On the evening of April 28th, Amazon embarked on its latest venture to rival SpaceX Starlink: the first launch of its Project Kuiper satellites. With 27 satellites now in orbit around the Earth, Amazon joins a growing number of companies working to put more than 1,000 satellites each into space to create their own mega constellation. With all of these objects in orbit, the dangers of overcrowding are increasing, and if any of these objects were to collide, the results could be disastrous.
Aside from Amazon and SpaceX, UK-based OneWeb, which merged with French satellite operator Eutelsat in 2023, has its own constellation, and there are several planned by Chinese companies, too. There is the Chinese government-backed Guowang mega constellation, which began its launches last year but remains veiled in secrecy, as well as the commercial Qianfan or Thousand Sails project, which began launches in 2023 and plans to place a total of up to 15,000 satellites in orbit.
A recent report from the European Space Agency (ESA) found that over 2,500 objects were launched into low-Earth orbit in 2024, more than five times the number of objects launched in any year prior to 2020. The major chunk of these launches were for commercial satellite constellations, for which the number of launches is increasing annually.
The number of active satellites is now comparable to the number of debris pieces in orbit. If current trends in launch continue, ESA estimates there could be almost 50,000 objects larger than 10cm in low-Earth orbit by 2050. Over the next few years, there could be an estimated average of eight satellites launched daily from Earth, or a total mass of four tons of material sent into space daily.
These satellites enable communications and internet access in remote locations, and in areas devastated by natural disasters or war. But the space around our planet is getting increasingly congested with both functioning satellites and the junk left behind by older missions — and the problem will worsen as more satellites are launched.
Experts agree that we urgently need more comprehensive rules around the management of objects in orbit, but in an increasingly polarized world, the idea of global cooperation to protect space seems more remote than ever.
“There is a race to fill low-Earth orbit,” says debris researcher Vishnu Reddy of the University of Arizona.
It’s not only working satellites that are filling up space. There are millions of pieces of junk floating around, many traveling at extremely high speeds. ESA estimates that over 1.2 million objects in orbit are “large enough to be capable of causing catastrophic damage” if they collide with anything. Low-Earth orbit is getting particularly crowded, with thousands of commercial objects in addition to thousands more pieces of debris.
The problem isn’t only that debris could damage a vital piece of equipment, such as the International Space Station. If enough collisions of even small debris pieces occur, they could create more and more debris, causing more and more collisions, creating a cascade effect, which could make access to space treacherous, or even require shutting down all global space programs in the future.
“The satellite operators are obviously tempted to put more and more satellites,” says astronomer Olivier Hainaut of the European Southern Observatory, who has worked on modeling the brightness of Starlink satellites. “However, if they put too many, there will be collisions. And once you start having collisions, you could have a chain reaction, Kessler syndrome, and you can have a whole range of orbits rendered unusable.”
The issue of orbital overcrowding is having effects now. Satellites that are too close together can interfere with each other’s transmissions. Climate change is making the problem worse, too, as the release of greenhouse gases causes the upper atmosphere to shrink, lessening its ability to pull down and destroy debris.
No one is suggesting that satellites or even mega constellations should be banned, but launching thousands of objects per year into orbit comes with a downside that isn’t often acknowledged. Researchers are starting to consider where the bounds of orbital capacity might be, and whether the current level of launches is sustainable in the long term.
It isn’t the functioning satellites that are themselves a problem. A satellite owned by a company is going to be tracked and monitored. But there are thousands of pieces of debris already whipping around in low-Earth orbit that are too small to track. The more satellites we put into orbit, the higher the likelihood of collision with a piece of debris.
Who is responsible for tracking debris and preventing collisions? No one, essentially. In practice, the space community looks to the US government for tracking information, and hopes that everyone behaves responsibly.
“Satellite operators are responsible for their satellites,” Reddy says. “The Space Force tracks a number of objects and updates the catalog a couple of times a day, and the hope is that people will be able to fend for themselves, based on what is freely being provided by the United States.”
That extends to disposing of inoperative satellites. SpaceX has been relatively responsible in deorbiting its defunct satellites, experts agreed. As Starlink satellites sit in a very low orbit, after a few years they naturally drop into the Earth’s atmosphere where they break apart.
Satellite operators don’t want to be fighting with each other for space, so they each use different orbits. The Project Kuiper satellites, for example, launched into a slightly higher altitude than the Starlink ones. However, it’s still necessary to move satellites through other orbits, which is why orbital crowding is a problem.
“What goes up must come down,” Reddy says. “So eventually Kuipers have to deorbit and go through the Starlink orbital range to reenter. What happens then?”
Amazon did not respond to questions about how it plans to deorbit its Kuiper satellites safely or how it plans to manage any potential conjunctions.
Avoiding the bad days
Potential conflicts between satellite operators could become a major issue, as avoiding collisions comes with a financial cost. If, say, a Starlink satellite and a Project Kuiper satellite were on a collision course — what experts refer to as a conjunction — then one or both satellites need to adjust their orbit by using up some of their very limited supply of fuel.
“Now you have the people at Starlink and Kuiper who have to decide who’s going to burn the gas to avoid hitting each other, and that’s going to eat into their profit,” Reddy says.
That’s actually one of the more positive scenarios, because at least Starlink and Project Kuiper satellites have owners who have clear responsibility for them. That isn’t the case for thousands of pieces of smaller debris in orbit.
“A good day is when you can have a conjunction between two satellites and both are operating,” Reddy says. “A bad day is when you have two things that don’t work, where the operators have disappeared, and there’s a collision. All you can do is sit and pray they don’t create debris.”
It’s virtually impossible to predict exactly how much debris any given collision would create, as it depends on the impact speed and direction, and what the objects are made of. With information about satellite composition sometimes kept proprietary, there’s no way to really know how much damage an impact could do.
This situation is compounded by satellite mega constellations, in which thousands of satellites share an orbit. If one satellite malfunctions and explodes, a company may need to move hundreds of its satellites to adjust — and those maneuvers could create even more conjunctions. The situation would be even worse, and even more chaotic, if multiple mega constellations are involved.
“The hope is that it won’t happen,” Reddy says. “But when it happens it can go bad really quickly.”
Space debris experts like Reddy aren’t against satellite companies making money in space. But he’d like to see these companies take more initiative in creating norms and guidelines around collision prevention: “It’s in their own financial interest to come up with the ground set of rules.”
The companies don’t need to wait for the slow process of international agreement to take an active role in managing this issue. “SpaceX has a lot more experience running a mega constellation than any regulator we can find on Earth,” he says, and they could make proposals on handling conjunction events — “So the burden is not on the world governments to come up with a plan.”
It’s also, frankly, better for the satellite companies themselves to take this issue seriously and avoid the significant risk that collisions can pose, especially as more and more companies are launching mega constellations of their own — including companies from outside the US.
What happens when, say, there are hundreds of potential conjunction events between Starlink satellites and Chinese mega constellation satellites, he wondered. With stakes this high, the question becomes: “Who’s gonna move? Are we going to sit there and see who blinks first?”
There needs to be a formal system of cooperation between satellite companies, agreeing on how to make maneuvers in the case of two satellites heading for each other, Reddy says. “It’s a much better thing than to say, okay, we’re gonna have a collision in three hours. Let’s try and scramble through the phone book and find out who in China I need to call. That’s not a good way to do business.”
The threat of a collision between satellites is not purely theoretical. In 2019, disaster almost struck when there was a near miss between a Starlink satellite and a European Space Agency (ESA) Aeolus satellite. ESA had to make a last-minute correction maneuver of its satellite to avoid a collision, which could have thrown debris across a large area of the orbit had it occurred.
That would be concerning in any event, but this case was particularly worrying because ESA tried and failed to contact SpaceX to raise the issue and coordinate the movement of the satellites. SpaceX said at the time that ESA’s email warning of the collision had been overlooked due to a “bug.”
The problem then, as now, is that there is no legal framework for dealing with these kinds of potential satellite collisions. We need rules similar to those for air traffic control but for space, experts agree, but those rules don’t currently exist — and a conjunction could happen at any time. The near miss between Aeolus and Starlink 44 was “a template for what we see every day,” said Holger Krag, ESA’s Head of Space Safety Programme, at a space debris conference earlier this month.
“Whenever two active spacecraft encounter each other you have to rely on cooperation. You will have to communicate, you have to coordinate action,” Krag said. However, there are currently no laws or rules making it clear whose responsibility this communication is, or how collisions should be avoided. “We are far away from a clear flight rule that would solve exactly the situation that Aeolus and Starlink had,” Krag said.
Further, as the number of satellites in orbit increases, ESA has warned that the current process for manually averting collisions by individually adjusting the position of each satellite will become impossible.
To create a system of enforceable laws regarding the use of orbital space would require an international resolution by a body like the United Nations, because no one nation can regulate space. But there is little international will to make that happen. The last significant piece of international space legislation, on which current law is still based, was the Outer Space Treaty passed nearly 60 years ago in 1967. That treaty never imagined operations in space by private companies, though, leaving a regulatory vacuum over whose responsibility issues like space debris are.
This is a classic tragedy of the commons. No one wants space to become inaccessible, but few groups are willing or able to tackle the issue directly.
Josef Aschbacher, the director general of ESA, summed up the problem at the conference: “The message is crystal clear: space debris is a problem and we have to do something about it.”
