The Kessler Syndrome: Starlink and the Closing of the Sky

Space, the final frontier. Stardate: November 25, 2025. You’re aboard China’s Shenzhou-20 spacecraft, a crew rotation vessel ferrying astronauts to and from the Tiangong space station.

You’re 250 miles above Earth, moving at 17,000 miles per hour.

Through the window, you watch the curve of the planet below. Then you notice something. A crack, spiderwebbing across the glass.

It doesn’t look like a manufacturing defect or a micrometeorite impact. Then it hits you.

Space debris has just punched into your ship ^[1]. Something man-made, traveling at orbital velocity, has damaged your ride home.

The debris wasn’t tracked. In fact, millions of fragments smaller than 10 centimeters orbit Earth completely invisible to current tracking systems ^[2]. You had no warning. Ground control had no warning. Nobody could have told you to move.

You wait nine days for the rescue mission to launch ^[1].

Nine days staring at that crack, wondering if it’ll spread.

Back on Earth, the incident barely registers as news. Orbital debris strikes aren’t shocking anymore. They’re becoming routine. So are the constant maneuvers satellites perform to avoid them. In just six months of 2025, Starlink’s 9,000 satellites executed 144,404 collision avoidance maneuvers ^[3]. That’s over 400 dodges per week, every week, just to keep one constellation operational.

A decade ago, a debris strike on a crewed spacecraft would have prompted international emergency meetings. Now? It’s just background noise.

We’ve normalized conditions in orbit that most people would consider a crisis if they understood them. Satellites have to perform hundreds of collision avoidance maneuvers every week just to stay operational. The crowding keeps getting worse as multiple countries and companies race to launch their own megaconstellations.

Each new satellite multiplies collision risk exponentially. At some point, the math stops working. One collision creates hundreds of fragments. Those fragments cause more collisions. The cascade becomes self-sustaining.

That point has a name: the Kessler Syndrome. And we’re closer to it than most people realize.

When the Math Stops Working

Let me start with something that may feel completely counterintuitive: space is not actually that big. At least not in the context of satellites.

Sure, the universe is vast. But the useful part of orbit where satellites actually work? That’s a thin shell about 1,200 miles thick surrounding Earth. And we’re filling it up fast.

Kessler Syndrome is the scenario where orbital debris becomes unmanageable. Named after NASA scientist Donald Kessler, who predicted it back in 1978, the syndrome describes a tipping point: when the density of objects in orbit gets high enough, collisions start causing more collisions ^[4]. One crash creates hundreds of fragments. Those fragments hit other satellites, creating thousands more. The cascade becomes self-sustaining.

Think of it like a chain reaction, except instead of splitting atoms, you’re shattering satellites.