Across nearly seven decades of space exploration, humans have launched objects into Earth’s orbit over 6,000 times. This has resulted in more than 130 million pieces of space debris orbiting our planet at high speeds.
As space becomes increasingly commercialized and greater numbers of satellites are launched, the amount of space debris will steadily rise. If mankind wants to continue to use Earth’s orbit, this space junk must be mitigated, and spacecraft must become more sustainable.
Why Is Mitigating Space Debris a Current Concern?
The growing number of human-made objects in Earth’s orbit presents a significant challenge for space sustainability. If left uncontrolled, space debris accumulation will become a major threat to active satellites, space missions, and even future explorations.
The risk of collisions increases as more satellites and missions are launched, leading to potential disruptions in communication, navigation, and scientific research. Because private space companies and governmental agencies are increasingly reliant on space-based technologies, mitigating space debris has recently become a global priority.
What Is Space Debris Made Of?
Space debris, also known as orbital debris and space junk, consists of defunct satellites, spent rocket stages, and fragments resulting from in-space collisions. The size of space debris ranges from tiny paint flecks to large, non-functioning satellites.
These objects travel at extremely high speeds, making even the smallest pieces dangerous to operational spacecraft. The United States Space Surveillance Network tracks space debris 10 centimeters (about the size of a standard playing card) or larger so it can be avoided, but that is a small percentage of overall orbital debris.
Sustainable Space Guidelines
To combat the growing problem of orbital debris, space organizations worldwide have developed sustainable space guidelines. The European Space Agency (ESA) created its Space Debris Mitigation Guidelines, which outlines best practices for a “Zero Debris approach” to prevent further debris accumulation.
The ESA’s guidelines include:
Deorbiting Defunct Satellites: Ensuring that satellites are either deorbited safely or moved to a graveyard orbit, which is an orbit away from common operational ones designated for satellites at the end of their operational lives.
Reducing In-Orbit Fragmentation: Designing spacecraft to minimize the risk of accidental explosions and collisions.
Limiting Mission-Related Debris: Avoiding intentional or unnecessary release of objects and components during launches and operations.
Active Debris Removal (ADR) – Encouraging the development of technologies to remove existing debris from orbit.
These sustainable space guidelines provide a framework for businesses and space agencies to conduct responsible space exploration and operations. However, there is not currently an enforceable global treaty to ensure any of these measures are followed.
Mitigation Through Capturing Debris: Common Removal Methods
Private businesses and space agencies are investing in the development of space debris capture and removal methods. The European Space Agency and Swiss startup ClearSpace have planned the first mission to remove a piece of space debris from orbit, called ClearSpace-1.
There are many different technologies being explored for active debris removal. Some of the most promising include:
1. Harpoon Technology
Harpoon-based systems have been developed to capture and secure large pieces of debris. Airbus has tested harpoon technology as part of their RemoveDEBRIS mission, even successfully spearing a piece of mock debris in orbit. Once captured, the debris could be safely deorbited or repositioned to minimize collision risks.
2. Net Capture Systems
Net capture involves deploying a large net to trap debris and prevent it from drifting further in orbit. The ESA successfully tested this method by capturing a scale-model satellite with a deployable net, demonstrating the technology’s potential for future cleanup efforts.
3. Robotic Arms and Claws
Robotic arms and claws provide a more precise method of capturing and moving debris in space. This is the technology ClearSpace is developing. Its debris removal spacecraft has robotic arms to grab defunct satellites and guide them to a controlled descent into Earth's atmosphere, where they will burn up upon re-entry.
4. Laser Ablation
Laser ablation involves using ground-based or space-based lasers to change the trajectory of small debris pieces. The lasers precisely target the debris to create a force that can push objects into lower orbits, where they will eventually burn up in Earth's atmosphere. This technology is still in its early stages, but unlike other methods, it is a non-contact approach that could be used on any-sized space debris.
5. Magnetic Capture Systems
Magnetic capture systems use powerful magnets or electromagnets to attract and secure space debris that contains magnetic metals, such as defunct satellites and rocket parts. The Japanese company Astroscale is pioneering magnetic debris capture technology with its End-of-Life Services by Astroscale-demonstration (ELSA-d) mission. If future satellites are equipped with docking plates responsive to magnets, they could be more easily retrieved and deorbited.
How Sustainable Satellites Can Reduce Orbital Debris
While active debris removal is important, businesses are also focusing on designing more sustainable satellites to prevent debris from being created in the first place. Key strategies include:
Modular Satellite Designs: Modular satellites allow for in-orbit repairs and upgrades, extending their operational life and reducing the need for new satellite launches. Companies including Northrop Grumman are developing mission extension vehicles that dock with satellites and provide propulsion and support to extend their lifespans.
Self-Deorbiting Technology: Modern satellite designs incorporate propulsion systems or deployable sails that enable controlled re-entry at the end of their missions. This ensures that satellites do not become long-term debris hazards.
Biodegradable Materials: Advancements in material science have led to satellites that break down more easily upon re-entry, including ones designed with natural elements such as wood and flax. This helps minimize satellite debris creation and re-entry risks.
Smarter Satellite Placement and Management: Satellite operators are optimizing orbital placement to reduce crowding and the risk of in-orbit collisions. Companies such as Helsing and Loft Orbital have created AI-powered tracking systems to manage satellite constellations and avoid unnecessary debris generation.
Governments and private companies are increasingly collaborating and focusing on mitigating space debris through these innovative capture methods. But tackling this problem effectively will require international agreements and standardized regulations for space debris mitigation.
By also integrating cutting-edge technologies and responsible satellite design, space exploration can remain secure for future generations.
For more on how orbital sustainability can keep space safe and usable, read this article: Orbital Sustainability and the Future of Space Exploration