Sattelite debris might start conducting electricity, disturb magnetic field (Patreon)

[This is a transcript with links to references.]

We’ve heard that space debris is bad and the problem’s getting worse, but here’s a new thing to worry about. It could interfere with the earth’s magnetic field, which is our major protection from the highly energetic particles of the solar wind.

Space debris, aka space junk or orbital debris, comes from stuff like defunct or decommissioned satellites or spent rocket stages. It already poses a significant challenge to the sustainability of space activities. And as more junk accumulates up there, the risk of collisions increases, which will spread the debris further and make it harder to track.

The potential for cascading collisions of space junk is known as the "Kessler syndrome," named after Donald Kessler, a now retired NASA scientist. Kessler pointed out already 1978 that if we put too much junk into orbit that’ll eventually reach a critical density. Then, one collision will cause a chain reaction of other collisions. And this could eventually splatter debris all over the most precious orbits, making them unusable for potentially millions of years.

The problem is becoming more and more pressing now because a lot of companies, including Elon Musk’s Space X are shooting huge amounts of satellites into Earth orbit. By some estimates we might reach 100 thousand by the end of the decade and up to a million in the decades afterwards.

Efforts to mitigate space debris so far involve a lot of guidelines about how to responsibly decommission satellites by burning them upon re-entry in the atmosphere. Indeed, the European space agency recently tested this with the Aeolus satellite. After nearly five years of collecting wind data, they guided the satellite back through the atmosphere over the Antarctic, where it burnedup as planned, and not even the penguins raised any eyebrows. Do penguins have eyebrows.

The author of the new paper now points out that, well, burning the stuff doesn’t mean it disappears, it’s just that now you’ve distributed a lot of soot and ashes and very finely powdered debris in the upper atmosphere. Some of this stuff rains down on earth, some of it lingers around in the stratosphere, and some distributes in layers further up.

Indeed, according to a recent study, about 10 percent of the small particles in the stratosphere now contain metals that almost certainly come from space debris. These particles are called re-entry aerosols. Of course it's not just satellites and rockets that burn up in the atmosphere, there are also meteors. But their chemical composition is different. Man-made stuff tends to contain more lithium, lead, aluminium, and copper.

As you might have noticed, that’s a lot of metals. And while data is hard to come by, this stuff will also accumulate in the atmosphere above the stratosphere, especially in regions called the plasmasphere, magnetosphere, and the Van Allen Belts. These are different regions, but they have in common that they trap particles. Those particles then lose electrons from solar radiation, so they become charged. And that makes them interact with the magnetic field.

The author of the new paper now says that since a lot of the space debris is metals, these new bands will by all chance conduct electricity which in return will generate its own magnetic field. You might say, oh, well but there’s already stuff up there, so it doesn’t really matter if we add something to it, but the amount of mass that we put into orbit is dramatically higher than that which gets there by natural causes

According to the paper, since the beginning of the space industry, approximately 20 thousand tons of material have been demolished during re-entry, most of which stayed up there. This mass is over 100 billion times greater than the total mass that’s estimated to be in the Van Allen Belts.

It would be bad if the magnetic field that surrounds earth were to weaken because it’s our major protection from solar wind. Solar wind is made of highly energetic charged particles, and these get mostly deflected by the magnetic field. Not only is it unhealthy if we get hit by highly energetic particles. Without a magnetic field, Earth’d probably also lose its atmosphere. Indeed, this is what scientists think happened to Mars, that it once had an atmosphere but since it has no magnetic field, that atmosphere was basically ripped away by solar wind. And as if unhealthy radiation and being unable to breathe wasn’t quite bad enough, all that solar wind would also ruin your phone.

Now, I don’t want to be alarming. The paper doesn’t say exactly what’s going to happen  because quote “After consulting multiple magnetosphere models, the consensus was that it would take decades to simulate 500,000 satellites”.  But the magnetic field of earth is not created by the atmosphere but rather by its core where liquid metal is sloshing around, so it’s not like Elon Musk is going kill us all with satellite debris. At least I don’t think so. Still it’s another example where I feel like, guys, maybe we should think about the consequences before doing it.