As humanity’s ambitions in space increase, one of the biggest potential risks to to those ambitions is the dangers caused by the debris we’ve left on orbit over the first half century of space development. Since Sputnik’s launch in October of 1957, we’ve left over 18,000 pieces of debris on orbit that are larger than 10cm, and millions of pieces too small to track but big enough to destroy a satellite. One of the biggest threats comes from large satellites and more especially rocket bodies that were left on orbit during the early days of space development before countries properly realized the risks that leaving debris on orbit could pose. At last year’s IAC conference, a joint group of researchers from 11 countries published a list of the 50 most dangerous pieces of space debris on-orbit, and the vast majority of those 50 were rocket bodies, with most of them being ones launched by the now no-longer existent USSR.
Why Should We Care About Large Debris?
Derelict rocket bodies and large satellites have been known to breakup on-orbit, sometimes due to pressure vessels or batteries failing, and those explosions can create hundreds or thousands of new pieces of debris1. More importantly, derelict space objects can’t dodge, so while we can track them, there’s not much we can currently do if two school bus-sized derelict space objects are on a collision path at relative velocities several times faster than the fastest bullet2.
As Joe Carrol once put it, the best way to avoid creating “BBs” (untrackable but lethal space debris) and “hubcaps” (barely trackable lethal debris) is to get rid of the derelict school buses. If we want to see a world with multiple commercial LEO facilities, propellant depots, space settlements, and especially things like large fleets of Starship-sized spacecraft heading out to Mars or other destinations, we can’t allow the Low-Earth Orbit environment to become a shooting gallery of space debris.
What’s Standing in the Way of Solving this Problem?
Almost all of the most dangerous space debris up there was launched by governments as part of civil or military space missions. As such, it makes sense that governments should pay to clean up the environmental mess their activities created. While there are now early efforts in Europe and Japan to begin tackling Active Debris Removal of dangerous space debris launched by Europe and Japan, that still leaves most of the most dangerous pieces of space debris currently unaddressed.
As I understand it from conversations with my friends in the Space Law community3, a big part of the problem with addressing many of the most dangerous pieces of space debris is that as part of the Outer Space Treaty, which governs the actions of all major spacefaring nations, you’re not allowed to interfere with objects launched by other countries without their permission. Unlike on the oceans, there is currently no space equivalent of salvage law, or “flotsam and jetsam”. Once an object is launched by an actor within a state, that state retains responsible for those objects indefinitely. However, as I understand it, those states are only liable for damages if the object deorbits and damages something or hurts someone on the ground — if it damages something in space, holding them accountable would be really hard unless you could prove that they violated the accepted standards of care at the time they last had control of the object. So, as I understand it, most of the most dangerous space debris is owned by a country that can’t realistically pay to clean it up, can’t be deorbited by someone else without the original country’s express permission4, and space liability law won’t actually hold the owner responsible if that debris creates a ton of new debris, so they don’t have any incentive to clean things up, other than wanting to be a good citizen.
Additionally, the US government has been very reticent to fund developments in Active Debris Removal, because of the fear that adversaries might see these technologies as dual-use technology5, causing them to invest in similar technologies that could be used against the US.
Anyhow, at a World Economic Forum meeting on the topic of space debris and space traffic management, someone floated an idea for a potential way to solve these problems. I can’t remember who suggested the idea, to give proper credit, but I wanted to run with it, and try to bake it a little more6. The idea is what if we propose to clean up the most dangerous pieces of large debris via a joint international cleanup effort?
Concept for a Joint International Debris Remediation Effort
While we’re on the cusp of having the technology to solve the problem of large space object active debris removal (ADR), the policy and international relations issues are the bigger unsolved pieces of the puzzle. So the idea is, what if we find a way to jointly tackle the problem in a way that incentivizes all of the key players to act, and removes some of their bigger concerns about acting?
What I’m Proposing: A joint effort, involving at least the US and Russia, but possibly also China, Japan, and Europe, to capture and recycle7, and/or controllably dispose of the most dangerous 100-200 pieces of space debris.
Key Elements of the Concept:
- Most of the funding for the effort would need to come from the wealthier spacefaring nations. We have the wealth to do this, and stand the most to lose from inaction.
- To make it worth Russia’s while to participate, there should be a way for them to economically benefit from this effort — my suggestion would be to have them involved at least with the on-orbit recycling part of the effort. Helping them build up new and useful space economic capabilities and industries is a good incentive for cooperation. Though in theory, the funding states could maybe insist on these being joint ventures between companies in their countries and Russian companies, as a way to share in the upside.
- If China also wants to participate in this a mutually-acceptable portion of the project could be done via Chinese companies, or joint ventures with Chinese companies.
- It’s a good idea to have dissimilarly redundant RPO sensors, especially for something as dangerous as capturing and detumbling a spinning rocket stage. So, it might be possible to have both commercial-grade US and Russian (and Chinese?) RPO sensors on the vehicle, with the feeds from both of them being live streamed during RPO events for enhanced transparency8
- Having the most sensitive operations, like the RPO and detumbling/grappling efforts, lead by commercial companies in more neutral countries might also help. Companies from the US, Russia, or others could still develop technologies for use on these missions, but have them operated by someone that is as innocuous as possible to both US and Russia. Conveniently, two of the main companies working on active debris remediation are a Swiss company, Clearspace9, and the Singaporean/Japanese/US/UK/Israeli company Astroscale.
There are probably plenty of other elements here, but I wanted to get the idea out there. A joint US/Russia or US/Russia/China mission like this could be a way to break the logjam on cleaning up the space environment before the situation degrades further, while also helping greatly accelerate development in advanced on-orbit operations that could help enable not only in-space recycling, but also in-space construction and eventually asteroid mining.
What do you all think?
Jonathan Goff
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- We’re getting better at learning how to “passivate” rocket upper stages and satellites after their mission is over, to try and remove potential explosion sources by venting all pressure vessels and discharging batteries, but even so there are still occasional large body breakups by supposedly passivated space objects
- Having good Space Situational Awareness sensors that are able to track debris and accurately predict collisions, but not having a way to do anything about it reminds me of the scene from Robin Hood: Men in Tights where one of the characters says he has Robin’s back during a fight, only to let him get clobbered by multiple assailants. When Robin shouts “I thought you said you were watching my back!” the other character responds “Yeah, you just got punched there! Twice!” Funny, but not exactly helpful
- Aerospace engineers love opining on space law topics, but you should probably take anything you hear from one of us with a huge grain of salt unless you can get it verified by someone who actually has training and experience in the topic. Which I am not. But it’s hard to write an opinion piece like this without explaining my understanding of the space legal challenges. So caveat emptor.
- Which they’re supposedly reticent to give due to not wanting to risk giving away space technology secrets. And to be clear, I’m not positive that a mechanism has thoroughly been demonstrated for how liability transfers if one country interacts with another country’s space objects.
- Though to be fair, is there anything that isn’t dual-use technology at some point? You could make a spoon dual-use if you try hard enough
- Though calling it even half-baked at this point is probably overselling it
- For a great overview of some of the work being done on the concept of space recycling, you can check out this recording of a recent event held at Colorado School of Mines, with presentations and live demos by Astroscale, CisLunar Industries, NanoRacks, and Neumann Space. The concept isn’t as far out as it sounds, especially if we prime the pump on the economics by paying something for the scrapping process and allowing the scrapper to resell resulting materials
- If anything, with some of these derelict space objects, wrangling them might actually make for some nice and nailbiting TV… Some of the most dangerous debris are 8 tonne, schoolbus sized rocket bodies that are tumbling end over end every few seconds. People like watching stuff like Deadliest Catch or Ice Road Truckers, right? Imagine a series about all the technical challenges and risks of going after some of these debris objects. From the planning stages, technology development, the operations. With failures and frustrations and international competition… Ok, maybe I’m a nerd, but at least I would watch the heck out of that.
- It’s hard to get more neutral than the Swiss, am I right?
First thought is a couple of questions. Actually it was second thought after trying to figure out how to smelt it down in place and the equipment needed to do that.
Are any of the defunct rocket bodies large enough to be converted to a wet/rusty workshop? If so, how difficult would the conversion be? I’m thinking of occasionally tended things like Lunar Gee centrifuge for rodent level experiments. And things possibly too noxious for expensive manned stations.
How much of the defunct bodies have stuff that can be used almost as is with minor work? An obsolete solar panel or transmitter in place(orbit) might be more valuable than state of the art on the ground.
Further questions.
Study of the long term effects of radiation and microgravity on various materials by debris inspection?
Dim memory is that certain national obligations (debts?, treaties?) don’t go away with a regime change. Is it possible that under international law that Russia/Kazakhstan/Ukraine might still have some liability under international law?
Lots of thoughts, in no particular order:
1) If we’re going to go to the trouble of negotiating this diplomatically (and we absolutely should), folding in some operator best practices and responsibility for SSA maintenance makes sense. I don’t think that this will be particularly controversial.
2) I favor creating an international organization that can:
a) Curate SSA data and make it available.
b) Create a market where various flavors of SSA providers can bid for tasking and receive bounties for surfacing conjunction warnings.
c) Assess periodic fees on spacecraft operators for all objects placed in orbit, with some kind of grandfathering for existing objects. (Note: nations could decide to subsidize their operators’ assessments at whatever level they saw fit. But the money has to come from somewhere.)
d) Create a market for debris cleanup tasking.
3) You need a way to hold a cleanup provider harmless from a botched RPO or detumbling maneuver. There’s some irreducible minimum of risk associated with stuff like this, and we don’t want that risk to disable the market. The quid pro quo for that indemnification, though, ought to be placing all data in the public domain.
4) It’s a good point that all of this tech is dual-use. But maybe that’s OK if all of the RPO information goes public. At the very least, it kinda guarantees that everybody understands the minimum capability of their opponents’ ASAT systems. This is obviously going to be tough to negotiate.
5) The benefit to a country allowing one of its objects to be cleaned up ought to be that it’s indemnified forever from responsibility for it. That responsibility would then be transferred to the international organization that operates the public system.
6) I’d punt on the “recycling” question. Just get them deorbited. However, I’d extend salvage rights to any object transferred to the international system (see #5 above). But if the cleanup provider is going to do more than simply dispose of the object, it must “claim” the object, effectively becoming its “operator”. (In nautical terms: you’re indemnified for scuttling a hazard to navigation, but you assume responsibility if you try to tow a derelict into port.)
7) If you don’t have a fairly comprehensive agreement up front, I think you’ll wind up with a free-rider problem. For example, Russia would be happy to “sell” the US a dead booster, in exchange for it assuming responsibility for it. In steady state, though, Russia ought to be paying somebody to clean it up. Finding a formula that gives the international community access to the bad debris while ensuring that its “owners” at least pay some of the disposal costs is going to be tricky. It’ll be especially tricky for nations that would really rather spend the money elsewhere.
FWIW, I spun up an Open SSA Framework thread on NSF a while back but it didn’t get any traction. I pasted a link to this post into it, and updated my rudimentary architecture diagram to include cleanup providers.
— “At last year’s IAC conference, a joint group of researchers from 11 countries published a list of the 50 most dangerous pieces of space debris on-orbit, and the vast majority of those 50 were rocket bodies, with most of them being ones launched by the now no-longer existent USSR.”
“What I’m Proposing: A joint effort, involving at least the US and Russia,
but possibly also China, Japan, and Europe, to capture and recycle7, and/or controllably dispose of the most dangerous 100-200 pieces of space debris.”–
I am thinking of, why not have pictures of them?
So, that public can know what look like, know their trajectories, know their histories,
and know whenever they get close hitting something else.
Some people might even get overly fond of them, as some people like mass murderers- but make them famous, give them the top 100 or 200 in an accessible a web site.
In terms of using as resource, it seems the dead satellites in GEO, would more likely as
a beginning for this type of thing.
Start with GEO junk, and then later transition to dealing with LEO junk.