Hunt for 25,000 hidden asteroids as scientist reveals how we’d stop a dangerous city-killer rock hurtling towards Earth

NASA is about to begin a massive hunt for hidden asteroids, and may uncover city-destroying space rocks we've missed.

Thankfully if we do find one hurtling towards Earth, there's hope for humanity – as scientists reveal how we might stop it.

Nasa‘s NEO Surveyor mission plans to put a telescope into space to look for “near-Earth objects”.

The aim is to find objects that we'd struggle to see from Earth that might be dangerous to our precious world.

“We can only do something about hazardous near-Earth objects if we can find them first,” Nasa explains.

What gives Nasa's new telescope a big advantage is that it's capturing infrared light.

This will allow the NEO Surveyor probe to spot very-hard-to-see space rocks, some of which might be extremely dangerous.

“As it scans the solar system, NEO Surveyor's sensitive infrared detectors will track the most elusive near-Earth objects,” Nasa said.

“Dark asteroids and comets don't reflect much visible light, for example, but they will glow in the infrared spectrum as they’re heated by sunlight.”

But that's not all: Nasa faces another problem when trying to track asteroids from the ground.

The brightness of the Sun makes it extremely difficult to spot asteroids in that part of the sky.

That means totally hidden – and potentially dangerous – asteroids might be lurking there. They could be very large, and impossible to see without sending a probe into space.

“NEO Surveyor will be able to find asteroids that approach Earth from the direction of the Sun,” Nasa explained.

“As well as ones both leading and trailing our planet's orbit, where they are typically obscured by the glare of sunlight.

“All of these are threats that larger ground-based observatories could miss.”

The NEO Surveyor is expected to launch on one of Elon Musk‘s SpaceX Falcon 9 rockets.

It's expected to blast off from Florida in September 2027, with a launch window “no later” than June 2028.

And plenty of people will be happy after scientists revealed earlier this year that a 130-300ft asteroid had a small chance of striking Earth just before Christmas of 2032.

The impact probability for Asteroid 2024 YR4 peaked at 3.1% in mid-February, before thankfully falling to 0%.

Now Nasa is hoping to have the best chance of tracking down these potentially dangerous asteroids well ahead of time.

What's the difference between an asteroid, meteor and comet?

Here's what you need to know...

• Asteroid: An asteroid is a small rocky body that orbits the Sun. Most are found in the asteroid belt (between Mars and Jupiter) but they can be found anywhere (including in a path that can impact Earth)
• Meteoroid: When two asteroids hit each other, the small chunks that break off are called meteoroids
• Meteor: If a meteoroid enters the Earth's atmosphere, it begins to vapourise and then becomes a meteor. On Earth, it'll look like a streak of light in the sky, because the rock is burning up
• Meteorite: If a meteoroid doesn't vapourise completely and survives the trip through Earth's atmosphere, it can land on the Earth. At that point, it becomes a meteorite
• Comet: Like asteroids, a comet orbits the Sun. However rather than being made mostly of rock, a comet contains lots of ice and gas, which can result in amazing tails forming behind them (thanks to the ice and dust vapourising)

Picture Credit: Getty Images – Getty

“NEO Surveyor will find asteroids and comets that other space missions cannot,” Nasa said.

“Filling a critical gap in humanity’s ability to detect potentially hazardous near-Earth objects.”

Leading the mission is Amy Mainzer, a UCLA professor of planetary science, who said one of the key objectives is “having enough time to really make an informed plan”.

“We still don't know everything that's in our own backyard,” Amy told the Los Angeles Times.

Mainzer's mission is expecting to find two thirds of the expected 25,000 near-Earth asteroids larger than 459 feet across within the first five years after launch.

And within the first 10 years, it should have tracked 90% of those.

If one is found to be dangerous, it might need dealing with quickly.

One method is to “deflect” the asteroid, which works better if you have time on your side.

“It all comes down to doing things as early as you can, because then you barely have to do anything,” said Kathryn Kumamoto, the head of planetary defense at Lawrence Livermore National Laboratory, speaking to the LA Times.

“If we did want to, say, deflect the asteroid, we only have to nudge it a very little bit if we can get to it very far in advance.

“A change of a millimeter per second over decades will add up to thousands of kilometers, and that can be enough to make the asteroid miss the Earth entirely.”

Back in 2022, Nasa was able to change the trajectory of a near-Earth asteroid by crashing a spacecraft into it.

The Double Asteroid Redirection Test, known as Dart, nudged a small space rock around seven million miles away.

And a similar technique could be used for a genuine threat – if one is ever discovered.