A massive celestial body could crash into Earth in 2032. Discovered on December 27, asteroid 2024 YR4 measures between 40 and 90 meters in diameter. Last week, NASA increased the chance of 2024 YR4 hitting Earth to 1 in 43 (2.3%), with a potential impact date of December 22.
This Tuesday, February 11, in a “thread” on X, a scientist estimated that “we might not be able to prevent 2024 YR4 from hitting our planet, even with a deflection mission.”
Dr. Robin George Andrews, a volcanologist and science journalist, points out that we have less than eight years to potentially deal with it. However, he says, “it takes 10 years or more to build, plan and execute an asteroid deflection mission”.
Hey asteroid 2024 YR4 watchers! I'm seeing a lot of people claim that, if it is going to impact Earth in 2032, we can use a DART-like spacecraft to ram it out of the way.
Well, not necessarily. The DART mission was fab, but might not be able to stop 2024 YR4.
Let me explain pic.twitter.com/JzBfEx2TxG
— Dr Robin George Andrews (@SquigglyVolcano) February 11, 2025“So many things could go wrong if we tried to hit him”
With its Double Asteroid Redirection Test (DART) mission, NASA demonstrated that it was possible to deflect a celestial object off its collision course with Earth by hitting it with a spacecraft. While he acknowledges that the DART mission ‘worked wonders,’ Dr. Andrews believes that we may not be able to stop 2024 YR4 in the same way. “So many things could go wrong if we tried to hit it with something like DART“, he warns.
Most asteroids are not made of solid rock, but rather “rubble piles”: clumps of boulders, stones, and sand held together by the weak gravity of space. Except that at this time, we don’t know the exact size or composition of 2024 YR4.
So hitting an asteroid that’s made up of “rubble piles” with a spacecraft could potentially generate a cloud of debris that could head toward Earth anyway. Similarly, if 2024 YR4 “ is too big, we may not be able to deflect it with a single spacecraft. It would take several to hit it perfectly, let alone break it up.”
“It would hit the Earth in a place that should not have been hit”
“No one wants to accidentally ‘disturb’ an asteroid because its components can still head towards Earth, “ says Dr Andrews, who illustrates:
“It’s like turning a cannonball into a shotgun shell. ” And with just a few years to spare, we could accidentally deflect it, but not enough to make it avoid the planet. It would then hit Earth, but somewhere else that it shouldn’t have hit.”
He added:
“I’m not saying that a kinetic impact mission or missions couldn’t work. But we don’t have much time and we don’t yet have enough information about this rapidly disappearing asteroid to properly inform our planetary defense decisions.”
Indeed, today 2024 YR4 is moving away from our telescopes and will soon no longer be observable until 2028. “Perhaps the probability of 2024 YR4 will increase and we will succeed in deflecting it in 2028 using a monster-sized spacecraft. Or perhaps we will break an inconvenient taboo and choose instead to use a nuclear warhead to try to deflect it,” concludes Dr. Andrews.
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