Results from Estonian Satellite’s Solar Cell Degradation in LEO and Implications for ISRU Lunar Solar Cell Technologies
- Paper ID
103167
- DOI
- author
- company
Tallinn University of Technology
- country
Estonia
- year
2025
- abstract
The TTU100 Hämarik CubeSat, was a student-built nanosatellite launched by Tallinn University of Technology (TalTech), orbiting Earth from September 2020 until August 2024, far exceeding its initial two-year mission lifespan. The main goals of TTU100 were to test high-speed communications and X-band Earth observation cameras, allowing the first working proofs of nationally developed remote sensing technology in the visible and infrared range, the latter of which was in the end unsuccessful. Secondary objectives were to determine the life cycle and resilience of electric and electronic components. With TalTech’s international expertise on novel solar cell technologies, a specific project was created to evaluate the degradation of the satellite's solar panels over the mission duration, based on telemetry data collected between September 2021 and January 2024. The Hämarik satellite, operating in a 500 km Sun-synchronous low Earth orbit (LEO), used AzurSpace 3G30C triple-junction GaInP/GaAs/Ge solar cells. These panels supplied power to the satellite's systems through nine solar panel arrays distributed across the cube's faces, as well as on two deployable wings. Over the years of operation, a gradual loss of solar panel efficiency was measured due to exposure to space conditions, such as temperature fluctuations, vacuum disintegration of mineral boundaries, and radiation - both solar and cosmic. The analysed data demonstrates that current degradation is the dominant factor, as voltage generated by the cells remains mostly constant throughout the mission. Both two-dimensional and three-dimensional geometric models were used to estimate the satellite's orientation relative to the Sun to correct the measured solar panel currents. The results show that the solar panels' power output has declined at varying rates depending on their location on the satellite. This discrepancy is likely due to differences in solar exposure, shielding effects from other satellite components, and panel degradation caused by cosmic radiation. The findings provide valuable feedback for future satellite missions, emphasizing the importance of solar panel orientation, shielding materials, and degradation monitoring, especially when moving into further orbits or even lunar exploration. The full abstract and presentation at the IAC 2025 will focus on the necessity of clearly outlying degradation data and offer insights into estimated efficiency decay versus orbital lifetime in comparison to data from larger arrays.