Space race could pollute layers of Earth’s atmosphere – 01/10/2024 – Science

The high-altitude chase began over Cape Canaveral, Florida, on February 17, 2023, with the launch of a SpaceX Falcon 9. Thomas Parent, a NASA research pilot, was there when the rocket rose past the right wing, leaving him mesmerized before accelerating.

For about an hour, Parent dove in and out of the plume left by the rocket, while Tony Casey, the sensor equipment operator aboard the jet, monitored 17 scientific instruments.

The researchers hoped to use the data to prove they could capture a rocket plume and then observe the environmental effects of a space launch.

In recent years, the number of rocket launches has increased dramatically, with commercial companies — especially Elon Musk’s SpaceX — and government agencies launching thousands of satellites into low Earth orbit.

And that’s just the beginning. Satellites could number as many as 1 million, requiring an even greater number of space launches, which in turn could result in more emissions.

SpaceX has refused to comment on pollution caused by rockets and satellites.

Representatives from Amazon and Eutelsat OneWeb, companies also working to form satellite megaconstellations, said they are committed to sustainable operations.

Scientists, however, are concerned that the increase in launches will spread more pollutants into the pristine layers of Earth’s atmosphere. And regulators around the world, who assess some of the risks of these releases, do not set rules related to pollution.

Experts emphasize that they do not want to limit the space economy. However, they fear that the advancement of science will be slower than the new space race, that is, that we run the risk of understanding the consequences of pollution caused by rockets and spacecraft only when it is too late. There are already studies that show that the highest layers of the atmosphere are contaminated with metals from spacecraft that disintegrated upon returning to Earth.

“We are changing the system faster than our ability to understand those changes,” said Aaron Boley, an astronomer at the University of British Columbia and co-director of the Outer Space Institute.

90 seconds

When a rocket like the Falcon 9 takes off, it usually takes about 90 seconds to cross the troposphere. It was at the top of the latter that Parent began his pursuit and then overtook it, reaching a layer where the air density is so low that he and Casey had to wear pressure suits and heavy gloves, as well as helmets that supplied oxygen.

Commercial planes rarely fly at these altitudes, nor is there any pollution from the ground. So it’s quiet, pristine, and empty — except for the occasional rocket, which will pass by for three to four minutes on its way to space. When a rocket enters orbit, it will have shed layers of the atmosphere about two-thirds of its exhaust, which scientists predict will fall and accumulate in the stratosphere.

The stratosphere is home to the ozone layer, which protects us from harmful solar radiation. However, she is sensitive: even the smallest changes can have huge effects on her — and the world below.

When Mount Pinatubo erupted in the Philippines in 1991, it released enough sulfur dioxide gases into the stratosphere to trigger a period of cooling on Earth that lasted several years. This gas created sulfate aerosols, which heated the stratosphere while blocking heat from reaching Earth’s surface. Some scientists worry that rockets could affect the climate in similar ways.

Today, rocket exhaust is insignificant compared to that of aviation. The fear, however, is that even small additions to the stratosphere will have a much greater effect.

Rise

In the 1990s, when NASA’s space shuttle and other rockets were consistently launching from American soil, several studies predicted that spacecraft would cause local damage to the ozone layer. One suggested a loss of up to 100%, meaning the formation of a small ozone hole above Cape Canaveral that would allow more of the Sun’s ultraviolet radiation to reach the ground, increasing the risk of skin cancer, cataracts and immune disorders.

The studies were based on models and predictions, without observational data. So Ross and his colleagues collected data from high-altitude research flights, which found local ozone holes in the space shuttle’s wake. But they soon disappeared and were not large enough to affect Cape Canaveral, at least not at the frequency of launches at the time, about 25 per year.

The same may not be true in the future. In 2023 alone, SpaceX launched nearly a hundred rockets on its own, with most flights building on its Starlink satellite constellation. It will soon be joined by Amazon, which plans frequent launches for its Project Kuiper constellation, and other companies seeking substantial presences in orbit. These satellites offer a variety of benefits, including broadband internet almost anywhere.

But once these companies complete their constellations of up to thousands of satellites, the launches won’t stop. Many satellites have a lifespan of 5 to 15 years, requiring satellite companies to launch replacements.

It’s the beginning of a new era

“We don’t want to stop the space industry,” said Karen Rosenlof, a climate scientist at the National Oceanic and Atmospheric Administration’s Chemical Sciences Laboratory, who says satellites provide incredible services for people on the ground. But she and other scientists advocate a set of regulations that consider environmental implications.

Rosenlof argues that there are ways to reduce the impacts of the space industry. For example, if the level at which the space industry would begin to harm the environment is identified, it would make sense to limit the number of launches and satellites. Another alternative would be to try to adapt the materials or fuels used by the space industry.

But that would require regulations. And today there are few.

The Montreal Protocol, for example, successfully established limits on chemicals known to harm the ozone layer. But it does not address emissions from rockets or satellites.

In the US, the Environmental Protection Agency is not responsible for analyzing rocket launches. The Federal Communications Commission licenses large satellite constellations but does not consider their potential harm to the environment. And the Federal Aviation Administration evaluates the environmental impacts of rocket launches on the ground, but not in the atmosphere or space.

Thus, the future of the stratosphere may be in the hands of Elon Musk, Jeff Bezos and other executives from private space companies.