Transcript of conversation: Space trash could impact our ability to gather climate data, says former NASA astronaut, Kathy Sullivan, on TEDxLondon’s Climate Curious.

Transcript: Climate Quickie: What is space trash? 

Kathy Sullivan, TEDxLondon Climate Curious

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Hello, I’m former NASA astronaut Kathy Sullivan, and I’m here to talk with you about space trash.

What is space trash? 

Trash is the useless junk that’s been left in space from something like 60,000 launches that have happened since the start of the Space Age. And it ranges from spent rocket motors to lens covers, and even down to paint chips and bits of slag from Rocket motors.

There are over 28,000 bits that are large enough to track the location of from the earth and no doubt, millions of much smaller ones, all of which pack a heck of a lot of impact because they’re moving at very, very high speeds.

How does it end up floating in space? 

We send the satellite up. It usually starts with a rocket stage that lifts it the first bit off the earth. That bit usually falls back to Earth or is sent back to Earth and reused, but there’s usually a second stage and sometimes a third stage that gives that satellite another bit of push.

And those rocket stages when they drop away from this satellite, are just left in orbit. They usually have some fuel or propellant left in them. And oftentimes it’s that leftover of propellant that over the years starts to leak or heat up, and may eventually explode the spent rocket stage. So instead of having one rocket cylinder that you could track the location of, you end up with a cloud of particles. Some of them might be big enough to track, and others could be very, very small. But again, they’re moving at tens of thousands of miles an hour.

So if one of them hits you. They’ll pack quite a punch.

Importance of space-based observations for climate action 

All those bits, as they slowly decay from their orbit and fall back to earth, they mainly burn up in the atmosphere leading behind.

Some of the chemicals that they were made of. So that might be something to look at. The point that I care most about and worry most about is if space becomes so crowded with junk more than satellites, it could become too hazardous for satellites. You almost could seal off space and make it unusable and space-based observations play a really critical role in helping us understand our planet and how it’s working, and track the trajectory of everything from daily weather to our future climate. The data we get from space is indispensable to both weather forecasts and those kinds of climate predictions, so we need to be able to take the pulse of our planet and satellites in orbit are vital to that undertaking.

Kessler syndrome

The Kessler Syndrome refers to the potential problem that you get so many. Spent rocket stages left in space, for example, they start to collide with each other and each collision creates a cloud of particles that then can glide with other things.

There are projections that say if we stay on our current pathway and don’t get some clearer rules of the road in place, that before too long, the Kessler Syndrome could be what dominates the debris. So now it won’t be a rocket stage explodes, it will be all these other bits keep crashing into each other and crashing into each other and crashing into each other.

So it becomes an exponential growth of the space debris that could, in a sense, clog up Earth’s orbit so much, that we seal ourself off from access to space.

Setting international space rules 

So the best way to reduce this trash, in particular the spent rocket stages, is to set up an agreement that you have to design your rocket. Once your second stage booster does its bit, it maybe has enough propellant left to. To deorbit itself slow itself down so it drops back to earth.

Removing existing debris from space – can you shoot it out the sky? 

The other thing that’s being looked at seriously to control it is the challenge of removing existing debris from orbit. That’s a really tricky thing to do. I mean, you might think a big net, but this pieces are all moving so fast if you, if you are not matched exactly in the same orbit, every bit of debris would just shred your net.

There’s not really a way to shoot them outta the sky, like in Star Wars, because if you shot at one of the spent rocket stages, you just would’ve made your problem worse.

Soon as you fire something at it, it becomes a cloud of particles, bits and particles that are much smaller and probably hundreds of which you now can’t track. So now you’ve just created a fuzzball of uncertainty. There’s, there’s more stuff up there that’s worrisome and now I can’t tell you where it is that actually makes the problem.

You might think, well, how about a big magnet? So just attract it all and pull it down. , but for various physics reasons, spacecraft are not built out of magnetic materials. There’s nothing magnetic up there to go get. So it’s a challenging problem to be sure. 

Threat to satellites and climate data/ tracking 

My urgent concern vis-a-vis climate problem is that we really are critically dependent on satellites in space to monitor the earth, to study how it works in ever greater detail.

So if we lost this very precious ability to monitor the earth that would be really pampering to our efforts to solve the chemistry of the atmosphere.

Problem track emissions, track the temperature of the ocean, track circulation, changes in our ocean and our at. Satellites are absolutely critical to doing all of that. So we have to be able to keep our finger on the pulse of our planet, uh, really globally. Uh, and we have to have, uh, we have to have earth observation satellites in place to do that.

So if the debris problem became so severe that as soon as you put a satellite up there, it was likely destroyed within a week, we would effectively be blind. Those kind of trends and changes.`

Lifeboat theory 

I’m not a fan of the Lifeboat School of Thought, which says, well, we’ve, we’ve wrecked this planet so badly. It’s imperative that we go off to some other planet, or Jeff Bezos’s vision is not to other planets.

It’s to an array of large Space station communities throughout the Milky Way. I like this planet a lot. I’ve always been curious deeply about this planet. And I think it’s, well, to be blunt, I find that an amoral idea. It says, number one, it’s not gonna save all of humanity.

Those, would in a sense, become the most exclusive gated communities, right? You’re not, you’re not saving billions of people from earth. You’re taking maybe hundreds of thousands or couple million off to Mars as the seed stock for the next generation of humanity. And so who are they gonna be? How’s that chosen?

It’s not gonna be easy living on Mars or the moon, by the way, but it’s a little naive. And secondly, my philosophy about living on this planet is we are all crew members on a spaceship together.

We should be stewards, we should be good caretakers of this really rather exquisite planet that we’ve been given. So the notion that I’m just gonna muck it up and make a mess of it, and then go somewhere else and do it again; I think it’s abhorrent.


For people who’d like to know a little bit more, the European Space Agency and NASA both have good information about the current Space debris problem on their websites. I’ve done a number of episodes on my podcast, so you might check out some of my space stories on Kathy Sullivan Explorers dot com.