American researchers have warned that space rockets could do more damage to the ozone layer than old-school spray-cans and fridges.

"As the rocket launch market grows, so will ozone-destroying rocket emissions," said Professor Darin Toohey, atmosphere and ocean scientist at Colorado Uni. "If left unregulated, rocket launches by the year 2050 could result in more ozone destruction than was ever realized by CFCs."

Chlorofluorocarbons (CFCs) were banned from use in aerosol cans, freezer refrigerants and air conditioners by the Montreal Protocol in 1987. Some scientists believe that the upper-atmosphere ozone layer - which protects the Earth's surface from harmful solar ultraviolet - will return to normal by 2040 as a result.

But Toohey and his collaborators say the potential damage caused by rocket exhaust has been ignored.

"The Montreal Protocol has left out the space industry, which could have been included," says the prof.

Toohey's co-authors include Martin Ross of US government-funded R&D outfit The Aerospace Corporation. He, Toohey and the rest believe that more research is needed into the amount of ozone damage caused by different types of rockets. They argue that, should the ozone layer continue to deplete - or even fail to regenerate as expected - tough new regulations might outlaw the space industry.

"Space system development often takes a decade or longer and involves large capital investments," says Ross. "We want to reduce the risk that unpredictable and more strict ozone regulations would be a hindrance to space access by measuring and modelling exactly how different rocket types affect the ozone layer."

The scientists write:

Currently, global rocket launches deplete the ozone layer [approximately] 0.03%, an insignificant fraction of the depletion caused by other ozone depletion substances (ODSs). As the space industry grows and ODSs fade from the stratosphere, ozone depletion from rockets could become significant ... Large uncertainties in our understanding of ozone loss caused by rocket engines leave open the possibility that launch systems might be limited to as little as several tens of kilotons per year ... limitations on launch systems due to idiosyncratic regulation to protect the ozone layer present a risk to space industrial development. The risk is particularly acute with regard to the economic rationale to develop low-cost, high flight rate launch systems.

Their research, presented in the paper Limits on the Space Launch Market Related to Stratospheric Ozone Depletion, can be read here by subscribers to the Astropolitics journal. It was funded by the US National Science Foundation, NASA and The Aerospace Corporation - in other words by the US government. ®

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