Last week, three small Australian satellites belonging to Curtin University’s Binar space program burned up in Earth’s atmosphere. This was always going to happen. In fact, Binar means “fireball” in the language of the Noongar, Perth’s indigenous people. When a satellite is in low Earth orbit (2,000 km or less), it undergoes orbital decay as it approaches the surface and eventually burns up.

However, these cubesats (CubeSats), known as Binar-2, 3 and 4, entered the atmosphere much earlier than originally planned. They worked for only two months, a third of the expected time. This has greatly reduced the valuable time spent on science and testing of new systems.

What is the reason for their early deaths? Our Sun has gone into overdrive, and Binary moons are not its only victims. Recent high solar activity has been an unexpected headache for satellite operators over the past few years, and it’s only getting worse.

Why is the sun so active?

Solar activity includes events such as sunspots, solar flares, and the solar wind, which is a stream of charged particles moving toward the Earth. This activity is a product of the Sun’s ever-changing magnetic field, which completely reverses itself approximately every 11 years. In the middle of this cycle solar activity is at its highest.

Although this cycle is known, specific solar activity is difficult to predict; The dynamics are complex and predicting solar activity is still in its infancy. Over the past few months, solar activity has been one and a half times higher than predicted for this point in the current cycle, called the 25th solar cycle.

Effect of space weather

Space weather is an effect on the environment that originates from outside our atmosphere (mostly from the Sun). It affects us in a variety of visible and invisible ways on Earth.

The most obvious is the presence of the aurora borealis. In the last few months, the aurora borealis has been observed much more intensely and closer to the equator than in the last two decades. This is a direct result of increased solar activity. Space weather and especially solar activity also create additional challenges for satellites and satellite operators.

Increased solar activity means more solar flares and a stronger solar wind; This results in an increased flow of charged particles that can damage or disable electrical components on satellites. This also means increased ionizing radiation, leading to increased exposure to astronauts and pilots and potential disruptions to long-range radio communications.

But for satellites in low Earth orbit, the most consistent consequence of solar activity is that extra energy is absorbed by the outer atmosphere, causing it to be thrown outwards.

As a result, all satellites located at a distance of less than 1000 km from the Earth experience a significant increase in atmospheric resistance. This is the force that disrupts their orbit and causes them to fall towards the planet’s surface. Important satellites in this region include the International Space Station and the Starlink constellation. These satellites have thrusters to counteract this effect, but such corrections can be expensive.

Low Earth orbit also hosts many university satellites such as Binar CubeSats. Cubic satellites are rarely equipped with devices that can adjust their altitude, so they are completely dependent on space weather.

What happened to Binar?

The Binar Space Program is a satellite research program based at Curtin University. It aims to deepen our understanding of the solar system and reduce barriers to working in space.

The program launched its first satellite, Binar-1, in September 2021. This occurred less than a year before the beginning of the 25th solar cycle, when solar activity was relatively low. Under these conditions, the 10 cm satellite was launched at an altitude of 420 km and operated in orbit for 364 days.

The program’s next missions were Binar-2, 3 and 4, three CubeSats of the same size. These were expected to last about six months, thanks to the additional surface area from newly installed solar panels and the projected increase in solar activity.

Instead, they only worked for two months and burned out. Although cubesat missions are relatively cheap, premature termination of the mission will always be costly. This is even more true for commercial satellites, underscoring the need for more accurate space weather forecasts. The good news is that the Sun will calm down again. Despite the current unexpectedly high solar activity, it is likely to slow down by 2026 and return to solar minimum in 2030.

Although there was no clearly defined mission objective, the Binar space program clearly demonstrated the dramatic impact of solar activity on space operations. Although it was unfortunate that Binar-2, 3, and 4 were lost prematurely, work on future missions has already begun. They are expected to be launched in much more favorable space weather.