Solar weather is dropping satellites out of their orbits, and this is going to get worse

The obscurity of the sun, whose activity will continue to increase until 2025, represents a real threat to certain satellites.

For months now, the space weather has been particularly turbulent. According to the ESA, it is so bad that it has a significant impact on certain satellites, which only begin to fall out of their orbits. And according to the agency, the situation is likely to get worse in the short and medium term.

In general, all objects in the Earth’s lower orbit tend to lose altitude over time. This is the result of friction with a few air particles still present in the very upper atmosphere. This is a well-known phenomenon (we talk about orbital collapse) that engineers know how to respond without too many problems. Very briefly, you need to give a little boost to a certain point in the orbit to correct what you need to do.

However, the company has seen a strange dynamic in its SWARM swarm: some machines have started to dive at alarming speeds. In recent years, satellites have been “sinking” around 2 km per year. But between December 2021 and April 2022 this rate has increased significantly; Compared to a year ago, it now coincides with a decrease in height 20 km per year, According to the project director interviewed by Space.com.

Solar wind, a plague for satellites

And you don’t have to look far to identify the source of this phenomenon; The culprit is no one else, our sun itself. In fact, the latter regularly emits charged particles in favor of the solar flare (we speak of plasma). And as a result solar wind plays a very important role in the mobility of satellites in Earth orbit.

The Earth’s magnetic field and the interaction between these particles can disrupt the atmosphere. The exact details of the incident remain quite mysterious. But the researchers were able to experimentally observe that the lower, denser layers of the atmosphere, once bombarded with plasma, tend to increase temporarily.

NASA Goddard Space Flight Center

This increases the resistance to the movement of the satellite, much like a cyclist with an increasingly powerful headwind. The result: it loses momentum and, by extension, height. It is this phenomenon that is the source of the dramatic collapse of ESA’s SWARM. During severe solar storms, they can sometimes fall too fast when researchers are modifying their course.

The activity of the sun is increasing visibly

It is no coincidence that this dynamic has accelerated in recent months. Effective, The intensity of this solar wind Directly dependent Magnetic field activity The stars are estimated by calculating it The number of sun spots.

This activity varies according to the 11-year cycle. And the current cycle has started very recently. Officially, the sun has entered this new phase in December 2019. And since then, we’ve seen a Grow very fast The number of sun spots and the corresponding geomagnetic storms.

The latter already has some perceptible influence on the earth; We remember, for example, a few radio blackouts recorded over the Easter weekend (see our article). But most of all, that means there are very few satellites in orbit It is much more difficult to maintain an effective trajectory in this situation.

And unfortunately, this situation seems to be over. In fact, we are only at the beginning of this 25th solar cycle (these have been counted since 1755). And yet, it has already become much more intense than researchers expected.

If we look at the detailed graph of these predictions, we can see that the number of sunspots today At almost the expected level at the top of the cycle activity – Although it is not supposed to happen before 2025.

Our star recently entered the 25th solar cycle. The red line predicts the sunspot number and the purple line represents the actual calculation. © NOAA

Fear of dramatic events

Another problem is that this increasing activity significantly increases the likelihood of the Earth experiencing a major geomagnetic storm. In this case, the main risk is no longer even the downfall of the satellite; This is the survival of on-board electronics which is questionable.

Indeed, a particularly intense solar flame can easily engulf a large portion of the world’s electrical infrastructure (see our article). And as they evolve at the border – or completely outside – of the magnetic field that protects the Earth, these satellites will then find themselves. Specially exposed. All this refers to the ground communication network.

Anxious situation in the middle of a space race

Engineers have therefore been warned: they must make significant efforts to ensure the survival of their devices in low orbits. And there is no question of taking this warning of the sun lightly, especially since time is far from ideal.

No one was spared, we are now a New space race. And it’s not just SpaceX’s huge rockets that are making progress; The number of satellites is also increasing at an indicative rate. Among them, however, we find a whole bunch of cubesats, satellites perfectly adapted to this new commercial philosophy of space; They are ridiculously small, cheap, and carry only minimal.

সরকার Government of Canada

For this reason, many of them have chosen Switch completely from propellant. These satellites are therefore small high-tech boxes that are placed in orbit, then left to protect themselves. They Unable to modify their own orbits If they deviate.

So far, these crafts have been able to benefit from favorable space weather; The beginnings of this new space crowd have really coincided with a very quiet time in solar activity. But the closer we get to the peak of 2025, the more complicated the situation will become, especially for cubesats without thrusters.

Can art be complacent and underestimate the effects of the sun? The future will tell. But while this dynamic is worrisome, its impact must also be worthy. This situation is of concern only for instruments in very low orbits which, at the boundary of the Earth’s atmosphere, evolve about 150 km. More remote machines like SpaceX’s Starlink, which is parked at an altitude of 550 km, should be avoided.

The proliferation of debris in Earth orbit raises fears of a Kessler syndrome type scene. J Spacejunk3D

But as the situation normalizes, there is still good news in this story. Because only satellites are not affected by solar wind. This is also the case with the numerous debris that contaminates Earth’s orbit.

In concrete terms, this solar storm contributes so much Clear the orbit. And this is great news, knowing that the accumulation of this waste is the most significant threat to space conquest on a large scale.

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