Story at a glance
- As more billionaires launch their rockets into space, the prospect of commercial space travel moves closer to reality.
- However, there are currently no national or international regulations in place to curb any environmental impact this sector might have.
- In a new study, researchers laid out the detrimental effects of rocket soot pollution on the Earth’s ozone layer.
Space tourism may seem like an intangible, futuristic phase of human recreation, complete with daily blast offs of the Earth’s most privileged occupants. But new research concludes the effects of this boom may be all-too-real for those of us left with our feet on the ground.
When rockets launch into space and re-enter Earth’s orbit, they can emit harmful pollutants directly into the upper stratospheric ozone layer, trapping heat underneath and insulating the Earth. One major contributor to this phenomenon is black carbon, or soot.
“The soot emitted from rockets is up to 500 times more efficient at holding heat in the atmosphere than soot from any other source,” lead study author Robert Ryan, an atmospheric chemist at the University College London, told Changing America. This means it takes only a few rocket launches to match soot pollution from a number of land vehicles or aircraft.
Using models based on 2019 commercial rocket launches and re-entries, researchers developed air pollutant emissions inventories and projected what impact these expeditions might have if carried out on a regular basis.
Rocket travel is the only activity humans undertake that directly pollutes the upper atmosphere, or stratosphere, Ryan said. Because of this, it can have deleterious effects on this pristine environment and the Earth as a whole.
“The higher you place things in the atmosphere, the longer they stay there. So the time that the soot stays in the atmosphere increases from, on the order of weeks when it’s in the lower atmosphere, to the order of years when it’s in the upper atmosphere,” he continued.
“The higher you put the soot particles in the atmosphere, the more incoming radiation they absorb.” The increased radiation interception will cause more warming.
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Three billionaire-owned companies, Richard Branson’s Virgin Galactic, Jeff Bezos’ Blue Origin, and Elon Musk’s SpaceX, each tested commercial flights in 2021, and Virgin Galactic has indicated it plans to eventually conduct 400 flights each year.
Based on this plan, the researchers devised a future scenario that modeled daily suborbital launches by Virgin Galactic and Blue Origin, and weekly orbital launches by SpaceX.
Under this scenario, three years of rocket emissions were double that measured in one decade under the status quo. Black carbon accounted for a large chunk of pollution.
Despite the relatively small loss of ozone occurring under current space exploration rates, as the industry grows more competitive and as more countries develop space defense programs, the threat of this pollutant rises.
In direct contrast to the rest of the transportation sector, no national or global regulations exist for environmental oversight of rocket travel.
The United States’ Environmental Protection Agency declined to comment for this story when contacted by Changing America, while the National Oceanic and Atmospheric Association did not respond to inquiries.
The use of kerosene by SpaceX rockets and hybrid synthetic rubber fuels by Virgin Galactic contribute to projected high rates of soot pollution. While some fuels like liquid hydrogen, used by Blue Origin, produce no soot, this alternative does not come without environmental costs.
“Even though liquid hydrogen burns cleaner in the atmosphere and produces no soot, the current mechanism for producing liquid hydrogen here at the surface is very carbon intensive,” Ryan said. Currently, “there really is no clean green magic fuel that makes space tourism climate safe.”
Of the three companies included in future simulations, SpaceX accounted for more than half of all black carbon emissions.
SpaceX did not return Changing America’s request for comment. Neither Virgin Galactic nor Blue Origin immediately replied to inquiries.
Not only is black carbon more detrimental than traditional greenhouse gasses in this scenario, but its impact on the stratospheric ozone layer has already been successfully addressed.
In 1987, the United Nations passed the Montreal Protocol agreement to regulate the production and consumption of ozone-depleting substances. To date, it is the only protocol that has been signed by every country on Earth, and resulted in member states phasing out 98 percent of these harmful pollutants.
Coincidentally, 35 years later the upper stratosphere is the only part of the ozone that has shown strong recovery since the Protocol went into effect, Ryan explained. “That is exactly where the impact of rocket emissions will hit hardest.”
Transitioning to cleaner fuels is one possible mitigation strategy should the space tourism industry continue on its current trajectory. But some experts argue being mindful of the reasons behind these missions is even more crucial.
Policy makers will ultimately need to weigh the benefits of gathering important scientific data or information for satellites and global positioning systems against the detriments of joy rides to space when crafting regulations for this new phase of space travel, Ryan said.
“What we really need now is a discussion amongst experts on the best strategy for regulating this rapidly growing industry,” said study co-author Eloise Marais in a press release. Marais is an assistant professor of physical geography at the University College London.
More research also needs to be done to better understand the long-term effects of rocket-induced stratospheric ozone pollution. Rocket and space junk re-entry can lead to nitrogen oxide production which has further implications for the ozone layer.
“But in addition to producing nitrogen oxides, when these metallic components come back into the atmosphere from space, many of them burn up and they produce a whole host of other chemicals,” Ryan said.
“We don’t yet fully know what the impact of all those different emissions will be.”
Published on Jul 08,2022