Three small satellites of Curtin UniversityIt is Binary space programdesigned to eventually burn up upon re-entry, disintegrated in Earth’s atmosphere last week. Named “Binar”, which means “ball of fire” in the Noongar language of the First Nations of Perth, these CubeSats – Binar-2, 3 and 4 – were placed in low Earth orbit (less than 2,000 km above the surface), where orbital decay gradually drags the satellites downward, leading them to burn up.
However, the Binar satellites were not expected to re-enter the Earth’s atmosphere anytime soon. Lasting only two months, or only a third of their planned operating period, this incident reflects a current trend observed recently: high solar activity. In recent years, satellite operators have faced problems related to increased solar activity.

These solar activities, which include sunspots, solar flares and the solar wind, a stream of charged particles that move toward Earth, are driven by the Sun’s magnetic field. And about every 11 years, the Sun’s magnetic field reverses, reaching peak solar activity in the middle of the cycle. Even though we are aware of this cycle, forecasting solar activities and forecasting remains complex and difficult. The current cycle, known as solar cycle 25does not behave as expected. According to reports, solar activity indicators were more than one and a half times higher than predicted for this stage of the current cycle.

This increased solar activity has also had an effect on other objects in low Earth orbit. The most obvious is the presence of auroras. In recent months, auroras have been more intense, brighter and closer to the equator than in the past two decades.
Although the premature fire of the CubeSats was the first of these incidents, the increase in solar activities also has other implications for larger satellites and satellite operators. Increased solar activity leads to more frequent solar flares and stronger solar wind, leading to a greater influx of charged particles that can damage the satellite’s electrical components. It also increases levels of ionizing radiation, increasing exposure risks for astronauts and pilots and potentially disrupting long-distance radio communications.

For satellites in low Earth orbit, the main effect of increased solar activity is the absorption of additional energy by the outer atmosphere, causing it to expand outward. This expansion causes a notable increase in atmospheric drag on satellites located less than 1,000 km away, disrupting their orbits and bringing them closer to the Earth’s surface.