Orbital debris, also known as space debris or space junk, refers to all human-made objects in orbit around Earth that no longer serve a useful purpose.

The United States is responsible for the majority of orbital debris in Earth's orbit, due to its extensive space exploration and satellite programs.

Orbital debris originates from various sources, including abandoned satellites, rocket boosters, fragments from collisions, and other spacecraft components.

It is estimated that there are approximately 100,000 pieces of orbital debris larger than 10 centimeters in Earth's orbit.

It is estimated that there are approximately 100 million pieces of orbital debris smaller than 1 centimeter in Earth's orbit.

Orbital debris poses several concerns, including collision hazard to satellites and spacecraft, interference with radio communications, and potential damage to ground-based infrastructure in the event of re-entry.

The Kessler Syndrome refers to a scenario where the increasing amount of orbital debris leads to a chain reaction of collisions, creating even more debris and posing a significant threat to spacecraft and satellites.

Mitigating the growth of orbital debris involves a combination of active debris removal, passive debris removal, international cooperation, and regulations to minimize the creation and accumulation of space junk.

Examples of active debris removal missions include the RemoveDEBRIS mission, the e.Deorbit mission, and the Astroscale mission, which aim to capture and remove orbital debris from Earth's orbit.

Examples of passive debris removal methods include using drag sails to deorbit satellites, designing satellites to disintegrate upon re-entry, and raising the orbits of satellites to reduce collisions.

The United Nations Office for Outer Space Affairs (UNOOSA) is responsible for coordinating international efforts to address the issue of orbital debris, including promoting cooperation, developing guidelines, and facilitating research and development.

The Inter-Agency Space Debris Coordination Committee (IADC) aims to promote international cooperation on space debris mitigation, develop guidelines and standards, facilitate information sharing and research, and coordinate efforts to address the issue of orbital debris.

The Space Debris Act of 2022 aims to establish a comprehensive framework for space debris mitigation in the United States, promote international cooperation, provide funding for space debris research and development, and address the issue of orbital debris.

The European Space Agency's (ESA) Clean Space initiative aims to develop technologies for active debris removal, promote sustainable space practices, raise awareness about the issue of orbital debris, and contribute to the overall effort to address the problem.

The NASA Orbital Debris Program Office aims to conduct research on orbital debris, develop technologies for space debris mitigation, coordinate efforts with international partners, and contribute to the overall effort to address the issue of orbital debris.