TORONTO — Billionaire Sir Richard Branson rocketing to space on his Virgin Galactic winged rocket ship was another step in the beginnings of what some see as a significant new era of space exploration – space tourism.
But the promise of a future with regular launches carrying private citizens into orbit and beyond also comes with concerns about the environmental impact of all those rocket launches, including their potential carbon footprints and the impact of elements they will deposit in the upper atmosphere.
It’s an issue that hasn’t garnered much attention in the past, likely because the amount of emissions from factories, cars, jet airplanes and various other sources is currently much more significant than from space rockets. In 2020, for instance, there were 114 attempted orbital launches in the world, according to NASA. That compares to the airline industry’s more than 100,000 flights each day on average, according to flightradar24.com.
But the new version of the space race, one in which Branson’s Virgin Galactic is just one of several private players, opens the door to a massive expansion in the number of launches that researchers are struggling to wrap their heads around, says Eloise Marais, an associate professor of physical geography at University College London who is currently conducting research on pollutant emissions from rocket launches.
“It’s really hard to know how much the space sector is going to grow in the future,” she told CTVNews.ca in an interview.
While many might assume that the biggest environmental threat from increased space travel is from higher greenhouse gas emissions, Marais’ research is focused on an area some see as a more significant threat, which is the potential damage to the ozone layer, which helps shield the Earth from the sun’s harmful ultraviolet radiation.
Fears about damage to the ozone layer from chlorofluorocarbons in aerosol sprays and air conditioners prompted a phasing out of their use starting in the late 1980s. But Marais’ research, which is still in progress, shows the potential for damage to the layer from the enormous amounts of fuel rockets use to get them to the speeds necessary to reach space.
“A rocket is very high energy, very high temperature and so it emits things like nitrogen oxides which once released directly into the stratosphere can contribute to depleting ozone,” says Marais.
While launch systems such as the Russian Soyuz craft that currently ferries astronauts to and from the International Space Station, as well as Elon Musk’s SpaceX vehicle, use liquid rocket fuel, there are even more destructive effects from systems that use solid fuel, such as Virgin Galactic, says Marais.
“Solid rocket fuel is really the worst,” she said. “They produce a lot of chlorine, a lot of nitrogen oxides and those are quite efficient at depleting ozone.”
She isn’t the first researcher to point to the potential threat to the ozone layer from space flight.
“While there are a number of environmental impacts resulting from the launch of space vehicles, the depletion of stratospheric ozone is the most studied and most immediately concerning,” Jessica Dallas, currently a senior policy advisor at the New Zealand Space Agency, wrote in an analysis of research on space launch emissions published last year in the Journal of Cleaner Production.
In a separate report from 2019, authors Martin Ross and James Vedda of research firm The Aerospace Corporation, wrote that the current concerns about rocket emissions are similar to early concerns about space debris, which have since become an acknowledged threat to the space industry.
“Today, launch vehicle emissions present a distinctive echo of the space debris problem. Rocket engine exhaust emitted into the stratosphere during ascent to orbit adversely impacts the global atmosphere,” they wrote.
They point both to the threat to the ozone layer from chlorine emissions, and also to the potential threat of particles such as soot and alumina expelled from rockets into the upper atmosphere which can absorb and reflect solar energy, and change the temperature of both the upper atmosphere and the Earth’s surface. The possible heating of the upper atmosphere from this can also damage the ozone layer.
Marais said she hopes her research can help guide future space industry regulation that may become necessary as the space tourism industry expands.
“We essentially want to advocate against the use of solid rocket fuel. Because the space sector is inevitably going to grow, but we certainly want it to grow more responsibly,” she said.