The Growing Space Debris Problem

Operational and dead satellites, rocket booster stages, and fragments of fractured space hardware right down to flakes of paint moving at speeds up to 17,500 mph – that’s what constitutes ‘space debris’, which is accumulating in the Earth’s orbital space right now.

If you want a quick visual picture of the problem, log onto http://www.privateer.com. It is hosted by Privateer Space, a space debris tracking/solutions company founded by Apple co-founder Steve Wozniak, Ripcord CEO Alex Fielding, and orbital debris specialist Dr. Moriba Jah. Privateer’s rotatable Wayfinder app shows the cloud of satellites and space debris encircling the Earth. It allows users to search for specific spacecraft, and even calculates the probability of collisions through its Crow’s Nest feature.

Granted, the size and closeness of the objects in orbit are unavoidably exaggerated by Wayfinder’s scale, in order to display their moving locations on a standard computer screen. But their actual speed is visually diminished for the same reason. As YouTube space scientist Joe Scott (Answers with Joe/@joescott) explained in his video, ‘Somebody Is FINALLY Doing Something About Space Junk’, if an observer was floating in space and “the International Space Station flew past you at 17,000 miles per hour…you wouldn’t see it. You wouldn’t hear it. You wouldn’t feel a gust of wind blow off of it…Orbital speeds are ridiculous and there are tens of thousands of objects flying around at that speed.”

At this speed, “even small pieces of debris can do a lot of damage to an active satellite,” said Dr. T.S. Kelso, founder, chief scientist and CTO of CelesTrak (celestrak.org), a popular source of Earth orbital data with almost five million unique users a month. “For example, if I threw a bullet at you (about 22 mph), it might hurt a little but wouldn’t do any real damage. But if we put that in a high-power rifle at 2,237 mph, we know it can do substantial damage. That’s because the energy goes up as the square of the velocity.”

If this same bullet was a piece of space debris, it would be traveling much, much faster. “Objects in low-Earth orbit (LEO) go about 17,000 mph, so they have about 56 times as much energy as a high-power rifle bullet and in a head-on collision would have 225 times as much,” Dr. Kelso said. “If large objects collide, they can produce tens of thousands of pieces of debris bullet-size or larger.”

Such collisions have already occurred. Most of them have been unintentional, although some have been caused deliberately as a result of anti-satellite (ASAT) missile tests. For instance, the “Chinese FengYun-1C engagement in January 2007 (where a Chinese ASAT attacked its defunct Fengyun-1C weather satellite) alone increased the trackable space object population by 25%,” said esa.int, the website of the European Space Agency.

To date, “there have been more than 640 confirmed fragmentation events since the beginning of space history,” said Luc Piguet. He is CEO and co-founder of ClearSpace. It has been selected by the European Space Agency to test debris-clearing autonomous spacecraft in orbit by 2025.

“When two objects collide, they produce thousands of new pieces of debris, and these pieces also risk colliding with other objects, producing more and more pieces of debris in a cascading effect,” Piguet explained. “This is called the ‘Kessler Syndrome’. It is named for American scientist Dr. Donald J. Kessler who first raised awareness about this problematic interaction. According to the Kessler Syndrome if nothing is done, a few collisions will suffice to multiply exponentially the number of debris in orbit. It will increase the threats on current space infrastructure and make future space exploration and operation difficult or even impossible.”

Editor’s note: Dr. Kessler first raised this idea in his 1978 paper “Collision Frequency of Artificial Satellites: The Creation of a Debris Belt”, which was published in the Journal of Geophysical Research.

Too Much Space Debris

Just how serious is the current state of space debris? “There are currently around 36,500 debris objects greater than 10 cm (4 inches) in orbit, including failed satellites and used rocket bodies, in addition to approximately 7,500 live satellites,” answered Piguet. “On average, 74 new derelict objects are added to space each year, all of which orbit uncontrollably at 28,000 km/h. If not removed, these objects pose a risk of fragmentation through collisions or explosions.”

Notice that Luc Piguet makes his statement about space debris that is larger in size than 10 cm. Remove this limit, and “NASA estimates report there may be as many as 100 million pieces of debris larger than a millimeter, though many are too small to track from earth,” said Dr. Danielle Wood, assistant professor (joint) of aeronautics and astronautics at MIT.

To make matters worse, “these objects are not communicating anything to the ground, they’re just objects orbiting the Earth,” she said. Despite the efforts of ground-based space tracking systems, “we can’t see them, but we know they’re there because they often hit something and provide evidence of their presence.”

If this number remained stable, then at least the state of space debris would not be getting worse. But this isn’t the case. “In 2022 alone, there were 2,163 objects launched into space from around the world — that’s more than 2010-2016 combined,” said Marshall Smith. He is vice president of Exploration for Voyager Space (voyagerspace.com), a developer of commercial space stations. “This shows great momentum for the overall space economy, but also means the potential for more space debris and junk,” Smith said. “This also means we are at a critical juncture where we need to mitigate the issue now before it becomes too late.”

Many of these objects were Low Earth Orbit (LEO) communications satellite constellations, like the thousands of LEOs being launched by SpaceX for the Starlink internet broadband system. This being said, “SpaceX satellites are propulsively deorbited within weeks of their end-of-mission-life,” said the company in a February 22, 2022 posting at https://www.spacex.com/updates. “We reserve enough propellant to deorbit from our operational altitude, and it takes roughly four weeks to deorbit.”

Unfortunately, not all satellite operators are following SpaceX’s example. As a result, “with 7,500 satellites in orbit, growing 30% per year in the past four years, Earth orbits are now congested with more than 1,000,000 dangerous pieces of debris, between 1-10cm,” said Saloua Moutaoufik, public relations officer with Share My Space (www.sharemyspace.space), a provider of orbital/space surveillance data. “Only about 3% of these are tracked, which means that all the satellites are threatened by many untracked objects. The decreasing cost to access space is a major driver of the worsening situation.”

The bottom line: “If the problem of space debris is not properly addressed it could have serious and irreversible implications for future space activities,” said Kevin Stadnyk, CEO of Obruta Space Solutions (www.obruta.com), a start-up focused on developing ‘sustainable’ spacecraft, satellite servicing and space debris removal. “The risk of collisions with debris objects will only increase as more debris objects are created or added with future launches. Such collisions could result in the loss of critical space infrastructure, disruption of space missions and increased danger to astronauts in orbit.”

This dire outcome includes the formation of debris clouds due to the Kessler Syndrome becoming reality, Stadnyk warned. “If the amount of space debris in orbit becomes too high, it could limit the ability of countries and private companies to launch new satellites or conduct space missions which will have significant economic implications,” he said. “With this in mind, it is essential that we address the space debris problem to ensure the safety and sustainability of space activities for future generations.”

How We Got Here, or ‘The Tragedy of the Commons’

The reason humanity is faced with an ever-increasing space debris problem is due to a human behavior made plain in the ‘Tragedy of the Commons’.

Centuries ago, rural villages would have unsupervised shared pastures — ‘commons’ — where anyone could graze their animals. Unfortunately, these pastures inevitably ended up being overgrazed as villagers added more and more animals to the land with no thought to its limits and ability to regenerate. Eventually, the commons were so overgrazed that they couldn’t support any livestock, and this shared resource was lost to everyone

This destructive consumption of unregulated shared resources recurs so frequently in history that it has become a well-known metaphor for human short-sightedness and selfishness. “The whole idea of the Tragedy of the Commons is that there’s a finite resource, and what happens when you have participants making decisions and utilizing the resource without any sort of coordination and planning,” said Dr. Jah, an associate professor of Aerospace Engineering and Engineering Mechanics at The University of Texas at Austin where he is the holder of the Mrs. Pearlie Dashiell Henderson Centennial Fellowship in Engineering. He is the director for Computational Astronautical Sciences and Technologies (CAST), a group within the Oden Institute for Computational Engineering and Sciences as well as the lead for the Space Security and Safety Program at the Robert Strauss Center for International Security and Law and a space debris expert. “Eventually the resource’s capabilities reach the saturation point and it is unable to continue to provide.”

The growing space debris problem and the increasing dangers it poses to space-based activities is a classic Tragedy of the Commons conundrum. “With space, because these orbital highways are finite, there’s only so much carrying capacity that these orbits have,” Dr. Jah said. “By populating these orbits without coordination and planning by different participants who are making decisions, without knowing the decision-making criteria of others, we will eventually saturate this carrying capacity. Then these orbits will become unusable to provide the services and capabilities that we currently depend upon.”

So how did we get here? Answer: By humanity blithely viewing space as an endlessly infinite region where we could lob up any spacecraft into orbit without fear of it interacting with anything else.

So pervasive is this human prejudice, that it formed the basis of the opening joke in Douglas Adams’ wildly-popular novel, ‘The Hitchhiker’s Guide to the Galaxy’. “Space is big. Really big,” said this book’s opening lines. “You just won’t believe how vastly hugely mind-bogglingly big it is. I mean, you may think it’s a long way down the road to the chemist [in U.S. terms, the local pharmacy], but that’s just peanuts to space.”

It’s this kind of thinking that has guided humanity’s use of space since the first satellite, the USSR’s Sputnik 1, achieved Earth orbit on October 4, 1957. “In the early days of the space era, most countries felt safe launching rockets and operating satellites under the ‘big sky’ concept,” said Vince Hoffman, radar program manager with Lockheed Martin Rotary & Mission Systems. Its Space Fence ground-based radar system (officially designated AN/FSY-3) is being used to find and track objects as small as a marble in low Earth orbit. “According to the theory, space was so vast that one more satellite in orbit had little or no chance of colliding with another,” Hoffman said.

Thousands of satellites and other spacecraft have been launched since then, and many of them remain in orbit today. Sputnik 1 isn’t one of them. Aerodynamic drag caused it to deorbit on January 4, 1958. But other old-timers are still up there, decades after they died. The grandfather of them all is Vanguard 1, the world’s first solar-powered satellite, which was launched from Cape Canaveral on March 17, 1958. “Vanguard 1 was the second U.S. satellite in orbit, following Explorer 1, and remains the oldest artificial object orbiting Earth to this day,” said NASA.gov.

So here’s the problem: Space itself may be infinite, at least as far as we ‘know’. But orbital space around the Earth definitely isn’t, even though many nations and private space companies behave as if it is.

That’s how we got here.

Tech and Thought-Based Strategies Among Possible Solutions

Now that humanity is faced with a growing space debris problem that puts our continued use of orbital space at risk, many conscientious minds in academic, business and government are seeking solutions to this problem.

The answers being pursued include technology and thought-based strategies.

Tech Solutions to Space Debris

One promising technological approach to reducing space debris could be described as ‘garbage collection’. This is where companies such as ClearSpace and Voyager Space come to the fore. “For ClearSpace, the most promising solution is a servicer satellite — a space robot — that will reach the client debris object, inspect it, maneuver around it and capture it using robotic arms,” said Piguet. “It will then lower its altitude and let it disintegrate in the atmosphere.”

To use an automotive metaphor, “we believe that the major piece of the puzzle is to integrate a tow truck service into space operations,” he told ATR. “Space traffic has increased dramatically in the past ten years, but there is still no service available to remove old satellites and rocket bodies. To develop those services, ClearSpace is supported by the European Space Agency, which has commissioned the ClearSpace-1 mission for 2025. The mission will demonstrate the feasibility and effectiveness of space debris removal technologies, paving the way for future missions to remove larger and more complex debris from orbit.”

ClearSpace isn’t alone in its efforts.“Voyager Space is on the forefront of developing systems that can attach and deorbit larger pieces of space junk and debris,” said Smith. “Through the use of Altius’ DogTags grapple fixtures, which are commercially available, universal grappling points are built into satellites to support a variety of grappling approaches, including mechanical, magnetic and electrostatic grappling. They serve a unique purpose of helping preemptively mitigate the growing space debris problem by making it easier to deorbit or relocate defunct satellites.”

Of course, one way to slow the increase in space debris is to find ways to keep existing satellites in service longer – such as extending their ability to maneuver and stay ‘on station’ in orbit. Since fuel is the limiting factor in this regard, building satellites that can be refueled in orbit, and finding ways to attach ‘boosting rockets’ to those that cannot, could extend their lifespans and thus reduce the need to send up replacements over time.

This is why satellite refueling has been pursued by NASA under its Robotic Refueling Mission (RRM), a multi-phased project being conducted at the International Space Station (ISS). A case in point: The October 19-22, 2020 RRM3 mission used the ISS’ Dextre robotic arm to connect “an 11-foot long hose to a designated cryogen port while simultaneously using an inspection tool to verify the hose connection,” said NASA.gov. “RRM3 supplied the hose and robotic tools of a future servicer spacecraft, as well as a piping system representing that of a satellite in need of fueling.”

One company with a practical approach to in-orbit refueling is Orbit Fab (orbitfab.com). This company has developed a Rapidly Attachable Fluid Transfer Interface (RAFTI) for inclusion in new satellites under construction. “RAFTI is an open license TRL 7 cooperative docking and refueling interface that replaces your existing fill and drain valve to enable on-orbit and ground fueling,” said orbitfab.com

Here’s how it works: Once a satellite has been equipped with a RAFTI prior to flight and is now in orbit, it can be refueled by one of Orbit Fab’s flying tankers. “Our fuel shuttles deliver fuel directly to your RAFTI-equipped spacecraft — anytime, any orbit, any spacecraft,” said orbitfab.com.

Orbit Fab’s first spacecraft, Tanker-001 Tenzing, was launched on a SpaceX Falcon 9 rocket on June 30th 2021. This mission tested fuel storage tanks, fueling ports, thrusters, rendezvous and docking systems, and other key technologies to enable in-space refueling. Tanker-001 Tenzing is now in a sun-synchronous orbit and is carrying high-test peroxide (HTP) fuel.

By 2025, the company hopes to support RAFTI-equipped geosynchronous satellites with 100 kg Hydrazine deliveries at a cost of $20 million each. “Our technology roadmap includes traditional chemical propellants like Hydrazine, electric propulsion fuels like Xenon and Krypton, and ‘green’ propellants like HTP,” said James Bultitude, Orbit Fab’s CTO, in an August 30, 2022 news release.

This being said, these tech solutions are ‘fixes’ for the space debris problem, rather than specific solutions that prevent space debris from happening in the first place.

To make such prevention possible, “Every new object launched to LEO should have a realistic method for recovery, relocation, or a way to deorbit, in order to begin to control the proliferation of space debris,” Smith said. But that’s not all: “The industry needs some regulation and to adopt tools that currently exist to aid in the removal and deorbit of items that have ceased to function or are no longer needed in space,” he observed. “There’s also the vast amount of space debris that has already been generated in space that needs to be continually tracked and eventually removed. However, we are hopeful that if government and industry works together, we can slow the rate at which additional space debris is generated and eventually start to remove debris, making space a safer place to work and conduct business.”

Thought-Based Solutions

This brings us to the second overarching solution to space debris: Thought-based strategies such as the development of best practices for responsible use of orbital space, regulatory requirements, government-funded research, official certification of companies who use space responsibly, and international treaties. Just as they already do in areas such as air traffic control, national governments and their satellite industries (users, builders, launchers, servicers and trackers) need to cooperatively regulate/manage the ‘Commons’ of Earth orbital space to address this issue on a unified global basis, because this is a unitary global problem.

As unpopular as such a notion will be to many ‘free enterprise’-centric business people and like-minded politicians, such global coordination is a must. This is because a Tragedy of the Commons is unfolding in Earth’s orbital space right now — and getting harder to solve the longer it is allowed to continue.

The good news is that countries such as the United States are starting to take such steps. For instance, “the FCC has begun to mandate deorbiting provisions in its U.S. satellite licenses,” said Douglas Loverro, president of Loverro Consulting. “So are LEO companies such as Starlink, OneWeb and Project Kuiper. “They are going ahead and planning the deorbit of their satellites at the end of life, which is something, by the way, that Iridium never did.”

That’s not all: “The U.S. government has a National Space Council chaired by the U.S. Vice President with representatives from our government agencies who are concerned with space, and they’re reviewing these kinds of issues and eagerly checking to see what needs to be improved to make the space debris issue better,” said Dr. Wood. “Across multiple federal administrations, there have been policy documents highlighting how important it is to address space debris and to provide research funding for it, and the fact that it needs to be addressed more. The U.S. Space Force is also playing a key role because they have excellent sensors to track objects in space, and so they have, by default, become a key player in actually making announcements about [when] two satellites hitting each other or a satellite getting hit by debris.”

For his part, Loverro would like to see the U.S.’ efforts match those of the European Union. “The EU is funding some work to actually remove debris,” he said. “They may even become a regular paying client for those commercial companies who plan to remove space debris from orbit, but that’s not 100% certain yet.”

Loverro also wants governments “to start creating norms about debris removal from space,” he said. “In fact, Dr. John Plumb, the assistant secretary of defense for space policy was just on the stage out here at the National Space Symposium saying we lack progress on norms and space. He was talking a lot about the defense side of it, but this is just as much needed in the commercial space sector.”

MIT’s Dr. Wood and Privateer’s Dr. Jah are part of a team that is helping to develop a Space Sustainability Rating (SSR) for spacecraft and rockets. Launched by the World Economic Forum in 2016, “The Space Sustainability Rating is a tiered scoring system that takes a series of metrics based on models previously published by agencies and academic institutes that serve to quantify and measure sustainability decisions taken by operators,” said the SSR initiative’s website at spacesustainabilityrating.org. It is driven by “our desire to work collaboratively with all space actors to help reduce the risk of space debris, on-orbit collisions and unsustainable space operations.”

Under the nonprofit SSR process, companies voluntarily pay 10,000 Swiss Francs (about U.S.$11,275) to have their space vehicles rated for their levels of sustainability, “following a checklist of items that we developed, which are items that should help reduce production of debris or collisions,” said Dr. Wood. “It has to do with how they share data, how they respond to collision avoidance requests, how easy their space vehicles are to operate and observe from the Earth and how they handle end-of-life management.”

Having an SSR can be helpful to governments and space companies in many ways, said the SSR’s website. “Public concern about the state of the orbital environment is increasing, and the Space Sustainability Rating (SSR) offers an independent, transparent and data-driven solution to tackle the proliferation of space debris,” it advised. “Performing an SSR rating provides your organization with the most accurate assessment of where your mission stands on sustainability, and which adjustments can be made to gradually and durably enhance its scorecard. It also offers an impactful tool of reference to publicly and transparently communicate on your organization’s space sustainability and debris mitigation efforts to investors, insurers and the general public.”

These are just some of the thought-based approaches to reducing current space debris and preventing more of it in the future. For instance, “Guidelines which aim to limit the creation of new space debris objects and reduce the risk of collisions between large objects in orbit are being developed to encourage responsible design and operation of space missions,” said Stadnyk. “Over 50 companies and government organizations are developing missions to actively remove space debris from orbit using methods such as capturing debris objects with nets, harpoons, or robotic arms in order to deorbit them. Monitoring solutions are being implemented to improve space situational awareness and track the location of objects in orbit more accurately. This includes the development of both ground-based and space-based sensors to track the movement of all space objects. Lastly, there are also many efforts to raise public awareness about space debris and encourage governments and companies to adhere to responsible space behavior.”

Still, given the need to coordinate space debris removal/prevention on a global scale, the idea of an internationally-ratified approach to this problem — in other words, a Space Debris Treaty — seems unavoidable. Given the uneven track record of the world’s fractious national governments on similarly vital global issues, achieving this kind of agreement will not be easy. But it can be done, as has been proven by the 1987 Montreal Protocol on Substances That Deplete the Ozone Layer that has phased out the use of chlorofluorocarbons (CFCs).

If and when such a global space debris treaty conference comes to pass, Dr. Jah recommends including delegates from indigenous communities who have lived sustainably with their environments for centuries. “I define sustainability as humanity’s ability to use a resource in perpetuity,” he said. “Many indigenous populations accept that they are living in an existential crisis, and the only way through it is to have a successful conversation with the environment or else they don’t make it. So what I’m proposing is that governments listen to the voices of their indigenous populations and invite these folks to the table. After all, the Aborigines have a history of 60,000 years of surviving in very harsh environments in Australia.”

Dr. Jah describes his approach to this problem as ‘TEK solutions to space debris’. “TEK is Traditional Ecological Knowledge and the basis of my inspiration for space environmentalism,” he explained. “TEK tenets regard all things as being interconnected and embracing stewardship (attunement) as a path to achieve sustainability.”

Time for an Attitude Adjustment

Beyond all of the options outlined above for mitigating space debris, the one that likely matters most — and that can be implemented right now at no cost — is to stop treating orbital space as an infinite resource. Because it isn’t.

“We need to change our attitudes about space being a ‘big place’ and essentially using it as another dumping ground,” concluded Dr. Kelso. “Earth orbit is just like any environment humans operate in — such as the land, sea and air. All can be polluted by not thinking ahead and it is far more difficult and costly to clean up than it is to prevent the pollution in the first place. If the problem of space debris is not properly managed, it is possible that it will impede the use of Earth orbit, particularly for human missions.”