Scientists reveal a new way to stop giant asteroids obliterating the Earth

An asteroid as imagined from the Hollywood film Armageddon - Alamy

An asteroid as imagined from the Hollywood film Armageddon – Alamy

In Hollywood’s eyes, there’s only one way to deal with a meteor headed for Earth: a nuclear bomb.

But unlike the people behind Armageddon or Deep Impact, scientists believe we can derail the path of a giant asteroid in other ways.

The data shows that crashing a sacrificial spacecraft into an asteroid would be powerful enough to keep almost any rocks from hitting Earth, averting catastrophe.

Only asteroids larger than a kilometer would need a nuclear detonation to blow them off course, scientists now believe.

A rock that big would have to hit our planet once every 700,000 years and would create a crater the size of Manchester. An impact of this size would cause global devastation and the possible collapse of civilization, experts say.

Astronomers believe some 900 “near-Earth objects” — defined as within 120 million miles of our sun — are more than a kilometer across, and have identified 95 percent of them.

Nuclear warheads have long been, and continue to be, part of planetary defense plans, but only as a last resort.

A White House document recently said that the United States will continue to study when an explosive nuclear device will be needed to prevent an asteroid apocalypse.

It is prudent, says an official document, “to continue research into the potential of nuclear explosive devices to be used for the deflection of potentially dangerous objects.”

Scientists have long believed that a nuclear bomb would be needed to protect our planet from any asteroid more than 600 meters wide.

But new data from NASA’s Dart mission, which deliberately crashed a spaceship into an asteroid, led to the decision to raise the threshold.

Launching a nuclear bomb into space would require a global political agreement. It would also be extremely risky with no guarantees of success.

“A kinetic impactor, a spacecraft, is going to be much more accurate because you can select the impact mass, velocity and direction; you really can control the deflection,” Ian Carnelli, a planetary defense expert at the European Space Agency (ESA) told The Telegraph.

“However, it’s much more complex with a nuclear device, and that’s before we get into the political discussion because nuclear explosions in space are prohibited by UN treaties.

“But even so, the nuclear device isn’t like you see in Armageddon where you send drillers to put the bomb into the core of the asteroid and destroy it, the idea is to detonate it some distance away from the asteroid.

“Triggering an explosion at some distance from an asteroid is extremely complex and nobody would agree to test it before a real threat is identified, so you really would have a complete lack of knowledge of how to do it.

“Whereas the kinetic impactor is a proven technique and the technology is ready now and is much more controllable. It really is the ideal deflection technique.

For the past decade, scientists around the world have been planning for the unlikely event of an asteroid strike, and last year NASA crashed the Dart into an asteroid to see how effective physical collisions are at throwing asteroids off course.

Dart landed on asteroid Dimorphos on Sept. 26, 2022, and a new analysis has found that the impact was far more forceful than scientific models predicted.

Asteroid moonlet Dimorphos seen from the Dart spacecraft 11 seconds before impact - REUTERS

Asteroid moonlet Dimorphos seen from the Dart spacecraft 11 seconds before impact – REUTERS

A follow-up ESA mission, called Hera, will launch in October 2024 and study the asteroid in more detail. It should reach Dimorphos by Christmas 2026.

Observations of Dimorphos’ new orbit around a larger asteroid called Didymos have already shown that Dart’s impact was more powerful than expected.

This, according to the scientists, is because the dust ejected into the air by the collision gave the asteroid an extra boost, a phenomenon called ‘momentum boost’.

Scientists have never been able to study the interior of asteroids in detail, so it was impossible to estimate how strong this effect would be in practice.

For Dart, the effect was assumed to be negligible. But analysis of the Dimorphos-Dart collision found that it acted as a strong amplifier of the crash and created five times more thrust.

“When you think of an impact, you always have material from the asteroid being launched into space. Typically this is the material that is excavated from the crater,” explained Carnelli, project manager at Hera.

“That ejecta generates an additional thrust that acts almost like a small engine and gives an additional force to the asteroid. The amount of material ejected was much, much higher than any scientist had predicted before Dart.

“The current results, without even having Hera to obtain the data necessary to define this number, are between two and five, which means that you have up to a fivefold effect due to this object.

“This has a very important implication for planetary defense because it means we could actually use a kinetic impactor deflection technique for much larger asteroids because we know it’s actually more efficient than we thought it could be.”

A kinetic impactor would be a spacecraft, he said, weighing about two tons equipped only with solar panels, a camera and a navigation camera. Launching it from a rocket to an asteroid is easier, safer and faster than launching a nuclear bomb, Carnelli said.

“We are expanding the range of applicability of the kinetic impactor and this is very good for the community because we know more than 95% of the asteroids kilometer and we know that none of them pose a threat to the Earth,” he added. .

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