Value drops even further

Impact of asteroid YR4 unlikely after all

The probability that "2024 YR4" will actually collide with the Earth is very low again after a brief period of concern.

(Bild: ESA-Science Office)

New calculations show that the probability of asteroid 2024 YR4 impacting the Earth is lower than initially feared. Late on February 19, telescope observations led to a reassessment of the probability of an impact in 2032, which was reduced from the previously estimated 3.1 percent - the highest ever recorded threat from an asteroid - to 1.5 percent.

According to Richard Moissl, Head of the Planetary Defense Office of the European Space Agency (ESA) in Frascati, Italy, this figure is expected to fall further to below 1 percent. According to the current article in the scientific journal "Nature", the ongoing data evaluation reduces the uncertainties in the calculated trajectory of the asteroid.

Previously, the Earth was still at the center of the possible impact corridor, but current calculations show that our planet is now more likely to be at the edge of this region.

"It's not a question of if it will happen, but when"
 However, asteroid 2024 YR4 offers researchers a first opportunity to test the new international protocol for responding to potential threats. This procedure was introduced after the unexpected impact of the Chelyabinsk meteorite in 2013. With the increasing availability of new asteroid monitoring telescopes, more of these potential impact events are likely to be recorded in the future, says Moissl: "The question is not if it will happen, but when."

Early warning system in action
Asteroids regularly appear in scientists' observations, but rarely with such a high probability of impact as YR4. After the celestial body was first sighted in December 2023, the calculated impact probability exceeded the 1 percent mark on January 27, 2024. This activated the International Asteroid Warning Network (IAWN) mandated by the United Nations.

Since then, the network's scientists have been working intensively to calculate the asteroid's exact speed and trajectory, reports Moissl. Their aim is to reduce the risk to below 1 percent before YR4 disappears from the range of earthbound telescopes in April 2024 and will not be observable again until 2028.

Science "to save the world"
 IAWN regularly conducts exercise scenarios with hypothetical asteroids. In doing so, scientists learn to focus on the most important measurements to quickly and accurately predict when and where an asteroid could hit and what potential damage could occur.

Vishnu Reddy, planetary scientist at the University of Arizona and manager of the IAWN, compares this work to the rapid analysis of data by meteorologists and seismologists. "You have to understand that you're doing science here to save the world - to put it that way."