Are climate scientists worried too much about the particles from spacecraft in the atmosphere?
Elon Musk’s SpaceX plans to get rid of 100 Starlink satellites in the next six months. This is because they found a problem with the design that might make them stop working. Instead of risking harm to other spacecraft, SpaceX will bring these satellites back to Earth to burn up in the atmosphere.
But scientists who study the atmosphere are worried that dumping satellites like this could make climate change worse on Earth. One group of scientists recently found metals from spacecraft in the stratosphere unexpectedly. This is the part of the atmosphere where the ozone layer is.
The area around Earth where satellites that watch over our environment are located is getting more crowded. Starlink alone has over 5,000 satellites up there. Getting rid of space junk is a big concern for the space industry. When new satellites are launched, they need to be taken out of orbit within 25 years. The US now has a stricter rule of doing this within five years. They can either move them higher into a “graveyard orbit” or bring them down into the Earth’s atmosphere.
Satellites in lower orbits are made to use up any leftover fuel and the Earth’s gravity to come back into the atmosphere. There are two ways this happens. In controlled reentry, the spacecraft comes back into the atmosphere at a specific time and lands in a faraway spot in the Pacific Ocean called Point Nemo. In uncontrolled reentry, the spacecraft is left to naturally burn up in the atmosphere.
NASA and the European Space Agency encourage this way of getting rid of satellites. They call it “design for demise.” It’s a challenge to make a satellite that can work in space but also safely break apart and burn up when it comes back to Earth. People are still working on perfecting this.
Before satellite operators can launch their satellites, they have to prove that their design and plans for coming back to Earth won’t harm people. But they’re not so worried about how it might affect the upper atmosphere during reentry. This isn’t something they overlook.
At first, people didn’t think burning up satellites on reentry was a big problem for the environment, at least not for the atmosphere. After all, the number of particles from spacecraft is small compared to the 440 tons of space rocks, volcanic ash, and pollution from factories that enter the atmosphere every day.
Bad news for the ozone layer?Â
Are climate scientists worrying too much about the bits of spacecraft in the atmosphere? They’re drawing on 40 years of research about the ozone holes above the north and south poles, which started being noticed a lot in the 1980s.
Today, they’ve figured out that people-made gases from factories are causing the ozone to disappear. These gases mix with natural clouds way up high in the atmosphere, called polar stratospheric clouds. These clouds act like catalysts, turning harmless chemicals into ones that can quickly destroy ozone.
Dan Cziczo is a scientist who studies the atmosphere at Purdue University in the US. He helped with a recent study that found these harmful substances in the atmosphere. He says the big question is whether the new bits from spacecraft will help make more of these clouds and cause more ozone loss while the atmosphere is trying to get better.
Cziczo and other scientists are more worried that just a few new bits could make more of these polar clouds – not just high up, but also lower down where other clouds form. These other clouds, called cirrus clouds, are thin and made of ice. They let the sun’s heat in but keep it from getting out, so more of these clouds could make global warming worse. But we’re not sure about this yet – it’s still being looked into.
Cziczo says we’ve noticed that the high clouds above the poles are changing, but we don’t know why. Is it natural stuff like rocks from space or ash from volcanoes, or is it bits from spacecraft? We need to figure this out.
Atmospheric scientists who really dig into this topic haven’t jumped to conclusions because there isn’t enough solid proof yet. We do know there are bits from spacecraft in the stratosphere, but we’re not sure what that means for the ozone layer or the climate.
It might be tempting to exaggerate what we find in our research to get more support. But that’s a bad idea – it leads to problems down the line, and people who don’t believe in the research will use those shaky findings against us. We also shouldn’t just go with whatever’s popular. But we’ve learned that if we wait until we have absolutely solid proof, it might be too late, like what happened with the ozone layer. It’s a tough situation.
