Latest / Talking Science / Space Junk and the Kessler Problem

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Space Junk and the Kessler Problem · Talking Science

0:00
I want you to try something for just a second
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close your eyes and picture outer space like
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really put yourself there right if you're like
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most of us you're probably picturing this I don't
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know incredibly clean silent infinite black void
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yeah totally peaceful exactly peaceful fast but
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the reality especially in that immediate orbital
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shell right above Earth where all of our satellites
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live, is completely different. It's not a pristine
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void at all. No, not even close. It's basically
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a crowded hyperspeed junkyard. Yeah, and that
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contrast between the sci -fi imagination of space
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and the physical reality is, I mean, it's staggering.
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We tend to view orbit as this... cinematic backdrop,
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you know. But it's a highly active, highly polluted
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physical environment. And what's happening up
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there is no longer just a problem for like astronauts
0:51
or astronomers. It's this compounding environmental
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crisis. And it's actually beginning to threaten
0:55
the foundational technology that you rely on
0:57
every single day. Which is wild to think about.
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So welcome to this deep dive. Our mission today
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is to explore this invisible ring of rubbish
1:05
encircling our planet. We're going to dig into
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the terrifying physics of why A tiny fleck of
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paint in space can be as deadly as a bullet.
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Yeah, that part is crazy. Right. And we'll get
1:20
into the sheer logistical nightmare of managing
1:22
space traffic and the wildly ambitious ways engineers
1:26
are trying to clean it up before we essentially
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lock ourselves out of orbit. I'm really glad
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we're tackling this because we need to look at
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near Earth space the exact same way we look at
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our oceans or atmosphere. I mean, for decades,
1:38
humanity just treated orbit like an infinite
1:40
dumping ground. Out of sight, out of mind. Exactly.
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Yeah. But we are rapidly approaching a physical
1:45
limit. And understanding the mechanics of how
1:47
this happened, well, it's the only way we're
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going to figure out how to fix it. So I want
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to start with those mechanics. Yeah. Because
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before we even talk about how much junk is floating
1:55
around up there, we have to understand the physical
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reality of being in orbit. And the danger up
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there, it isn't really about mass, right? No,
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not at all. It's entirely about velocity. Yeah.
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And to put that in perspective, we first kind
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of have to redefine what it actually means to
2:09
be in orbit. Because when you watch footage from
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the space station, the astronauts appear to be
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floating. Right. They're doing flips and stuff.
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Zero G. Right. It looks like zero gravity. But
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gravity is actually still pulling on them with
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about 90 % of the force we feel right here on
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the ground. Wait, really? 90 %? Yeah. They're
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not floating. They are just falling. Okay, but
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they never hit the ground. Exactly, because they
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are moving forward so incredibly fast that as
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they fall, the curvature of the Earth essentially
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just drops away beneath them. Okay, wait, let
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me rephrase that because I know we need to nail
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down the speeds here for the listener. They have
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to travel fast enough to essentially match the
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curve of the planet. That is the crucial concept,
2:52
yeah. To maintain that freefall around the planet
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without hitting the atmosphere, an object in
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low Earth orbit has to travel at roughly 28 ,000
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kilometers an hour. 28 ,000? Yeah. That is the
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baseline speed limit for anything up there, whether
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it's a multimillion -dollar communications satellite,
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the space station, or, you know, a discarded
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wrench. Just a wrench hauling along at 28 ,000
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kilometers an hour. Let's ground that in an everyday
3:19
experience for you listening. Imagine you're
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driving down the highway at a normal speed, maybe
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100 kilometers an hour, and a bug hits your windshield.
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Right. It's a smudge. Right. Annoying, but harmless.
3:31
Now imagine a pebble hits your windshield at
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that same highway speed. You get a star crack
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in the glass. Yeah. But in space, objects aren't
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moving at highway speeds. They are moving at
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like 10 times the speed of a rifle bullet. And
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this is where the physics of kinetic energy gets
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genuinely terrifying. Oh, I bet. Because the
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formula for kinetic energy squares the velocity.
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So if you double your speed, you don't just double
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your destructive power, you multiply it by four.
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Oh, wow. Yeah. So when you scale a speed up to
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28 ,000 kilometers an hour, the amount of energy
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carried by even a microscopic object becomes
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just completely catastrophic. I was reading up
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on the damage sustained by the International
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Space Station, and this one detail completely
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blew my mind. The reinforced multilayer glass
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windows on the ISS, they've actually been chipped
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and cratered by literal flecks of paint. Yeah.
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Like a piece of paint that just peeled off an
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old rocket stage somewhere. It's true, and the
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mechanics of that impact are fascinating because
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it doesn't just bump into the glass. At orbital
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velocities, a fleck of paint doesn't even behave
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like a solid object hitting another solid object
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anymore. What does it do? Well, the kinetic energy
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is so high that upon impact, the paint and the
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immediate surface of the glass instantly vaporize
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into plasma. Wait, vaporize into plasma from
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a pin chip? Yes. It creates this tiny shock wave
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that literally blasts a crater into the material.
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That is, I mean, that's horrifying. It is. Now
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take that mechanism and scale the object. up
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from a paint chip to something the size of a
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Markle or, you know, a lost bolt from a rocket
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hatch. Right. A strike from an object just a
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few centimeters across doesn't just dent a spacecraft.
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It hits with the explosive force of a hand grenade.
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It will punch completely through the shielding,
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vaporize the internal electronics, and instantly
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kill a satellite. Which makes me wonder how anyone
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in their right mind thought it was okay to leave
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trash up there. because knowing how devastating
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a single collision can be, How do we end up with
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a massive cloud of these high speed projectiles?
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Well, I mean, for decades, the standard operating
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procedure for the most advanced engineering projects
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on the planet was to just detach their garbage
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and leave it in orbit to become rogue shrapnel.
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Yeah, I mean, we really have to look at the historical
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constraints of rocketry to understand why that
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happened. Getting any mass into orbit is just
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punishingly expensive. Right, and fuel costs.
5:55
Exactly. It requires a tremendous amount of fuel.
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So in the early decades of the space race, every
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spare ounce of was dedicated to the payload itself.
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Reserving extra fuel just to steer a dead rocket
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stage back down to Earth? Unthinkable. Yeah,
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it was considered an unacceptable waste of resources.
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So the engineers just kind of assumed space was
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infinitely large and, you know, a few dead rocket
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stages wouldn't hurt anything. The ultimate out
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of sight, out of mind. Precisely. And for a long
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time, the sheer volume of space meant that the
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risk of two things colliding was statistically
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close to zero. Sure. So satellites would reach
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the end of their 10 -year lifespans, run out
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of the propellant they used to maintain their
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orientation, and operators would just shut off
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the transmitters and leave them tumbling in the
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dark. But the routine, the dead satellites and
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all that, that's only half the story, right?
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Yeah. Because my research for this deep dive
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showed that the truly massive spikes in space
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junk didn't come from dead satellites just slowly
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accumulating. They came from what are called
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bulk events. Yeah, those bulk events are the
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real turning points in this crisis. A bulk event
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is a sudden catastrophic fragmentation. Like
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an explosion. Exactly. Sometimes it happens because
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an old dead rocket stage was abandoned with leftover
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pressurized fuel still inside its tanks. Oh,
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that sounds like a bad idea. It is. Years later,
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the thermal stress of passing in and out of the
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sun's shadow causes the tank to rupture. And
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the entire stage explodes, turning one large
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piece of trackable debris into thousands of jagged,
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untrackable pieces. And some of them were intentional,
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which is wild. I was looking into that 2007 incident
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where... a country decided to test an anti -satellite
7:37
weapon. They literally fired a missile into one
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of their own defunct weather satellites. Yeah,
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and that test remains one of the most severe
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debris generating events in history. By intentionally
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obliterating a large satellite in a heavily populated
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orbit, they instantly created over 3 ,000 pieces
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of trackable shrapnel. 3 ,000. And probably hundreds
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of thousands of pieces that are just too small
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to track. But even that intentional explosion
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kind of seems overshadowed by what happened two
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years later in 2009. This is the event that really
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caught my attention. It wasn't a missile strike.
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It was a complete accident. Yeah, the 2009 collision.
8:11
Right. An active communication satellite, Iridium
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-33, and a massive, completely dead Russian military
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satellite, Cosmos -2251, just slammed into each
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other at orbital speeds. That was a massive wake
8:23
-up call for the entire global aerospace community.
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meaning the speed at which those two huge satellites
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were moving toward each other was over 40 ,000
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kilometers an hour. Unbelievable. They completely
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annihilated each other. And that added another
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2 ,000 large fragments to the orbital environment.
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Now, here is the part I really struggled to understand
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when I was reading about that. We have all these
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ground radars, right? We know where the active
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satellites are. Right. So how on earth did nobody
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see two school bus size objects? speeding toward
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each other why didn't the active one just you
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know swerve Well, the tracking systems did see
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them, but it highlights this massive flaw in
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how we monitor space traffic. Radar isn't like
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GPS on your phone. When you track an object using
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ground -based radar from hundreds of miles away,
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there's a margin of error. You don't know exactly
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where the satellite is down to the millimeter.
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You know it's somewhere within a three -dimensional
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bubble of probability. A bubble of probability.
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Yeah, often shaped kind of like a long pizza
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box. A pizza box. Okay, so when the radar predicts
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a close pass, it's really just... saying, hey,
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these two pizza boxes, these uncertainty bubbles,
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they might overlap. Precisely. And back in 2009,
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there were no automated space traffic control
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rules. The company operating the active satellite
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was receiving dozens, sometimes hundreds of these
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close approach warnings every single week for
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their entire fleet. Hundreds of warnings. Yeah.
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And almost all of them were false alarms. Swerving
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a satellite uses precious fuel, which actually
9:56
shortens its lifespan. So operators become desensitized.
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Boom. It's the boy who cried wolf. It's the ultimate
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boy who cried wolf scenario until the one time
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the wolf is actually there. And the consequence
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of that impact is that those thousands of pieces
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of frapnel don't just fall back to Earth. In
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those higher orbits, they keep whipping around
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the planet, spreading out like a net, just crossing
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through busy traffic lanes for centuries. Which
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leads us to a concept first described in the
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late 1970s, the Kessler syndrome. Right. Donald
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Kessler. He was an astrophysicist at NASA who
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looked at the math of these collisions and realized
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we were heading toward a runaway tipping point.
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The logic is chillingly simple, honestly. Every
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collision creates a cloud of new fragments. And
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I found the easiest way to visualize this is
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like a game of pool. Oh, that's a good analogy.
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Yeah, imagine the opening break. where the cue
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ball slams into the triangle and the balls scatter
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across the table. But imagine if, instead of
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the balls eventually losing momentum and stopping,
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every time a ball hit a bumper or another ball,
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it shattered into 10 smaller balls. And those
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smaller balls kept flying around at full speed,
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shattering into even smaller pieces every time
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they hit something. Eventually, the entire table
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is just this chaotic, inescapable blizzard of
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shrapnel. That cascading chain reaction that
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is the Kessler syndrome, once the density of
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debris in a specific orbital shell reaches a
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critical threshold, the rate of random collisions
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basically outpaces the rate at which atmospheric
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drag pulls the debris out of orbit. So it just
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feeds itself. Exactly. The environment begins
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to aggressively pollute itself even if we never
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launch another rocket. But the timeline on this
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is important to clarify, right? Right. Because
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it's really easy to picture a Hollywood scenario
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where a satellite blows up and suddenly, boom,
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the entire sky is full of explosions. Yeah. Gravity
11:44
style. But the reality is much slower, which
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in some ways actually makes it harder to mobilize
11:49
people to care. A full Kessel Cascade doesn't
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happen in an afternoon. It takes decades. Decades.
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Right. A collision happens, creating a cloud
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of debris that slowly spreads out over months.
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Ten years later, a piece of that debris hits
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another satellite. It is a slow generational
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locking down of our most valuable orbital real
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estate. And this is where it stops being an abstract
12:11
problem for astronauts and starts being an immediate
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problem for you, the listener, because it's incredibly
12:16
easy to take space for granted. But if we lose
12:19
safe access to those orbits, modern life essentially
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breaks down. I really don't think most people
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realize how deeply their daily routine relies
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on a clear orbital path. Oh, it is entirely invisible
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infrastructure. I mean, most people understand
12:32
that satellite television or the mapping app
12:34
on their phone relies on space, but it goes so
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much deeper into the industrial backbone of society.
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Like what? Well, for example, the global financial
12:43
system relies entirely on the precise timing
12:46
signals beamed down by GPS satellites. Wait,
12:48
really? The stock market uses GPS? Oh, absolutely.
12:52
Every GPS satellite carries a highly precise
12:55
atomic clock. When a bank processes millions
12:58
of high frequency trades or even when you just
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swipe your card at an ATM, the system needs a
13:03
universally synchronized timestamp to prevent
13:06
fraud and keep the ledgers in order. And they
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get that from space. They pull that timing signal
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straight from GPS. If you lose the GPS constellation
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to a debris cascade, the global supply chain,
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aviation routing, worldwide banking systems,
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they would all face catastrophic disruptions
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within hours. That is terrifying. And what makes
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this even worse is that Kessler was worried about
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this tipping point back when there were only
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like a few hundred active satellites. Today,
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the volume of traffic in space is skyrocketing
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at a rate we've never seen before. Yeah, we have
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officially entered the era of the mega -constellation.
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Right. Private tech companies are launching networks
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made up of thousands and soon tens of thousands
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of small satellites to beam high -speed internet
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to every square inch of the globe. Which is an
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incredible technological feat. It is. And I want
13:55
to be fair here, because bringing low -latency
13:58
internet to remote and underserved areas, that's
14:01
a massive leap forward for humanity. But from
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a traffic management perspective, how do you
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manage thousands of new vehicles merging onto
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a highway that is already filled with invisible
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hypervelocity shrapnel? You've hit the nail on
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the head. It fundamentally changes the math of
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orbital risk. These Internet satellites operate
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in lower orbits, which means they need huge numbers
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of satellites to get full global coverage because
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each one can only basically see a small patch
14:28
of the Earth at a time. OK, so that. drastically
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multiplies the number of objects we have to monitor.
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Yes. I was looking at the mitigation strategies,
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and honestly, it feels like we're just dodging
14:37
bullets in the dark. The Space Force and international
14:40
agencies use giant ground -based radars to track
14:43
the big stuff, right? They do. We currently track
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over 25 ,000 objects larger than, say, a softball.
14:50
And that data is fed to operators around the
14:53
world. So they have a heads up. Yeah. When the
14:56
International Space Station gets a red alert
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that a piece of tracked debris is going to violate
15:00
its safety box, they literally fire up the thrusters
15:04
and physically alter the station's orbit to dodge
15:07
it. Wow. They have to execute these avoidance
15:09
maneuvers constantly now. But that only works
15:12
for the objects large enough to bounce a radar
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wave back to Earth. Right. What about the lost
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bolts, the shattered pieces of that Cosmos satellite,
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the paint flecks? And that is the structural
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vulnerability of our current space economy. There
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are estimated to be over a million fragments
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ranging from a centimeter to 10 centimeters in
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size, and we just cannot track them. We're just
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blind to them. Spacecraft operators simply have
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to accept the risk. There is no dodging what
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you cannot see coming. Which means we can't just
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play defense anymore. We have to actively clean
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up the mess. And I was diving into some of the
15:45
engineering proposals for active debris removal,
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and it honestly sounds like science fiction.
15:50
Space harpoons, robotic tentacles. Active debris
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removal, or ADR, is the absolute frontier of
15:56
aerospace engineering right now. The basic concept
15:59
is launching a specialized chaser spacecraft
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that matches orbit with the dead satellite, captures
16:05
it, and then physically drags it down into the
16:08
atmosphere to burn up. Okay. And they are testing
16:11
concepts that use giant nets, magnetic tethers,
16:13
and yes, literal harpoons. A harpoon in space.
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But the engineering challenges of a space harpoon
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seem almost insurmountable. I mean, if you have
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a multi -ton dead satellite tumbling end over
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end at 28 ,000 kilometers an hour and you shoot
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a metal spear into it, aren't you risking hitting
16:29
a pressurized fuel line and creating the exact
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kind of explosion you're trying to prevent? Yes.
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You are hitting on the core nightmare of debris
16:37
removal. These targets are completely uncooperative.
16:40
They aren't designed to be caught. Right. They
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have no handles, they're spinning chaotically,
16:44
and their structural integrity might be degraded
16:47
from decades of solar radiation. If your robotic
16:50
arm slips or your harpoon shatters a solar panel,
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you just turn one piece of trackable debris into
16:56
a hundred pieces of untrackable trapdoor. Oops.
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Yeah, very expensive. Oops. It requires a level
17:03
of autonomous precision that we are really only
17:05
just beginning to achieve. And dragging dead
17:08
satellites out of orbit? One by one, that sounds
17:10
exhaustingly expensive. Who's going to pay $100
17:13
billion just to take out the trash? Yeah. But
17:16
from my research, it seems nature... actually
17:19
offers us a helping hand here. There's this geographic
17:22
wrinkle to how orbits work. The Earth's atmosphere
17:24
doesn't just hit a hard ceiling and turn into
17:27
a perfect vacuum. Exactly. The atmosphere's boundary
17:29
is actually pretty fuzzy. It fades out very gradually.
17:32
Down in low Earth orbit, which is where the space
17:34
station flies and where all these new internet
17:36
mega constellations are being deployed, the environment
17:39
is not a true vacuum. There is still a microscopic
17:42
whisper of atmospheric gases up there. A whisper
17:46
of the atmosphere. So let me try an analogy here
17:48
to see if I've got this. Imagine you're jogging
17:51
on the dry sand at the beach, and then you decide
17:54
to start wading into the ocean. Even if the water
17:57
is only up to your ankles, that tiny bit of fluid
18:00
dragging against your legs It slows you down
18:03
over time. Analogy, yes. You have to expend more
18:06
energy to keep your speed up. That is exactly
18:08
what happens to objects in low Earth orbit. That
18:11
faint atmospheric drag is constantly pushing
18:13
against the satellites and the debris. Just a
18:15
little bit of friction. Yeah. And over a period
18:18
of months or years, that friction steals kinetic
18:20
energy from the junk. It slows down, its orbit
18:23
decays, and eventually gravity pulls it deep
18:26
enough into the thick atmosphere that it safely
18:28
burns up upon reentry. So low orbit actually
18:31
has a built -in natural self -cleaning mechanism.
18:34
It does. And interestingly, this natural cleanup
18:37
even accelerates during periods of high solar
18:39
activity. Wait, how does the sun help? Well,
18:41
when the sun releases a solar flare, it heats
18:44
up the Earth's upper atmosphere, causing it to
18:46
expand outward. That increased density acts like
18:49
a giant brake on low -orbit debris, dragging
18:51
it down much faster. That is an amazing natural
18:54
fail -safe. But there's a catch, isn't there?
18:57
Not all satellites are in low orbit. The massive
19:00
telecommunications and weather satellites sit
19:02
in geostationary orbit, which is, what, over
19:05
35 ,000 kilometers up? Yeah, and up there, that
19:08
faint atmospheric drag completely vanishes. You
19:11
are operating in a true vacuum. So no friction
19:13
at all? None. If a satellite breaks apart in
19:16
geostationary orbit, nature is not going to help
19:19
us clean it up. Debris at that altitude will
19:21
linger for centuries, maybe even millennia. Wow.
19:24
So understanding this altitude difference between
19:26
the self -cleaning shallow end of space and the
19:30
infinite deep end that really dictates the future
19:32
of space strategy. It defines the new rules of
19:35
the road. We can utilize the lower orbits for
19:37
large fleets of expendable satellites, provided
19:40
we design them to de -orbit quickly when they
19:42
fail. Right. Let the atmosphere do the work.
19:45
Exactly. But we must guard the high orbits jealously,
19:48
because up there, whatever we break stays broken
19:52
forever. Okay, so bringing this all together,
19:54
we have hypervelocity paint chips, dead rocket
19:57
hulks, the looming threat of the Kessler syndrome,
20:00
and experimental space harpoons. What does this
20:03
all mean for us as a society? What is the core
20:06
takeaway you want the listener to walk away with?
20:09
I think the underlying lesson is actually a deeply
20:11
familiar one. We've just relocated it to a new
20:14
frontier. What do you mean? For the first 50
20:16
years of the space age, we treated the space
20:18
around Earth as infinite and resilient. We treated
20:21
it the exact same way the Industrial Revolution
20:23
created our rivers and our air. Ah, as a place
20:27
where you could dump your byproducts without
20:29
consequence. Exactly. We thought space was too
20:31
big to fail. But we're learning that near -Earth
20:33
orbit is a shared, limited environment. It's
20:36
a commons. Right. It can be spoiled. Keeping
20:39
it usable for future generations is going to
20:41
require immense global cooperation, strict regulations
20:45
on what gets launched, and heavy investments
20:48
in active cleanup technologies. Space is not
20:52
an empty void. It is a delicate neighborhood.
20:55
And we are absolutely responsible for keeping
20:57
it clean. A delicate neighborhood. I love that.
21:00
Thank you so much for bringing your insight to
21:02
this and walking us through the mechanics of
21:04
all this. It's been incredibly eye -opening.
21:05
My pleasure. It is a really critical conversation
21:07
to have right now. And to you listening, I want
21:09
to leave you with one final thought to mull over,
21:11
something that builds directly on this idea of
21:14
space as a shared commons. Down here on Earth,
21:17
if you rear -end someone's car on the highway,
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there is a clear system for liability. You call
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your insurance, they sort it out. But space is
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an environment without borders. So who actually
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pays the bill or takes legal responsibility when
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a piece of anonymous 40 -year -old space junk
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launched by one nation takes out a brand new
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multimillion -dollar satellite owned by a company
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in another nation? That's the million -dollar
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question. Right. While there are treaties from
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the Cold War era that broadly say nations are
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responsible for their space objects, practically
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applying that to a cloud of untrackable hypervelocity
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shrapnel is an entirely different story. It is
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the ultimate intergalactic traffic dispute, and
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humanity hasn't quite figured out the insurance
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policy for it yet. We really haven't. So next
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time you look up at that clean, silent, black
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night sky, remember, there's a whole lot of high
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-speed history flying around up there. Catch
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you on the next deep dive.