Evrim Yazgin
Cosmos science journalist
Global planetary defence procedures have been triggered after NASA scientists’ prediction that an asteroid has a 1.3% chance of hitting Earth in 2032.
The rock, dubbed 2024 YR4, was first spotted on 27 December last year. It is 40–100m wide and about 220 million kg.
2024 YR4 isn’t big enough to wipe out humanity. For comparison, the asteroid which is believed to have caused the mass extinction at the end of the “Age of Dinosaurs” is believed to have been 10–15km wide (the size of Mount Everest) and weighed up to 2 billion times more than 2024 YR4.
But the asteroid spotted last month could still destroy an entire city.
Scientists say that the asteroid is not likely to impact Earth, but it does raise questions about how prepared we are to defend the planet against potential devastation from other space rocks.
“The first thing to stress here is – don’t panic!” says astronomer Jonti Horner from the University of Southern Queensland in Australia. “Whilst this sounds like a scary story, it’s actually a really good example of how the search for potentially dangerous asteroids works.
“The asteroid in question – 2024 YR4 – was first discovered about a month ago, and as astronomers have tracked it since, we’ve gained a better understanding of its orbit around the Sun.”
“Asteroid 2024 YR4 is significant,” says Evie Kendal from the Ethical, Legal and Social Implications of Emerging Technologies research group at Australia’s Swinburne University of Technology. “Not because it is likely to actually hit Earth – with current predictions suggesting it will most likely pass us by without incident – but because it highlights the need for a global strategy for other asteroidal and cometary impact hazards that might.”
Kendal says there are technologies which could redirect an asteroid on an impact trajectory. But the “ethico-legal governance issues for if and how we should deploy such systems have not been settled”.
In 2022 NASA’s Double Asteroid Redirection Test (DART) mission successfully crashed into and redirected the asteroid Dimorphos in a proof-of-concept test for such technologies.
“But whose responsibility is planetary defense on a global scale? Can we decide in advance what we should do in the face of a future threat?” Kendal asks.
“Asteroid 2024 YR4 reminds us that questions of international governance for planetary defense systems have not been answered, and that addressing them will require global cooperation and collaboration efforts in ethics and policy for guiding human interactions with the space environment,” she adds.
NASA notes that no other large asteroids are known to have a higher than 1% probability of hitting Earth.
