When Yuletide rolls around in 2032, you might not want to make any big plans. Forget the turkey and Christmas pudding. Don’t worry about decorating the tree. The gift atop your wish list might be a fallout shelter. In less than eight years, an asteroid heading for Earth could seriously disrupt your festive season.
It’s called Asteroid 2024 YR4 – let’s be friendly and call it YR4 – and, like an unwanted relative during the holiday season, it’s scheduled to make a flying visit you won’t enjoy on December 22, 2032.
YR4 was last week calculated to have a 2.3% chance of striking Earth: one of the highest ever recorded risks of an asteroid collision.
A one-in-48 risk may not sound terribly worrying – but would you cross the street knowing that you had the same odds of being struck by an 18-wheeler juggernaut?
Experts call YR4 a “city killer”, with good reason.
“It feels like science fiction, but this is science fiction in real life,” says astrophysics professor Tamara Davis, of the University of Queensland, Australia, who might have in mind such Hollywood asteroid disaster movies as Armageddon and Deep Impact.
“Asteroid impacts are a genuine concern. We know that they can have quite destructive effects. If it were to hit, it has thepotential to wipe out something the size of a city.”
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Heading our way at 38,000 mph, early estimates put it between 130 feet and 330 feet long.
An asteroid of similar size to the smallest estimate struck Siberia in 1908 and destroyed an area of more than 800 square miles, twice the size of New York City.
Astronomers believe that before hitting the ground, YR4 could create a mid-air explosion equivalent to 500 Hiroshima atom bombs, with a roughly 30-mile radius of devastation. Millions could die from the shock wave.
An asteroid strike in the ocean could unleash a tsunami to equally deadly effect.
Scientists are scrambling to find ways of deflecting or destroying the flying mass before it reaches Earth. But even if YR4 speeds harmlessly by, faster than Santa’s sleigh, there are many others like it out there spinning in orbits that could bring them perilously close to wreaking havoc.
There are millions of asteroids – slabs of rock and ice – in our solar system, and smaller chunks hit the Earth each year. But there are more than 40,000 near-Earth asteroids. Half of those were discovered in the last five years, and more than 11,000 are 460 feet wide or larger.
NASA considers any asteroid that comes within 4.65 million miles of Earth’s orbit “potentially hazardous”, so one that appears to be heading straight for us might keep astronomers up at night even more than usual.
Earth bears evidence of large asteroid hits in the past. Mexico’s Yucatán Peninsula is believed to have been formed when an asteroid, six miles in diameter, struck 65 million years ago, killing off the dinosaurs.
Asteroid Apophis, 1,500 feet wide, swings close to Earth in 2029 and 2036, but scientists have ruled out a possible Earth impact – at least, for the next 100 years.
Until then, we can worry about YR4.
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“Currently, no other known large asteroids have an impact probability above 1%,” NASA has said. And astronomers, excited as they are concerned, insist that you shouldn’t worry yet.
They are quick to point out that there’s more than a 97% chance we’ll just see a giant rock in the sky and won’t have to duck, so it’s premature to start building your own rocket ship to escape the planet for a few weeks’ R&R.
While scientists continue to track YR4 with increasing accuracy, the odds of a collision may change – but many are taking no chances, investigating ways to stop this or future asteroids landing a knockout blow.
Slamming a spacecraft into an oncoming asteroid to change its trajectory is the method favoured by NASA.
Its Double Asteroid Redirection Test programme, or DART, deliberately crashed a ￡260million spaceship the size of a golf cart into an asteroid called Dimorphos in 2022, proving that the speeding space rock could be nudged slightly off course.
“The dramatic experiment gives astronomers hope that perhaps we could do it again to avert an apocalypse,” wrote Popular Science.
Tom Statler, NASA’s lead DART scientist, admits the danger has always lurked: “If you’d asked me 30 years ago, ‘Can we be confident we won’t be wiped out by a giant killer asteroid a week from next Tuesday?’ I would have had to say no.”
But following DART’s initial success, he adds: “We will know what to do about it when something new is found.”
However, even the DART technique is not without its problems. The spaceship’s collision also unleashed almost 1,000 tons of loose rock, and there are concerns that such an impact could create more chaotic objects heading to Earth at even faster speeds.
Researchers are also exploring a “gravity tractor” which would involve flying a large spaceship alongside an asteroid, using the craft’s weak gravity to slowly pull the asteroid away from a collision course with Earth.
And laser ablation – in addition to being a Beverly Hills cosmetic procedure to stimulate collagen growth – could also be used on a larger scale to shoot laser beams at an asteroid, and vaporise its rock.
Small plumes from the impact would theoretically push the rock in a different direction. Also being considered is sending a spacecraft to the oncoming asteroid and firing its thrusters so that an ion beam would push the rock away.
Having almost eight years’ preparation to avert catastrophe seems like a long time – but it may already be too late.
Not only can it take years to build spacecraft and refine the technology for asteroid interception, but it can also take years more to actually send the craft into space to get alongside the speeding rock.
Even then, laser ablation, gravity tractors and ion beam propulsion may take years to have the desired effect.
NASA’s DART project has only been tested once. As a last resort, some have proposed firing nuclear missiles into space to detonate near the asteroid, pushing it off course.
A direct hit is undesirable, because the ensuing debris could create thousands of radioactive mini-asteroids heading to Earth in a deadly firestorm.
There is also the potential danger of the missile exploding either on the launchpad or in the atmosphere – and if it somehow misses the asteroid, there’s no telling what alien planet may one day be blown up in a galaxy far, far away.
While multiple space agencies, satellites and space telescopes are searching for other asteroids coming close enough to Earth to test their deterrents, YR4 continues racing toward us.
Scientists are hoping that additional measurements that will be taken when the asteroid next swings by Earth at a safe distance in December 2028 will serve as evidence that the odds of it hitting our planet are less than anticipated.
But NASA admits: “It is possible its impact probability will continue to rise.”
At present, YR4’s trajectory indicates it is headed for a potential impact zone stretching from India across Africa to South America and the Atlantic, so plan your 2032 holiday accordingly.
But the strike zone could easily change following further analysis, and Britain could find itself in the asteroid’s crosshairs.
Still, many scientists fancy our chances of survival.
“You should tell the people you care about that you love them,” advises theplanetary defence researcher and DART scientist Andy Rivkin, “but not because of 2024 YR4.”