Space Debris & Mitigation Technologies | Science & Technology for UPSC CSE PDF Download

Understanding Space Debris

Space debris, often called "space junk," refers to human-made objects in Earth's orbit that no longer serve a purpose. These include old satellites, rocket parts, and tiny fragments, all floating in space and posing risks to active spacecraftSpace Debris

What is Space Debris?

• Definition: Any non-functional human-made object in orbit, such as defunct satellites, spent rocket stages, collision fragments, or small particles like paint flecks or bolts.
• Size and Quantity:
  • Over 40,000 objects larger than 10 cm are tracked using ground-based radars and telescopes.
  • Millions of smaller pieces (1 mm to 10 cm) exist, which are harder to track but dangerous due to high speeds (up to 28,000 km/h).
• Orbital Regions:
  • Low Earth Orbit (LEO): 200–2,000 km above Earth, where most debris accumulates (e.g., satellites for internet, weather).
  • Geostationary Orbit (GEO): ~36,000 km, used for communication and TV satellites.
  • Medium Earth Orbit (MEO): ~2,000–36,000 km, for navigation systems like GPS or GLONASS.

Sources of Space Debris:

• Satellite Operations: Satellites stop working but remain in orbit.
• Rocket Launches: Upper stages of rockets are left behind after deploying satellites.
• Collisions: Accidental crashes, like the 2009 Iridium-Cosmos collision, create thousands of fragments.
• Anti-Satellite Tests (ASAT): Tests like India’s Mission Shakti (2019) or China’s 2007 ASAT test generate debris.
• Explosions: Leftover fuel in satellites or rockets can explode, breaking them into pieces.
• Wear and Tear: Aging satellites shed parts like paint, insulation, or screws over time.

Why is Space Debris a Problem?

• Risk to Spacecraft: Even tiny debris can damage satellites, the International Space Station (ISS), or astronauts due to high speeds.
• Impact on Services: Damaged satellites disrupt GPS, weather forecasting, internet, and TV signals, affecting daily life and economies.
• Economic Costs: Space agencies and companies spend millions to protect satellites or maneuver them to avoid debris.
• Strategic Concerns: Military satellites for surveillance or communication are at risk, impacting national security.
• Space Exploration: Debris threatens future missions, like India’s Gaganyaan (human spaceflight) or lunar explorations.

Recent Developments

• ESA Space Environment Report (2025): Reported multiple satellite breakups in 2024, adding thousands of new debris pieces. Noted that LEO is increasingly crowded, with over 14,000 satellites launched since 2020, raising collision risks.
• Market Growth: The space debris monitoring and removal market is projected to reach USD 2.05 billion by 2033, driven by rising satellite launches and private companies like Astroscale.
• LEO Capacity Warning: Studies (2025) estimate LEO can support only ~100,000 satellites before debris density becomes critical, emphasizing the need for better management.

Kessler Syndrome

Kessler Syndrome is a worst-case scenario where space debris in LEO becomes so dense that one collision triggers a chain reaction, creating more debris and making orbits unusable.

What is Kessler Syndrome?

• Proposed by NASA scientist Donald J. Kessler in 1978.
• Describes a cascading effect: A single collision (e.g., between satellites) produces thousands of fragments, which then hit other objects, creating more debris.
• LEO is most at risk due to its high concentration of satellites (e.g., for internet, Earth observation).

How It Happens:

• LEO has thousands of satellites and debris moving at high speeds.
• A collision (e.g., satellite vs. debris) creates fragments that spread out, increasing the chance of more collisions.
• This cycle could make LEO unusable for decades, as debris spreads and persists.

Consequences:

• Space Operations: Satellites and spacecraft can’t operate safely in affected orbits.
• Economic Loss: Replacing damaged satellites or losing services (e.g., internet, GPS) costs billions.
• Space Exploration: Future missions, like Mars or Moon landings, face higher risks.
• National Security: Military satellites for surveillance or navigation could be destroyed.
• Real-World Example: The 2009 Iridium-Cosmos collision (US satellite vs. Russian satellite) created over 2,000 trackable debris pieces, raising Kessler Syndrome fears.

Recent Developments 

• ESA Warning (2025): Fragmentation events (collisions, explosions) are outpacing natural cleanup (debris burning up in the atmosphere). ESA suggests stricter rules, like de-orbiting within 5 years instead of 25, to prevent Kessler Syndrome.
• Research Insights: A 2025 study highlighted that LEO’s debris density is approaching a tipping point, with over 30,000 trackable objects and rising collision risks.
• UN Discussions (2025): UNOOSA emphasized the need for global action to avoid Kessler Syndrome, including better tracking and removal technologies.

Mitigation Technologies

Mitigation technologies aim to prevent new debris and clean up existing junk. There are two approaches: passive (designing systems to avoid debris creation) and active (removing debris with technology). International guidelines, like those from the UN, guide these efforts.

Passive Mitigation:

• Better Design:
  • Satellites and rockets are built to avoid explosions (e.g., draining fuel tanks after use, called passivation).
  • Use materials that don’t break apart easily (e.g., stronger casings).
• End-of-Life Disposal:
  • De-orbiting: LEO satellites are pushed into Earth’s atmosphere to burn up within 25 years (per UN COPUOS guidelines).
  • Graveyard Orbits: GEO satellites are moved to a higher, unused orbit at the end of life.
• Example: ISRO’s PSLV-C56 mission (2023) tested de-orbiting, reducing the rocket’s upper stage orbit time from decades to months.

Active Debris Removal (ADR):

• Actively removing debris using advanced technologies.
• Methods:
  • Robotic Arms: Satellites with mechanical arms grab debris. ISRO tested a tethered capture system with visual guidance in 2023.
  • Nets and Harpoons: Nets wrap around debris, or harpoons spear it for removal. These are being tested by ESA and private companies.
  • Lasers: Ground- or space-based lasers nudge debris into lower orbits to burn up. Japan’s JAXA is developing laser-based systems.
  • Drag-Enhancing Devices: Attach sails, balloons, or tethers to debris to increase drag, making it fall faster. Examples include CubeSail and DragSail technologies.
  • On-Orbit Servicing: Special spacecraft rendezvous with debris to capture or de-orbit it. ESA’s ClearSpace-1 (planned for 2026) aims to remove a rocket part.
• Challenges:
  • Cost: ADR systems are expensive to develop and launch (millions of dollars).
  • Technical: Capturing fast-moving debris requires precision and risks creating more debris if it fails.
  • Legal: Debris ownership is unclear—removing another country’s debris needs permission.
  • Coordination: Countries and companies must work together globally.

Emerging Technologies:

• Space Situational Awareness (SSA): Tracking debris with radars, telescopes, and satellites. ISRO’s NETRA monitors Indian assets.
• AI and Robotics: Smart systems for autonomous debris capture and orbit planning.
• Recyclable Satellites: Designing satellites for repair, refueling, or recycling in space to reduce waste.
• Example: Japan’s Astroscale is testing ADR with its ADRAS-J mission to inspect debris.

Recent Developments 

• ISRO’s De-orbiting Success: In April 2025, ISRO de-orbited the PSLV Orbital Experiment Module (POEM-4) into the Indian Ocean, avoiding new debris. The PSLV-C60 mission (2024) also disposed of its upper stage responsibly.
• ESA’s ClearSpace CLEAR Mission (2025): Completed Phase 2, testing capture technology for debris removal. Adjusted plans after a debris collision to improve safety and speed.
• Astroscale’s ADRAS-J (Japan): Ongoing demonstration (2025) to inspect debris, a step toward full-scale removal.
• MIT Scoring System (2025): Proposed a “debris score” for missions to evaluate their mitigation plans, encouraging better design.
• Japan’s Laser Research: JAXA advanced laser-based debris removal, aiming to nudge small debris into lower orbits by 2027.

International and Indian Perspectives

Space debris is a global issue requiring cooperation, as debris doesn’t follow national boundaries. India, with its growing space program, plays a key role.

Global Framework:

• UN COPUOS: The UN Committee on the Peaceful Uses of Outer Space sets guidelines, like de-orbiting satellites within 25 years.
• Outer Space Treaty (1967): States that space is for peaceful use, and countries are responsible for their objects, including debris.
• Inter-Agency Space Debris Coordination Committee (IADC): Sets technical standards for mitigation, followed by major space agencies.
• International Telecommunication Union (ITU): Manages satellite orbit slots to avoid crowding and collisions.
• Key Players:
  • NASA (USA): Leads in SSA and mitigation research.
  • ESA (Europe): Developing ClearSpace-1 for ADR.
  • JAXA (Japan): Testing laser-based removal and ADR missions.
  • Roscosmos (Russia): Contributes to IADC guidelines.
  • Private Companies: SpaceX (Starlink), Astroscale, and others add to debris but also innovate solutions.

India’s Role:

• ISRO’s Efforts:
  • NETRA: A network of radars and telescopes to track debris and protect Indian satellites.
  • De-orbiting: Experiments like PSLV-C56 (2023) and PSLV-C60 (2024) show ISRO’s commitment to reducing debris.
  • Responsible Launches: ISRO designs rockets and satellites to minimize junk, following UN and IADC guidelines.
• Mission Shakti (2019): India’s ASAT test created debris, drawing global criticism. ISRO has since focused on cleaner practices.
• Space Policy 2023: India’s draft policy emphasizes sustainable operations and a goal of Debris-Free Space Missions (DFSM) by 2030.
• Global Cooperation: India participates in IADC and UN COPUOS, advocating for shared responsibility in debris management.

Recent Developments

• ISRO’s NETRA Upgrade (2025): Added a new radar in Chandrapur to enhance debris tracking, protecting India’s 50+ satellites.
• ISRO’s DFSM Goal: Reaffirmed commitment to debris-free missions by 2030, with all launches designed to minimize junk.
• UN Discussions (2025): UNOOSA emphasized remediation (cleaning existing debris) and stricter rules for new launches.
• Japan’s UN Proposal (2025): Pushed for global funding and coordination for ADR at UN COPUOS, supported by India.
• US National Orbital Debris Plan (2024): Outlined 44 actions for mitigation, tracking, and removal, influencing global standards.
• NASA Cislunar Guidelines (2025): Best practices for debris management in lunar orbits, as missions to the Moon increase.