Last May, a massive solar flare generated a massive geomagnetic storm near Earth. The event produced spectacular auroras across the globe…and wreaked havoc in orbit. According to a pre-publication study from MIT spotted by Space.comthousands of satellites had to perform trajectory correction maneuvers to compensate for the effects of the phenomenon. A report reminds us of how much humanity will benefit from monitoring solar weather like a hawk.
When a magnetic field line breaks on the surface of our star, it produces a burst of extremely intense X-rays and gamma rays. This is called a solar flare, and these are sometimes associated with a coronal mass ejection—a large bubble of plasma traveling at very high speeds. When these phenomena head toward our planet, it is subjected to a veritable deluge of high-energy radiation. This is bad news for all satellites, since electronic components do not mix well with these charged particles. But not all devices are in the same boat.
Unprecedented satellite migration
The other problem is that these rays are absorbed by the upper layers of the atmosphere. In extreme cases, this transfer of energy is so great that it can significantly heat the ionosphere and thermosphere, which has the effect of increasing the volume of the densest gases. And this is very annoying for satellites positioned in orbits relatively close to the surface; This expansion can significantly increase their friction with the atmosphere, which manifests itself by a progressive loss of altitude.
This is exactly what happened last May when the atmosphere was pummeled by a G5 solar flare. Thousands of satellites in low Earth orbit had their trajectories significantly altered, and began to plunge slowly but surely toward Earth. This forced operators to react relatively quickly to preserve their vehicles by correcting their trajectories. For a few days, we witnessed a mass migration in orbit.
A risk of orbital pile-up
The latest news is that no satellites have been lost. So we had a lucky escape, because according to the authors of the study, this frenzy could have led to unprecedented chaos. Typically, every move a satellite makes is planned in advance, to ensure that each maneuver can be carried out safely.
But that wasn’t the case in this episode that took everyone by surprise. Some of the craft could have collided. To top it all off, these impacts would have created clouds of hypersonic debris that could have threatened other satellites that were rapidly raising their orbits. And so on, with potentially catastrophic consequences for the countless services that depend on these craft.
Such a chain reaction is statistically very unlikely — but not impossible. In fact, the risk has increased significantly in the space of a few years. The last flare of this magnitude was in 2003, at a time when only a few hundred satellites shared the entire low orbit. But the landscape has changed radically since then. The orbit has started to get crowded faster and faster with the emergence of private aerospace, and in particular SpaceX. The firm alone has already deployed plus de 6200 satellites StarlinkIn total, there are now nearly 10,000 vehicles in low Earth orbit.
This explosion in traffic requires operators to be more vigilant than ever to avoid collisions… but in the rush, all these protocols seem to have collapsed.
« The geomagnetic storm of May 2024 was the first major storm of this new era in which low Earth orbit is dominated by small commercial satellites. By inflicting large and unpredictable perturbations on satellite trajectories, it posed a serious challenge to the tracking infrastructure. This combination of factors made it very difficult, if not impossible, to identify potential crossings during the storm and in the days that followed. ” write the authors of the study.
An edifying reminder
The good news is that there are some very clear lessons to be learned from these findings. First, space agencies and companies are going to have to find a way to coordinate better. Perhaps that means establishing a global emergency protocol so that all operators can safely relocate their spacecraft in the event of an even bigger solar flare.
The other priority will be to strengthen our ability to anticipate the whims of the Sun. This is an exercise that is notoriously complex and risky. But the stakes are now so high that the prediction of Solar weather is no longer an option: it is now a major economic and logistical imperative.
Fortunately, the big names in aerospace are fully aware of this and are starting to tackle the problem head on. For example, last May, ESA signed a €340 million contract with Airbus’ Defence and Space division to build Vigil, a sentinel satellite that will help humanity anticipate the vagaries of solar weather.
It is expected in 2031, a few years before the next peak in the Sun’s activity cycle where these events are much more frequent and intense. All that remains is to cross our fingers that the armada of satellites we depend on every day will hold out until then!
Source: www.journaldugeek.com
