According to a recent report, the ozone layer is on track to heal within four decades UN reportbut this progress could be reversed by an increase in the number of missile launches expected over the same period.
The ozone layer protects life on Earth from the sun’s harmful ultraviolet (UV) rays. The destruction of the ozone layer became a major international problem in 1985 when the “ozone hole” emerged discovers over Antarctica.
Thanks to a coordinated global effort, the Montreal Protocol came into effect in 1987, leading to a ban on a class of chemicals called hydrochlorofluorocarbons (CFCs), which were used in aerosol cans and refrigeration. There was a global crisis avoided as result.
But the global space industry is growing rapidly, with an increasing number of annual rocket launches. As we show in our new reviewcould the gases and particles emitted by rockets as they smash through the atmosphere lead to delays in the recovery of the ozone layer.
Rocket fuel emissions are not regulated
The launch industry today relies on four major fuel types for rocket propulsion: liquid kerosene, cryogenic, hypergolic, and solid. By burning these fuels, modern rockets create a range of gaseous and particulate exhaust products, including carbon dioxide, water vapor, black carbon, alumina, reactive chloride, and oxides of nitrogen. These products be famous destroy ozone.
In the stratosphere, a higher level of the atmosphere where the protective ozone layer is located, emissions linger much longer than lower. Small amounts of an exhaust by-product can have greater destructive effects in the upper atmosphere than close to the Earth’s surface.
One new fuel is methane, which is used in several rocket engines being developed by major launch companies. The emission products of methane are still poorly understood.
As we outline, rocket emissions into the upper atmosphere can deplete the ozone layer, but are not regulated. We argue that this policy gap needs to be filled to ensure sustainable growth of the rocket launch industry and protection of the ozone layer.
Solid rocket fuel contains a chemical that releases chlorine into the upper atmosphere and destroys ozone. CFCs were banned because they contain chlorine.
Fortunately, the number of launches so far is so small that the effects on the ozone layer are currently insignificant. However, the launch industry will grow significantly in the coming decades. Financial estimates indicate that the global space industry could grow to $3.7 trillion by 2040.
Rockets have exciting potential to enable industrial-level access to near-Earth space and exploration throughout the solar system. This makes them “charismatic technology” – and the promise of what the technology makes possible encourages deep emotional investment.
The lure of possibility may even get in the way of discussing how missiles can achieve these ambitious goals without damage. We must be able to have clear discussions.
Many communities – missile launch suppliers, environmental regulators, atmospheric research scientists and government agencies – need to move forward together at the international level. Discussions on how best-practice operations for sustainability can be set up need not hinder the growth of the aerospace industry, as possible actions are well within reach.
The greatest contribution any community can make is primarily data collection and sharing. For example, those who build and launch rockets can estimate emissions during their design work and then measure the actual emissions for their launchers.
Working with researchers to sample emissions plumes in the atmosphere could provide a better understanding of the real-world effects of emissions on the ozone layer. The current lack of these measurements for modern launch vehicles limits the predictive power of atmospheric modelling. Making data easily accessible to researchers is necessary for meaningful progress.
To evaluate emissions in early stages of rocket development, we also need accurate models of the impact emissions have on the atmosphere. This is where coordination between the aerospace industry and the ozone research community is essential – each community has a complementary puzzle piece, both of which together shape the regulatory discussion.
Creating sustainable global rocket launches will require coordination between space companies, scientists and governments: it’s feasible, but we need to start now. This is our chance to lead the way.