How does the space programme affect Earth’s atmosphere? Earlier this year, scientists presented the first evidence of potential harm…
In the hit film Gravity (2013), astronauts played by Sandra Bullock and George Clooney get stranded in orbit when their shuttle is shredded by extremely fast-moving metal fragments — the debris from a destroyed satellite. It’s dizzying, nail-biting stuff, but space debris is a real problem, not least because of its effect on the atmosphere.
Photo courtesy of Leibniz Institute of Atmospheric Physics
Earlier this year, a team of scientists in northern Germany made headlines around the world when they shared the first evidence of the potential scale of harm.
‘We’ve been interested in the problem of space debris for years,’ says Dr Robin Wing from the Leibniz Institute of Atmospheric Physics, lead author of the team’s academic paper. ‘It wasn’t really an issue when there was relatively limited activity in space, all launched and run by governments. But there’s been a rapid, huge expansion of commercial activity in space over the past few years. The issue of space debris has become a big topic since around 2020, when Starlink started launching mega-constellations of satellites. Then there was a groundbreaking study in 2023 where the Americans flew a high-altitude glider over Alaska and found that 10% of stratospheric aerosols are already contaminated by space debris.’
Dr Robin Wing, photo courtesy of the Leibniz Institute of Atmospheric Physics
That study directly influenced Dr Wing and his team to try to measure space debris more closely. ‘When we saw that American study, we thought we could get an old, existing lidar [light detection and ranging] instrument out of mothballs and get it running in a matter of weeks. The instrument is older than I am!’ They decided to look for traces of lithium in the atmosphere, as it is only rarely found in natural meteoroids. ‘We’d been measuring lithium for a few months,’ says Dr Wiing, ‘when we got lucky.’
In the small hours of 19 February 2025, the upper stage of a SpaceX Falcon 9 rocket made an uncontrolled re-entry into the atmosphere over Europe, producing a visible fireball. ‘In the morning, we saw the news announcement that the rocket had landed in Poland, and we thought, “Hey, this is a chance to test our instruments!” We started up the lidar that night, and detected a 10x increase in lithium in a part of the atmosphere at an altitude of 96 km. Working with colleagues, we calculated local and global wind circulation, and were able to backtrack the trajectory of this lithium plume. It intersected directly with the re-entry path of Falcon 9, at an altitude of 100 km a little west of Ireland.’
The team shared their findings in, ‘Measurement of a lithium plume from the uncontrolled re-entry of a Falcon 9 rocket’, published in the Nature journal Communications Earth & Environment in February – and soon made international news. ‘The response has been absolutely overwhelming. Today, as I talk to you, the paper is no. 1 in the journal statistics, and there have been more than 190 new stories about it in different countries. We never expected to have such an impact.’
One reason, says Dr Wing, is that we’ve taken the atmosphere for granted. ‘We’ve tended to treat it a bit like a waste-paper bin for the space programme,’ he says. ‘Everything we send up has to come back down, and if we’re not going to land it safely on the ground we assume it can just burn up in the atmosphere and the problem goes away. But burn-up puts a lot of metal particles into the atmosphere. Aluminium, for example, is a major component of rockets and satellite hulls, so it’s a major component of space debris. It also serves to catalyse ozone destruction in the stratosphere.’
‘You probably remember the huge concern in the 1980s about holes in the ozone layer of the atmosphere, caused by chlorofluorocarbons or CFCs in spray cans and refrigerators. The ozone layer protects us from ultraviolet radiation from the Sun, without which we get cataracts and skin cancers. Life in general is not a fan of UV light. We learned in the 1980s that the middle atmosphere is very delicate, and serves a really important function in keeping us from harm.’
Could a spacecraft burning up create a hole in the ozone layer? ‘A single rocket or satellite would create small, localised holes that might last a few hours. That’s not a major concern. There are two big problems. First is the sheer amount of material we now have re-entering the atmosphere from orbit. Second, we don’t know what effects a lot of this stuff will have.’
Of course, there has always been a certain amount of material passing down through the atmosphere. ‘Yes, like natural meteors which are basically rocks made of things like silica, iron, nickel, potassium and sodium. What’s different with space debris is that it involves a lot of engineered materials: as well as aluminium, there’s copper, lithium, rubidium, caesium and all the stuff you get in modern electronics. Some of it is highly reactive and we don’t yet really know how any of it interacts with the atmospheric system. That, combined with the increasing volume, is a real concern.’
The team measured levels of lithium in March 2025 but the paper wasn’t published until February 2026. ‘We took some time on it. We had an initial draft within a couple of months but it then went through not only the usual scientific review but also legal review to ensure SpaceX couldn’t object, since we mentioned their rocket.’ At the time of writing, SpaceX has made no comment on the findings. ‘I don’t think they’re really care about the findings of our crazy little team in Germany,’ laughs Dr Wing.
But, as noted, others have been quick to note the significance of these findings. As every scientific paper always does, this one concludes that more research is needed. ‘Yes, that’s standard,’ laughs Dr Wing. But what should he — and we — be looking into next?
‘Other people can look into this. We were able to set up our detector pretty quickly using existing kit. It’s also relatively easy to look for interesting parts of the sky to study. The EU monitors all incoming space debris and I set up an automated thing so I get an email whenever something of significant size is re-entering. We can then go and look.’
Are other people doing this? ‘There have been some noises. I know of two American proposals to build an instrument similar to ours. The Canadians were interested in setting up a high Arctic station to measure space debris pollution, and I expect that our Chinese colleagues will put together something to study this at some point.’
But that means Dr Wing’s team are currently the only ones studying this area. ‘We’re committed to it now. We’re building a new, more advanced detector system here. We know this is something we’re going to be studying for years, so we’re spending the money to build a whole new system from the ground up. As well as lithium, we’ll be able to use that to measure sodium, too, and there will be a third flexible channel which we can use to measure every other different element and material associated with space debris in the upper atmosphere.’
Even better would be to have such a device established in Earth’s polar regions. ‘The poles are the epicentre for climate change,’ Dr Wing explains. ‘The impacts will be felt most extremely there, but they’ll also have the most sensitivity to space debris, because there is a large circulation in the mesosphere, pole to pole. In winter, the air goes from south to north, in the summer, it goes north to south, so the space debris gets kind of swept along and focused on the poles. It would therefore be better to conduct measurements in the polar regions, but developing these new systems in the poles would be a challenge! It’s much easier to develop and perfect them here at the institute and then have a version we can ship around the world.’
The current system might not look much to an observer. ‘What you’d see is three green beams of light coming out of our building, reaching up into the sky. We’re using them to measure temperature and wind at an altitude of 30 to 100 km. In studying space debris, we’ve added other colours: a red-orange beam and an ultraviolet one which you won’t see with the naked eye. We run the system every clear night. It’s automated, so we don’t have to spend all night at work.’
Photo courtesy of Leibniz Institute of Atmospheric Physics
Given that we’re discussing pollution, isn’t there an issue of light pollution from the detector itself? ‘Yes, historically, but now we use optical filters.’
With the potential harms of space debris having been identified, and more evidence to follow, what can we do to minimise the risks? ‘I think we need to consider the commercial use of space in the same way we consider transportation or industrial manufacturing, and apply similar environmental regulations. There’s no reason why space should be exempt. Policymakers could consider things like the composition of hardware and fuel. We know that aluminium is a problem so we could look at limiting the amount of that used. We could look at limits on numbers of launches.’
Are launches themselves a problem? ‘That’s an interesting question. We have a second site for lidar at ALOMAR, near the rocket launch site at Andøya Space in Norway. That gave us a beautiful measurement of a rocket plume at launch. It’s different to what we’re seeing in the atmosphere: the concern with launches is the use of activated chlorine in some of the booster stages, which really isn’t good for the environment. Again, regulation might be needed there. But these are questions that go beyond my expertise. What motivates me is providing the evidence to help policymakers make those kinds of decisions.’
‘Again, it’s like any industry. You say, “Oh, we need rules on pollution,” and the first response from those working in the given sector is, ‘Well, show us the pollution.” Now we can do that. We measure it at source, when the space debris first enters the area at the top of the mesosphere, when the signal from the pollution is most clear — and thereby track it to source. We’ll also continuing measuring, going forward, so we’ll be able to track any general increase in trace elements like lithium or copper. At the moment, we’ve only a single year of measurements.’
He laughs again. ‘More research is needed.’
This article first appeared in Air Quality News Magazine issue #32 (June 2026).
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