A growing corpus of scientific evidence suggests that the Earth’s vital ozone layer may now face a new threat from the fast increasing number of space launches.
Our ozone layer is frequently hailed as a major victory for the environment. Countries all around the world have united to stop producing and emitting the chemical compounds that contributed to the rapid thinning of the ozone layer above Antarctica since the adoption of the Montreal Protocol, an international convention to safeguard the ozone, in 1987. The most current United Nations report, published in January, shows that we’re on schedule for a complete ozone recovery by 2066, despite a temporary decline in the 2010s.
The U.N. study did, however, include a caution: Just because we are moving towards ozone recovery doesn’t imply it is a given. Decades of global advancement could be thwarted by a variety of threats, both ancient and new. Geoengineering plans to lessen climate change are among these potential threats to the ozone layer. There is also the danger of climate change itself; increased emissions of aerosols and greenhouse gases may jeopardise ozone recovery. Space launches are another another issue for us to think about, as the U.N. notes.
The scientists state in their paper that the total amount of stratospheric ozone is currently only slightly impacted by rocket launches. However, the paper warns that when new propellants, satellite constellations, and an ongoing rise in the frequency of space launches become available, this is likely to change. According to a research study published last month in the Journal of the Royal Society of New Zealand, the number of satellites launched has been growing exponentially, and in 2022, more than 180 rockets were sent into space, the most ever in a year.
“We have known since the early 1990s that emissions from rocket launches may cause the ozone layer to disintegrate. But because there have been so few launches, the consequences have never really been a huge issue, according to Laura Revell, an atmospheric chemist at the University of Canterbury in New Zealand and the study’s principal author, in a video conversation with Gizmodo.
But, Revell remarked that is beginning to change, and as a result, so must research, monitoring, and space exploration. She said that there is little monitoring or control over the effects of rocket launches on the upper atmosphere. Yet, we believe that now is the ideal time to solve it, before the number of launches globally truly starts to increase.
The recent assessment by Revell and two other experts evaluated the growing danger posed by space launches. The scientists examined dozens of prior research and discovered evidence that various exhaust products from launches can adversely affect the ozone through a variety of chemical reactions or the temperature changes they induce. Water vapour, nitrogen oxides, black carbon, alumina particles, hydrogen gas, and hydrogen chloride are just a few of these alarming pollutants. Furthermore, because of the way launches work, these ozone-damaging chemicals and particles are being sent right to the stratosphere, where 90% of the atmosphere’s ozone is found, where they can cause the most harm.
Although some academics have started to examine the actual effects of specific launches, this area of study is still in its infancy, and the science is still mostly based on models rather than actual observations. Revell stressed that there are numerous things that we do not yet understand. The majority of the most recent data heavily relies on plume modelling or the best estimates from combustion calculations because measurements of exhaust plumes are few. Even liquid kerosene, the most widely used fuel, is still only very imperfectly predicted in exhaust quantities, according to the study’s authors.
Researchers frequently discover unsettling findings when they examine the intricacies of particular launches. The 2016 Falcon 9 launch of the Thaicom-6 satellite was modelled in a 2022 study, and the results showed that this single launch most likely caused a metric tonne of ozone-depleting nitrogen oxides, or nearly 1,400 automobiles’ worth of annual emissions. The 2022 modelling analysis also shows that the total ozone loss from rocket launches may be more than ten times greater than previously thought due to a lack of thorough investigation.
Yet, the ozone layer should not get thinner just because there are more rocket launches. Revell and her co-authors not only identified the issue of rising space launches and probable ozone effects, but they also recommended a way forward for atmospheric researchers and private space enterprises to address the issue. They believe that a sustainable future for space travel is possible and that the sooner adjustments are made, the better.
Their recommendations include expanding access to open data on launch emissions as well as conducting additional research and monitoring to maintain track of launch emissions. Another suggestion is for launch service companies to take into account how their rockets will behave in the stratosphere throughout the design and testing phases.
In an email to Gizmodo, Tyler Brown, an astrophysics researcher at the University of Canterbury and the study’s first author, emphasised that this wasn’t a doom-and-gloom forecast. In the future, a lot of things can and will change. Our fundamental objective is to start real conversations about action—not simply awareness—in the present about a sustainable rocket business.