Space debris. An environmental problem still less known, that might cost us dearly in the future

In March 2024, a piece of metal that weighed nearly a kilogram dropped from the sky on a family’s home. The piece came from low Earth orbit, and NASA admitted it belonged to them. It was a piece detached from a package released from the International Space Station (ISS), that did not completely disintegrate in the atmosphere. The incident happened in Florida, USA, but it is not the only one.

In December 2024, a giant metal ring from a space rocket fell in a Kenyan village, Reuters reports. The piece of space junk reportedly weighed more than 500 kilograms, fell in a field, and was still glowing hot when locals reached it. However, there was no significant damage made, the Kenyan Space Agency said.

Such situations can happen anywhere in the world, because on Earth’s orbit there are tons of debris of all sizes, which can damage satellites, space missions, and, sometimes, our homes.

The problem of space junk is getting worse as the number of satellites and space programs grows. Earth’s low orbit is littered with fragments from decommissioned satellites, pieces of abandoned rockets, and other debris from collisions and failed missions. Some estimates say there are as many as 46.000 objects larger than 10 centimeters, moving at about 28.000 kilometers per hour. Add to that another one million pieces of debris between 1 and 10 centimeters that are hard to spot because they are too small and moving too fast to be easily tracked.

“That’s the stuff we’re very worried about”, John Crassidis, a professor in the Department of Aerospace and Mechanical Engineering at the University at Buffalo, told Panorama.

The researcher, who has worked with NASA and U.S. Air Force to monitor this space debris, says the problem is serious. This debris could hit satellites anytime and could affect the activity on the International Space Station. In fact, on June 26, 2024, the astronauts aboard it went on alert after an inactive Russian satellite broke into more than 100 pieces. They had to take preventive shelter for an hour in the rocket attached to the Station, fearing a collision. Fortunately, the incident was averted.

Satellites, like the Russian one that caused problems on the ISS, are one of the main sources of space debris. The European Space Agency (ESA) says only about a third of the satellites launched into orbit over the years are still functional. The rest have become unusable and are polluting space. Some have broken into tiny pieces, such as the Chinese FengYun-1C weather satellite, which broke into 3.000 fragments during an anti-satellite missile test in 2007.

If a piece of space debris of 5 centimeters diameter hits something, the high velocity of about 28.000 kilometers per hour makes the energy generated on impact similar to that of a collision with a bus, the Aerospace Corporation calculated. Colliding with a blueberry-sized piece of space debris is equivalent to colliding with a heavy metal anvil.

Monitoring space debris

Monitoring space junk is complicated. It’s small, it moves at huge speeds, and measurement sensors have errors, so there are situations when the observed objects get lost. Space debris is easier to see after it enters the atmosphere because it disintegrates and catches fire. However, once the object cools down, it’s very hard to tell where it is. There are also “undeclared” satellites, because not all countries report where their satellites are.

The main methods for monitoring satellites and space debris are telescopes and radars, but there is a problem of accuracy, especially when it comes to small objects.

Some of the biggest problems in tracking space debris come from space itself. The drag of air molecules on low orbiting satellites, differences in gravity, solar pressure, all influence how satellites and space debris move on orbit, except satellites are large enough and have propulsion mechanisms for control, whereas space debris does not.

Carolin Frueh, an associate professor of Aeronautics and Astronautics at Purdue University in the United States, is researching a method to allow solar-based monitoring called light curves. “We have satellites in space, and the Sun is shining on the satellite and it’s reflecting back, and if we’re in the right position, we are receiving some of the reflection. But we can also look not only at the position of the object, but also the brightness, how much light per time is reflected, and that is the so-called light curve”, she explains in an interview for Panorama, via Google Meet.

The way light is reflected depends on many factors that can help Frueh learn more about the object – shape, direction, material, the way it moves. Based on these, researchers can make assumptions about its behavior. 

The light curve method is used in parallel with traditional observations. “In traditional observations you try to get the orbit of the object, where is it gonna move and where it has been in the past”, says Frueh. With light curves, orbit is needed because light has to fall on the object in a certain way for it to reflect the light and for the experts to find characteristics such as center of gravity and other parameters.

The clutter of objects on orbit could create even bigger problems in the future

Earth’s orbit is getting crowded and that can also pose communication interference problems.

One of the most famous satellite networks is that of SpaceX, a company owned by Elon Musk. There are currently more than 7.000 Starlink Internet satellites in orbit, but Musk plans to launch 20.000 more in the future. This has outraged researchers in the field, and more than 100 of them have signed a letter to the U.S. government calling for an environmental impact assessment first.

The concern among experts in the field about pollution of Earth orbit also stems from the fact that the crowding of “junk” on space orbit can lead to a phenomenon called the Kessler Syndrome, a chain phenomenon in which collisions on orbit generate space debris, which in turn will generate more collisions and debris. “I truly believe that if we don’t do something, in the next 50 years we’ll be there”, John Crassidis says for Panorama.

Such a phenomenon would affect the launch of new space missions, which will find it increasingly difficult to find launch windows through the belt of debris orbiting the Earth. It could also affect the operation of geostationary satellites that are at about 36.000 kilometers in altitude.

Incidents on geostationary orbit are not lacking – in October 2024, an Intelsat communications satellite produced by Boeing and launched in 2016 exploded in orbit due to an “anomaly”, CBS News reports. The explosion caused new space debris.

The “satellite rush” affects astronomers’ observations

Beyond the possible communication hazards, there are also problems in observing outer space. Adrian Șonka, an astronomer at the Vasile Urseanu Astronomical Observatory in Bucharest, says satellites can get between the telescope and the object being observed, or can appear in images taken for research.

Șonka sees first-hand that the situation is getting worse. If five or six years ago he could capture a satellite during a half-hour exposure, today he might have satellites in 80% of the images taken during a 10-minute exposure. “They’re not all ruined, because they don’t all pass right over the object, but I also have images where the satellites pass right over the object I’m observing. So, basically, I’ve been observing for nothing, wasting resources for nothing”, he says.

The astronomer points out that while, on surface, space entities are concerned with cleaning up outer space, they are the ones who also approve the launching of satellites into orbit, so they are also creating the problem they are seeking to solve. “It’s a huge hypocrisy where states complain that there are too many satellites, but the same states are still giving authorizations to launch satellites”, says Șonka. “With the amount of money that’s floating around in this area, nobody is going to be able to regulate anything.

[…] As long as there is a lot of money at stake, there is no chance, it will always be like this and it will get worse and worse. Until an out-of-control satellite falls on a bus with kindergarten children and they all die, nothing will happen”, Adrian Șonka continues.

The astronomer emphasizes that without artificial satellites there is no space junk.

Space sustenability

Satellites are, in fact, space debris in the making because none of them stay active forever and sooner or later they will become “junk” on orbit. That’s why experts in the field are looking for solutions, even though we don’t yet have sufficiently evolved technologies to effectively clean orbit.

Satellite manufacturers are coming up with some rules for low-orbiting satellites. For example, companies are required to create satellites that have enough fuel to be taken out of orbit, meaning that they can reach over the Pacific Ocean and burn up in the atmosphere, says John Crassidis. It’s also forbidden to build satellites out of titanium, because titanium doesn’t burn. Another rule is size. “If the satellite doesn’t have a thruster on board, it can’t be bigger than a shoebox size”, Crassidis says. Companies also have to show that the drag of the air molecules will get the satellite back to Earth within five years.

In an effort to see how well wood stands up to the space environment, LignoSat was launched from the ISS in January 2025. The 10-centimeter wooden satellite will stay in orbit for six months, before re-entering Earth’s atmosphere. LignoSat was created by Kyoto University and a Japanese wood-processing company and could open up new approaches to space sustainability.

ESA also developed a series of policies to achieve zero cosmic waste, while the UN has created a guideline of recommendations to enable the peaceful use of outer space.

What we could do would be to apply circular economy principles to space so that we can prevent pollution through reuse and recycling, especially since all the equipment we are launching now is only usable once, says Moriba Jah, a professor of Aerospace Engineering and Engineering Mechanics at The University of Texas at Austin, who has also worked at NASA’s Jet Propulsion Laboratory and Air Force Research Laboratory, in an interview for Panorama via Google Meet.

The key, he also believes, would be to borrow from the indigenous peoples’ approach and to try to strike a balance with the environment.

Jah was also involved in the creation of the Space Sustainability Rating, a multidisciplinary initiative dedicated to space sustainability.

“The premise was coming up with a way to measure satellites design, choices of orbit, to weigh the different choices that we can make that minimize the long-term impact to the environment. It’s a framework where people can submit their own design, and their choices for orbit and these sorts of things, and is a way to quantify it and end up with a rating that gives some indication of how it contributes or doesn’t contribute to long-term sustainability of the space environment”, Moriba Jah explains for Panorama.

Who bears the responsibility

As far as responsibility for cleaning up space is concerned, there are no clear treaties and laws yet, and this creates a legal vacuum where, at least for the time being, nobody is held accountable. Even if there are international recommendations for space debris mitigation, they do not make it mandatory to clean up that debris. “Because we don’t have any hard international treaties, really nobody is in charge, and that’s a problem”, John Crassidis explains.

Moriba Jah says that there are laws, but the content of those laws is not sufficiently covering it because “we do have international laws related to liability and damage, but we don’t define damage as pollution, so that’s part of the problem. Damage in the context of current international treaties and laws needs to be defined in a way that also includes pollution of the orbital space and the environment.”

Such legislation would be difficult to create, though, because all countries would have to reach a consensus. 

Carolin Frueh believes that, in addition to limiting the production of waste, governments need to be involved, so that satellite manufacturers are encouraged to adopt end-of-life strategies for their products.

“Like any other environmental consideration, the companies are not gonna do it out of their own free will, I think therehave to be regulations in place that encourage this. Of course, there is the public pressure, we see that acting on big companies like SpaceX, but that’s not sufficient.There are many small companies which don’t feel public pressure. So I think it will work through regulation and, then, there are actually repercussions if you violate certain guidelines. But there has to be in the national laws of the launching nations”, Frueh explains.

However, an initiative on space debris management has reached the US Congress. The ORBITS Act provides for regular reporting on how space debris is being “actively remediated”, which does not include the deorbiting, reuse, or passive destruction of space debris.  

Space debris has archaeological value

Aside space pollution and the dangers it can pose, space debris has anthropological value. Alice Gorman is an associated professor at Flinders University in Australia and an archaeologist specializing in the memory and history of space exploration and space debris. Gorman applies archaeological methods to places or objects that come from space, and in doing so gains a new perspective about them.

Some countries may preserve their important moments or history in such objects which, at first sight, are just debris. This way, space debris takes on social or symbolic significance and becomes a social common ground.

Gorman says that bringing a non-functioning satellite or space debris back to Earth may seem to preserve its anthropological value, but it is important that the object remains in space, or it loses its significance. The archaeologist says that, to preserve the memory of objects in space, they should not be deorbited unless there is a good reason to do so.

From an archaeological perspective, in-situ preservation is always preferable, so, while she says she doesn not want to preserve everything in orbit, Gorman believes a selection should be made of those that have significance and can be landmarks for future generations, such as parts of Vanguard 1, the oldest satellite, or the oldest objects sent by man into space. In addition to cultural and historical information, this approach could also provide important scientific insights. “They’ve been up there for 60 years. If we’re gonna visit them now, that tells us something about how aluminum survives in space for 60 years”, she explains.

Preserving the memory of space objects is hard to do with small fragments, which lose their significance because it’s harder to identify where they came from, but things like rockets or other items that are still whole can be preserved and be historically valuable.

As for the “environmental” impact of space debris, Gorman believes that an approach based on responsibility and sustainability can help in the future, coupled with regulation and environmental impact assessment, either in national legislation or in self-imposed standards. Another scenario would be a move to terrestrial infrastructure. 

“We need investments in terrestrial telecommunications, navigation, observation, but also Earth observation technologies. We shouldn’t just assume that it all needs to be from space”, Alice Gorman explains.

Space ecology is still a distant dream

A sustainable future of space exploration is still under construction. For now, we don’t have the technology to clean up the orbit, and the lack of global legislation and coordination in this area still leaves the subject open.

Without wishing to be pessimistic, John Crassidis thinks that the next few decades will not bring significant changes. “The stuff that gets created is more than the one that comes down (note: from orbit). So it means the space debris field is growing. Until we get our leader together,  this is going to get worse”, he explains.

Beyond how much “space junk” we produce, there is a need for technological evolution, Adrian Șonka believes. Humans have been using the same principles and methods to explore outer space for decades, so any emerging technology bumps up against the fact that launches have been working in the same way since the 1950s.

“It’s the same principle and the same way. I get on the carriage and take the emerging technology where? So, the base remains the same, and in fact the base is the problem, because it’s very expensive and resource consuming”, Șonka says.

Carolin Frueh places the key to solving the problem on a better approach to thinking about space exploration.

“Have your mission on minimal debris strategy and then get the debris out of the way. My long term vision would really be that we should recycle more, we raise stuff up and then it stays up and we can reuse it fully, completely”.

The coming decades do not seem likely to bring a solution to space pollution. So, sometime in the future, the millions of debris pieces orbiting the Earth will start to create major problems. Beyond the technology needed, the hardest thing may be to reach a consensus that will lead to solutions that make a difference and save us from the scenario where we repeat in space the same “ecology mistakes” we make on Earth.

Article edited by Andrada Fiscutean.