Everyone knows that space is big. But, somewhat counter-intuitively, it's also crowded.
This is why NASA signed an agreement with SpaceX at the beginning of 2021 to enter a closer relationship to ensure "continued safe on-orbit operations and avoidance of conjunctions between" Starlink satellites and human missions. In low-Earth orbit (LEO), conjunctions are a pleasant way of describing a catastrophic collision of two or more objects in space.
This is necessary because we have a major problem unfolding in low-Earth orbit (LEO), one that traces a path from cutting-edge engineering to Space Race 2.0. And emerging geopolitical struggles threaten to spill into the mix amid the conflict between Russia and Ukraine — which at any moment could involve more parties.
So, apropos of everything, how do we clean up space junk?
New satellite mega-constellations are going up, and this means more space debris
The problem of space junk stretches back to the dawn of the space age. Entering into force in 1967, the U.N. Outer Space Treaty stipulates that space belongs to no single nation, but is the "province of all mankind". This goes for all signatories, including the United States, the United Kingdom, and the Russian Federation, who agreed that "outer space is not subject to national appropriation by claim of sovereignty, by means of use or occupation, or by any other means."
What this means today is "that you can't extend national jurisdiction anywhere in outer space — we retain jurisdiction of objects we put up there, but you can't have the United States claiming rights over LEO or the moon," explains Alexander Salter of the American Institute for Economic Research, to IE.
To Salter, this treaty creates an inherent problem: Since nobody has the right to stop nations or companies from installing satellites into orbit, a hidden incentive is born "to put something into orbit without considering the cost to everyone else of cluttering up space," he says. And, in the decades since its signing, this appears to be exactly what happened.
From the launch of the first satellite, Sputnik, into space in 1957 to 2019, humanity had launched "altogether around 9,000 objects into orbit," says Siamak Hesar, Founder and CEO of Kayhan Space, to IE. But, "just in the past two years, because of SpaceX and Starlink, that number has gone up to about 11,000. In the next decade, we are talking about multiple mega-constellations going into orbit; that's hundreds of thousands of satellites."
Satellites in LEO need to deorbit themselves
This is only the tip of the LEO iceberg when it comes to the abundance of space junk. But how did it get this way? Early in the 21st century, satellite launches began to pick up in frequency, but few if any anticipated it reaching the level of thousands — or tens of thousands — launched annually.
With the future of LEO satellites in the international blindspot, the rule of thumb about putting assets in orbit was for all space powers to deorbit their satellites within 25 years of launch. You read that right, the guidelines for satellites in LEO, published in 2007 by the Inter-Agency Space Debris Coordination Committee, suggest that all satellites spend no more time in space than 25 years after operations are completed — to reduce the risk of collisions, and, in turn, the generation of space debris.
However, this is a guideline, not a rule. And it "was an early attempt to establish standards or regulations for space assets," says Hesar. "It says: if you're putting a satellite in orbit, the government won't give license to launch unless you show you can deorbit after 25 years. That might have made sense back then," argues Hesar, "but today it doesn't make sense."
If the population of satellites had stayed at the levels of the early 2000s, maybe a 25-year guideline would have worked. But with SpaceX's Starlink requesting approval for the launch of another 30,000 satellites, this is no longer the case. And it's why more companies are turning to satellites that can deorbit themselves — to ensure that their mission goals — public or private — don't interfere with those of other space powers.
Satellites in GEO were retired in "graveyard orbits"
For assets in LEO, which is roughly 1,200 miles or less above the Earth, there is at least some solace in knowing that, on a long enough timeline, atmospheric drag will eventually pull everything down into deorbital destruction. But for satellites in geosynchronous orbit (GEO) — which is more than 20,000 miles higher than LEO (at 22,236 miles) — any recommendation for mitigating space debris build-up was practically non-existent.
"Up until a few years ago, when your satellite died in GEO you just left it there," explains Joseph Latrell, the founder of quub — a rapidly accelerating satellite development company — to IE. Geosynchronous orbit (GEO) is where satellites orbit the Earth while maintaining the same location (in terms of longitude) relative to the surface below. "Add 186 miles to GEO and that's where" many orbital missions leave dead satellites.
There are satellites whose missions demand GEO, like the NOAA's recently launched GOES-T, but most commercial interests in orbit will be placed firmly in LEO.
"Our satellite flew on SpaceX's Transporter-3 — the 12th set of satellites deployed by Elon Musk's firm," says Latrell. And his company's satellites are much smaller than most and fly exclusively in LEO. "The satellite we sent is what we call a 'PocketQube,'" he adds, referencing his firm's focus on developing tiny, cube-shaped satellites.
Atmospheric drag will eliminate all LEO satellites, but not fast enough
"Essentially, PocketQubes are one-eighth the volume of a CubeSat, and it's tough trying to fit everything in there," explains Latrell. CubeSats have been around since 2003, when one reached orbit atop a Russian Eurockot in June 2003. The appeal of CubeSats is multifarious: Because of their low mass and small stature, they don't take a lot of fuel to lift into orbit, and can "piggy-back" with other, larger satellites. This cuts launch costs significantly.
Latrell and his firm, quub, took this to the next level — making even smaller satellites that are 5 cm (1.96 inches) on each side. Needless to say, this cuts costs to unprecedented lows — without sacrificing mission parameters. "Our satellite was a cyber security test," he says. "We developed some software for a client to test the possibility of remotely exchanging data via satellite. It's an IoT communications system."
Any satellite in LEO will eventually fall into the atmosphere. But for this to occur fast enough to achieve meaningful sustainability (in other words, leave space uncluttered), there are many steps satellite developers can take. For example, onboard thrusters can propel the satellite into a terminal trajectory.
Building planned obsolescence into LEO satellites
"Our [first] satellite is the last we'll launch without thrusters," says Latrell. "All the next ones will have thrusters with separate computer systems." Thanks to decades of advancements, we can fit tiny computers inside drinking glass-sized containers, which enables engineers to build in planned obsolescence.
"All of our satellites are designed to be LEO, never above 310 miles," says Latrell. Indeed, if satellites rise much higher than that, they "run the risk of staying up there longer. We have planned obsolescence in our satellites. They're designed to fail when we start." But beyond adding little thrusters to tiny satellites, the makeup of satellites can also cut down on space junk.
"We avoid a lot of metal, and grow the frames for our satellites out of a carbon fiber nylon composite," says Latrell. This material will vaporize when it hits the atmosphere. "There's also aluminum and stainless steel for the screws, then carbon-fiber composite for the frames, and circuit boards — which are fiberglass and copper."
"Those don't do too well when hitting atmospheric re-entry temperatures of 3,000 degrees Fahrenheit," says Latrell. Satellite developers also often employ solar arrays for power. And, since solar panels have a wide surface area, they increase the atmospheric drag. This forces them "deeper and deeper into the atmosphere. At roughly 74 miles up, [they hit] thicker layers of the atmosphere, and at that point, there's no way for anything to survive."
But even if every private aerospace and satellite firm planned five-year obsolescence into their satellites, there's still a lot of junk to clean up.
How to retrieve and deorbit space junk
Luckily, there are multiple ways of retrieving space junk. "Static grapplers are of special interest to orbital aerospace firms," says Latrell. "With the velocities, you need to achieve orbital flight, just getting in front of the junk is difficult. And if you mess up the angles, it's going to tear right through you."
"At full orbital speed, even a tiny piece of space junk makes a huge hole," says Latrell. "Static attachment would be a light attachment point and then you grab it with something else. But there's a limit to what you can deorbit" in this way. Another method, like a mesh net, can wrap around objects in space. One could also "get in front of" space junk objects, "and just like a baseball mitt, you catch it."
"You can also use aerogel, and just embed the material, and when the gel reaches maximum capacity, you deorbit that satellite," explains Latrell. His company, quub, could likely hunt space junk objects between 4.4 and 6.6 lbs. "I'd actually just take a satellite and make it a miniature factory. When it catches the space junk, attach a small thruster on it, and let it go. The thruster fires and the object deorbits."
Latrell says that "quub can build satellites like that very cheaply." In fact, his firm is already building a miniature robot arm that could do exactly that. "You have to be patient though, because orbital mechanics requires a lot of energy."
But to clean space junk objects from LEO, we first have to find them.
Expanding space debris detection is crucial
There are roughly "9,000 objects" that humans have sent into space, according to Hesar. And this is just the beginning. "All the ancillary rocket bodies as a result of those launches," some of which are indescribably small, have "contributed to 1 million small and large space objects" in LEO.
And these are only the ones we can track. "Right now, the space surveillance network — a large network of radar telescopes — enables us to track on the order of 30,000 objects," says Hesar. And many of these objects are smaller than 4 inches. "Later this year, Space Fence," which is a much more powerful, ground-based radar, "will come online, and that will track satellites" less than an inch in diameter.
"This will allow us to see up to 100,000 objects," explains Hesar. If that seems like enough, you're sadly mistaken. "That is just 10 percent of objects that cause high-risk events" like damaging a critical satellite, or even puncturing the ISS and endangering astronauts in space.
It's not a very realistic proposition to clean up 100,000 objects in space. But, luckily, the largest objects pose the greatest general risk to the viability of LEO for future assets. "By removing a handful of those objects, we can bring down the overall risk significantly." Since large objects are like popcorn bags of tiny space junk, every inactive satellite is one accident away from firing thousands of tiny pieces of debris into LEO.
With so much potential space junk floating around in space, this raises the question: who's in charge, here?
Cooperation between private aerospace firms
"We are in an international legal situation where no single nation-state can adjudicate and resolve these disputes, explains Salter. "If a schism happens between a U.S. company and the U.S. government, that’s easy. Not so between U.S. entities and foreign governments or foreign commercial entities."
Most precedent for litigating space junk, and creating policy around it, will "probably come from contingent decisions as things go forward," says Salter. Disputes, on the other hand, will depend on the commodity. "If the commodity is valuable operating space in LEO, you're going to get more and more industry groups that are composed mainly of operators who'll adopt best practices about collecting data on what hardware is up there."
But until these disputes happen, "there's no real legal issue," explains Salter. "There has to be some agreement or claim about who owns that resource first." But eventually, it will happen. "Sooner or later, commercial claims are going to interfere with each other — at that point, once you have concrete plans that come in conflict, that's when you'll see that arbitration."
Corporations are uniquely positioned to leverage space assets
To Salter, large firms are best suited for leveraging the vast potential of space. This is because, despite rivalries between competing aerospace firms, they all have a financial incentive to create sustainable economic practices that are suited for long-term investments. "Corporate citizens in space are going to have to be responsible, because they have to make it on the long-haul, otherwise they're not going to make any money," he says.
"What I'm worried about isn't conflict in faraway colonies," says Salter. "I'm worried about a quick chain of LEO events that causes geopolitical conflict over confusion about who has the right to do what in space."
The ISS had a close call with such a chain of events, when, in November 2021, Russia executed a weapons test that generated more than 1,500 chunks of supersonic space debris — in an anti-satellite missile test (ASAT) that put not only NASA's, the ESA's, and other national space agency hardware in danger, but also human astronauts. The danger was palpable: even a Russian cosmonaut aboard ISS at the time had to take shelter as a precaution from incoming space debris.
Russia's wake-up call to the dangers of space junk
"Russia's ASAT test was a wake-up call," says Latrell, of quub. "Fortunately, nobody was hurt." Luckily, the ISS wasn't seriously damaged during the ordeal, but it illustrated the need for greater awareness among all those concerned with LEO assets. "A dramatic case where the ISS gets hits by an object we haven't tracked is very possible," says Hesar of Kayhan Space. "Last year, Canada's robotic arm that sticks outside of ISS and moves around — the insulation material of that was destroyed or punctured by a debris object that was not tracked."
"That's why it's very important for people to understand that the space environment (and LEO especially) is not an unlimited resource," stresses Hesar. "It's a tragedy of the commons — a finite resource. And the more you exploit it uncontrollably, the more you're going to damage it."
To Hesar, nations and companies need to collaborate in their efforts to track, monitor, and communicate efforts in space. It's a far more difficult task than Earth-based aviation (since there are no clear borders in space), but the best way to avoid a collision is to keep communications open. "Having in-situ tracking capabilities will help, since ground systems like radars and telescopes are only seeing the tip of the iceberg," says Hesar. "Space tracking has been under the Air Force's jurisdiction, and now the Space Force handles it — there are no really open communication systems between China, the U.S., and Russians because it's on a military level."
While China has expressed an openness to building an official line of communications, it seems corporations and civil institutions need to collaborate on building a legal framework capable of regulating the use and stewardship of LEO, and beyond. That means an integral tracking and international communications network like we've never seen before. "Being able to track objects up close, and improve solutions for hard-to-track objects" will help achieve this goal.
Planned obsolescence and recycling material are key to minimizing space junk
But to take tracking to the next level, the implementation of algorithms — A.I. software — "will help us better predict space weather and [atmospheric] drag environments — this is critical in protecting our assets," says Hesar.
Reduce, reuse, recycle - As for the satellites themselves, the two primary means of helping to clean up LEO include in-situ satellite propulsion (so they can deorbit themselves), and creating new ways of recycling the space junk and debris floating around. "We need to design into our systems ways of responsibly disposing of satellites," says Latrell. "'Reduce, reuse, recycle' is not a bad idea in space. The death of the satellite should be inherent to its design, from when the satellite is still on the dry-erase board."
"If you can't deorbit it, we need to recycle it," explains Latrell. It sounds like the major space powers of this century have a lot of work to do. But it can be done.