ASAT tests may last only seconds, but the space debris they generate threatens satellites, astronauts, and the $1.8 trillion global space economy for decades to come.
On November 4, 2025, a piece of space debris collided with China’s Shenzhou-20 spacecraft. This forced China to delay the return of its three astronauts while engineers and authorities assess the damage to the craft. Although the exact nature of the strike and the extent of the damage are unknown, it is possible that the offending piece of space junk was no bigger than a few millimeters. But at orbital speeds, debris can collide with objects in space nearly ten times faster than the speed of a bullet.
The Dangers of Space Debris
What is more concerning is that there are tens of thousands of pieces of debris larger than 10 centimeters, each capable of crippling satellites or endangering crews, and there is currently no reliable way to remove them. More concerning still, many of these hazards were not the result of accidents. They were generated through deliberate anti-satellite (ASAT) tests.
On January 11, 2007, China used an ASAT weapon to destroy its aging Fengyun (FY-1C) polar-orbit weather satellite, creating a cloud of debris that persists to this day. ASAT weapons involve the deliberate destruction of satellites in orbit, often using kinetic interceptors launched from Earth. The strike was hardly unprecedented: both the United States and the Soviet Union tested ASAT systems during the Cold War. However, those strikes rarely created significant debris because they were conducted at lower altitudes.
From the Cold War to Today’s Space Race
For Washington and Moscow, ASAT tests were once part of a broader contest to prove the ability to degrade space-based capabilities. Even then, such demonstrations were uncommon. They are frowned upon in the international community, with both the United States and the United Nations (UN) calling for moratoriums on ASAT tests in recent years. ASAT weapons imperil the norm of open and free access to space, as they hold Global Positioning System (GPS), weather forecasting, geospatial intelligence, spacecraft, and other critical services in their crosshairs. By extension, they also threaten the growing $1.8 trillion space economy.
Though framed by countries as demonstrations of military capability, the consequences of ASAT tests extend far beyond the moment of impact. Apart from directly making satellites vulnerable, such weapons also generate clouds of orbital debris. This raises collision risks for operational satellites, threatens human spaceflight (as evidenced by the Shenzhou collision), and complicates space traffic management.
China’s Role in the Creation of Space Debris
In late 2022, the United Nations General Assembly adopted a resolution to ban direct-ascent ASAT tests, which are the most likely to cause significant space debris. The United States was the first country to commit to a moratorium, and the only one of the four countries that had tested ASAT weapons to do so. Shortly after Washington announced its pledge, China not-so-obliquely issued a pointed response, accusing “a certain superpower” of having conducted more ASAT tests than any other nation and having “created more space debris than any other country.”
But the data shows this claim was incorrect then and remains incorrect now.
In the case of the FY-1C, the ASAT test produced more than 3,400 individually tracked debris fragments greater than 10 centimeters (cm) in size (and countless more too small to track, but not too small to do significant damage at orbital speeds), making it the largest single debris-generating event. Two decades later, fragments from FY-1C account for nearly 23 percent of active space debris in low-earth orbit (LEO). It also accounts for over 10 percent of all orbital debris ever catalogued since 1958, including decayed debris.
The altitude of the FY-1C destruction at around 860 kilometers placed the debris in a region where orbital decay is extremely slow, often spanning hundreds of years.
Persistent Hazards in Low-Earth Orbit
As a result, most of the fragments remain in orbit, continuing to pose hazards to satellites and crewed missions in LEO. A 10-centimeter piece of debris might not seem dangerous, but at orbital velocities, its impact is equivalent to seven kilograms of trinitrotoluene (TNT) or a 550-pound object traveling at 60 miles per hour (mph) on Earth. In fact, according to the National Aeronautics and Space Administration (NASA), “orbital debris is the number one threat to spacecraft, satellites, and astronauts.”
While we can track debris objects 10 cm or larger with relatively high fidelity, it remains extremely challenging to monitor the likely many thousands of smaller pieces. Effectively invisible to governments, militaries, and companies operating in space, these fragments can still do sufficient damage to disable missions and satellites.
Evidence from Past Collisions
This threat is not hypothetical. In 1981, a Soviet-era navigational satellite, Cosmos 1275, suddenly ceased operations and fragmented. While the cause of this sudden destruction is not definitively known, it is widely suspected that Cosmos 1275 was the first casualty of orbital debris. In turn, Cosmos 1275 debris today contributes 3.15 percent of all debris (over 10cm in size) active in orbit today, and itself is a repeat offender in damaging and threatening collisions with other satellites and space missions. A few months after the FY-1C event, NASA’s Terra spacecraft had to maneuver to avoid colliding with a piece of its debris. In 2013, it was reported that a Russian satellite was impacted by debris from FY-1C, spiraling the laser-ranging retroreflector satellite out of orbit and ending its mission. In 2016, the International Space Station (ISS) was dinged by a micrometeorite-sized fragment of debris, likely a paint fleck, causing damage to the cupola.
Following Russia’s 2021 ASAT test against Cosmos 1408, the second-largest single debris-generating event, ISS astronauts were forced to find shelter within the space station and delay a planned spacewalk. And now, the Shenzhou-20 crew is unable to leave the Tiangong space station because of an orbital debris strike.
Systemic Risks to the Orbital Environment
Unlike other sources of debris, such as upper-stage breakups or fragmentation that contribute debris over time, ASAT tests tend to produce sudden, large spikes of high-velocity fragments. This makes them highly visible in the debris record and disproportionately influential in shaping the orbital environment. While ASAT capabilities pose an immediate risk to space assets, the long-term ramifications of a single test can lead to a passive, pervasive denial of access to space for all actors. In the case of FY-1C, although the aim was to destroy one satellite, the debris created by this destruction will pose a lasting risk to many other satellites.
The debris fields from ASAT events in LEO, although initially compact, eventually diffuse and can render entire orbital corridors functionally unusable. The sudden fragmentation dramatically increases collision risk across orbits and could push satellite operators into constant evasive maneuvers or abandonment of those orbits altogether. At the extreme, these events raise the specter of the Kessler syndrome, a scenario in which space becomes self-blocking through exponential debris growth.
A Call for Mitigation and Enforcement
Addressing this threat demands serious investment in debris mitigation and removal, paired with international norms to deter debris-generating activities, particularly ASAT tests. Programs like NASA’s Orbital Debris Office, the European Space Agency’s (ESA) ClearSpace-1, and Japan’s work with Astroscale’s ADRAS-J are significant early efforts in exploring this issue. Yet these primarily focus on objects such as defunct satellites or upper stages and cannot address the clouds of smaller debris in orbit. Programs like these need funding, partnerships, and strong political signaling to ensure Earth’s orbits are free and open for commercial and exploratory activities. Although these efforts represent a positive step toward reducing the risk of damage from certain types of debris created by accidents or negligence, they would be quickly and dramatically outpaced in the event of another ASAT test.
Existing norms and agreements designed to protect free movement in space (including in keeping it free of damaging space junk), such as the Outer Space Treaty, Artemis Accords, and the UN’s Space Debris Mitigation Guidelines and Long-Term Sustainability of Outer Space Activities, are largely voluntary, non-binding, and weak on enforcement. In recent years, new initiatives have sought to raise these standards, such as ESA’s Zero Debris Charter, which aims for debris neutrality, similar to carbon-neutral goals, by 2030, by promoting end-of-mission disposal and collision avoidance. But without robust verification, enforcement mechanisms, and meaningful legal or financial consequences, norms will remain insufficient to deter deliberate debris-creating actions. To truly secure Earth’s orbits for commerce and exploration, the international community must move beyond voluntary pledges towards enforceable agreements and credible penalties.
The Need for Accountability
The need for enforceable norms is not abstract. It is driven by the reality that major powers are actively developing capabilities that threaten the long-term sustainability and security of space. Chief among these is China, whose growing counterspace arsenal and record of debris-generating tests underscore the risk of leaving norm-setting weak and voluntary. Without credible international frameworks that impose costs on destructive behavior, states will face few disincentives to conduct debris-creating ASAT missions or adopt orbit-denial strategies.
ASAT weapons are not just tools of targeted destruction. They are generators of enduring, indiscriminate hazards. Once unleashed, debris clouds cannot be easily cleaned up with current technological capabilities, and their reach can span entire orbital regimes. This threatens the backbone of modern security, commerce, and scientific discovery. Preserving the shared domain of space requires recognizing that the true danger of ASAT tests lies not in the instant they occur, but in the decades of vulnerability they leave behind. Incidents like the debris strike on the Shenzhou spacecraft have happened before and are likely to continue as space activity increases, and if ASAT tests persist.
About the Authors: Kathleen Curlee and Lauren A. Kahn
Kathleen Curlee is a research analyst at the Center for Security and Emerging Technology (CSET) at Georgetown University.
Lauren A. Kahn is a senior research analyst at the Center for Security and Emerging Technology (CSET) at Georgetown University.
Image: Frame Stock Footage/Shutterstock
