Space Debris Mitigation Guidelines Explained: IADC, UN and National Rules

Ask what law stops a satellite operator leaving a dead spacecraft in orbit and the honest answer is: not much at the international level. The Outer Space Treaty requires “due regard” for other States and the Liability Convention attaches liability to fault in orbit, but neither says when a satellite must be removed or how. That work is done by space debris mitigation guidelines, which are technical, voluntary at international level, and very influential.

This explainer sets out which guidelines exist, what they require, how they turn into enforceable rules, and where they are heading.

Why guidelines and not a treaty

States have never negotiated a treaty on space debris. Instead, space agencies worked out technical practices together, and the UN endorsed a simplified version. The advantage is speed and technical detail; the disadvantage is that nothing in them is binding unless a government makes it so.

There are three layers to keep apart. At the top are international guidelines (the IADC and UN COPUOS texts). In the middle are technical standards and agency requirements, such as ISO 24113 and the internal rules of NASA and ESA. At the bottom, and the only layer that binds companies directly, are national licensing rules. I covered why the debris problem is so hard to reverse in our piece on Kessler syndrome.

The IADC guidelines

The Inter-Agency Space Debris Coordination Committee (IADC) is a forum of 13 space agencies: those of Italy, France, China, Canada, Germany, Europe (ESA), India, Japan, South Korea, the United States (NASA), Russia, Ukraine and the United Kingdom. Its guidelines, document IADC-02-01, were first published on 15 October 2002 and revised in 2007, 2020 and 2021.

The current text is Revision 4, dated 16 January 2025, which the IADC submitted to the UN’s Scientific and Technical Subcommittee in February 2025. They apply to the planning, design and operation of spacecraft and rocket stages placed in Earth orbit, and they “describe existing practices” rather than create new obligations.

The guidelines protect two regions. Region A is low Earth orbit (LEO), from the surface up to 2,000 km. Region B is the geosynchronous region, 200 km either side of geostationary altitude (35,786 km) and within 15 degrees of the equator.

What the IADC guidelines ask

They are organised around four aims.

Limit debris released during normal operations. Spacecraft and rocket stages “should be designed not to release debris during normal operations”. If that is not feasible, releases should be minimised in number, area and orbital lifetime.

Prevent break-ups. At end of mission, all stored energy should be removed, a step known as passivation: venting or burning leftover propellant, discharging batteries and relieving pressure vessels. Intentional destruction “should be avoided”, and if it cannot be, it should happen at low altitude so the fragments are short-lived.

Dispose of spacecraft after their mission. For anything passing through LEO, the preferred option is direct re-entry. Otherwise the object should be put into a decaying orbit “with residual orbital lifetime limited to be as short as practicable and no more than a maximum of 25 years.” The probability of successful disposal “should be at least 90% with a goal of 99% or better.” For geostationary satellites, the guidelines call for a move to an orbit that stays outside the protected region for at least 100 years, and give a formula: a minimum perigee increase of 235 km plus an allowance for solar radiation pressure, with eccentricity no higher than 0.003. Re-entering debris should not pose “an undue risk to people or property”, and the guidelines recommend 1 in 10,000 as the upper limit for expected human casualties per re-entry.

Prevent collisions. Missions should estimate and limit the chance of collision, plan avoidance manoeuvres where reliable data exist, and, since Revision 4, make hard-to-track objects easier to track with on-board components.

What changed in 2025: constellations

Revision 4 is the first version with a section on large constellations. It notes that “some agencies use a lower limit of 100 spacecraft” to define one, and recommends separation within a constellation, at the intersections of its orbital planes, and from other constellations and busy orbits. It encourages operators of demonstrators, low-reliability spacecraft and constellations to commission them in sparsely populated orbits with short lifetimes, away from crewed stations. And it says the “cumulative risk due to more frequent re-entries from constellations” should be minimised.

It also acknowledges that the 25-year ceiling is no longer the practice for large systems: “many constellation operators limiting residual orbital lifetimes to weeks or months.” That sentence matters, because guidelines that describe existing practice can be used to argue what a reasonable operator does.

The UN COPUOS guidelines

The Space Debris Mitigation Guidelines of the Committee on the Peaceful Uses of Outer Space are the version most States have formally signed up to. They were adopted by the Committee’s Scientific and Technical Subcommittee in February 2007, accepted by the Committee in June 2007, and endorsed by the UN General Assembly in resolution 62/217 of 22 December 2007, which invited States to implement them “through relevant national mechanisms”.

There are seven:

1. Limit debris released during normal operations.
2. Minimise the potential for break-ups during operational phases.
3. Limit the probability of accidental collision in orbit.
4. Avoid intentional destruction and other harmful activities.
5. Minimise potential for post-mission break-ups resulting from stored energy.
6. Limit the long-term presence of spacecraft and rocket stages in LEO after the end of their mission.
7. Limit the long-term interference of spacecraft and rocket stages with the GEO region after the end of their mission.

They are shorter than the IADC text and contain no numbers: guideline 6 does not mention 25 years. They also say plainly that they “are not legally binding under international law” and that exceptions may be justified.

In 2019 the Committee adopted a wider set of Guidelines for the Long-term Sustainability of Outer Space Activities, covering regulatory frameworks, safety of operations, cooperation and research. They are also voluntary.

Standards and agency rules

Engineers need requirements they can verify, so the guidelines have been turned into standards. ISO 24113:2023, now in its fourth edition, published in May 2023, sets the “primary space debris mitigation requirements” for uncrewed systems in near-Earth space.

Agencies apply their own versions to their missions. NASA’s procedural requirements, NPR 8715.6E, took effect on 18 April 2024, and the US Government’s Orbital Debris Mitigation Standard Practices, established in 2001, were updated in 2019. ESA issued its Space Debris Mitigation Requirements in 2023.

ESA has also gone beyond the guidelines with its Zero Debris approach, which aims for debris neutrality by 2030. The related Zero Debris Charter “is not legally binding”, according to ESA’s own FAQ; ESA says over 200 companies, research centres and international organisations and more than 20 countries have joined it.

How guidelines become law

Guidelines bind operators only when a regulator makes them licence conditions. Three examples show the range.

In the United States, the FCC requires satellites in LEO it licenses or grants market access to be disposed of within five years of the end of their mission, a deliberate step beyond the IADC’s 25 years. I explained the background in our piece on the FCC’s five-year deorbit rule.

In Europe, France sets debris requirements in the technical regulation under its Space Operations Act, which the IADC cites in its version of 28 June 2024. In the UK, orbital operators need a licence from the Civil Aviation Authority, as set out in our guide to UK space licensing.

At EU level, the Commission’s proposal for an EU Space Act, published on 25 June 2025, would make collision avoidance, debris mitigation and end-of-life disposal binding requirements for operators serving the EU market. It is still going through the legislative process, as I explained in our EU Space Act explainer.

Why voluntary guidelines still matter in disputes

The Liability Convention makes a launching State liable for damage in space only if the damage is due to its fault. With no treaty standard of care, the obvious place to look for one is the debris guidelines that almost every spacefaring State has endorsed. An operator that ignored passivation or left a dead satellite in a crowded orbit for decades would struggle to argue that it acted reasonably. I set out that argument in more detail in our piece on who is liable for space debris.

What I would watch

The first is the 25-year figure. The IADC still uses it as an upper limit, the FCC has moved to five years, and the IADC itself now records that many constellation operators work to weeks or months. I expect pressure for a shorter international figure at the next revision.

The second is constellation separation. Revision 4’s recommendations on spacing between constellations are qualitative. If regulators start writing numbers into licences, it will change how new constellations are designed and coordinated.

The third is re-entry. The 1 in 10,000 casualty threshold applies per re-entry, while the new constellation section talks about cumulative risk. How regulators measure the combined risk from thousands of re-entries is an open question.

The fourth is the EU Space Act. If it passes with binding debris rules for any operator serving EU customers, it will extend European standards to non-EU operators in the same way the FCC’s rules reach foreign satellites seeking US market access.

This explainer reflects the IADC guidelines (Revision 4), the UN COPUOS guidelines and the other sources linked above as at 23 October 2026. It is general information, not legal advice.

Questions people actually ask

What are the space debris mitigation guidelines?

They are technical guidelines for limiting space debris. The main sets are the IADC Space Debris Mitigation Guidelines, agreed by 13 space agencies and last revised in January 2025, and the UN COPUOS Space Debris Mitigation Guidelines, endorsed by the UN General Assembly in resolution 62/217 on 22 December 2007.

Are the UN space debris mitigation guidelines legally binding?

No. The UN COPUOS guidelines state that they are not legally binding under international law. States are invited to implement them through national mechanisms, which is how they become binding on operators through licences and regulations.

What is the 25-year rule for satellites?

Under the IADC guidelines, a spacecraft or rocket stage in low Earth orbit should be removed by direct re-entry or placed in an orbit that decays as soon as practicable and within 25 years at most. The FCC now requires disposal within five years for the satellites it regulates.

What changed in the 2025 IADC guidelines?

Revision 4, dated 16 January 2025, added a section on large constellations covering separation between and within constellations, commissioning in sparsely populated orbits and cumulative re-entry risk. It also encourages high disposal success rates in LEO and better trackability of small objects.

What happens to geostationary satellites at end of life?

The IADC guidelines say they should be moved to a disposal orbit that stays outside the geosynchronous protected region for at least 100 years, using a minimum perigee increase of 235 km plus an allowance for solar radiation pressure, with eccentricity no higher than 0.003.

Who enforces space debris mitigation guidelines?

No international body does. National regulators enforce them through licensing, such as the FCC in the United States and the CAA in the United Kingdom, and space agencies enforce their own requirements on their missions. The proposed EU Space Act would add binding EU-wide rules.