Frequently Asked Questions
1. What is orbital debris?
Orbital debris is any human-made object orbiting Earth that no longer serves a useful purpose.
2. What are examples of orbital debris?
Examples of orbital debris include derelict spacecraft and launch vehicle upper stages, carriers for multiple payloads, debris intentionally released during spacecraft separation or mission operations, debris created by spacecraft or upper stage explosions or collisions, solid rocket motor effluents, and tiny flecks of paint released by thermal stress or small-particle impacts.
3. How much orbital debris is currently in Earth orbit?
Approximately 50,000 large, trackable objects orbit Earth, along with an estimated 100 million pieces of millimeter-sized orbital debris. The number of debris objects increases rapidly as size decreases, meaning the vast majority of orbital debris is too small to track routinely. As of August 2026, the U.S. Space Surveillance Network had cataloged more than 34,000 objects in Earth orbit, including active and defunct spacecraft, spent rocket bodies, fragmentation debris, and other cataloged debris.
4. Can all orbital debris be tracked?
The U.S. Space Surveillance Network routinely tracks larger orbital debris, generally objects greater than 10 centimeters. Smaller debris is too small to track routinely, so NASA uses ground-based radars, statistical measurements, and models to characterize and estimate the population of smaller orbital debris.
5. How is the number of orbital debris determined?
The U.S. Space Surveillance Network routinely tracks and catalogs larger objects in Earth orbit, generally those larger than 10 centimeters. NASA uses statistical measurements and models to estimate the amount of smaller debris that sensors cannot routinely track. NASA also uses ground-based radars to detect debris as small as a few millimeters in low Earth orbit and uses those observations to estimate the population of smaller orbital debris.
6. What is the principal source of large orbital debris?
Spacecraft and launch vehicle explosions and collisions are major sources of large fragmentation debris. Historically, explosions of launch vehicle upper stages and spacecraft created many debris-generating events. Major events, including the intentional destruction of the Fengyun-1C weather satellite in 2007 and the accidental collision of Iridium 33 and Cosmos 2251 in 2009, significantly increased the amount of large debris in Earth orbit.
7. Is orbital debris uniformly distributed about the Earth?
Orbital debris is not evenly distributed. Most orbital debris orbits within 1,243 miles (2,000 kilometers) of Earth’s surface. Within this region, the amount of debris varies significantly with altitude. The greatest concentration of debris orbits between 750 and 621 miles (1,000 kilometers) above Earth.
8. How fast is orbital debris traveling?
In low Earth orbit, below 1,243 miles (2,000 kilometers),, orbital debris travels at speeds of about 15,659 to 17,896 mph (7 to 8 kilometers per second). Orbital debris strikes other space objects at an average relative speed of approximately 6.2 mph (10 kilometers per second) and can reach relative speeds of about 9.3 mph (15 kilometers per second, more than 10 times the speed of a bullet. As a result, collisions with even small pieces of debris involve considerable energy.
9. Does the International Space Station have to dodge orbital debris?
The U.S. Space Surveillance Network regularly monitors the trajectories of large orbital debris to identify potential close approaches. If a tracked object is projected to come within a few miles of the International Space Station, the station normally maneuvers away from it if the chance of a collision exceeds 1 in 10,000. The International Space Station has performed such collision avoidance maneuvers 41 times since 1999.
10. How is the International Space Station protected against orbital debris?
The International Space Station is the most heavily shielded spacecraft ever flown. Its shielding allows critical U.S. components, including habitable compartments and high-pressure tanks, to normally withstand impacts from debris as large as 1 centimeter in diameter. Debris between 1 and 10 centimeters in diameter poses a slight risk of striking a critical station component, and NASA continues to investigate ways to reduce this risk.
11. Do the low altitude, commercial communication satellite networks pose special debris issues?
Large satellite constellations increase the number of spacecraft operating in Earth orbit, making debris mitigation and responsible end-of-mission disposal increasingly important. Spacecraft operators can reduce the creation of long-lived debris by limiting debris released during normal operations, preventing accidental explosions, and safely disposing of spacecraft at the end of their missions. NASA studies the evolving orbital debris environment to better understand and mitigate these risks.
12. How long will orbital debris remain in Earth orbit?
The higher the altitude, the longer orbital debris typically remains in Earth orbit. Debris in orbits below 373 miles (600 kilometers) normally falls back to Earth within several years. At altitudes of 497 miles (800 kilometers), orbital decay often takes centuries. Above 621 miles (1,000 kilometers), orbital debris normally continues orbiting Earth for 1,000 years or more.
13. Is reentering debris a risk to people and property on Earth?
Most orbital debris does not survive the severe heating that occurs during reentry. Surviving debris will most likely fall into an ocean or sparsely populated area. Although reentering debris can pose a risk to people and property, the likelihood of debris striking an individual is unlikely.
14. What about orbital debris in the geostationary orbit near 36,000 km altitude where many telecommunications and meteorological spacecraft operate?
The amount of orbital debris in geosynchronous orbit is generally less severe than in low Earth orbit. NASA uses ground-based optical telescopes to characterize debris in this region, including objects too small or faint to track routinely. To help preserve the geosynchronous region, spacecraft operators typically move spacecraft nearing the end of their missions into disposal graveyard orbits above the geosynchronous region.
15. With so many objects in Earth orbit, what is the likely outcome of collisions between orbital debris and operational spacecraft?
Submillimeter-sized orbital debris and micrometeoroids routinely strike spacecraft with little or no effect. Millimeter-sized orbital debris represents the highest mission-ending penetration risk to most robotic missions operating in low Earth orbit because it can damage critical spacecraft systems such as fuel tanks and pressurized components. The probability of two large objects greater than 10 centimeters accidentally colliding is very low, and operators can often reduce the risk from trackable objects through collision avoidance measures.
16. What can be done about orbital debris?
The most important action currently is to prevent the unnecessary creation of additional orbital debris. This can be done through prudent vehicle design and operations. Cleaning up the environment remains a technical and economic challenge.
17. What is the U.S. policy on orbital debris?
The United States has long recognized the importance of minimizing the creation of orbital debris.
The United States Government Orbital Debris Mitigation Standard Practices provide guidelines for limiting debris released during normal operations, minimizing accidental explosions and collisions, and safely disposing of spacecraft and launch vehicle stages at the end of their missions.
18. How do U.S. Government agencies handle orbital debris issues?
Since 1988, U.S. policy has emphasized minimizing the creation of new orbital debris. The 2010 National Space Policy reinforced the importance of preserving the space environment and directed
NASA and the Department of Defense to research technologies and techniques to mitigate and remove orbital debris, reduce hazards, and improve understanding of the debris environment.
NASA and other U.S. government agencies implement requirements and practices to limit orbital debris.
NASA follows NASA-STD-8719.14, Process for Limiting Orbital Debris,
which addresses debris released during normal operations, accidental explosions and collisions, post-mission disposal, and reentry. Other federal agencies incorporate orbital debris mitigation requirements into their
regulatory and licensing activities.
19. Does U.S. industry follow similar guidelines?
Manufacturers and operators of U.S. spacecraft and upper stages recognize the hazards of orbital debris and the need to limit its growth. Many firms voluntarily follow measures designed to limit the growth of orbital debris. Orbital debris mitigation for commercial launches and reentries is regulated by the Federal Aviation Administration. Orbital debris mitigation for commercial spacecraft is regulated by the Federal Communications Commission.
20. Do other countries have guidelines on orbital debris?
Russia, China, Japan, France, and the European Space Agency have issued orbital debris mitigation guidelines.
21. Is there an international treaty on orbital debris?
No, but the world’s leading space agencies formed the Inter-Agency Space Debris Coordination Committee to address orbital debris issues and encourage operations in Earth orbit that limit the growth of orbital debris. Since 1994, the Scientific and Technical Subcommittee of the United Nations Committee on the Peaceful Uses of Outer Space has also assessed and discussed orbital debris. Both organizations have published orbital debris mitigation guidelines for the international community.
22. Where can I read more about orbital debris?
NASA’s Orbital Debris Program Office website
provides information on the orbital debris environment, measurements, modeling, mitigation, and related research.
The Orbital Debris Quarterly News provides regular updates on NASA’s latest orbital debris research, observations, and activities.
Additional information on debris mitigation is available through NASA's orbital debris standards and the U.S. Government Orbital Debris Mitigation Standard Practices.