Scientists sound the alarm over the problems posed to space missions from orbital junk the accumulating debris from mankind's six-decade exploration of the cosmos
Paris: Scientists sounded the alarm on Tuesday over the problems posed to space missions from orbital junk — the accumulating debris from mankind’s six-decade exploration of the cosmos.
In less than a quarter of a century, the number of orbiting fragments large enough to destroy a spacecraft has more than doubled, a conference in Germany heard.
And the estimated tally of tiny objects — which can harm or degrade spacecraft in the event of a collision, and are hard to track — is now around 150 million.
“We are very much concerned," said Rolf Densing, director of operations at the European Space Agency (ESA), pleading for a worldwide effort to tackle the mess.
“This problem can only be solved globally."
The peril from debris comes from hypervelocity. Travelling at up to 28,000 kilometres (17,500 miles) per hour, even a minute object impacts with enough energy to damage the surface of a satellite or manned spacecraft.
In 1993, monitoring by ground-based radar showed there to be around 8,000 manmade objects in orbit that were larger than 10 centimetres (4.5 inches) across, a size big enough to inflict catastrophic damage, said Holger Krag, in charge of ESA’s space debris office.
“Today, we find in space roughly 5,000 objects with sizes larger than 1 metre (3.25 feet), roughly 20,000 objects with sizes over 10 centimetres... and 750,000 ‘flying bullets’ of around one centimetre" (half an inch), he said.
“For objects larger than one millimetre (0.04 inch), 150 million is our model estimate for that."
Risks of a collision are statistically remote, but they rise as the litter increases and more and more satellites are deployed.
“The growth in the number of fragments has deviated from the linear trend in the past and has entered into the more feared exponential trend," Krag warned.
The conference in Darmstadt, whose opening speeches were broadcast on the internet, is the biggest-ever gathering dedicated to space debris.
Experts will spend four days discussing the problem, including measures to mitigate space litter such as by “de-orbiting" satellites at the end of their working lives.
Krag pointed to two events that had amplified the problem at a stroke, creating debris fields with the potential to generate further junk as pieces smashed into each other.