Earth’s orbit is so crowded that there are 1,000 collision warnings per year. day

• Space debris has filled Earth’s orbit so much that it endangers satellites and astronauts.
• The company Kayhan Space issues about 1,000 space collision warnings a day.
• Earth orbit experts fear debris will cause an “unstoppable chain reaction” that aborts launches.

So much junk fills Earth’s orbit that avoiding collisions has become a busy business.

“We’re talking about the dead satellites, the rocket bodies, the fairings, the wrenches, the gloves and those kinds of things that have been left in orbit,” says the physicist. Thomas Berger said in a press briefing at the fall meeting of the American Geophysical Union in Washington DC on December 11.

Along with these recognizable objects are millions of bits of debris in orbit traveling faster than a bullet.

All that build-up increases the risk of explosive space collisions, which are dangerous for astronauts and satellites.

Earth’s orbit is so full of junk now about 1,000 warnings of possible impending collisions are issued to satellite operators each day, Berger said.

For example, Araz Feyzi, a co-founder of orbital data firm Kayhan Space, told BI in an email that some of its customer satellites get up to 800 alerts a day from the US Space Force.

Siamak Hesar, the company’s other co-founder, later wrote in a SpaceNews editorial that the company tracks “more than 60,000 alerts per week for a constellation of about 100 satellites.”

Most of these warnings come from a quarter of Earth’s orbit, about 550 kilometers (340 miles) in altitude, where SpaceX’s Starlink satellites reside.

“It becomes difficult for satellite operators to determine which of these warnings are important and which to pay attention to,” said Berger, executive director of the Space Weather Technology, Research and Education Center at the University of Colorado, Boulder.

Because trackers cannot perfectly predict objects’ positions in space, these collision warnings are triggered when objects are expected to pass each other at close range. Only a small proportion of the warnings actually end up in a collision.

When space objects collide, they eject high-velocity debris in multiple directions, creating a new zone of hazardous junk in orbit.

“That can generate a chain reaction, an unstoppable chain reaction of further collisions, ultimately resulting in a completely crowded space environment,” Berger said.

In the worst case, the orbit could become so crowded that there is no safe space for new rocket launches.

It’s a situation experts call Kessler syndrome and “that we hope to prevent,” Berger said.

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Close calls and near misses

Although rare, large collisions and explosions have occurred a few times.

In 2009, an American satellite and Russian satellite crashed together, ends up in nearly 2,000 pieces of debris large enough to detect — at least 4 inches wide — with thousands more smaller pieces.

In 2021, a Chinese satellite and a Russian rocket collided, creating at least 37 pieces of debris large enough for Earth systems to track.

And anti-satellite missile tests by Russia, China and India have blasted dead spacecraft into orbit, sending thousands of pieces flying.

Each of these events created its own field of hazardous debris that is still rocketing around the planet today with potentially dire consequences.

For example, astronauts on the International Space Station receive debris alerts several times a year and prepare to evacuate if the station is hit. When this happens, spaceships docked to the station will fire their engines to push it out of the way.

Satellite operators often respond to warnings by moving their satellites out of the way. SpaceX told the FCC in July that its satellites had performed nearly 50,000 collision avoidance maneuvers during the first half of the year, Space.com reported.

Unfortunately, not all satellites are maneuverable.

In March, NASA had to sit on its hands and watch as a long-dead Russian spacecraft raced toward the agency’s TIMED satellite, which was designed in the 1990s and lacks the ability to move on command.

Fortunately, the two spacecraft missed each other by 17 meters (56 feet)—not very far by space standards.

“It would have been a hypervelocity impact that created thousands of pieces of debris,” Berger said.

Daniel Baker, who directs the Laboratory for Atmospheric and Space Physics at UC Boulder, urged the US Congress to pass the ORBITS Act. The legislation would require federal agencies like NASA and the FCC to support technologies that can remove junk from orbit.

“I believe we are seeing the tragedy of the commons unfold in low Earth orbit right before our eyes,” Baker said in the briefing.

“We need to take this seriously and recognize that unless we do something, we are in imminent danger of rendering a large part of our terrestrial environment unusable,” he added.