Space Debris and Orbital Sustainability

After six decades of space activity, Earth orbit contains millions of pieces of debris traveling at velocities that make even small fragments dangerous. As mega-constellations deploy thousands of new satellites, ensuring the long-term sustainability of space has become one of the industry's most pressing challenges.

The Debris Problem

Space agencies track approximately 36,500 objects larger than 10 cm in orbit, with an estimated 1 million objects between 1-10 cm and over 130 million smaller fragments. At orbital velocities of 7-8 km/s, even a centimeter-sized fragment carries the kinetic energy of a hand grenade.

Major debris-generating events have significantly worsened the problem:

• 2007 Chinese ASAT test: Intentional destruction of the Fengyun-1C satellite created over 3,500 trackable fragments
• 2009 Iridium-Cosmos collision: Accidental collision between an active Iridium satellite and defunct Cosmos created over 2,300 fragments
• 2021 Russian ASAT test: Destruction of Cosmos-1408 created over 1,500 trackable debris pieces, threatening the ISS

Kessler Syndrome

Proposed by NASA scientist Donald Kessler in 1978, Kessler Syndrome describes a potential cascade where debris collisions create more debris, which causes more collisions. If triggered, this cascade could render certain orbital regimes unusable for generations.

Current modeling suggests certain LEO altitude bands may already be at or near the tipping point where debris will grow even without new launches. Active debris removal will likely be necessary to prevent cascade conditions.

Space Situational Awareness

Tracking objects in space is essential for collision avoidance and space operations. Multiple organizations maintain space surveillance capabilities:

Government Programs

• U.S. Space Force: Operates the Space Surveillance Network, tracking 40,000+ objects
• ESA Space Debris Office: European tracking and research capabilities
• Russia/Roscosmos: Independent tracking network

Commercial Providers

Commercial space situational awareness (SSA) providers supplement government tracking with commercial services:

• LeoLabs operates a global network of phased array radars providing commercial tracking services
• ExoAnalytic Solutions uses a global telescope network for space surveillance
• COMSPOC provides conjunction analysis and space safety services

Active Debris Removal

Removing existing debris from orbit is technically challenging but increasingly recognized as necessary. Several companies are developing debris removal capabilities:

Astroscale

Astroscale is the leading commercial debris removal company. The company's ELSA-d mission demonstrated rendezvous and capture technologies, while ADRAS-J inspected a defunct Japanese rocket stage. Astroscale is developing commercial services for satellite deorbiting and debris removal.

ClearSpace

ClearSpace is developing the ClearSpace-1 mission under ESA contract to remove a Vega rocket payload adapter. The Swiss company is pioneering robotic capture technology for debris removal.

Other Approaches

• Nets and harpoons: RemoveDEBRIS demonstrated net capture and harpoon technologies
• Laser ablation: Ground or space-based lasers could vaporize debris surface to alter orbits
• Drag enhancement: Devices that increase atmospheric drag to accelerate deorbit

Satellite Servicing

Rather than leaving defunct satellites as debris, on-orbit servicing can extend their lives or safely deorbit them:

• Northrop Grumman's Mission Extension Vehicles dock with GEO satellites to provide station-keeping
• Astroscale offers end-of-life deorbit services for satellites with docking interfaces
• Orbit Fab is developing in-space refueling to extend satellite life

Regulatory and Policy Frameworks

Debris Mitigation Guidelines

International guidelines recommend:

• Deorbit within 25 years of mission end (now being shortened to 5 years by some regulators)
• Passivation of remaining energy sources at end-of-life
• Design to minimize debris generation
• Collision avoidance maneuvering

Evolving Regulations

The FCC now requires 5-year deorbit timelines for U.S.-licensed LEO satellites. ESA's Zero Debris policy aims for no debris generation from new missions. However, enforcement remains challenging, and many nations lack effective space debris regulations.

Mega-Constellation Impacts

Starlink, OneWeb, and upcoming constellations add thousands of satellites to LEO, dramatically changing the orbital environment:

• SpaceX conducts over 10,000 collision avoidance maneuvers annually for Starlink
• Operators must coordinate increasingly complex orbital traffic
• End-of-life disposal becomes critical with 5-year satellite lifespans
• Failed satellites become debris if they cannot maneuver for disposal

Constellation operators argue their low-altitude orbits naturally decay within 5 years, mitigating long-term debris risk. Critics note that even short-lived debris can cause collisions, and failure rates become significant at large scales.

Industry Initiatives

The space industry has launched several sustainability initiatives:

• Space Safety Coalition: Industry group promoting best practices and transparency
• Net Zero Space: Commitment to debris-neutral operations
• Space Sustainability Rating: World Economic Forum initiative to rate satellite mission sustainability

Conclusion

Space debris represents an existential threat to space operations if not managed properly. The combination of improved tracking, active debris removal, satellite servicing, and stronger regulations offers a path to sustainable space operations. The industry's explosive growth makes addressing this challenge urgent—failure could limit humanity's access to space for generations.