When the Outer Space Treaty was signed in 1967 to establish international guidelines for policing ventures in space, only two spacefaring nations were launching spacecraft – the Soviet Union and the United States. The space debris they left behind – now commonly referred to as space junk – seemed like a problem for future generations to solve.
But now, private companies are launching satellites worldwide and even producing megaconstellations that contribute hundreds of objects to the traffic in low Earth orbit (LEO). Many scientists are sounding the alarm that space debris, no matter how small, is a big problem.
At LEO, objects travel at 27,359 kph (17,000 mph), Smithsonian Observatory astrophysicist Jonathan McDowell notes. “So, if you are hit by even a small object at that velocity, the kinetic energy involved is enough to do your satellite a lot of damage,” McDowell told Apogee. “Or, particularly if you were an astronaut, maybe doing a spacewalk, you’re really a little nervous about being hit by this bullet coming out of nowhere at 17,000 miles an hour. That is going to hurt.”
There are nearly 50,000 objects being tracked in Earth’s orbits, and 80% of those are in LEO. But the U.S. Space Force can only track objects 10 centimeters or larger in diameter. Its radar, optical telescopes and data fusion algorithms are restrained by natural limits in resolution and are not sufficient to track anything smaller. That means something the size of a baseball goes undetected.
NASA estimates the number of particles between 1 centimeter and 10 centimeters in diameter is about 500,000, and the number smaller than 1 millimeter in diameter is in the millions. At 17,000 mph, McDowell said, even a paint chip can severely damage a satellite.
In an interview with Harvard Magazine, he recalled the worst space collision to date – the 2009 crash of an active U.S. Iridium satellite with a defunct Soviet satellite. The impact was the equivalent of 50,000 times the energy of a high-speed car crash. “It pulverized the satellites,” McDowell said. “The debris clouds just passed through each other and kept on going.”
Many modern satellites can perform dodge maneuvers because they are equipped with propulsion systems, McDowell said, which is a step in the right direction to reduce space junk. “Twenty years ago, satellites didn’t even have engines,” he told Harvard Magazine. Dodging debris is now routine. According to NASA, the International Space Station corrected its course 32 times between 1999 and 2022 to avoid satellites and space debris.
But it’s hard to dodge what you can’t see. The Aerospace Corp., a federally funded nonprofit research organization, agrees with McDowell that small debris is becoming a significant worry. “Anything that is in orbit is moving very fast, typically 7.5 km/sec, or more than 17,000 mph in low Earth orbit,” Aerospace states on its website. “This is ten to twenty times faster than a bullet. If you are in orbit, you are also moving that fast, and the debris may be coming at you from the other direction, so the relative speed may be twice as fast. The result is that even tiny particles can be extremely deadly, and an object the size of a pinhead can pack a huge wallop.”
Private sector enthusiasm
Space debris can be as large as a rocket body over 10 meters long or as small as a barely visible microscopic particle. “The ones that we are most worried about are those larger than 3 mm (BB sized), although even impacts of very small debris can gradually degrade a solar panel or ruin a scientific instrument,” Aerospace states.
While no large-scale remediation of small debris is in the immediate offing, the U.S. government is turning to the private sector for innovation. In May 2025, U.S. senators reintroduced the Orbital Sustainability Act (ORBITS) to establish a demonstration program to reduce orbital debris. The ORBITS Act would empower “NASA to partner with the U.S. space industry in active debris removal technology to tackle space junk threats,” U.S. Sen. Roger Wicker of Mississippi, one of the bill’s sponsors, said in a news release. “The United States is the world’s premier spacefaring nation, and I look forward to continuing our leadership.”
The smaller debris population doesn’t stay up that long, so it’s continually being replenished. So if we clean up our act on the bigger side, we will eventually clean up our act on the smaller side. ~ Jonathan McDowell, Smithsonian Observatory
About 8,000 metric tons of debris are on orbit, including at least 900,000 pieces of debris that are potentially lethal to satellites, the news release stated. Because these threats are already on orbit, simply preventing more debris in the future is not enough, the bill’s sponsors said. “The ORBITS Act will jumpstart a program focused on research, development, and the demonstration of technologies capable of safely carrying out successful Active Debris Remediation (ADR) missions to create a robust commercial market for these services,” the bill’s sponsors said in the news release.
That commercial market is rapidly growing. NASA is the largest spender on debris monitoring, according to a July 2025 report by Fortune magazine. It has partnerships with SpaceX, United Launch Alliance and LeoLabs for debris mitigation and situational awareness. Although the U.S. government is out front with spending for debris tracking and mitigation, startup companies worldwide are trying to grab a piece of the potentially lucrative market. From controlled deorbiting of space debris to laser-based debris removal, tech companies that have only been in existence for two to three years are joining the pursuit. The artificial intelligence-powered research platform StartUs Insights Discovery predicts high startup activity in the space debris removal field in London; Los Angeles; Melbourne, Australia; New York; and San Francisco.
Its top startup firm to watch was Australia-based Paladin Space, which is developing a reusable, on-orbit space debris remover. The company, based at the University of South Australia, showcased its Triton technology at a private demonstration on May 25, 2025. The debris remover can capture debris from multiple targets and store it on satellites for recycling, reducing the cost of debris removal and making the process more sustainable, the company says on its website.
Then-South Australian Treasurer and Minister for Defence and Space Industries Stephen Mullighan said Triton’s potential demonstrates the impact that startups are having in space technology. “Space startups play a critical role in accelerating the growth of the South Australian space industry and strengthening our economic resilience and relevance,” Mullighan said, according to the Paladin website. “Paladin Space’s innovative technology, which has been developed right here in South Australia, is a perfect example of what’s possible when you foster an environment that nurtures bold ideas.”
Collecting debris isn’t the only way to attack the problem. Japan-based startup Orbital Lasers, for example, is developing satellite-based laser technology for removing debris by altering its trajectory with directed energy. Its lasers are designed to vaporize small debris surfaces to create thrust that guides the fragments into Earth’s atmosphere for disintegration.
And space junk must be tracked to be cleaned up, so Austin, Texas-based Space Cowboy Active Debris Remediation, a startup founded in 2022, is working on technology that would approach debris, collect data and then collaborate with space domain awareness providers to improve debris characterization and tracking. The company repurposes captured debris as raw materials for in-space manufacturing, enhancing sustainability in space operations.
The company, founded by 26-year U.S. Army veteran Joe Guzman, purports to be supporting the growth of an “off-world economy.” By operating a fleet of microsatellite spacecraft, the technology collects fragments between 1 centimeter and 10 centimeters in low Earth orbit. “Each of these fragments, while small, could completely destroy an operational satellite and create thousands of additional pieces of debris,” the company states on its website.
NASA challenges researchers
NASA took its push to invigorate the private sector even further, creating a contest to come up with ideas for remediating small space debris. In March 2024, NASA announced the winners of its challenge, “Detect, Track, and Remediate: The Challenge of Small Space Debris.” The ideas submitted ranged from a tracking method that uses a constellation of optical imaging satellites to a remediation proposal that featured a rotating tethered debris sweeper.
The winners split $120,000 in prize money. Here are some of their ideas:
Daniel Gebhardt, of San Diego, California-based Agonic Technologies, won first place and $20,000 in the detect and characterize category for his proposal to create Synchronous Correlated Imaging for Detection of Debris On-Orbit (SCIDDOO). The core component of SCIDDOO is a constellation of optical imaging satellites in or just above LEO to detect and characterize small debris.
Christophe Choquet of France snared $20,000 and first place in the tracking category for his proposal to develop binocular twin satellites to track small space debris.
And in the remediation category, U.S.-based engineer Dmitri Garin won $20,250 and first place for his proposal to create a rotating tethered debris sweeper.
Nonprofit research groups and academics also have joined the quest. The Aerospace Corp. has developed tools for analyzing potential collisions, studied reentry breakups of satellites, and modeled debris in space. The corporation’s Center for Orbital and Reentry Debris Studies focuses on space debris, collision avoidance and reentry breakup.
McDowell, who has worked at the Harvard-Smithsonian Center for Astrophysics for 37 years, maintains his own catalog of space debris. He bases it on public satellite data and makes it available online for free through his personal blog.
The challenges go beyond the science and technology it takes to track and remediate small space debris. A big hurdle is convincing the public and the world’s governments that debris removal is cost-effective and worth funding. The Aerospace Corp. makes its case. “It might be surprising to learn how much we depend upon satellite technology for communications, navigation, utilities, and services,” it notes on its website. “Almost everything we do in our modern way of life uses satellite technology. Space debris adds to the cost of operating those satellites. If space debris destroys a satellite, it may take years and hundreds of millions of dollars to restore that service.”
McDowell points out that small debris often results from larger debris breaking up. “The more we can decrease the amount of junk overall,” he told Apogee, “the more we will decrease this smaller debris population. The smaller debris population doesn’t stay up that long, so it’s continually being replenished. So if we clean up our act on the bigger side, we will eventually clean up our act on the smaller side.”