Asteroid 2024 YR4 triggered automatic asteroid warning systems after it was spotted by state-of-the-art telescopes in the Rio Hurtado in Chile last December.

Since then, the asteroid has been at the top of the danger list – a catalogue of all space objects that could potentially collide with our planet.

Although we are far from panicking, according to experts the probability of an impact on Earth has almost doubled from 1.2 percent in January to around 2.3 percent now.

But how much do we know about the asteroid and when will we know for sure whether we are safe? And what could happen if it actually comes towards us?

"Asteroid 2024 YR4 has a 99 percent chance of safely passing Earth on December 22, 2032, but a possible impact cannot yet be completely ruled out."

With these words, the European Space Agency (ESA) caused a stir at the end of January. Now the situation has worsened again: New calculations assume a probability of up to 2.2 percent (NASA) and 2.02 percent (ESA) that the space rock could actually collide with our planet in 2032.

Is the Earth in the asteroid's line of fire?

The roughly 40 to 100 meter large boulder from space, called 2024 YR4, was only spotted at the end of last year by the ATLAS telescope in Río Hurtado (Chile). The European Space Agency immediately put it at the top of its risk list - and accordingly turned all eyes on the potential troublemaker. According to initial scenarios, it could hit the south if it hits, reports mdr .

"It is still too early to determine exactly where on Earth a possible impact could occur," says ESA. Astronomers around the world are working hard to investigate how dangerous the situation really is. The goal: to determine the course of 2024 YR4 with millimeter precision in order to gain clarity as to whether we are really in the line of fire.

Experts worldwide react

In the meantime, several teams have even been mobilized: "Two international asteroid groups supported by the United Nations - the International Asteroid Warning Network (IAWN) and the Space Mission Advisory Group (SMPAG) - are currently considering their next steps." In addition, ESA is increasingly relying on high-resolution data from space. To determine the size of the rock - estimates vary between 40 and 90 meters, possibly even up to 100 meters - the James Webb Space Telescope (JWST) will measure in the infrared range. "Infrared observations enable a much more accurate estimate of the size of an asteroid," ESA writes in a recent press release. This method can eliminate uncertainties about reflectivity and thus clarify how great the risk of impact really would be.

China has also begun building a planetary defense team to counter the threat posed by near-Earth asteroids, reports South China Morning Post.

Even the German Aerospace Center (DLR) is preparing for the worst case scenario. The "Bluesky" platform emphasizes how "important asteroid defense projects are." The NASA DART mission has already tested this: a small asteroid was "pushed" out of its orbit with a lot of kinetic energy - so you could call it a "shoot down."

At the same time, however, scientists remain cautiously optimistic: According to the latest data, things will be pretty close in December 2032 (it will only come within around 170,000 kilometers), but ESA emphasizes that this chunk will most likely fly past us. Nevertheless, "in order to accurately assess the danger posed by the asteroid 2024 YR4, we need a more precise estimate of its size."

What happens now?

The asteroid is currently tens of millions of kilometers away from Earth and is moving further and further away from it in its orbit around the Sun.

This means that scientists only have a few months left to observe the asteroid before it disappears behind the sun.

“We will be able to observe the asteroid until April,” Dr Conversi told Sky News.

"In the worst case scenario, the probability can be as high as 20 percent. But most likely it will drop to 0 percent by then," he adds.

So by April, scientists can rule out a collision with Earth with a high degree of probability. If that doesn't work, they'll have to wait until the asteroid becomes visible again in 2028 to find out how likely it really is that it's coming towards us.

Behind the scenes, organizations like NASA and ESA, both of which have planetary defense departments, are working together to gather as much information as possible before the asteroid disappears from view.

“It is truly fascinating to see the global community coming together in a unique and coordinated effort to learn as much as possible about this object in a very limited time,” says Dr. Conversi.

While there are still seven years between now and a possible impact, that time frame is a little misleading because if scientists haven't ruled out a collision by the time they lose sight of the asteroid in April, they'll have to make decisions before they see it again in 2028.

What could be done about it?

Only when scientists better understand the asteroid's orbit and size will they be able to recommend measures - if necessary.

If it moves in that direction, one possibility is to launch a spacecraft to collide with the asteroid and change its trajectory - something NASA successfully did in 2022 with the 160-meter-wide asteroid Dimorphos .

It was called the Double Asteroid Redirection Test (DART) and was intended as a dress rehearsal in case such an object should ever threaten the Earth.

The mission was successful in that it reached and hit the asteroid, changing its orbit by about 32 minutes. But now another probe, called HERA, is on its way to the asteroid to check how successful the mission really was. It is not expected to arrive until January next year.

Speaking to Kay Burley on Sky News, astronomer Dr David Whitehouse said scientists may need to go a step further with a view to the fourth year, 2024.

The astronomer speaks when the probability of an impact on Earth was 1.2%

"We may even need to consider drastic measures, such as launching a nuclear weapon at the surface of this asteroid to deflect it even further," he said.

Well-known physicist Brian Cox said that preparing a diversion mission was a good investment, "even if we don't need it this time."

"It's as if the universe decided to conduct an experiment to see if planet Earth is still capable of making rational decisions," he wrote on X.

Dr. Conversi believes it is very plausible that experts are already starting to "plan and actually execute a mission" to take care of the asteroid as it orbits the Sun, before there is any confirmation that it is heading toward Earth.

However, this only applies if the risk is not eliminated before April; after that they lose sight of it.

The Space Mission Planning Advisory Group (SMPAG), led by ESA, will submit a recommendation to the United Nations Office for Outer Space Affairs on how to proceed if the threat cannot be ruled out by the fourth Space Day in 2024.

Dr Conversi told Sky News that the launch of an asteroid scheduled to hit Earth in its fourth month in 2024 would only be considered if it was confirmed that the asteroid was larger than 50 metres.

He added that the success of such a mission was not guaranteed.

Image: NASA/Johns Hopkins APL

"However, there will also be certain uncertainties: the launch could fail, or the asteroid could fail to de-orbit as we predicted," he said.

The alternative, he said, is not to take any "active" damage control measures and instead allow the bomb to hit the ground and evacuate the area where it is expected to land.

"I always like to remind people that less than five percent of the Earth's surface is inhabited, so it's unlikely that the impact will occur in a populated area," he said when asked why this might be a possible option.

He also says that while it is possible for the moon to hit the Earth, "it would be better if there were no impact at all."

Should we really be worried about the fourth year, 2024?

Organizations such as NASA and ESA continue to downplay the threat, insisting that the probability of impact is still "extremely low" and that the asteroid can be effectively combated even if it is heading toward us.

Astronomers including Dr Whitehouse have expressed their concerns. He told Sky News the likelihood of the asteroid hitting Earth "cannot be ignored" and that means "we have to make some very serious decisions".

He claimed it could turn out to be "the most dangerous thing in space," adding: "I can't stress strongly enough that this threat is not some astro-fun, it's a 'my goodness, isn't this incredible?' kind of thing."

“This could actually turn out to be a serious threat to our planet.”

When asked what the scientists behind the scenes think about it, Dr. Conversi replies that there is a kind of "hype" because it is a rare event where they can "try out all their systems and knowledge on a real case."

"However, the probability of an impact is low, so we are neither concerned nor do we anticipate any life-threatening scenarios," he adds.

He says he told his family and friends: "We are not worried, on the contrary: we know that in all probability the impact will not occur."

He adds: "I also try to convey the excitement this property is generating in the community and explain all the steps we have taken - and are taking."

Has this ever happened before?

It is very rare for an asteroid of this size to have such a high probability of colliding with Earth.

Comparisons have been drawn between 2024 YR4 and the asteroid Apophis, discovered in 2004, which was briefly estimated to have a 2.7% chance of hitting Earth in 2029.

But within a few days, this probability of impact dropped to almost 0%. It was Apophis's extreme size - 300 m - that attracted the most attention.

The Earth is directly hit by asteroids similar in size to 2024 YR4, but only once every few thousand years.

In 1908, a slightly smaller asteroid - estimated to have been 60 m in diameter - exploded over Siberia. The incident, known as the Tunguska Event, leveled 80 million trees in a remote area of ​​2,000 square kilometres.

According to NASA, eyewitnesses in the sparsely populated region reported seeing a fireball and hearing a massive explosion. However, no one was injured.

Asteroids are ancient space rocks from the formation of the solar system that are thought to have brought complex molecules and possibly early life to Earth billions of years ago.

Author: Editor T.Weyermann
Source NASA