Overview
MOVE-IIIa is a student-developed 3U CubeSat from WARR at the Technical University of Munich. Its DEDRA payload supports the investigation of orbital debris. The thermal analysis examines how the spacecraft’s structure, solar panels, internal electronics and battery respond to the environment in orbit.
The work connects a three-dimensional thermal model with available thermal-vacuum test measurements. The resulting model supports component-level temperature assessment and investigation of thermal-control options, with particular attention to the board stack and battery during cold conditions.
My Contribution
My contribution focuses on thermal modelling and simulation within the WARR MOVE team. I work on the COMSOL model and the Python workflow used to prepare test data and evaluate simulation results. I also co-authored our ESTEW 2026 presentation, bringing together the thermal analysis and results with the team.
- Developing and iterating the satellite thermal model, including conduction paths, internal radiation and orbital environmental loads.
- Preparing chamber-temperature and thermocouple data for COMSOL boundary conditions and comparisons with simulated temperatures.
- Evaluating transient temperatures of the structure, board stack, battery and external components using Python and COMSOL.
- Investigating mesh continuity, radiative surface selections and optical surface-property assumptions when results do not match the expected thermal behaviour.
- Assessing the influence of surface coatings and optical properties on the satellite’s thermal balance.
Thermal Model and Orbital Environment
The COMSOL model represents the main structural parts, solar panels, battery and electronics as thermal domains. Heat Transfer in Solids resolves conduction and thermal storage, while the radiation model represents energy exchange between exposed surfaces. Material properties and thermal connections determine how heat moves through the spacecraft.
Orbital Thermal Loads supplies the changing radiative environment from direct sunlight, Earth albedo and planetary infrared radiation. Orbit, attitude, eclipse and shadowing affect which surfaces receive these loads. These inputs feed the transient thermal calculation, alongside component heat dissipation. Repeated orbital loads can be reused while the spacecraft temperatures evolve over successive orbits.
TVAC Correlation
A separate chamber simulation uses measured TVAC temperatures to reproduce the test environment. Python processing aligns the asynchronous sensor readings and prepares the chamber-temperature history for interpolation in COMSOL. Simulated temperatures are then compared with the available thermocouple measurements at the GNSS, TOSS and S-band positions.
Simulated S-band temperatures agree with the measurements within approximately 10 K. The model does not reproduce the measured temperature spikes. Correlation is partial because internal component measurements are limited. It provides a basis for assessing the thermal model, while orbital radiation inputs and surface-property assumptions require their own checks.
Mesh and Thermal Connections
The model uses component-level meshing to balance spatial detail with computational cost. The mesh has an average element quality of 0.72 and a minimum of 0.11.
One important modelling issue was preserving heat-transfer continuity between components after mesh changes. We restored continuity using continuity pairs and reworked component geometry. Checking conduction paths alongside surface-to-surface radiation was essential to avoid interpreting disconnected components as a physical cold case.
Surface Properties and Coatings
Optical surface properties are central to the satellite’s thermal balance. Solar absorptivity determines how much incident solar energy a surface absorbs, while infrared emissivity governs its thermal radiation. Surface finishes and coatings can change these properties and therefore affect both external and internal component temperatures.
I investigate their influence through sensitivity studies and orbital simulations with surface coatings. The temperature maps and radiative heat-flux visual below show results from that model.
Findings and Limitations
The analysis highlighted a colder internal bus than expected and the need to examine battery and electronics temperatures in more detail. It also showed why model topology, heat dissipation and surface properties must be checked together before selecting a thermal-control change.
The available TVAC data constrain parts of the model, but do not establish a complete board-by-board power history or fully validate internal temperatures. The orbital results depend on operating modes, attitude, thermal contacts and optical properties. The figures document the analysis and its iterations, rather than flight-measured temperatures or a final thermal qualification.
