Space Sweepers

December 4, 2024 5:55 AM

Global Push for Cooperation as Space Traffic Crowds Earth Orbit - "More than 14,000 satellites including some 3,500 inactive surround the globe in low Earth orbit, showed data from U.S.-based Slingshot Aerospace. Alongside those are about 120 million pieces of debris from launches, collisions and wear-and-tear of which only a few thousand are large enough to track." (/. ;)

"There's no time to lose on space traffic coordination. With so many objects being launched into space, we have to do everything we can to ensure space safety, and that means facilitating the sharing of information between operators, be they public or private, in order to avoid collisions," said panel co-chair Aarti Holla-Maini, director of the United Nations Office for Outer Space Affairs.

Low Earth orbit must remain safe to prevent costly disruption to the technology behind global communication, navigation and scientific exploration, she said.

Yet there is no centralised system that all space-faring nations can leverage and even persuading them to use such a system has many obstacles. Whereas some countries are willing to share data, others fear compromising security, particularly as satellites are often dual-use and include defence purposes. Moreover, enterprises are keen to guard commercial secrets.[1]

In the meantime, the mess multiplies. A Chinese rocket stage exploded in August, adding thousands of fragments of debris to low Earth orbit. In June, a defunct Russian satellite exploded, scattering thousands of shards which forced astronauts on the International Space Station to take shelter for an hour.[2]

Low Earth orbit is the region most congested with human-made objects as it offers a balance between cost and proximity, making it a prime target for the rapidly growing commercial space sector. It has also seen a 17% rise in close approaches per satellite over the past year, Slingshot data showed.

Projections point to tens of thousands more satellites entering orbit in the coming years. The potential financial risk of collisions is likely to be $556 million over five years, based on a modelled scenario with a 3.13% annual collision probability and $111 million in yearly damages, said Montreal-based NorthStar Earth & Space.

"We are at a critical point with respect to putting regulations and structure in space to monitor and manage the growing congestion. With Starlink launching thousands of satellites per year, China and others preparing to follow, we will soon push the bearing capacity of prime orbits," said NorthStar CEO Stewart Bain.[3,4]

World's First Selfie From Space! - "But you'll notice, I didn't say you need to worry about crashing into other satellites orbiting in space. This might come as a surprise if you've ever seen this picture that accurately represents the number of satellites and other objects currently orbiting our planet because it looks really, really crowded. The problem is those satellites aren't drawn to scale just as the airplanes and this representation of daily flights across the United States aren't drawn to scale."

SATGUS doesn't even need thrusters to avoid another satellite because the chances of a collision happening are so incredibly low. In fact, if you calculate based off volume of usable space occupied in orbit in a given day, space is 1 million times less crowded with satellites than our skies are with airplanes.

And then think about how rare it is to ever see even two airplanes close to each other in the sky. So space is 1 million times less crowded than that. Just to be sure though, as humans, we actively track all 44,000 satellites and objects orbiting earth that are larger than a baseball. And there's international rules now, if you put a satellite up in orbit, it needs to burn up and disintegrate after a few years.[5]

Bigger Little Questions - "I'm Lt. Col. Mia Walsh and I'm the Commander of the 18th Space Control Squadron... We think that they're probably more like a half a million, close to half a million objects in space."

Kessler:[6] At the beginning of the space program there was the general attitude that space was a big sky. That you could put anything in it that you wanted and not fill it up. The problem that you quickly run into... If we don't change the way we operate in space, all this results in exponentially increasing amount of debris until all objects are reduced to a cloud of orbiting fragments that are capable of discarding any spacecraft that attempts to operate anywhere within that cloud.

Latif Nasser: Which would mean no satellites, no weather satellites, no GPS, no any other kinds of satellites. And then in the future if things go really badly, uh, you know, we'd just be stuck here forever and ever on Earth.[7]

previously: The Kessler Syndrome and Space Junk!

posted by kliuless (13 comments total)

The number of small rapid satellite launchers being funded these days implies that in future engagements, militaries will be pumping replacement satellites into orbit to replace mass attrition. The physics gets ugly fast.
posted by nickggully at 6:09 AM on December 4 [4 favorites]

Kessler syndrome is the ultimate externality.

Put one piece of shit into orbit and it will eventually break apart into millions of pieces of shit that will be more than happy to help fragment other pieces of shit into millions of pieces of shit.

It's the perfect physics takedown for corporate malfeasance.
posted by seanmpuckett at 6:22 AM on December 4 [6 favorites]

I just read a really freaky piece about this, shared on Mastodon by James Gleick, who I know to be a serious science writer.

In short, the Kessler Syndrome describes a scenario in which space pollution impacts result in the generation of even more debris, which leads to more collisions. Kessler basically determined that once “a critical population density of objects” in space is reached, collisions among this debris will increase the overall population of dangerous objects, regardless of whether more objects are added via new launches.
[...]
Just recently, a team of scientists recalculated Kessler’s probabilities of a sizeable event happening based on the volume and nature of space launches since the 1990s. Their conclusions are disturbing.

Assuming the current launch rate going forward of around 1,500 satellites per year, the researchers estimate that the “critical population density” turning point will occur around 2050. By that year, a catastrophic event in low earth orbit becomes inevitable—if one has not already happened. The timeline shortens if launches increase in number.
[...]
Because of its reliance on information provided by satellites, the global economy would screech to a halt. People would not be able to withdraw money, and global supply chains would freeze. The electronic economy’s vascular system is pumped by the global satellite network.

Okay, so that sounds like a bad outcome for everyone, in the relatively near term. So we need to be de-orbiting satellites, right?

But then I also follow Prof Sam Lawler on Mastodon. And she's shared some links showing that de-orbiting satellites and allowing them to burn up on re-entry releases a lot of metallic vapor into the upper atmosphere, where you would not historically find metals. These metal compounds can chemically react with ozone, once again damaging the ozone layer. Another recent study suggested the increased electrical conductivity this might impart to the upper atmosphere could even decrease the Earth's magnetic field.

These are maybe just worst case scenarios, but they seem plausible enough that personally, even as a big space nerd who has worked in the aerospace industry for most of my career, I think it might be worth a moritorium on unecessary launches until we better understand these risks.
posted by OnceUponATime at 7:36 AM on December 4 [4 favorites]

Astroscale is another company in this space, they have a reasonably plausible concept for deorbit. Went to a talk recently where their CTO got grilled by an entire university astronautics department and held up pretty well. Limitations of the technology include that they need access to blueprints and a reasonably intact defunct satellite to recover - this is not a trawler.
On the regulatory front, they're also pushing for US and European satellites to have a planned deorbit time of 5 years after end of usable life (currently 25, down from 'who cares when they come down' (link is a joke) in the early days), and I know people who are working on low-weight propulsion for that.
The problem exists and is big but we do have the power to stop it getting worse.
Stopping launches altogether until the somewhat nebulous deadline of 'until we better understand these risks' is currently not a realistic option, because satellites do have a limited useful life (and expire and get deorbited and replaced on a planned schedule) and a lot of modern technology does hinge on having satellite data available, so loss of coverage would have significant impact on ordinary people on the ground.
FWIW, I'm currently working on more environmentally-friendly satellite main propulsion, so 'what happens when the satellite deorbits' is a good angle to consider, thanks for adding that, OnceUponATime!
posted by ngaiotonga at 7:44 AM on December 4 [2 favorites]

"Stopping launches altogether" isn't the same as "moritorium on unecessary launches" though. Obviously a lot depends on how you define "unecessary," but I mainly mean Starlink and other private commercial fleets, satellites whose main reason to exist to make someone money.

It's great that Astroscale has concept for de-orbiting satellites, but if you read my comment again, you'll see that the risks involved in de-orbiting are exactly the poorly understood risks I am talking about. As far as I know there's only been a single study about this magnetic field risk. Our magnetic field is what prevents all life on earth from getting fried by radiation from space, so even if there's a very small probability of us weakening it in the near term... the impact would be so catastrophic that we need more than one study before we accept really ANY risk.

I believe that the literal "impacts" of solid pieces of de-orbited space junk are a well understood risk -- they can hit like bombs, so people have been figuring out how and where they are likely to hit for a long time. That's probably the risk that Astroscale got grilled about, and the one I'd expect they have good answers to.

But this magnetic field thing? Or the ozone layer damage? Nobody was even thinking about those problems until very recently, when the number of launches started climbing so steeply. We're very much doing a "shoot first, ask questions later" thing with this mass scale up of satellite launches. I think maybe we should ask the questions first, for once.
posted by OnceUponATime at 7:58 AM on December 4 [2 favorites]

For some reason I genuinely thought there was some international cooperation on orbit tracking. Like spy satellites, sure, but there's no central database of the commercial stuff? Wow.

It does seem like clearing it out is going to become a profitable enterprise, SKY Perfect JSAT is planning a laser ablation deorbiting platform for example. It also definitely seems like satellite materials are going to be the next CFCs.
posted by lucidium at 8:47 AM on December 4

The vast, vast majority of global data is going over fiber. A tremendous amount of what we now think of as "GPS" is data from cell towers and access points. Hardly anyone even uses it for TV at this point. The biggest impact of losing satellites would probably be felt at sea. We aren't nearly as dependent on satellites as we were a couple of decades ago.
posted by phooky at 9:13 AM on December 4

The biggest impact of losing satellites would probably be felt at sea.

Doubly so without the ability to do meteorological forecasts to even remotely the same degree, without weather satellites.

You may not see the ways they're used day to day, but satellites are pretty important to a lot stuff we take for granted around us.
posted by Dysk at 9:21 AM on December 4 [3 favorites]

Phooky, can you provide some links to support those claims? I'm particularly skeptical about the GPS one.
posted by OnceUponATime at 9:21 AM on December 4

Answer: it’s complicated. Short answer is that GPS breaking would still destroy a LOT. Plus, you’re not always around three terrestrial radio sources, which is the minimum required to pinpoint you inside even a several kilometer distance.

But GPS sats wouldn’t be at high risk any time soon for space junk. They orbit at ~20,000km, whereas the heaviest congestion we are producing will be in LEO between 150km - 1000km. You can still launch and maintain satellites at orbits sufficiently removed from the one you fouled up, as far as my understanding of Kessler Syndrome goes.
posted by Room 101 at 10:11 AM on December 4 [2 favorites]

"Hardly anyone even uses it for TV at this point."

I'm skeptical of this too. True, most people don't have satellite dishes on their roofs. But any time you are streaming live TV or getting a signal over the air from your local station? I think the station you are watching is getting that signal by satellite. NBC sends out a satellite feed of the Monday night football game to all the stations in its network, and your local NBC affiliate relays that to you via your antenna or your internet connection.

Re: GPS... cell phone towers can tell you a little bit about your location, but are not precise enough for turn-by-turn guidance. The military has been investing in "GPS denied navigation" technologies for a long time (this is actually the field I worked in until very recently) but errors tend to accumulate, so that the uncertainty in your actual location increases as time goes on. There is still no really good replacement for GPS over long timescales.

That link I quoted from above, quoting a Ted talk by an aerospace engineering professor, does claim that "The most immediate sign to the public would be the sudden failure of broadcast TV. Not long after, travelers and operators would notice that their GPS no longer worked. Air Traffic Controllers would have to quickly start grounding airplanes while trying to safely land those already airborne. While complicated, this could possibly be done without incident as most airliners have other systems to assist in guiding them, but it would at least cause significant chaos."
posted by OnceUponATime at 10:13 AM on December 4

Just to clarify -- that's a quote about "all satellites" being destroyed. I shared it to support my claim that we do in fact rely on satellites for TV and navigation, along with a bunch of other stuff which is crucial to the global financial system.

But I think Room 101 is right that Kessler syndrome is only an immediate threat to low earth orbit so the GPS satellites are probably safe from that for now. (Though not from being deliberately destroyed, of course, which the thing militaries tend to worry about.) Losing all the low earth orbit satellites would still be really bad, though.

So that's about the scope of the Kessler syndrome problem, which is about satellites and their debris destroying each other in low earth orbit.

Then there are these separate problems with de-orbiting satellites from anywhere by burning them up in the atmosphere. We are just starting to understand the effects of that on our atmosphere, and they don't look good. So that's not necessarily a solution to Kessler syndrome, and also we should be careful how many satellites we put up in any orbit, if we think they're eventually going to come back down through the atmosphere.
posted by OnceUponATime at 10:32 AM on December 4 [1 favorite]

Very timely considering the ceo of the communication company that owns a significant number of the satellites entering LEO and the ceo of the company making money from the launches of those satellites is shortly going to be in charge of increasing efficiency of the US government which is barely disguised code for eliminating regulation and firing all the people who write, interpret and enforce any remaining regulations. I'm sure we can depend on the USA to lead the way to mitigate the looming problem due to said CEO's well known leadership style of reasoned, careful, conservative decisions that account for all externalities and keeps in the forefront the interests of all stakeholders.
posted by Mitheral at 1:54 PM on December 4 [1 favorite]