Nasa increases chance of ‘city destroyer' asteroid hitting Earth in 2032 to one in 43

The National

18-02-2025

Scientists around the world are tracking a newly-discovered asteroid that has been given a one-in-43 chance of striking the Earth in seven years, and Nasa said the odds on could 'continue to rise'. The rock, designated Asteroid 2024 YR4, could hit on December 22, 2032, according to the US space agency. Scientists want to learn more about YR4's trajectory and size, but the asteroid is too faint to observe as it is moving away from Earth right now. It is estimated to be between 40 to 91 metres wide and could, in theory, unleash about 500 times the energy of the atomic bomb that hit the Japanese city of Hiroshima on August 6, 1945. Jonathan Ward, a fellow with the Royal Astronomical Society, told The National that several factors could influence the asteroid's trajectory, including the Yarkovsky effect, where the asteroid absorbs and radiates enough heat from the Sun that it changes course. 'We won't know anything better about its potential for an impact in 2032 until it comes back by the Earth in 2028. And in fact, we're going to lose it to Earth-based telescopes within the next several weeks,' he said. 'The James Webb Space Telescope will probably still be able to track it from infrared radiation (heat signatures) for a while. But we won't be able to track it all the way around the Sun.' Observations so far also show that the asteroid is a stony type rather than a metal-rich one, which means if it does reach Earth, it could break up in the atmosphere before reaching the ground. But if more detailed observations show it is metal-rich and with the current size estimates, it means the asteroid would create a force equivalent to as much as eight megatons of TNT, hundreds of times more powerful than the Hiroshima bomb. It could create a crater hundreds of metres wide, with severe destruction in a 10 to 20km radius. A land impact near a populated area could cause mass casualties and infrastructure damage. If the asteroid hits an ocean, it could generate a tsunami that would produce waves tens of metres high near coastal regions. An atmospheric explosion would result in an even stronger blast, potentially causing citywide destruction. Historical asteroid events provide context for what could happen if 2024 YR4 were to hit Earth. In 1908, the Tunguska event in Siberia was caused by an asteroid or comet estimated to be 50 to 60 metres in diameter. The explosion flattened more than 2,000 square kilometres of forest. In 2013, the Chelyabinsk meteor, which was 20 metres across, created an airburst that shattered windows across hundreds of kilometres, injuring more than 1,500 people. Khadijah Ahmed, operations manager at the Dubai Astronomy Group, told The National that researchers continue to refine the asteroid's orbit. 'The key issue is that the asteroid's path is still uncertain, and it's moving away from Earth, making it harder to track,' she said. 'We could stop an asteroid like 2024 YR4 if we act early, but we need better tracking, more advanced tech and faster decision-making to be fully prepared.' Nasa had carried out the DART mission in 2022, where it crashed a spacecraft into an asteroid to demonstrate how a space rock's course can be changed in the event of a real threat to Earth. Mr Ward said that mission was the 'best chance we have' in terms of mitigation, however, it would take about three-to-five years to prepare and launch. 'If we can change the course of the asteroid in such a way that its orbital period changes by 10 or 20 minutes, that will be enough for it to miss the Earth,' he said. 'But the problem is we don't know where the asteroid is going to be until 2028. So, that gives us little time to be able to launch a mission and intercept the asteroid directly.' Researchers are now using space-based infrared telescopes, like James Webb and Neowise to monitor the asteroid. Ms Khadijah said that a special space mission, similar to Nasa's upcoming NEO Surveyor, could also provide crucial data by tracking the asteroid in infrared, which is better for detecting dark space rocks. 'A nuclear detonation could be a last-resort option to push the asteroid off course – not blowing it up, just pushing it – but there are many legal and political challenges to using nukes in space,' she said. 'Another option would be laser/ion beams. These are more experimental ideas where lasers or ion beams slowly push the asteroid over time. They require technology that isn't fully developed yet, but in the future, they could offer a precise, non-destructive way to redirect space rocks.' The asteroid is classified as a Level Three threat under the Torino Scale, which is used to assess the risk posed by near-Earth objects like asteroids. Level Three means that the asteroid 'needs monitoring' and that there is a small chance of impact. For perspective, Level eight to 10 was the Chicxulub asteroid, an event that wiped out the dinosaurs 66 million years ago.