Maarg Manthan · Topic 12.15

Space Junk and Graveyard Orbits

Science & Technology › Space Technology and ISRO · Topic 12.15

Space junk, also called space debris, is the collection of human-made objects in orbit that no longer serve a useful purpose, including dead satellites, spent rocket stages, pieces from explosions and collisions, and tiny flecks of paint. Objects in orbit move at about 7 to 8 kilometres per second, so even a small fragment can damage a spacecraft. Tracking networks follow tens of thousands of objects larger than about 10 centimetres, and estimates put the number of objects between 1 and 10 centimetres in the hundreds of thousands and those above 1 millimetre in the hundreds of millions. A graveyard orbit, or disposal orbit, is a region a few hundred kilometres above geostationary orbit to which old satellites are moved at the end of life so that useful orbital slots stay free.

5 min read · UPSC Prelims · Science & Technology · Space Technology and ISRO

At a Glance

Speed of debris About 7 to 8 km per second
Main danger Collision chain, Kessler syndrome
Graveyard orbit Above GEO
Guideline body IADC
Indian system NETRA
Exam link UPSC Prelims, Science & Technology: Space Technology and ISRO

Where Does It Fit?

This topic follows the account of anti-satellite weapons, which can create debris. It explains why the crowding of low orbits and the geostationary ring has become a safety and policy problem. Previous topic: Space Weaponry: Anti-Satellite (A-SAT) Technology. Next topic: South Asia Satellite.

What Is Space Debris and How Does It Arise?

Source or issue	Details
Dead satellites	Satellites that have stopped working but remain in orbit
Rocket bodies	Upper stages left in orbit, sometimes with fuel that can explode
Fragmentation events	Explosions and collisions, such as the Chinese anti-satellite test of 2007 which created thousands of tracked pieces, and the collision between the Iridium 33 and Cosmos 2251 satellites in 2009
Anti-satellite tests	Destructive tests make long-lived debris, as in Space Weaponry: Anti-Satellite (A-SAT) Technology
Small fragments	Paint flakes, bolts and insulation, which can still damage windows and solar panels
Kessler syndrome	A scenario in which debris collisions produce more debris, setting off a chain that makes some orbits unusable. Proposed by Donald Kessler in 1978
Crowded regions	Low Earth orbit between 700 and 1,000 km and the geostationary ring are most crowded

How Is Debris Tracked, Reduced and Managed?

Tracking: radar and optical telescopes follow large objects, and the United States tracks most of them and shares warnings
Collision avoidance: satellite operators and the International Space Station fire thrusters to move away from a predicted close approach
25-year rule: guidelines suggest that satellites in low orbit should leave orbit or fall back within 25 years after the end of their mission, and some agencies now ask for 5 years
Passivation: releasing leftover fuel and charge from a dead spacecraft to avoid explosions
Graveyard orbit: geostationary satellites are raised about 300 km above the ring, usually 235 km plus a margin, using the last fuel
Active removal: proposed methods include nets, harpoons, robotic arms, lasers and drag sails. A Japanese firm and ESA have planned demonstration missions
Design for demise: building satellites so that they burn up in the atmosphere on re-entry
International guidelines: the Inter-Agency Space Debris Coordination Committee and a United Nations committee have issued mitigation guidelines

What Else Should You Remember?

India’s actions: ISRO set up the Directorate of Space Situational Awareness and Management and the system called NETRA, Network for space object Tracking and Analysis, to detect and track debris and protect Indian satellites
IS4OM: ISRO System for Safe and Sustainable Space Operations Management in Bengaluru, created in 2022
Debris Free Space Missions: ISRO has set a goal of debris free space missions for the Indian government and private sector by 2030
PSLV Orbital Experimental Module: PSLV’s last stage is used as a platform for experiments and then deorbited, which avoids leaving debris
Controlled re-entry: ISRO brought down the dead Megha-Tropiques satellite in a controlled re-entry in March 2023 over the Pacific Ocean
Debris from Chandrayaan: launch stage re-entries and lunar craft need disposal plans
Registration Convention: countries must register space objects with the United Nations
Liability Convention: the launching State is liable for damage caused by its space objects on Earth or to aircraft, and fault based liability in space
Mega constellations: thousands of new satellites in LEO raise collision risk, as in Space Technology Innovations: Nanosatellites, Electric Propulsion, Satellite-Based Internet
Space traffic management: rules and coordination for orbit use are being discussed internationally
Sustainability: space is treated as a limited resource like air and sea, so long term sustainability guidelines have been adopted by the UN
Link: orbit crowding depends on orbit choice, as in Types of Orbits (LEO, MEO, GEO, Polar, Sun-Synchronous)

Why Does It Matter for the Exam?

Terms: Kessler syndrome, passivation, graveyard orbit
Events: 2007 Chinese test, 2009 collision
Indian measures: NETRA, IS4OM, 2030 goal
Current affairs link: mega constellations and debris removal
Common errors: saying that graveyard orbit is below geostationary orbit

As an analytical point, debris is a shared problem that needs shared rules. Strong mitigation, tracking and responsible design by all operators, including private ones, are needed to keep orbits usable.

Why Is This Topic Important?

Terms Kessler, passivation
Events Collisions and tests
India NETRA

What Came Next?

The next topic covers the South Asia Satellite built by India for its neighbours. Next topic: South Asia Satellite.

Key People and Terms

Debris Useless orbiting object
Kessler syndrome Collision cascade
Passivation Removing stored energy
Deorbit Bringing down from orbit
SSA Space situational awareness
Graveyard orbit Disposal orbit above GEO

Exam Corner

Points to Remember

Debris speed: about 7 to 8 km per second.
Kessler syndrome proposed in 1978.
Chinese test: 2007; collision: 2009.
Graveyard orbit is above GEO.
ISRO goal: debris free missions by 2030.

Do Not Confuse With

Space junk and meteoroids Human-made versus natural
Graveyard orbit and transfer orbit Disposal versus stepping stone
Passivation and deorbiting Removing energy versus bringing down

Memory Hook

Seven kilometres a second makes a speck a bullet; push the old ones above, bring the low ones down.

Mains Angle

Questions ask about causes, risks and mitigation. These points help.

Problem Growth of debris
Mitigation Rules and removal
India NETRA and 2030 goal

A Question You May Face

An original practice question, not a past paper question.

“Discuss the threat posed by space debris and the national and international measures to ensure the long term sustainability of outer space activities.”

How to Answer

Threat Collision cascade.
Causes Tests, rockets, satellites.
Measures Rules, tracking.
India NETRA, 2030.

GS Relevance

Prelims: debris sizes, Kessler syndrome, graveyard orbit, mitigation rules, ISRO NETRA. GS Paper 3: science and technology, space, environment.

Frequently Asked Questions

What is space junk?

Space junk, or space debris, is all the human-made objects in orbit that no longer serve any purpose, such as dead satellites, used rocket stages and fragments from explosions or collisions. Because it travels at about 7 to 8 kilometres per second, even a tiny piece can damage or destroy an active spacecraft.

What is the Kessler syndrome?

The Kessler syndrome is a scenario proposed by NASA scientist Donald Kessler in 1978 in which collisions between objects in orbit create more fragments, which cause further collisions in a chain reaction. This could make certain orbits so full of debris that they become unusable for satellites for a very long time.

What is a graveyard orbit?

A graveyard orbit, or disposal orbit, is an orbit a few hundred kilometres above the geostationary ring where satellites are moved when they reach the end of life. This frees valuable slots in geostationary orbit, because it would take far too much fuel to bring such high satellites down to Earth.

What is ISRO doing about space debris?

ISRO tracks objects and plans manoeuvres through its Directorate of Space Situational Awareness and Management and the NETRA system. It set up IS4OM in 2022 and aims for debris free space missions by 2030. It uses the last stage of PSLV as an experiment platform and brought down the Megha-Tropiques satellite in a controlled re-entry in 2023.

What are the international guidelines on space debris?

The Inter-Agency Space Debris Coordination Committee and the United Nations Committee on the Peaceful Uses of Outer Space have issued guidelines to reduce debris. They include avoiding intentional destruction, releasing stored energy from dead spacecraft, moving geostationary satellites to graveyard orbits and removing low orbit satellites within about 25 years of mission end.

PYQ Practice — Statement Analysis

1 A graveyard orbit lies above the geostationary orbit.

True

For disposal of old satellites.

2 The Kessler syndrome describes a chain of debris-creating collisions.

True

Proposed in 1978.

3 NETRA is a satellite for navigation developed by ISRO.

False

It is a debris tracking network.

4 Space debris travels slowly and rarely damages satellites.