The rapid increase in rocket launches could slow the recovery of the ozone layer, according to a recent study. Scientists warn of potentially underestimated impacts.
Emissions from rockets and re-entering space debris accumulate in the middle layers of the atmosphere. Unlike ground-based pollutants, they persist there much longer, exacerbating their effect on ozone. This protective layer, essential for filtering harmful UV rays, already shows signs of fragility.
View of the Raptor engines on the Super Heavy booster during Starship's second flight.
Image SpaceX
Research by an international team, published in
npj Climate and Atmospheric Science, reveals alarming projections. With an estimated 2,040 annual launches by 2030, ozone levels could decrease by 0.3% on average, peaking at 4% over Antarctica. These figures add to the historical damage caused by CFCs.
Fuel choice plays a crucial role in rockets' environmental impact. Solid-fuel engines, rich in chlorine, and those emitting soot particles are particularly harmful. Only systems using cryogenic fuels, such as liquid oxygen and hydrogen, pose a low risk to ozone.
The effects of satellite re-entries remain poorly understood. These events release metals and nitrogen oxides, which may worsen ozone depletion. The absence of this data in current models suggests the actual impact could be underestimated.
How do rockets affect the ozone layer?
Rockets release substances like chlorine and soot particles into the atmosphere, damaging the ozone layer. Chlorine acts as a catalyst, destroying ozone molecules, while soot heats the atmosphere, accelerating harmful chemical reactions.
These emissions are particularly problematic in the middle atmospheric layers, where they persist for long periods without natural removal processes. Unlike ground pollutants, they are not washed away by rain, prolonging their impact.
Solid-fuel engines are the main emitters of chlorine, while most rocket fuels produce soot. The projected increase in launches could thus worsen the situation, delaying ozone layer recovery by decades.
What are the alternatives to harmful rocket fuels?
Cryogenic fuels, such as liquid oxygen and hydrogen, offer a promising solution. They emit virtually no chlorine or soot, minimizing their impact on the ozone layer.
However, their use is limited. Handling them requires specialized infrastructure and strict precautions, increasing mission costs and complexity.
Other alternatives, such as biofuels or less polluting propellants, are under study. These options could reduce the environmental footprint of launches without sacrificing performance.
The development and adoption of these technologies will depend on investments and regulations encouraging their use.