This long-exposure photograph taken on July 24, 2020, shows a view of the Comet Neowise (or comet C/2020 F3) in the sky over Shwebo, Sagaing region, in Myanmar. It was discovered on March 27, 2020, by the Near Earth Object Wide-field Infrared Survey Explorer (Neowise), which is a space telescope launched by Nasa in 2009. -- TNS
FOR a brief window, Asteroid 2024 YR4 looked like a planetary hazard in the making. At up to 90m in diameter, it was described as a potential “city killer”. On its estimated trajectory, it could’ve collided with Earth as soon as 2032.
According to the Torino Impact Hazard Scale, used to characterise such threats, it ranked a Level 3 out of 10 – a highly unusual designation, suggesting a “close encounter” was plausible.
Panic is no longer in order: The US National Aeronautics and Space Administration (Nasa) has just reduced the odds of impact to 0.0017%, down from a high of 3.1%. But the uncomfortably uncertain path of this asteroid, discovered only in late December 2024, offered a timely reminder of how vulnerable humanity remains to hidden perils whirling through space, and how much still needs to be done to protect the planet.
More than 38,000 asteroids are known to be in Earth’s vicinity, including 973 “planet killers” of more than 800m in diameter. Most pose no risk. But Nasa estimates that only about 43% of nearby asteroids exceeding 140m have so far been found. A direct impact from one could cause mass casualties and untold damage; many more rocks the size of YR4 remain undetected.
To Nasa’s credit, defences have significantly improved in recent years. The agency has created a monitoring system, called Sentry, to scan for and publish data on nearby asteroids; established the Planetary Defence Coordination Office; and plans to launch a new infrared telescope in 2027.
Most spectacularly, in 2022, its Double Asteroid Redirection Test (DART) smashed a spacecraft into a 170m rock some 11 million kilometres away, knocking it off course and confirming Nasa’s ability to deflect an inbound threat.
As for YR4, defensive measures were quickly set in motion. Because its chance of impact exceeded 1%, its detection triggered a global alert among space agencies.
A team of astronomers was dispatched to use the James Webb Space Telescope to study the asteroid. Two UN-sponsored groups helped coordinate an international response. Thankfully, new observations determined the worst will be avoided.
Even so, the world’s planetary- defence planning still needs work.
As a start, Nasa needs to make faster progress on US Congress’s 2005 mandate to find 90% of larger nearby asteroids. The new space telescope, called NEO Surveyor, will help. But the agency’s budget is under constant strain from an unnecessary and impractical mission to return astronauts to the moon on a government-built rocket, which has cost US$100bil (RM441.40bil) and counting.
A rededication to practical science like asteroid detection is overdue. (It is also, not incidentally, the public’s top priority for Nasa.)
Relatedly, Congress should fund more missions to test interception capabilities in space, on the DART model. Smashing stuff into approaching asteroids – “kinetic impact”, as the nerds say – is only one method among many and may not be appropriate for every threat.
Other options, including gravity tractors, ion beams, and nuclear devices, may provide better defences and should be the subject of serious study.
Global coordination, finally, is a work in progress. An interagency exercise last year concluded that there was “limited readiness” for an impending strike, and that the decision-making process “remains unclear”.
Congress should specify what role executive-branch agencies should play in such a scenario, and the US should continue to conduct planetary-defence exercises with other spacefaring nations and the United Nations Office for Outer Space Affairs.
Although YR4 no longer poses a threat, it is increasingly clear that Earth inhabits a dangerous neighbourhood. Keeping out of harm’s way will require ambition, vigilance, and no small amount of human ingenuity. – Bloomberg Opinion/Tribune News Service
