The European Space Agency (ESA) has warned that Earth’s orbital environment is becoming increasingly congested, with rising numbers of satellites, rocket bodies and fragments creating greater risks for future space missions.

Its latest Space Environment Report shows that the rapid expansion of space activity is outpacing efforts to keep the orbital environment sustainable. More than 300 launches took place during 2025, placing over 4,000 new payloads into orbit, according to the report.

The growth of large satellite constellations and rideshare missions means significantly more spacecraft are now being deployed, while the space debris population continues to grow through both fragmentation events and defunct satellites.

ESA’s assessment suggests the problem is moving beyond simply managing an increasing number of objects. The agency says the orbital environment is now showing signs of the self-reinforcing process associated with the Kessler syndrome, in which collisions generate debris that can trigger further collisions.

Without stronger prevention and active debris removal, some orbital regions could eventually become increasingly difficult or unsafe to use.

Space activity is expanding rapidly

The latest Space Environment Report highlights how quickly the commercial space sector is changing.

More spacecraft are being launched in each mission, largely because of the expansion of satellite constellations and the increasing use of rideshare launches.

At the same time, satellites are becoming distributed across a broader range of orbital altitudes rather than remaining concentrated within a small number of established orbital bands.

That expansion creates a more complicated environment for operators. More spacecraft sharing orbital space increases the importance of accurate tracking, coordination and information exchange between satellite operators.

ESA also reports a growing number of detected objects whose origins it cannot yet identify. Improvements in observation technology mean more fragments can be detected, but many cannot be confidently connected to a particular satellite, rocket or fragmentation event.

The agency says this widening gap between detection and identification underlines the need for better monitoring and space traffic management.

Space debris continues to accumulate

The increase in launches is only part of the problem.

Objects already in orbit can break apart through collisions or other fragmentation events, producing large numbers of smaller pieces travelling at extremely high speeds. Even relatively small fragments can pose serious risks to operational spacecraft.

The latest assessment indicates that the long-term trajectory of the debris population has worsened despite improvements in mitigation practices.

ESA says projections for objects larger than 10 centimetres are now showing higher numbers than in previous years, with the forecasting period shortened from 200 years to 100 years while still producing more concerning results.

The significance is that simply slowing the creation of new debris may no longer be enough.

If fragmentation continues to generate debris faster than objects naturally fall back into the atmosphere, the number of hazardous objects can keep increasing even if no additional satellites are launched.

Kessler syndrome becomes a growing concern

The report identifies the potential development of the Kessler syndrome as the most serious long-term threat.

The concept describes a cascading process in which collisions between objects create fragments, increasing the probability of further collisions. Those subsequent impacts generate still more debris, potentially creating a cycle that becomes increasingly difficult to control.

ESA says the effects of this runaway process are becoming visible earlier than previously expected as active satellite numbers and large constellations continue to grow.

This raises concerns not only about individual missions but about the long-term availability of important orbital regions. If debris densities become sufficiently high, operating spacecraft in some areas could become considerably more challenging.

More spacecraft are being disposed of responsibly

The picture is not entirely negative.

Reentry activity remained high during 2025, with ESA reporting around 10 objects launched each day and more than 10 intact objects returning to Earth daily. The increase reflects both the overall expansion of space activity and better compliance with debris mitigation requirements.

The shift towards shorter orbital lifetimes is particularly significant. Disposal targets for low-Earth orbit have moved from the traditional 25-year benchmark towards a five-year target, encouraging operators to remove spacecraft from useful orbital regions more quickly.

Controlled rocket-body reentries also outnumbered uncontrolled reentries for the second consecutive year, which ESA identifies as evidence of progress towards more responsible space operations.

However, responsible disposal does not eliminate the wider debris problem.

Ground risks from reentering debris

ESA has introduced a new measure in its 2026 report examining the potential casualty risk from fragments that survive atmospheric reentry.

The agency stresses that the probability of an individual person being harmed remains low compared with many everyday risks. Nevertheless, the upward trend matters because the number of launches, satellites and reentries continues to increase.

One potential response is greater use of controlled reentries, alongside spacecraft designed to burn up more completely in the atmosphere. These so-called design-for-demise approaches could reduce the quantity of material reaching the Earth’s surface.

ESA also says atmospheric pollution from spacecraft reentries is becoming an increasingly important issue and that further data is needed to understand its scale and determine whether additional mitigation measures are required.

ESA calls for debris removal

The Space Environment Report makes clear that preventing new space debris remains essential, but ESA argues that prevention alone is no longer sufficient.

The agency is pursuing its Zero Debris Approach, with a goal of significantly limiting debris generated by future missions, programmes and activities in Earth and lunar orbits by 2030.

Measures include tighter debris mitigation requirements, international cooperation through the Zero Debris Charter and the development of spacecraft designed specifically to minimise debris generation.

At the same time, ESA and its partners are developing technologies capable of removing existing objects from orbit.

The ClearSpace-1 mission is intended to demonstrate active debris removal, while other initiatives are examining ways to make spacecraft easier to capture, service or deorbit in the future.

Towards a more sustainable space economy

ESA is also looking beyond debris removal towards a more circular approach to spaceflight.

Instead of treating satellites as disposable assets, the agency sees potential in technologies that allow spacecraft to be refuelled, repaired, maintained and eventually reused in orbit.

Such an approach could reduce the need to continually launch replacement spacecraft while changing how satellites are designed and operated.

The latest findings underline a central challenge for the rapidly expanding space industry: keeping access to orbit sustainable while launch rates and satellite populations continue to rise.

ESA’s Space Environment Report makes the message increasingly clear.

Better tracking and responsible disposal can slow the growth of space debris, but avoiding a future in which orbital collisions become self-sustaining will require a combination of stricter mitigation, improved space traffic management and active removal of existing debris.