Zombie satellites and graveyard orbits: Exploring the debris that haunts space technology

This Halloween, you may have seen your fair share of ghouls and supernatural entities around campus. But there’s a whole other army of zombies in space — zooming around us at a rate of 15,700 miles per hour in what scientists call a “graveyard orbit.” 

And, spookiest of all: they could crash into Earth at any moment.

According to NASA, over 27,000 pieces of broken human technological equipment are currently circling around the Earth’s atmosphere. These human-made pieces of equipment, from rocket stages to satellites, have lost connection with their home bases.

Sometimes, “zombie satellites” sputter back into contact with Earth, transmitting irregular messages to home bases. But the home bases do not have any control over these pieces of debris.

That means sometimes the orbital debris ends up circling Earth aimlessly for decades. Other times, it crashes back onto Earth in an uncontrolled spiral.

This July, a team of UBC researchers published an analysis of uncontrolled rocket re-entry risks in Nature Astronomy. Their work found that there is a 10 per cent chance orbital debris will cause human casualties within the next decade.

“There's a lot of dead equipment in orbit, and it is poised to come down in very scary ways,” said co-author Dr. Michael Byers, a UBC political science professor and co-director of the Outer Space Institute.

While it’s most likely that orbital debris will land in the ocean, it may also strike a city or even an aircraft. “We call these low-probability, high consequence events,” said Byers. 

“So it's extremely unlikely that a Boeing 777 would be struck by a piece of returning space debris, but it could kill everyone on board.”

As more material gets launched, more material is added to orbit, increasing the risk of collision with Earth or other space missions leaving the planet.

Just today, the Long March 5B was launched into orbit by the China National Space Administration. The rocket is set for an uncontrolled deorbit back to earth in November.

“It could come down pretty much anywhere between 41 degrees north and 41 degrees south,” said Byers. “It has been abandoned in low Earth orbit. And it is low enough that that gas drag from the upper atmosphere will cause it to come back.”

To address the issue, future missions could enforce two types of solutions. The first is engineering missions that save material, leading to less waste and debris. The second is building contingencies for controlled re-entry back to earth. 

“We need to have an international agreement to this effect to bring everyone on board,” Byers said. “Just like we used to think the oceans were too big to worry about dumping garbage in the ocean, we now realize that both the ocean and Earth's orbit have limits.”

In the meantime, near orbit’s growing collection of zombies will continue to circle above our atmosphere long after the spooky season ends.