeled to predict on-orbit and near-planet thermal behavior.

Simcenter 3D Space Systems Thermal provides several simulation objects to model solar and planetary heating effects. Solar heating accounts for collimated solar flux incident on spacecraft surfaces and can include atmospheric attenuation, diffuse sky radiation, and ground reflection. These effects are particularly important for objects located on or near a planet’s surface, where atmospheric and ground interactions influence the absorbed heat flux.

In low-altitude orbits, additional heating can occur due to interactions with rarefied atmospheric particles. This effect is modeled using the Free Molecular Heating simulation object, which accounts for heat generated by collisions between the spacecraft and low-density gas molecules.

Ground radiation and atmospheric effects can be explicitly modeled to improve accuracy. Diffuse sky radiation and reflected ground radiation are computed using environmental parameters, view factors, and shadowing. For higher-fidelity analyses, the planet or ground surface can be explicitly meshed to capture geometric effects on radiation and shadowing.

Model orientation is a key factor in solar and planetary heating. Orientation can be defined relative to the Earth or another celestial body, or by using Sun Planet Vectors to specify time-varying positions of the Sun and planet with respect to the model coordinate system. These definitions control illumination conditions over time and enable accurate modeling of day–night cycles and seasonal effects.

Radiative heating from solar, infrared, or spectrally defined sources is modeled using the Radiative Heating simulation object. Ray tracing is automatically used to account for specular reflections and transmissions, while secondary diffuse reflections are computed using view factors from the Radiation simulation object. Local refinement of radiation accuracy can be achieved using Radiative Element Subdivision without increasing computational cost for the entire model.

Together, these capabilities allow you to model solar and planetary heating effects across a wide range of mission scenarios, from ground-based exposure to complex orbital environments.

Hands-on material

To gain experience with the topics discussed here, complete the following:

• Analyze diurnal heating of a rover
• Apply boundary conditions and solve a satellite model

Further learning