China is building early warning system to spot Earth-smashing asteroids
Beijing will use ground telescopes and orbital satellites to track dangerous space rocks that currently go undetected
China is developing an early warning system to spot asteroids that might smash into the Earth, according to the scientist leading the national mission.
China planned to deploy multiple telescopes on the ground, alongside a constellation of satellites in orbit, state-run Science and Technology Daily quoted Li Mingtao, chief scientist at the asteroid monitoring and early-warning research centre under the China National Space Administration, as saying.
None of the asteroids that had been discovered so far were thought to be on a clear collision course with Earth, Li said in the report on June 30, which the United Nations designated as International Asteroid Day.
More than 95 per cent of near-Earth asteroids larger than 1km (0.62 miles) in diameter – large enough to trigger global catastrophes – had already been identified, he said.
But only about 45 per cent of asteroids measuring around 140 metres (460 feet) across, which could devastate a small country, were believed to have been discovered, he added.
“These undiscovered near-Earth asteroids pose the greatest risk. They are numerous, very faint before their approach and may even suddenly approach from the direction of the sun,” Li said.
“That is why the world is stepping up efforts to strengthen monitoring and early-warning capabilities and catalogue these asteroids as soon as possible,” Li said, adding that “we cannot take the impact risk lightly, nor do we need to be overly anxious”.
China would select “excellent sites to build multiple large-aperture optical telescopes”, according to the Science and Technology Daily report, which said that this would achieve “wide sky coverage and accurate measurements”.
The space-based component of the system would help to compensate for some of the weaknesses of observatories on the ground, as satellites are not limited by the day-night cycle or weather. Orbital observatories can also spot asteroids travelling towards Earth from the direction of the sun, like the space rock that went undetected until it lit up the sky over Chelyabinsk, Russia, in 2013.
Once a potential hazard is detected, the system will assess its trajectory and the probability of impact. Li said that if the threat was deemed credible and urgent, the authorities would be notified.
China had already made breakthroughs in algorithms used to assess the risk of asteroid collisions, Science and Technology Daily reported.
Li said that the most practical way of dealing with an asteroid threat was kinetic impact – altering the rock’s trajectory by hitting it with a spacecraft. The approach was demonstrated by Nasa in 2022, when the agency successfully redirected an asteroid.
He said that while asteroids could be redirected by using lasers, particle beams or gravity, these methods were relatively weak and could take years to have a major effect on an asteroid.