With the rapid growth of satellite launches and commercial ventures such as Starlink and OneWeb, technological advancements have soared. But this progress comes with a challenge: the increasing threat of orbital debris. From old satellites and used rocket parts to collision fragments and even stray tools, orbital debris poses major risks to active satellites, astronaut safety and future space missions.
Given the greater likelihood of debris-related collisions, many experts say urgent action is needed to rein in debris. However, absent binding rules among nations and private satellite operators to manage debris, what’s the best way forward? Some experts suggest, at least in the short term, focusing on existing nonbinding guidelines that encourage responsible conduct in space. Then, if one can be achieved, hammer out a binding, enforceable treaty.
“Making nations understand why debris mitigation is to their benefit and making sure they have the tools to carry out those capabilities, as opposed to spending time trying to get a treaty discussion going … is frankly better time spent,” Victoria Samson, chief director for Space Security and Stability at the Secure World Foundation, told Apogee. “With Russia being Russia, it’s a challenge these days to get agreements. So, I think it would be better doing more work looking at the substance versus what type of agreement it is.”
Most space debris is found in low Earth orbit (LEO), from 100 kilometers to 2,000 kilometers above Earth’s surface, with the greatest concentration at 750 kilometers to 1,000 kilometers. Determining how much debris is whizzing through space is harder to gauge because small debris — objects less than 10 centimeters in diameter — is difficult to find and track. In the United States, public and private space agencies rely on government monitors to identify space objects. Responsibility for this labor-intensive task falls to the U.S. Space Force, which operates the Space Surveillance Network (SSN), a global system of ground-based radars, optical telescopes and space-based sensors.
The SSN currently monitors about 47,000 orbital objects, although that number constantly changes due to the proliferation of satellite constellations such as Starlink. Most of those objects are in LEO, including 10,500 active satellites, another 3,000 or so inactive ones, and space junk — from derelict rocket bodies and other large fragments caused by separation to millions of objects too small to track. Of those, the European Space Agency (ESA) estimates about 1.2 million are between 1 centimeter and 10 centimeters and another 140 million from 1 millimeter to 1 centimeter — roughly the size of a paint chip or a small screw.
This vast amount of small, untracked objects worries researchers. Among them is Jer Chyi Liou, chief scientist for orbital debris at NASA. At a 2020 conference of the International Academy of Astronautics (IAA) on space situational awareness, Liou noted that due to high impact speed in space – 10 kilometers per second in LEO — even sub-millimeter debris poses “a realistic threat” to human spaceflight and robotic missions. “Mission-end risk for most operational spacecraft is driven by small, millimeter-sized debris,” he said during the presentation.
One way to tackle the issue, he said, is to deorbit satellites after 25 years of service — the so-called 25-year rule. In modeling presented during the conference, Liou noted that, as a baseline, if no satellite operators worldwide enacted the rule, the volume of debris in LEO would soar by 330% within 200 years. By contrast, if 90% followed the rule, the increase would drop to 110% over that period.
Liou’s study also indicated that deplatforming satellites at a quicker pace produces nominal benefits. For example, if satellites are deorbited after five years, instead of 25, the volume of debris would increase by 100%, instead of 110%, over 200 years. “It’s not a statistically meaningful benefit,” he said at the time, as reported in SpaceNews. In addition, satellite operators would incur significantly higher costs under the five-year scenario.
While some scientists have challenged the 25-year rule, a number of agencies worldwide still adhere to it, among them NASA, the United Kingdom Space Agency, the United Nations Office for Outer Space Affairs (UNOOSA) and the Inter-Agency Space Debris Coordination Committee (IADC). In the United States, the Federal Communications Commission, which regulates communications satellites, takes a different position. It requires satellites to be deorbited within five years of completing their missions. The ESA backs this approach as well.
Making nations understand why debris mitigation is to their benefit and making sure they have the tools to carry out those capabilities, as opposed to spending time trying to get a treaty discussion going … is frankly better time spent. ~ Victoria Samson, chief director of space security and stability for the Secure World Foundation
Deorbiting rules are among several key debris-limiting ideas to emerge in recent years. In 2002, the IADC introduced a raft of proposals collectively known as the Space Debris Mitigation Guidelines, designed to curb debris during and after a satellite’s lifespan. The report marked a turning point in that it was the first broad-based list of recommendations — though nonbinding — to be endorsed internationally since the approval of the 1979 “Moon Agreement” creating a plan for resource management on celestial bodies and the 1975 Convention on Registration of Objects Launched into Outer Space. The source of the IADC guidelines, the 13-member IADC, includes not only NASA and a host of European civil agencies but also the China National Space Administration, the Indian Space Research Organisation and the Russian Federal Space Agency.
Building on those recommendations, UNOOSA in 2010 released its own debris-mitigation handbook, the Space Debris Mitigation Guidelines of the Committee on the Peaceful Uses of Outer Space (COPUOS). Like the IADC version, the U.N. guidelines are purely voluntary with no enforcement mechanism, and they do not strive to create a debris-removal market. Still, the U.N. guidelines are acclaimed for having gained consensus from nations and private operators worldwide — a remarkable achievement that likely wouldn’t have happened had the committee sought agreement on enforced, binding regulations.
“COPUOS is a consensus-driven organization, which means that everyone had to agree, and this included countries like the United States, Russia, Iran and China,” Samson said. “But I think there’s a difference between achieving agreement on nonlegally binding ideas versus legally binding approaches. There has not been a legally binding treaty in the United Nations regarding space since the ’70s. So, I think that is probably not going to be a helpful approach.”
In February 2025, a group of scientists from New Zealand, the U.K. and the U.S. recommended another U.N.-based, nonbinding strategy. Writing for the journal One Earth, the authors suggested that orbital debris mitigation be classified as a U.N. Sustainable Development Goal (SDG).
Adding space sustainability to the U.N.’s SDG list would establish a framework to mitigate space debris and encourage cooperation among nations, they wrote in their report, “A sustainable development goal for space: Applying lessons from marine debris to manage space debris.”
The other 17 SDGs, adopted by the U.N. in 2015, include tackling weather challenges, world hunger and poverty. Most have 15-year targets. Progress toward the goals has been spotty, amid global tensions, violent weather and fallout from COVID-19. Only about half have achieved minimal or moderate improvement, according to a 2024 U.N. assessment.
The researchers contend that because of the outsized role satellites play in daily life, it’s imperative to shield space from further debris-related risk. Seventy-seven nations now host space programs, and the domain already supports about $470 billion in human activity per year, including banking, navigation, phone communications and satellite TV. “To take just one segment of orbital activity, a failure of global positioning systems (GPS) would cause a daily loss of $6.3 billion USD to the UK economy,” the study said.
The scientists’ greatest worry is a scenario called the Kessler syndrome, in which debris-related collisions produce more debris, fueling a cycle of collisions and debris generation until large areas of LEO become unstable. “Furthermore, full Kessler syndrome does not need to occur for orbital usage to become unusable, as there will come a point where it costs too much in fuel to maneuver within an orbit to avoid collisions and maintain an operation,” the report said.
The study draws inspiration from the 14th SDG, “Life Below Water,” which focuses on stemming plastic pollution in marine environments and cleaning the oceans. Like with plastic pollution, technology exists now to limit the growth of debris in space, the report said. It makes five recommendations:
- Improvements on extended producer responsibility
- • Development and enforcement of international legislation, including fines and other incentives to ensure accountability
- Measures to incentivize companies toward innovative solutions to mitigate orbital debris
- Collective cooperation informed by science
- Introduction of SDG-18 focusing on sustainable use of Earth’s orbit through the whole life cycle of space-based platforms
Of course, with rapid growth in commercial satellite constellations comes higher risk of debris-related collisions. “I would say across every context it’s pretty dire,” study co-
author Melissa Quinn, general manager of international business at California-based space tracking and analytics company Slingshot Aerospace, told Apogee. “We’re seeing levels of debris that we’ve never seen before.”
Adding space debris mitigation to the U.N.’s SDG program, she said, would further spotlight the planet’s dependency on space and push forward more dialogue about debris mitigation strategies. Space “is part of our environment. It is deeply connected to Earth, and it’s also deeply connected to our well-being. From health care to finance to education, we’re all using space, and yet it’s something that we are just treating literally like trash,” Quinn said. “Once again, humans are making that same mistake” as with plastic pollution in the oceans.
Data from Slingshot Aerospace showed 10,828 active satellites on orbit in 2024, a 17% increase from 2023. At the same time, the number of close approaches per satellite in LEO saw a 17% year-over-year spike in 2024. Scientists have sought to curb space junk for decades. The most complicated of space debris issues — the removal of tons of small, untracked debris objects — is another matter, with many experts suggesting that the problem is virtually impossible to solve, at least in the near term. Instead, many have called for focusing on larger fragments along with mission procedures that ensure debris-limiting best practices are carried forward, from launch to the end of mission.
A recent initiative by the World Economic Forum goes a step further. In June 2022, the forum unveiled the Space Sustainability Rating (SSR) system to encourage public and private space agencies to limit debris generation. The rating was developed by a consortium that included the European Space Agency, Massachusetts Institute of Technology, the University of Texas at Austin and BryceTech, an Alexandria, Virginia-based analytics and engineering firm.
Under the system, space operations are rated bronze through platinum based on their impact to the domain, with the aim of incentivizing best practices in space. The idea is to get satellite operators to pursue long-term sustainability, or best practices in space. The Eutelsat Group, for example, achieved a platinum-level SSR, signifying responsible and innovative space operations in regard to debris. The company’s OneWeb constellation includes more than 600 satellites on orbit, plus another 37 geostationary spacecraft.
SSR policies may prove useful to developing space programs. A 2024 study published in the Journal of Space Safety Engineering touted the rating program’s benefit on a range of space operations, including those of emerging nations. The study, called “The political and legal landscape of space debris mitigation in emerging space nations,” examined multiple agencies, including the National Space Research and Development Agency of Nigeria and Geo-Informatics and Space Technology Development Agency of Thailand. The study concluded that by integrating SSR principles, “these [and other] nations can strengthen their national and regional legal and regulatory frameworks, align with international norms, and actively contribute to the global effort to ensure the long-term sustainability of outer space.”
SSR and the SDG proposal may not solve the space debris crisis, but they may help to further raise awareness of the problem and boost policies that discourage debris creation. “I think there are a few different views,” Quinn said. “I think if we continue to see the numbers go in the way that they’re going, then it’s pretty likely that we’ll see a collision, especially in low Earth orbit, and that will have high consequences to the use of that orbit.
“There are a few different kinds of paths I see, but they all tend to end in something pretty critical happening,” she added. “I’d like to think that it wouldn’t take something like that to wake everybody up to the need to sort out responsible uses of space. But I do feel and fear that a lot of the time, for humans, it does take a pretty catastrophic incident for people to wake up to what the risk and the problem is.”