Three Australian CubeSats from Curtin University’s Binar Space Program recently burned up in Earth’s atmosphere after only two months in orbit one-third of their expected mission duration. Named Binar-2, 3, and 4, these satellites were intended to last around six months in low Earth orbit but met an untimely end due to unexpected solar activity. In fact, “Binar” fittingly means “fireball” in Noongar, an Indigenous Australian language.
Launched to gather scientific data and test new systems, the Binar satellites faced increased atmospheric drag caused by the Sun’s heightened activity. The Sun is currently in the peak phase of its 11-year solar cycle, known as solar cycle 25, during which solar flares, solar winds, and charged particles intensify. Recent solar indicators have shown activity more than 1.5 times higher than predicted for this cycle, creating severe challenges for satellites like the Binar CubeSats, which lack thrusters to adjust their altitude.
The heightened solar activity impacts satellite orbits by heating Earth’s outer atmosphere, causing it to expand and intensify drag on low Earth orbit satellites. Even large satellites with thrusters, like the International Space Station, require expensive orbital adjustments, while smaller university satellites like the Binar CubeSats are fully vulnerable to these forces.
Curtin University’s program, which launched its first CubeSat, Binar-1, in 2021, originally experienced lower solar activity, allowing the satellite to remain in orbit for nearly a year. However, the increased solar activity during Binar-2, 3, and 4’s mission reduced their operational lifespan drastically. With space weather forecasting still in its infancy, researchers are working toward better predictions to support such missions.
Though the early end of Binar-2, 3, and 4 is a loss, the program serves as a valuable case study in the dramatic impact of solar activity on satellite missions. Curtin University has already started preparing future missions, with hopes that a quieter solar environment by 2026 will offer more favorable conditions.