After all the years of hard work to restore the ozone layer, are rocket launches threating the success?
In the past five years, the world has gone from launching 90 rockets annually to 130 – a number that we expect to keep increasing.
But the effect of rocket emissions on the atmosphere is neither regulated internationally, nor closely tracked.
A review in the Journal of the Royal Society of New Zealand has pointed out that rocket launches can damage the ozone layer, which absorbs much of the Sun’s UV rays in the Earth’s stratosphere.
“The current impact of rocket launches on the ozone layer is estimated to be small but has the potential to grow as companies and nations scale up their space programmes,” says study co-author Dr Laura Revell, an associate professor in environmental physics at the University of Canterbury, New Zealand.
“Ozone recovery has been a global success story. We want to ensure that future rocket launches continue that sustainable recovery.”
Rocket fuel emissions can include black carbon (soot), alumina, chlorine, and nitrogen oxides. In total, they also emit around six kilotons of water vapour and 10 kilotons of carbon dioxide each year: this is equivalent to the carbon footprint of around 650 Australians.
But these gases and particles are emitted much higher in the atmosphere, where they can have very different effects. Carbon dioxide has a cooling influence in the stratosphere, for instance, while water vapour can react to destroy ozone.
With new rocket fuels constantly being developed, it’s difficult for researchers to keep up with the atmospheric effects.
“Rockets are a perfect example of a ‘charismatic technology’ – where the promise of what the technology can enable drives deep emotional investment – extending far beyond what the technology also affects,” says study co-author Dr Michele Bannister, a planetary scientist also at the University of Canterbury.
Read more: How safe are rocket launches?
In their paper, the researchers urge for stratospheric and ozone effects to be included on rockets’ environmental impact statements, alongside a range of other actions the space industry and ozone research community could take to make launches sustainable.
“The international ozone research community has a strong history of measuring atmospheric ozone and developing models to understand how human activities could impact this critical layer of our atmosphere,” says Revell.
“By working with launch providers, we are well-placed to figure out what impacts we might see.”