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A recently identified asteroid, named 2024 YR4, is currently on a potential collision course with Earth, raising concerns among scientists and space agencies. The asteroid, first observed at the end of 2023, is estimated to be between 130 to 300 feet (40 to 90 meters) in diameter—potentially larger than the Statue of Liberty.
Initial assessments placed the probability of impact at 1.2%, but recent updates have increased this likelihood to 2.3%, translating to a 1-in-43 chance. If 2024 YR4 were to strike Earth, the projected impact date is December 22, 2032.
Expert Warns of Limited Time for Deflection Efforts
In a concerning update shared on X (formerly Twitter), Dr. Robin George Andrews, a volcanologist and science author based in London, expressed doubt about humanity’s ability to prevent a collision within the available timeframe.
“You need 10 years or more to build, plan, and execute an asteroid deflection mission,” Dr. Andrews stated. “We have less than eight years to potentially deal with it. We don’t have much time.”
NASA’s Double Asteroid Redirection Test (DART) mission, completed in September 2022, demonstrated the feasibility of altering an asteroid’s trajectory by crashing a spacecraft into it. The mission targeted Dimorphos, a 560-foot-wide asteroid orbiting a larger space rock, Didymos, located 6.8 million miles from Earth.
The collision successfully shortened Dimorphos’ orbit by more than half an hour, exceeding expectations. However, neither Dimorphos nor Didymos posed any real threat to Earth; instead, the mission served as a trial for potential future threats.
Understanding Asteroid 2024 YR4
The asteroid, dubbed a “city killer,” was first detected by the NASA-funded Asteroid Terrestrial-impact Last Alert System (ATLAS) station in Chile in December 2023. Since then, the probability of impact has increased, making it an object of growing concern.
Most asteroids are not solid rocks but rather “rubble piles”—clusters of boulders, stones, and dust held together by weak gravitational forces. Scientists are currently uncertain whether 2024 YR4 falls into this category. If it does, attempting to deflect it with a kinetic impactor could potentially create a cloud of debris, parts of which could still head toward Earth.
“Nobody wants to accidentally ‘disrupt’ an asteroid because those components can still head for Earth,” Dr. Andrews explained.
Probability of Impact: Should We Be Worried About the Asteroid?
Despite the concerns, Dr. Andrews reassured that the odds of impact remain relatively low at 2.3%.
“It’s like having 43 buttons in front of you and being asked to press one of them,” he explained in a blog post. “I don’t think you should be concerned.”
He also noted that as more observations refine the asteroid’s trajectory, it is likely that the probability of impact will drop to zero.
However, if the asteroid were to strike, the consequences would depend on the location. “If its point of impact is in the middle of a desert or the ocean, it will harm nobody. But if it hits a town or city, it will destroy much of it,” he warned.
According to NASA’s Near-Earth Object Program, Earth is struck by a football field-sized asteroid roughly every 5,000 years, while civilization-ending impacts occur approximately once every million years.
Lessons from the Tunguska Event
Asteroid 2024 YR4 is believed to be at least the same size as the Tunguska asteroid, which had an estimated diameter of 130 feet. The Tunguska event, which occurred in 1908, remains the largest impact event in recorded history, flattening 830 square miles (2,150 square kilometers) of Siberian forest. While fatalities were limited, some individuals lost consciousness, and at least three deaths were reported as a direct consequence, according to a 2019 study.
Scientists have proposed various strategies for deflecting or neutralizing an asteroid threat. These include:
- Multiple Bumps: Researchers in California have been experimenting with projectiles fired at meteorites, suggesting that multiple small impacts could be needed to shift an asteroid’s trajectory.
- Nuclear Explosion: Detonating a nuclear device near the asteroid to break it apart has been suggested, but this method carries the risk of creating smaller, still-dangerous fragments.
- Ion Beam Deflection: This approach involves using plumes from a space probe’s thrusters to gently push the asteroid over time.
- Gravity Tractor: A spacecraft could use its own gravitational field to slowly alter the asteroid’s course.
While 2024 YR4’s probability of impact remains relatively low, the asteroid’s discovery highlights the broader issue of planetary defense preparedness. A 2023 NASA report found that even with 14 years’ notice, current preparedness for an asteroid impact is inadequate.
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