A new phase of the space race is unfolding far above Earth, but its effects may not stay there. Satellite launches have increased sharply recently, largely driven by commercial mega-constellations designed to provide global broadband and other data services. Currently, the planet is home to nearly 15,000 active satellites, many designed to endure only a few years before their replacement. When they fail or reach the end of service, operators typically guide them back into the upper atmosphere, where they burn up. This practice aims to reduce space debris in low orbit. Researchers are starting to investigate the impact of repeated burn-ups on atmospheric chemistry, ozone stability, and long-term climate processes that remain incompletely mapped.
The new space race is building a crematorium for satellites above Earth
According to a study published in The Conversation, most retired satellites are deliberately de-orbited so they disintegrate during re-entry. Engineers describe this as demisability. The idea is simple. Hardware should not survive the fall.But when thousands of objects burn up each year, the process stops looking small. Scientists studying upper atmospheric aerosols in 2023 detected metal particles linked to spacecraft. Aluminium is widely used in satellite frames. When it burns, it forms alumina particles. These can remain suspended for long periods at high altitude.The exact material mix inside commercial satellites is not publicly detailed in most cases. That makes modelling difficult. Researchers are working with estimates. The uncertainty itself is part of the concern.
Plans for one million satellites would change the scale
In early 2025, SpaceX applied to the Federal Communications Commission for approval to expand its Starlink network dramatically. The proposal outlines up to one million additional satellites, described in filings as supporting future AI data infrastructure.Current Starlink V2 mini satellites weigh around 800 kilograms. Later versions are expected to be heavier. Proposed V3 models would be larger again, closer in size to a small aircraft in mass and structure.Each satellite would eventually re-enter. Using assumptions similar to earlier atmospheric studies, researchers have estimated that one million satellites could release close to a teragram of alumina into the upper atmosphere over time. That figure sits alongside emissions from rocket launches themselves, which already contribute to upper atmospheric heating and ozone loss.The chemistry at those altitudes is complex. Small particles can alter how heat is absorbed and how ozone reacts. The models are still being refined.
Collision risk in orbit is already rising
The pressure is not only atmospheric. In low Earth orbit, avoidance manoeuvres are becoming routine. The Outer Space Institute maintains a model known as the CRASH Clock. It estimates that if active avoidance stopped, a collision could occur within days.Experts have long warned of the Kessler syndrome, a cascading effect where debris from one collision triggers others. More satellites increase the statistical likelihood. Insurance markets are watching closely. So are national regulators.Not every satellite fully burns up on reentry. Some debris reaches the surface. Recent assessments suggest that the probability of a casualty from falling debris during a five-year cycle is significant and may approach 40% as constellations expand. The risk extends to aircraft as well.
