Space traffic rises: Isro performed record 140 collision-avoidance manoeuvres in 2025

What Happened

• The Indian Space Situational Assessment Report (ISSAR) 2025, released by ISRO, revealed that ISRO conducted a record 140 collision-avoidance manoeuvres in 2025 — the highest in any year since the programme began tracking threats in 2010.
• The sharp rise in manoeuvres reflects the unprecedented growth in orbital congestion: 4,651 objects were placed in orbit in 2025 alone, driven by global mega-constellation deployments and increased commercial launch activity.
• Key missions requiring protective manoeuvres included the NISAR satellite (India–NASA joint Earth observation mission) and Chandrayaan-2 (which required 16 trajectory corrections, including two significant revisions to avoid close approaches).
• ISRO conducts these manoeuvres using its Space Situational Awareness (SSA) programme, centred on Project NETRA (Network for Space Objects Tracking and Analysis), which operates radars and optical telescopes from its control centre at ISTRAC, Bengaluru.
• ISRO's Debris Free Space Mission (DFSM), launched in 2024, commits all Indian space actors — government and private — to zero new debris generation by 2030.
• The report underscores the growing risk to India's operational satellite fleet and to internationally significant missions from the rapidly worsening debris environment in Low Earth Orbit (LEO).

Static Topic Bridges

Space Situational Awareness (SSA) and Project NETRA

Space Situational Awareness refers to the comprehensive knowledge of the space environment — tracking objects in orbit (functional satellites, defunct satellites, rocket bodies, and fragments), predicting potential conjunctions (close approaches), and enabling timely avoidance manoeuvres. Project NETRA (Network for Space Objects Tracking and Analysis) is ISRO's indigenous SSA initiative, announced in 2019. The dedicated SSA Control Centre "NETRA" at ISTRAC (ISRO Telemetry, Tracking and Command Network), Bengaluru was inaugurated in 2020. NETRA uses radars and optical telescopes to detect and catalogue space objects, reducing India's dependence on foreign SSA data — historically dominated by the United States Space Surveillance Network (US SSN).

Kessler Syndrome: The Cascading Debris Catastrophe

Proposed by NASA scientist Donald Kessler in 1978, the Kessler Syndrome describes a scenario where the density of objects in Low Earth Orbit (LEO) becomes so high that collisions generate fragments which cause further collisions — creating a self-sustaining cascade that could render certain orbital bands unusable for centuries. LEO (altitudes roughly 160–2,000 km) is the most commercially and scientifically valuable orbital zone — it hosts Earth observation satellites, weather satellites, the International Space Station, and the emerging mega-constellations (Starlink, OneWeb, Kuiper). The 2009 Iridium–Cosmos collision (the first major accidental satellite-to-satellite collision) and the deliberate ASAT test debris (India's Mission Shakti in 2019, China's 2007 ASAT test) have significantly increased the tracked object count.

UN COPUOS and International Space Debris Governance

The Committee on the Peaceful Uses of Outer Space (COPUOS), established by the UN General Assembly in 1959, is the primary international forum for space governance. It operates two sub-committees: the Scientific and Technical Subcommittee (which handles debris issues) and the Legal Subcommittee. In 2007, COPUOS adopted the Space Debris Mitigation Guidelines — a set of voluntary best practices covering design, operations, and end-of-life disposal of spacecraft and rocket stages. The Inter-Agency Space Debris Coordination Committee (IADC), a technical body with 13 member agencies (including ISRO), developed the underlying technical standards. However, COPUOS guidelines and IADC standards are non-binding — compliance depends on voluntary adherence.

NISAR: India–NASA Joint Earth Observation Mission

NISAR (NASA–ISRO Synthetic Aperture Radar) is a joint satellite mission being developed by NASA and ISRO. It will carry two radar systems — NASA's L-band and ISRO's S-band — making it the first satellite to use dual-band radar. NISAR will systematically map Earth's land and ice surfaces every 12 days, enabling monitoring of glaciers, forests, earthquakes, volcanoes, subsidence, and sea-level changes. It has wide relevance for UPSC: it is a flagship India–US science cooperation project, involves technology transfer in advanced radar, and produces data for disaster management and climate change monitoring.

Key Facts & Data

• ISRO collision-avoidance manoeuvres in 2025: 140 (record high since 2010)
• Objects placed in orbit in 2025: 4,651 (unprecedented global launch activity)
• Chandrayaan-2 trajectory corrections in 2025: 16 (including 2 major revisions)
• Project NETRA: ISRO's indigenous SSA initiative; control centre at ISTRAC, Bengaluru (2020)
• DFSM (Debris Free Space Mission): launched 2024; target — zero debris generation by Indian actors by 2030
• COPUOS Space Debris Mitigation Guidelines: adopted 2007, non-binding
• IADC: 13 member agencies including ISRO; develops technical debris standards
• NISAR: dual SAR (L-band NASA + S-band ISRO); maps Earth surface every 12 days
• Kessler Syndrome: self-sustaining collision cascade first described by Donald Kessler (NASA, 1978)
• India's Mission Shakti (2019): ASAT test at low altitude; most debris re-entered within weeks
• Outer Space Treaty 1967: foundational legal framework; no specific debris provisions