GRBBeta Undergoes a Trial by Fire

The Slovak satellite of the Technical University of Košice, GRBBeta, launched into orbit on July 9 by the new European Ariane 6 rocket, is currently facing demanding conditions. Due to its specific orbital path with an inclination of 62 degrees, the satellite entered a nine-day phase on Sunday, October 27, 2024, during which it is continuously illuminated by sunlight and does not pass into Earth’s shadow. This phenomenon results from the satellite’s orbit being nearly aligned with the terminator line (the boundary between the sunlit and shadowed parts of Earth), and at its altitude of 580 km, the Sun never dips below the horizon.

Since the operators responsible for the satellite’s functionality had not previously encountered such a situation, they were unable to predict exactly how the satellite would behave under these conditions. There was a potential risk of critical overheating of key satellite components, which could jeopardize its thus-far flawless performance. To minimize the risk of uneven heating, the satellite was spun up using reaction wheels just before entering this phase. Additionally, several subsystems were deactivated to reduce power consumption, leaving only those necessary to keep the satellite functioning properly active.

In the days leading up to this phase, as the satellite was only passing through Earth's shadow for a few minutes each day, temperatures within the satellite began to rise to record levels. None of the operators could predict whether or at what maximum temperature levels might stabilize. One of the most critical components is the satellite’s power supply unit, where battery damage is a potential risk. By the second day (Monday, October 28, 2024), temperature readings reached critical levels but fortunately stabilized just a few degrees below the upper safety limit.

Another critical component is the solar panels, which are directly exposed to sunlight. Here, the satellite’s rotation plays a key role. The panels, mounted on four sides of the satellite and rotating regularly in sunlight, are stable at around 30 degrees Celsius. The panel on the bottom side, which is exposed to sunlight for a longer period, reaches a maximum of 80 degrees Celsius. The construction of the satellite and the panel itself, combined with the duration of sunlight exposure, has resulted in record-setting temperature fluctuations for this solar panel, with temperatures ranging from several degrees below zero to a peak of 80°C.

At the time of writing, the satellite is about halfway through this phase. Thanks to the responsible approach taken by the operators, the temperatures of all critical systems remain within safe ranges, and the satellite is expected to endure this phase without major issues. Once this phase ends and temperatures return to “operational” levels, operators will stop the satellite’s rotation, resume standard operations, and reactivate individual experiments. The data gathered during this period may help better understand the thermal dynamics of the satellite and simplify preparations for similar periods, which are expected to occur regularly in the future.