Will Parker
Appearances
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
And that's bad news for the long-term sustainability of the environment for us to use for all the things that we rely on spaceport.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
Sure. Well, we rely on the upper atmosphere to clean up low Earth orbit. So, you know, we like to think of space as being a vacuum, but really there's a little bit of air at the very top reaches of the atmosphere where most of our satellites are operating. Basically, if it weren't for that atmosphere, any debris, any satellite that we abandoned in space would stay there forever.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
We rely on that atmosphere to basically reduce the energy from our satellites so that they spiral towards the Earth and eventually deorbit. So we need that cleaning force. If we don't have that force, then we would have these things in space forever. That is catastrophic to the environment, right? We have no way to remove the old junk so that we can have stuff to do in the future.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
So we built on some previous studies that have started to show that while we see a significant warming effect from greenhouse gases in the lower atmosphere, we actually see pretty significant cooling and contraction in the upper atmosphere. And so that's caused by two things.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
One of them is that the greenhouse gases in the lower atmosphere trap heat close to the surface of the Earth and prevent it from reaching the upper atmosphere. And the heat that does make its way into the upper atmosphere is emitted more easily into space. So those two mechanisms together mean that we're seeing a cooling effect in the upper atmosphere where most of our satellites are operating.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
And because of that cooling effect, we're seeing that the entire atmosphere is contracting. So it's retreating away from low Earth orbit where we rely on that atmosphere for drag on our satellites. The effect of that retreat, that shrinking of the atmosphere, is that it's not doing as good a job at cleaning out low Earth orbit.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
And again, we rely on that cleaning force because we have no other way to remove most of this debris. So the danger and the thing that we found is that it actually reduces the number of satellites that we can sustainably operate in low Earth orbit because we don't have this cleaning force.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
So if there's a collision or an explosion, anything that's going to cause debris in low Earth orbit, the consequence of that event is getting much greater over time because it'll take a lot longer to clean it up.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
So the Kessler syndrome is always a concern, right? This runaway growth in the debris population. It's something that we take a lot of care to prevent. It's important that we're able to model these scenarios and understand how our actions in terms of how we populate space and how satellite operators are acting impact this long-term sustainability.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
Because once this cascading debris generation starts, there's no way to stop it. And once space is cluttered, it can stay cluttered for decades or longer. because it'll close off key routes to space. Today, satellite operators are avoiding collisions by performing maneuvers.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
So back in the 80s, 90s, early 2000s, we sort of came up with these strategies for how we would avoid collisions between satellites. But back then, we, again, just figured that space was big. So it was mostly just an academic exercise. Today, that is not the case. It is fully operational. The Starlink Constellation did over 100,000 collision avoidance maneuvers last year.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
So it's something that is very much used in practice by necessity, right? We need to avoid debris objects and other satellites because it is getting so congested in space. And that's making it more difficult to operate spacecraft there.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
Well, our study went to 2100 and we saw that relative to the year 2000, we're seeing in the worst case scenario, at least a reduction of 50% in our carrying capacity, the number of satellites that we can sustain. It depends, right? The point of the study is to be able to show that we have a lot of levers at our control to be able to manage the space debris problem.
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SPECIAL | Space junk: the impact of global warming on satellites
is to more effectively manage our access to space and make sure that internationally we have rules of how we operate spacecraft and how we manage our use of space. The other that is maybe unintuitive is that you don't need to be an aerospace engineer to make a difference in reducing the space debris problem.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
Everybody can sort of do their part to try to reduce the greenhouse gas emissions and every country should We're trying to do that for lots of reasons, right? We don't need more reasons to reduce our greenhouse gas emissions, but it turns out that reducing those emissions not only helps us on Earth, it also helps to enable the long-term sustainability of space, which was a cool outcome.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
Yeah, so what we found is in the lower part of the atmosphere, we can fit a lot of satellites if we're trying to avoid this long-term debris accumulation that we're looking at. Because as long as you stay in the part of the atmosphere that is very thick, then any time you have some sort of debris generating event, it'll be removed from orbit very quickly.
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SPECIAL | Space junk: the impact of global warming on satellites
And so what we recommended in the paper is if you want to make sure that you are not doing long-term damage to the environment, it's really important that satellite operators reduce the altitudes that they operate at. So if you fly at a lower altitude, it ends up being a little bit safer for the overall environment.
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SPECIAL | Space junk: the impact of global warming on satellites
And it's something that I think we're going to start to have to do more and more as time goes on.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
So for really large pieces of space junk, so I'm talking large satellites that are abandoned or we have upper stage rocket bodies that are floating around in space. For those things, there have been several companies and governments that have been working on what they call active debris removal strategies.
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SPECIAL | Space junk: the impact of global warming on satellites
So that means that we take basically independent satellites, we launch them to space specifically to remove these large objects. Basically, it's a one-to-one. We send up a satellite to remove a satellite. That's incredibly expensive. It's something that we need to do, but it is not a scalable problem. We have hundreds of millions of objects when you get down to the really small scales.
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SPECIAL | Space junk: the impact of global warming on satellites
We have no way to remove those objects. We can remove maybe five or 10 objects a year using this active debris removal, but that will never, ever scale to the problem. I liken it to direct air capture for removing greenhouse gases from the atmosphere. The direct air capture is useful for sort of trying to clean up the mess that we've already made.
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SPECIAL | Space junk: the impact of global warming on satellites
But it's always a lot cheaper to not make a mess in the first place than it is to clean up a mess that has already been made. So that's what we're advocating for. I think that the active debris removal will be a useful component to trying to ensure this long-term sustainability. But really, the atmosphere is all we rely on to do 99.9% of the cleanup.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
Well, we've seen recently, certainly in the news, lots of instances of space debris that makes its way all the way to the ground and maybe poses a hazard to people on the surface. That is certainly a concern, and it's something that I think will constrain our space activity. It's important to, one, be able to understand what will these satellites do as they're burning up in the atmosphere.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
Will they burn up completely? In a lot of cases, we thought they would, and they're not in practice. So that's a concern, and that's something that the space industry needs to work on. The other component is we need to sort of better coordinate between all of the decision makers and all the people that need to know the information that we have available.
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SPECIAL | Space junk: the impact of global warming on satellites
So if we have a satellite that's reentering that may not make it to the ground, we need to do a better job of coordinating with airline pilots, with people in the ground that may be impacted in advance. And that's certainly a concern, I think, for people's safety.
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SPECIAL | Space junk: the impact of global warming on satellites
Obviously, it's a pretty low risk just because we don't have satellites reentering all the time and the Earth is very big and it's mostly water. So we haven't seen an issue yet. But as we're launching more things into space and as the atmosphere is removing more of those objects, we're going to start to see more of these reentries happen. So it's important to get a grip on that problem.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
The mega constellations are a new trend in the way that we operate satellites. It was initially driven by companies like OneWeb and SpaceX. Today, SpaceX's Starlink constellation is over 60% of all of the active satellites in orbit. And they operate, at this point, many thousands of satellites in a very tight altitude regime.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
And they are designed in a very structured way, so they can fit a lot of satellites in a very tight space. The idea with these mega constellations, in particular, these large constellations in low Earth orbit, is mostly to provide broadband internet to people on Earth. And the reason that they are in low Earth orbit, very close to the surface, is because we have pretty low latency.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
So for internet, I can communicate with a satellite very quickly, whereas historically, our satellites for internet had to be really far away. And so it took a long time for that signal to propagate. These constellations are an entirely new means of operating in space. And so the rules are fundamentally changing.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
We don't have a lot of regulations in the way that we use space, especially in the way that we use frequency spectrum to be able to communicate with our satellites. So there are a lot of constraints on operations that these constellations are now starting to stress because we've never had to think about populations in space this large.
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SPECIAL | Space junk: the impact of global warming on satellites
And that's causing some significant disagreement, I think, within the industry.
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SPECIAL | Space junk: the impact of global warming on satellites
You know, like I said, space is a shared resource for everyone. Everyone stands to benefit from it. I think in the last few years, we've seen that the cost to access space has gone down dramatically. So that's cost to build a satellite, to launch a satellite and to operate a satellite. I think that that's really good for the players that have never had access to space before, right?
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
We have this new accessibility to space that didn't exist before. We have these pathways that are well-defined.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
The problem is that, you know, while having cheap access to space is something that provides this improved access for the people that have never had access before, what's happening in practice is that the people who have always had access are exploiting that resource and really, really trying to expand their use of space in a way that makes it difficult for others to operate there.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
Yeah, you know, we used to live in this world where we had a mentality that space is big and we didn't have to be sustainable in the way that we acted in space because we didn't have to worry about collisions between satellites or debris objects. It was mostly a clean environment when we started our operations in space in the late 50s. Today, the environment is very different.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
And so that's the problem, right? Is that, again, we have these major players that have always been around that still dominate the scene and probably will for a long time. We have this new capability for new players to come and participate in space activities, but it is still increasingly difficult for them to do that.
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SPECIAL | Space junk: the impact of global warming on satellites
We want to make sure that we give everyone access to be able to use space as a resource because it's valuable to everyone.
The Excerpt
SPECIAL | Space junk: the impact of global warming on satellites
We have, like you said, tens of thousands of objects that are orbiting Earth, many more smaller debris objects that we have a hard time tracking. And so because of that, satellite operators constantly have to dodge debris. So the operating environment is becoming really complex and really difficult.