Space Debris

Space debris (or orbital debris) refers to human-made objects in Earth’s orbit that are no longer functional. These include defunct satellites, rocket stages, fragments from explosions or collisions, and other mission-related waste. These objects, moving at high velocities in orbit, pose serious risks to active satellites and spacecraft.

Current Situation

According to the European Space Agency’s (ESA) 2025 Space Environment Report, more than 36,500 objects are being tracked in orbit, of which approximately 36,500 are larger than 10 centimeters. The vast majority of these are non-functional and classified as space debris. Low Earth Orbit (LEO) is particularly concentrated with this debris.

Main Sources

Space debris consists of human-made objects in Earth’s orbit that have lost functionality. These debris originate from various operational processes and unexpected events. The main sources of space debris are:

Defunct Satellites

Satellites that have completed their missions, suffered malfunctions, or lost control continue to orbit and contribute to space debris. Due to their large size and long orbital lifetimes, these objects pose significant risks and represent one of the largest categories of space debris.

Rocket Stages (Rocket Bodies)

During launch missions, the stages of carrier rockets used to deliver satellites to their target orbits are jettisoned. Some of these stages remain in orbit permanently, becoming long-term debris. In particular, second stages are frequently responsible for generating debris.

Debris from Collisions

Collisions between defunct satellites or rocket fragments produce numerous small, fast-moving fragments. Such collisions create new debris fields, increasing the risk level in the space environment. For example, the 2009 collision between the Iridium 33 and Cosmos 2251 satellites generated thousands of fragments.

Debris from Explosions

Residual propellants or batteries in launch vehicles can rupture over time due to increasing internal pressure. The resulting fragments spread uncontrollably in orbit and constitute a threat to active space assets.

Mission-Related Small Objects

Small components released during launch and operational procedures—such as lens caps, connection elements, and equipment parts—remain free-floating in orbit and fall into the category of small-sized debris.

Intentional Artificial Debris (Anti-Satellite Weapon Tests)

Anti-satellite weapon tests conducted by some states have resulted in the fragmentation of targeted satellites, generating new debris. These activities have significantly increased the amount of debris in low Earth orbit.

Risks and Threats

Due to their high velocities in orbit, space debris poses serious risks and threats to both current and future space activities. The main risks and threats identified by the European Space Agency (ESA), NASA, and the United Nations Office for Outer Space Affairs (UNOOSA) are listed below:

Collision Risk

Space debris travels at speeds of approximately 7 to 8 kilometers per second. Even small fragments can cause severe damage to active satellites, spacecraft, or the International Space Station (ISS). Collisions can lead to system failures, mission cancellations, and even loss of life in crewed missions.

Kessler Syndrome

The Kessler Syndrome describes a scenario in which collisions generate new debris, triggering further collisions and cascading debris creation. This chain reaction could render certain orbital regions unusable for space activities.

Threat to Crewed Space Missions

For crewed missions such as the International Space Station (ISS), space debris presents serious hazards. The ISS regularly performs orbital maneuvers to avoid potential collisions. Even a small fragment can cause catastrophic outcomes such as cabin depressurization or structural failure.

Impact on the Economic Value of Space Assets

Loss of active satellites due to collisions can disrupt critical infrastructure including communications, weather forecasting, and GPS services.

Risk of Re-entry to Earth’s Surface

Large uncontrolled debris fragments in orbit can eventually re-enter Earth’s atmosphere. Although most of the planet is covered by oceans, limiting the risk, the possibility of debris impacting populated areas has not been eliminated. The uncontrolled re-entry of the Skylab space station in 1979 is one historical example of this risk.

Space Commerce and Limitations

Increasing debris density complicates the planning of new launch missions. Rising collision risks threaten both commercial ventures and scientific research projects, creating significant barriers to the sustainable use of space.

Strategies

To mitigate the structural and operational risks posed by space debris, international organizations and national space agencies have developed technical and administrative strategies. Institutions such as the European Space Agency (ESA) and the United States National Aeronautics and Space Administration (NASA) recommend that spacecraft be removed from orbit in a controlled manner after mission completion. For vehicles operating in Low Earth Orbit (LEO), it is recommended that they be deorbited within 25 years after end-of-life to ensure atmospheric burn-up. For spacecraft in higher orbits such as geosynchronous orbit, it is recommended that they be moved to graveyard orbits after losing functionality.

Collision avoidance maneuvers are also a primary protective measure for active satellites. Satellite systems are continuously monitored for potential collision threats, and orbital correction maneuvers are performed when necessary. Efforts are ongoing to develop and standardize space traffic management systems at an international level.

Measures such as venting residual propellants, passivating batteries, and safely depressurizing tanks are implemented. These technical practices aim to prevent uncontrolled post-mission explosions and the resulting generation of new debris.

Spacecraft design aims to reduce unnecessary detachable components, enhance structural integrity, and improve resistance to collisions.

Active debris removal initiatives aim to safely remove existing large-scale space debris from orbit. One such project, the ClearSpace-1 mission, supported by the European Space Agency, seeks to capture a specific piece of space debris and deorbit it for controlled atmospheric destruction. Similarly, the company Astroscale is developing systems that use magnetic docking technologies to safely remove defunct satellites from orbit.

Finally, international standards and legal instruments on reducing space debris provide a common normative framework. Documents such as the United Nations’ “Space Debris Mitigation Guidelines” (United Nations Office for Outer Space Affairs) outline principles and standards that are non-binding but widely accepted in practice by states and private sector operators.

Applications and Future Plans

Various applications are being implemented and future plans developed to reduce current threats from space debris and ensure the sustainability of the space environment. These efforts are carried out through collaboration between public institutions and the private sector.

Orbital Monitoring and Space Traffic Management

Many countries and organizations continuously monitor objects in orbit to prevent potential collisions.

• The Space Surveillance Network operated by the United States Space Force tracks more than 43,000 objects.
• ESA’s Space Debris Office coordinates European orbital monitoring and data-sharing activities.
• In the future, a globally integrated Space Traffic Management System is targeted.

Active Debris Removal Missions

Several active debris removal projects have been developed to eliminate large and hazardous debris already in space:

• ClearSpace-1 (ESA project): Planned for launch in 2026, this mission aims to capture a piece of space debris and destroy it in a controlled atmospheric re-entry.
• RemoveDEBRIS (European Union-supported project): In 2018, it conducted experiments testing net and harpoon technologies to capture small objects.

Advanced Satellite Designs

Next-generation satellites are being designed with systems that facilitate safe disposal at end-of-life.

• Autonomous de-orbit sails
• Passive de-orbit capability via propulsion systems
• These technologies aim to minimize future space debris generation.

International Policies and Standards

Under the United Nations Office for Outer Space Affairs (UNOOSA) and the Committee on the Peaceful Uses of Outer Space (COPUOS), international guidelines for reducing space debris have been established.

• The 2019 Guidelines for the Long-term Sustainability of Outer Space Activities, adopted by COPUOS, assign responsibility to all states and space operators for combating space debris.
• Efforts are ongoing toward developing binding international agreements in the future.

Sustainable Space Environment Initiatives

• ESA’s “Zero Debris Charter” Initiative: Aims to eliminate new space debris production in Europe by 2030.
• NASA’s “Orbital Debris Program Office”: Develops technical and operational solutions to minimize debris generation from spacecraft and launch operations.

Private Sector Involvement

Private companies are actively contributing to debris removal and space traffic management solutions. Firms such as Astroscale, Northrop Grumman, and LeoLabs are making significant technological contributions to the fight against space debris.