Experts Call for Urgent Action on Space Debris

Humankind may lose access to orbits around Earth if it doesn't keep space clean. We need more than prevention at this point, experts warned last week at the European Space Debris Conference in Bonn, Germany: “Preventing the addition of new space debris is no longer sufficient,” said Josef Aschbacher, Director General of the European Space Agency (ESA), at an opening press conference. “We must now actively clean up the space-debris environment to halt the onset of a chain reaction that could render heavily utilized regions unusable.”

Holger Krag, who leads ESA’s Space Safety Program, had the numbers: Around 40,000 objects considered space debris — including burned-out rocket stages, retired satellites, and smaller fragments — are currently tracked by ground-based radars. Maneuvers to move active spacecraft out of harm’s way are executed on a daily basis. And there are 130 million smaller fragments that radars can’t pick up, in which case there’s no way to prevent collisions.

When collisions happen, they produce even more debris: A millimeter-size object traveling at a few thousand kilometers per hour hit a solar panel on ESA’s Sentinel A satellite in 2016. The collision didn’t destroy the spacecraft, but it released fragments large enough that they’re now among those tracked by radar. “Some of them have already triggered collision warnings on other satellites,” Krag said.

While most debris circles Earth at low altitudes of a few hundred to a few thousand kilometers, even the Moon and its environment is starting to become affected. While the debris there isn’t yet a big problem for future missions, it shows that attitudes haven’t changed much, Carolin Frueh (Purdue University) reports. The relatively clean environment near the Moon “would have provided a chance to avoid the tragedy happening near Earth”, she says. “Unfortunately, we’re repeating the same mistakes here, too.”

Space debris has been around for decades. What’s changed in recent times is that space is becoming more crowded as private, large-scale satellite “megaconstellations” are installed to provide global broadband internet. With this additional space traffic, large-scale collisions between active satellites are becoming more probable. Krag accounts a near miss between a Starlink satellite (launched by SpaceX) and ESA’s Aeolus Earth observatory in 2019: “This happened a few years back but was actually a template for what we [now] see every day.” 

Since the incident, Starlink’s satellites have grown in number, from less than 70 to more than 7,100. Competitors have been busy, too. Any day now, Amazon is due to launch the first batch of its Project Kuiper network, which will contain more than 3,000 satellites. China, too, is advancing two of its own projects, requiring more than 1,000 launches. According to critics, this will leave mid-level orbits littered with discarded rocket stages. Experts estimate that up to 100,000 satellites and their associated trash might swirl around Earth within a decade.

Without guidelines and procedures, catastrophe may only be a question of time, Krag fears. “There are no flight rules,” he says. “At the moment [satellite-avoidance maneuvers] are manual tasks in which operators have to get in touch and agree on what to do.” Imagine civil aviation without air traffic control: Pilots would fly at will, avoiding others based on ad hoc decisions and sometimes at the very last moment.

Just one such collision in space would be enough to create a large, expanding cloud of debris, triggering a cascade of secondary impacts until certain orbits are too polluted to be considered safe. Only at altitudes around 400 kilometers (250 miles) can atmospheric drag slow debris down, making it fall back within a few years to burn up in Earth’s atmosphere. Higher up, debris won’t drop out of orbit for decades, centuries, or even millennia. American astronomer Donald J. Kesser first described this scenario back in 1978. Today it might be closer to reality than ever before.

Urgent Solutions: Regulations and Removal

Rules and regulations should therefore be implemented quickly, experts at the conference agreed, to define how operators should maneuver their spacecraft to avoid collisions, how to deorbit satellites at the end of their useful life, and how to avoid adding trash at launch. Ultimately, though, it’s up to national governments and international organizations such as the United Nations to define and enforce these rules, Aschbacher says, adding, “ESA is a technical agency, not a regulatory one.”

Regulation alone may not be enough: Even without any additional launches, the number of space debris is likely to keep growing. Fragmentation events, in which spacecraft break apart due to exploding batteries, fuel tanks, or fatigue are creating new debris faster than atmospheric drag can clean lower orbits. Several such events happened in 2024, ESA reports, adding thousands of new debris objects.

That’s why the ability to actively remove uncontrolled spacecraft is also needed, Aschbacher concludes. The first such mission, called Clearspace 1, is set to launch in 2028. It’s a “tow-truck” satellite that will use gripper arms to catch a spacecraft and guide it into Earth's atmosphere. The mission had to be rescheduled a few years ago, because the original target object was hit by other space debris and broke into several fragments. 

The desperately needed regulations and removal missions seem far on the horizon in an uncooperative global political climate. If we indeed close our access to space thanks to careless pollution, it will not come out of nowhere. We have been warned.