Space junk has hidden dangers

Scientists say defunct satellites and spent rocket stages returning to Earth, from the thousands launched every year, can be catastrophic

- Sheree Bega

During the afternoon of 30 December last year, residents of Mukuku village in Makueni County, Kenya, were alarmed by a sudden loud crash.

“In the middle of a field lay a mysterious, smouldering metal ring, 2.5m across and weighing nearly 500kg,” academics Richard Ocaya and Thembinkosi Malevu wrote in the journal, Nature.

“Elsewhere, in western Uganda in May 2023, villagers reported seeing streaks of fire in the sky before debris rained down, scattering wreckage across a 40km-wide area.”

Ocaya is an associate professor in the department of physics at the University of the Free State and Malevu is a distinguished associate professor in the department of physics in the North-West University.

These were no ordinary meteorites, they said. “Across the world, from Texas to Saudi Arabia, from Cape Town to the Amazon rainforest, objects launched into low Earth orbit (LEO) are now falling back to Earth.”

Some burn up in the atmosphere, but others, especially those made of titanium and heat-resistant space-age alloys, survive re-entry and “slam into the ground”.

With thousands of satellites launched every year, the growing danger of space debris, particularly defunct satellites and spent rocket stages returning to Earth, can “potentially be catastrophic”.

“People everywhere on the planet, flying in aeroplanes, as well as in space, are increasingly at risk,” Ocaya and Malevu wrote, warning that the growing amount of space junk has become an immediate danger, necessitating space-traffic management and collision-avoidance strategies.

When people think about space law, they imagine something remote or relevant rules written during the Cold War that are meant for superpowers, said Ocaya.

“But the reality is far more pressing. The space above our heads is getting dangerously crowded and the fallout literally is starting to reach the ground.”