Encore: The atmospheric impacts of satellite re-entry.

Summary

Podcast Summary:

T-Minus Space Daily
Episode: Encore: The atmospheric impacts of satellite re-entry
Host: Maria Varmazas (N2K Networks)
Guest: Professor Mink Kwan Kim, University of Southampton
Date: April 26, 2026

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Brief Overview

This encore episode explores the atmospheric impacts of satellite re-entry, a subject gaining prominence as the number of satellites in Low Earth Orbit (LEO) rapidly increases. Host Maria Varmazas speaks with Professor Mink Kwan Kim about his team’s recently published study, commissioned by the UK Space Agency, which examines the risks and unknowns associated with burning satellites during their deorbit process. The conversation addresses current industry practices, potential environmental harms, and the urgent need for collective research and regulation.

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Key Discussion Points & Insights

The Context & Scope of the Research

• Satellite Re-Entry & Atmospheric Ablation: When satellites re-enter and burn up, they release particles and gases, notably metals like aluminum, into the atmosphere, impacting atmospheric chemistry. (01:24)
• The UK Space Agency commissioned multiple studies, summarized recently at a workshop, to investigate these potential impacts. The summit aimed to make research findings more accessible and serve as a foundation for broader studies in the field. (03:31–04:45)
• Professor Kim’s team focused specifically on the environmental risks and research gaps associated with current satellite deorbiting practices. They did not seek solutions but aimed to identify problems and direct future research. (06:22)

Key Findings from the Study

Estimating Ozone Layer Impact

• The practice of deorbiting satellites via atmospheric re-entry aims to manage space debris but brings new environmental questions. The team examined if this is an “environmentally safe way” to dispose of satellites. (05:06)
• Using a representative satellite model, the team estimated that burning one satellite could produce 6–8 tons of metal oxides, primarily aluminum oxide, which can deplete the ozone layer. (07:08–08:14)
  • Quote: “We predicted... metal oxide is the environmentally toxic by decomposing the ozone. Based on our estimation, it is somewhere around six to eight tons for one satellite.” – Prof. Kim [08:00]

Scale of the Problem: Mega-Constellations

• Although a single satellite's effect is small, mega constellations (with tens of thousands of satellites) could introduce 60,000 to 80,000 tons of ozone-depleting oxide annually. (08:14–09:16)
  • Quote: “One mega constellation can impact like 1% of the ozone layer. If we have two mega constellations, literally we have 2% of the ozone layer deflections.” – Prof. Kim [09:28]
• Even a 1% depletion of ozone can translate into a 1% increase in skin cancer rates worldwide (according to the WHO). (09:28–10:01)

Longevity & Complexity of Atmospheric Impacts

• The duration that by-products linger in the stratosphere is uncertain: estimates range from 4–5 years to 30 years, depending on models and satellite types. (10:28–11:29)
  • Quote: “Predictions... vary from 30 years from some researchers to four to five years from others, including us.” – Prof. Kim [10:45]
• The challenge is compounded by fragmented, unorganized scientific knowledge across disciplines. (11:44–12:22)

Moving Forward: Next Steps & Industry Collaboration

• Scenario Development: The team is working to build generic satellite models and scenarios to standardize impact assessments without revealing proprietary industry data. (13:41–15:03)
  • Quote: “Industry is very keen to support this problem... Their legal design detail is the issue, so we're creating some generic satellites for modelling.” – Prof. Kim [15:03]
• Mitigation & Regulatory Hurdles: Ongoing efforts aim to understand which satellite materials present the most risk (“bad guys” list), with aluminum oxide identified as the most problematic due to mass dominance and potential impurities. (16:13–17:26)
  • Quote: “Definitely the top one is the metal oxide... aluminum oxide is pretty much the top one.” – Prof. Kim [16:30]
• The process of satellite re-entry is likened to cooking, where the same basic ingredients can produce vastly different byproducts depending on the “recipe.” (17:45–18:49)
  • Memorable Moment: Prof. Kim compares re-entry to cooking steak, where the method significantly changes the result—emphasizing that even with the same satellite materials, burn-up conditions may affect environmental outcomes.

Regulatory and Policy Challenges

• Addressing satellite re-entry impacts raises complicated jurisdictional and legal questions, since space activities cross borders, and regulated handoffs occur as debris passes from space treaties to national law upon re-entry. (19:29–20:03)
• The challenge is the "timing"—scientific findings, regulation, and mitigation typically occur in sequence, but this problem requires these steps to happen in parallel due to the pace of satellite deployment. (20:12–20:41)

Call to Action for the Space Community

• Prof. Kim encourages industry, academia, and government to contribute to scenario development through surveys and feedback.
• He stresses that no single entity can solve the problem alone—international, multidisciplinary collaboration is crucial. (22:08–23:29)
  • Quote: “It is too big a problem to be solved by one university or company. We must tackle it together, including policymakers and regulators.” – Prof. Kim [22:20]

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Notable Quotes & Memorable Moments

• “Is it environmentally safe way if we bomb the satellite at the high altitude or the upper atmosphere, could it cause any significant environmental impact? We also have the experience for the global climate changes. So we don't want to make any similar mistake again.” – Prof. Kim [05:06]
• “One mega constellation can impact like 1% of the ozone layer... 1% ozone layer deflection is... a 1% increase of the skin cancer rate.” – Prof. Kim [09:28]
• “Predictions to how long it takes to reduce the particle... vary from 30 years to four to five years.” – Prof. Kim [10:45]
• “When I have the same ingredient with my wife... same recipe, but slightly different way to cook, they have the different taste... Same satellite, how we burn it, how we 'cook' it, the byproduct is very different.” – Prof. Kim [17:45]
• “Once we get the data showing... this is really problems we literally make some the technology ready. Okay. This is our mitigation.” – Prof. Kim [22:40]

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Important Timestamps

• 03:31 – How and where the study was presented; dissemination at the Secure World Foundation Sustainability Summit
• 05:06–06:22 – Scope and aims of the research, focusing on risks rather than solutions
• 07:08–08:14 – Methodology: representing satellite and quantifying potential ozone destruction
• 09:28–10:01 – Scale and impact of mega-constellations; link to public health (skin cancer rates)
• 10:28–11:29 – The unknowns: estimating the time particles remain in the atmosphere
• 13:41–15:03 – Industry collaboration and generic scenario creation
• 16:13–17:26 – Prioritizing problematic materials; aluminum oxide as a principal concern
• 17:45–18:49 – The cooking analogy: process-dependent toxic byproduct formation
• 19:29–20:03 – Legal and jurisdictional challenges in regulation
• 22:08–23:29 – Call to action for community collaboration

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Tone & Language

The episode maintains an accessible, inquisitive, and collaborative tone. Professor Kim communicates complex science with metaphors and practical links, making the case for cross-disciplinary and international solutions. The host, Maria Varmazas, facilitates with curiosity and care, ensuring clarity for non-expert listeners while drawing out actionable insights for the space community.

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Summary Conclusion

With megaconstellations on the rise, understanding and managing the atmospheric impacts of satellite re-entry is urgent yet fraught with scientific, industrial, and regulatory unknowns. Prof. Kim’s UK Space Agency-funded team is helping to lay the groundwork for standardized assessment and collaborative problem-solving, emphasizing the need for shared scenarios, industry input, and multidisciplinary mitigation strategies. The stakes—potential impacts on the ozone layer and human health—warrant broad, urgent cooperation across sectors and nations.

Transcript

[A]

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[B]

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[C]

Eduardo hi everybody. A quick note here before we start. I'm away from the microphone and on a family vacation at the moment when you're hearing my voice. So we're actually running an encore show for you today. It's an interview that we ran last year that feels to me as important as ever. As the race for satellite broadband dominance in LEO continues to heat up,

[D]

When satellites burn up upon re entering Earth's

[C]

atmosphere, they release particles and gases, including metals like aluminum, which may affect atmospheric chemistry. And this process, known as atmospheric ablation, is still poorly understood. But early evidence does suggest that metal content in the atmosphere is rising.

[D]

Should we be concerned?

[C]

Let's find out more. Today is April 26th, 2026. Maria I'm Maria Varmazas and this is T minus.

[D]

To address the uncertainties around atmospheric ablation,

[C]

the UK Space Agency commissioned three targeted studies to investigate the potential impacts of satellite reentry.

[D]

I spoke to Professor Mink Kwan Kim

[C]

from the University of Southampton about his findings.

[D]

Dr. Kim, thank you so much for coming back on the show. It's been about a year. I really am glad to see you again.

[E]

Yes, it's great to see you again, demaria. So we finished our initial study funded by the UK Space Agency recently and we publicly released our findings recently through the UK Space Agency, the public blog.

[D]

That's wonderful because that is indeed when we last spoke. You were very kind in telling me, listen, wait till it's all released. And so I've been sort of eagerly awaiting the news that it's public now. So here I am, very eagerly. I'm a student sitting down going, I really want to learn. So let's start first with the event at which I think a lot of your work has been recently unveiled. Let's start with that to sort of set the scene when and where was that and what happened there.

[E]

So yeah, so after we finished the study funded by the UK Space Agency, so we produce really long document. It's still over the couple hundred pages. So that is the detailing all of the our findings. But we understand it is very difficult to read all of the document. So with the support with the UK Space Agency, we actually organized the workshop to disseminating our findings with the conjunction with the Sustainability Summit organized by the Secure World Foundation. So right on the workshop we actually the summarizing all of the four studies. So the one is from us, one is from the Tottenham University, one is from the University of Dalid, one is from the Bested, which is private company. So the workshop is basically the disseminating what we founded and also the hope the community can use our research finding as the foundation for the broader study.

[D]

Excellent, excellent. So I'm going to narrow the scope because it sounds like there's a lot more conversations I need to have, but I'm going to narrow the scope specifically to what you and your research team, what you all worked on. So please let's review for folks who may have forgotten or didn't listen to our last episode. What what were you specifically researching?

[E]

So yeah, so what we doing done through the studies we study about the risk of the current the practice to disporting the satellite. So we know the space W is the big issue. So to mitigate the space W problems the international community they have the regulation to the orbiting the satellite within the 25 years recently changed to the five years by the US but the current practice is the best way to removing from the orbit is the atmospheric reentry. The other means is the bonnet. So our studies to basically start with a simple questioning. Is it environmentally safe way if we bomb the satellite at the high altitude or the upper atmosphere, could it cause any significant environmental impact? We also have the experience for the global climate changes. So we don't want to make any similar mistake again. So that is our starting point.

[D]

That is quite a starting point. Anything that we should know that was not in scope of this investigation just for our context.

[E]

Yeah. So this is very complicated the problems. So the basically through this study we don't want to find the solutions. So what we want to understand through this study is basically the risk of these problems and what potential the problem can be caused by this kind of the practice and what is the research gap we have and what is the direction we have to push this kind of the area into the next level. So that is the main envelope of our study.

[C]

Sounds great.

[D]

If you don't mind, could you walk me through all of those? I know it's a lot, but I'm sure it's all top of mind for you right now. So walk me through all that because I really am eager to find out.

[E]

So the first we have to understand what is the potential risk of this one. Obviously it is really complicated problems. So we have to simplify the situation. Because the problem is every satellite is the unique design. They have the unique the shape, the unique, the composition of the material. So we have to invent some genetic satellite which is the most popular. So we using the one satellite and the two estimate okay, if we desatelize the bond how much the metal oxide can be produced. And we predicting it is basically the metal oxide is the environmentally the toxic by decomposing the ozone. So we estimated like how much ozone can be potentially can be destroyed by the one satellite. So based on our very love estimation, it is somewhere around six to eight tons for the one satellite.

[D]

Six to eight tons from one satellite?

[E]

Yeah. So it is not large amount because something earth is quite big.

[D]

Yeah, the Earth is huge. Okay. Yes. Granted, yes.

[E]

So don't be panicked. So we have plenty of the ocean, but some of the constellations, we call these the mega constellations. So they plan to let go 40,000, 50,000. So there's a large number of the satellite and often their lifetime is the four to five years. So literally means the one big mega constellation. They have to bond about the 10,000 satellite annually. So we have the simple mass, it is about the 60,000 to the 80,000 tons. It seems like a large number. It's actually not. The large is like less than 1% of the oceans can be destroyed by the 1 constellations still.

[D]

Yeah, I was going to say the scale is hard, I think for an average person to wrap their head around because we're talking such massive numbers and amounts. So yeah, thank you for that percentage. That's very important.

[E]

Easy translations to understand the Lacanoma people. Basically the 1 mega constellations can impact like 1% of the odor layer. If we have the 2 mega constellations, literally we have the 2% of the original layer deflections. And there are some studies done by the WHO a while ago. Basically the 1% odor layer deflection is to literally translate into the 1% increase of the skin cancer rate.

[D]

Interesting. Not desirable.

[E]

Yeah. So if it increases 1%, basically it is representing about the southern souls.

[D]

Wow. My goodness. That's important context. Honestly, that's something that you mentioned when I spoke to you last year was also about how long the. I'm summarizing this poorly, I apologize. How long things remain in the upper stratosphere. Because that was also. Did your research cover that as well?

[E]

Yeah. So we do some very brief research because of the we first we have to understand what we don't know.

[D]

That's right.

[E]

In the context. So we call this the known unknown and the unknown unknown.

[D]

Rumsfeld honors.

[E]

Yes. Because of this area is so complex. So the predictions to how long it takes to reduce the particle coming down is varying from the which node are we using? It is getting from the 30 years prediction from some of the researchers and the four to five years prediction from some of the other researchers, including us. So you can get judging one hand is the three decade, other hand is the half decade. So still there are some unknown. So basically that is the role of the scientist like me to improve the accuracy. So this is like a weather forecast.

[D]

Yeah, no, this area so much about this realm is just completely unknown. So it must be fascinating for you to be studying this frontier, frankly of and just learning about something that we've just known very little about.

[E]

So honestly, the community has the good knowledge related to this area, but the problem is that they are not the organized well, so this is our first problems from the space the ages. So we have the knowledge from the different area, but we didn't concentrate those knowledge to tackle this problem.

[C]

We'll be right back.

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[D]

So there's a lot of things that we still don't know and I'm sure that that is a lot of what you are thinking. About in moving forward. So what is, what is your next step from here? What are you looking at next?

[E]

So basically what we want is we want to make some generic case. What I want is to help all of the community to focus to address these problems. Currently everyone has in their different view, different assumptions because of the, the complexity of the problem. So therefore we want to basically propose some of the genetic scenario with the generic. The configuration of the satellite. For that we are consulting with the industries. So we're just consulting the different industry to see, okay, this, the genetic, the satellite configurations could be representing your system, your missions. So then we can focus on those. The one simplified scenario to say, okay, what happened under this scenario, Whether this is the problem for the next ten years or twenty years or hundred years.

[D]

That's right, yeah. Mitigation is. That is the place where my mind goes is how does one mitigate this? And that is the. We're figuring that part out. Yeah. So I won't ask because I know it's like we're still figuring that out. I'm curious how your discussions have gone with industry so far. What have you been hearing?

[E]

So actually the industry is very keen to support this problem because of these are directly related to their operations. So the problem is actually their Lego design detail. So industry, they don't want to rebuild their design detail, but they still want to contribute in it. So therefore our solution is okay, let's see the generating some generic satellite without revealing their detailed design. Later they can optimize the satellite or tailor the satellite configuration to the actual satellite to predicting their emissions. Our first stand is that literally consulting with them and to basically configure like a generic representative the satellite model.

[D]

Are there certain composites or elements that are maybe more of a problematic? Is aluminum a really big one? I'm just curious, is there anything that any conclusion we can draw or is that just completely too.

[E]

Basically we released some of the top five top ten. We call these the bad guys. So because of that there are different species. We have the like more than 100 different byproduct. So we have to prioritize. Okay, which one is the most problematic. So definitely the top one is the metal oxide. So is the, the, the aluminum oxide is the pretty much the top one because they are dominated by the mass and the, the silicon oxide. The. This is another one and the other one is like lithium oxide or the mangan oxide, magnesium oxide. Other oxide is not critical. But the problem of the aluminum oxide is not just the aluminum oxide. Basically that is the impurity so aluminum oxide alone itself is very stable. But if there are some impurity in there, these guys act like awesome badly basically.

[D]

Interesting.

[E]

Yeah.

[D]

Huh. Wow. Oh. So it. There are so many different implications of this. And I'm just going to be so fascinated to hear how this resonates with a lot of different. Not just industries, but other researchers. Because there's just a lot. I'm just thinking material scientists, their heads must be really, really spinning when I

[E]

communicate with the public to understand this problem. So I open the explain using the cook. So this problem is very similar to the cook. So I'm not good cook. So when I have the same ingredient with my wife, she's actually good cook. So if I having the same ingredient like a meat. So same recipe, but slightly different way to the cook. They have the different taste. For example, if we have the like the same beef, whether you we cooked like the grill like a steak, while we don't be using the French cooking style like a confit, you can see the taste is very different, texture is very different. So which means same satellite how we bonnet how we cooking it. So our taste like byproduct is very different. So what we scientists like me, we try to do is to finding the best recipe to minimize the dose toxic product.

[D]

So it is to be continued to find out what that recipe is for exactly cooking of the satellite steak. But the work continues. But I'm so fascinated by what you have already found because I have to tell you, I think of all the conversations that I have had, what I have learned from you, I have told to so many people who are not interested in space whatsoever because it affects everybody. It affects our whole planet. And I've had a lot of fascinating conversations with people about, you know, well, what's the difference between a satellite and just a random space rock coming in?

[C]

It's just like.

[D]

It's just really interesting hearing those how people are thinking about it. So I'm just. It's so cool that you're researching this.

[E]

Yeah. And also through the study we also figured out it is the. The very challenging to set some regulations because of this problem. It's not just in the space, it happened in the ground. So the space obviously governed by the space law, the U.S. the outer space Treaty. If it comes down, it's going to be governed by the individual countries then who going to reset the regulations how they can be enforcing it. So this kind of the thing is the other kind of the difficulties.

[D]

Yeah, no, yeah, yeah. Regulations are extremely, extremely difficult. Sorry, I didn't mean to interrupt you. I know you were. You were midfield. Sorry.

[E]

So what we understand is the challenge is actually the timing. So normally once we find the scientific evidence, we set the regulations where we implying it we finding the mitigation strategy. This take a really long cycle.

[C]

Yeah.

[E]

With this kind of the problems we don't have such elegant timeline. So basically we have to do the both in the parallel

[D]

when it gets to the implementation phase with a lot of things where it gets very tricky. My sympathies. I'm curious if I recognize this is probably a little out of scope, but a lot of our listeners are in the space industry. So is there anything that you specifically want to tell them want them to know? I suppose a call to action may be a bit much, but if there is one, if there's anything you want to say to them specifically.

[E]

So basically we tried to do some simple survey through the space industry to basically create most representative scenarios and the satellite configurations. So we tried to disseminate some of our initial survey to basically. Okay, this is the satellite. Whether is the representative your satellite, yes or no. Basically we have the simple questions and also try to create some of the generic scenario to whether it's representing your scenarios, yes or no. So based on that is basically the feedback from the industry, from the academia and the government. We try to basically create most reliable or representative the scenario for all of the industry, all of the people.

[D]

So that sounds like something that maybe we can share with our audience so they can respond to that. Okay, I will make sure that we include that as well. Is there anything else that you would like to leave the audience with? Since we're coming up on time, I want to give you the final word. Anything else?

[E]

Yeah, so this we understand this is the problem which we don't know whether it could be problems or not. So but this is some of the area we need to having some the support from the community. So also we have to tackle this one together. So it is the two big problem solved by the one university is solved by the one company. So we have to tackle this problem together. Because this is not just done by the the scientists or engineers also need to done by the policymakers and the regulation makers. So once we get the data showing, okay, this is really problems we literally make some the technology ready. Okay. This is our mitigation. Okay. How this is the solve the problem. We also try to to set some small international like a working group or small community basically to do some brainstorming. Okay. How we can solve the problem was data exchange. Okay, which model is the better and how we can focus our effort to tackle this problem together.

[D]

Oh, fascinating. Well thank you Professor Kim. Thank you for sharing your findings with us. This is so fascinating and so important.

[C]

So thank you.

[D]

I look forward to learning more as more is learned and please come on back and share. I really enjoy these conversations. Thank you so much for what you do.

[E]

Thanks Maria. And I want to also appreciate my deeply appreciation to the UK Space Agency. So they actually funded this study and they actually supported this problem first in the global level and to basically disseminating this issue globally.

[D]

Foreign.

[C]

That's T minus deep space Brought to you by N2K CyberWire we'd love to know what you think of our podcast. Your feedback ensures that we deliver the insights that keep you a step ahead in the rapidly changing space industry. If you like our show, please share a rating and review in your podcast app or you can send an email to [e-mail] we're proud that N2K CyberWire is part of the daily routine of the most influential leaders and operators in the public and private sector. From the Fortune 500 to many of the world's preeminent intelligence and law enforcement agencies, N2K helps space and cybersecurity professionals grow, learn and stay informed. As the nexus for discovery and connection, we bring you the people, the technology and the ideas shaping the future of secure innovation. Learn [e-mail] N2K's lead producer is Liz Stokes. We're mixed by Elliot Peltzman and Trey Hester with original music by Elliot Peltzman. Our executive producer is Jennifer Ibin. Peter Kilfey is our publisher and I'm your host, Maria Varmazas. Thanks for listening. We'll see you next time.

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Sa.

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