Will Rocket Launches Deplete the Ozone?

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A new study predicts that Earth’s stratospheric ozone layer will suffer significant damage from future unregulated rocket launches. The study provides a market analysis for estimating future ozone layer depletion based on the expected growth of the space industry and known impacts of rocket launches. The increase in launches could cause ozone depletion that eventually could exceed ozone losses from CFCs (chlorofluorocarbons) which were banned in the 1980’s. “As the rocket launch market grows, so will ozone-destroying rocket emissions,” said Professor Darin Toohey of CU-Boulder’s atmospheric and oceanic sciences department, a member of the study. “If left unregulated, rocket launches by the year 2050 could result in more ozone destruction than was ever realized by CFCs.” The study says more research should be done on how different rockets affect the ozone before imposing stricter regulations on chemicals used in rocket fuels.

Current global rocket launches deplete the ozone layer by no more than a few hundredths of 1 percent annually, said Toohey. But as the space industry grows and other ozone-depleting chemicals decline in the Earth’s stratosphere, the issue of ozone depletion from rocket launches is expected to move to the forefront.

Rockets around the world use a variety of propellants, including solids, liquids and hybrids. Martin Ross, lead author of the study from The Aerospace Corporation Ross said while little is currently known about how they compare to each other with respect to the ozone loss they cause, new studies are needed to provide the parameters required to guide possible regulation of both commercial and government rocket launches in the future.

Since some proposed space efforts would require frequent launches of large rockets over extended periods, the new study was designed to bring attention to the issue in hopes of sparking additional research, said Ross. “In the policy world, uncertainty often leads to unnecessary regulation,” he said. “We are suggesting this could be avoided with a more robust understanding of how rockets affect the ozone layer.”

“Twenty years may seem like a long way off, but space system development often takes a decade or longer and involves large capital investments,” Ross continued. “We want to reduce the risk that unpredictable and more strict ozone regulations would be a hindrance to space access by measuring and modeling exactly how different rocket types affect the ozone layer.”

Highly reactive trace-gas molecules known as radicals dominate stratospheric ozone destruction, and a single radical in the stratosphere can destroy up to 10,000 ozone molecules before being deactivated and removed from the stratosphere. Microscopic particles, including soot and aluminum oxide particles emitted by rocket engines, provide chemically active surface areas that increase the rate such radicals “leak” from their reservoirs and contribute to ozone destruction, said Toohey.

In addition, every type of rocket engine causes some ozone loss, and rocket combustion products are the only human sources of ozone-destroying compounds injected directly into the middle and upper stratosphere where the ozone layer resides, he said.

The research team is optimistic that a solution to the problem exists. “We have the resources, we have the expertise, and we now have the regulatory history to address this issue in a very powerful way,” said Toohey. “I am optimistic that we are going to solve this problem, but we are not going to solve it by doing nothing.”

Source: EurekAlert