Impact risk just over 3 percent: Asteroid 2024 YR₄ surpasses Apophis

With a temporary impact probability of more than three percent, the near-Earth asteroid 2024 YR₄ has exceeded the previous maximum value for a celestial body of significant size. This was previously held by Apophis with a value of 2.7 percent. In addition, 2024 YR₄ now holds the record for the longest time in which an impact probability of more than one percent was determined. This was determined by the European Space Agency shortly before the calculated risk dropped significantly again. The asteroid is now back on the NASA and ESA lists with an impact probability of 1.5 and 1.4 percent respectively.

Waiting for James Webb

As the ESA also explains with the help of graphics, the increasing number of observations of the asteroid reduces the uncertainty regarding its exact route shortly before Christmas 2032. However, as long as the Earth is within this area, the calculated probability of a collision may increase. Only when the Earth is outside the uncertainty range will the probability of impact fall to 0. Another graph illustrates the decreasing uncertainty and makes it clear that this fall-out could occur in just a few days. That would be before the James Webb space telescope can provide final certainty about the orbit of the celestial body.

According to current estimates, 2024 YR₄ is between 40 and 90 meters in size. If the smaller value is correct, the consequences of an impact would be localized; in the case of a larger asteroid, the effects would be at least regional. However, only the James Webb space telescope will provide a more precise indication of the size. The asteroid was discovered at the end of December and has been at the top of ESA and NASA's list of the riskiest celestial bodies for weeks. Although it can still be assumed that it will miss the Earth, the length of time it will remain in this position is unusually long.

On the so-called Turin Scale for classifying the danger posed by asteroids, 2024 YR₄ remains at class 3, which is another reason why planetary defense committees have already begun to deal with it. This week, the German space company OHB also announced that it is working on plans for a possible defense mission. This could, for example, make use of the fact that the asteroid will pass Earth again in 2028. It could then be minimally deflected with the help of a probe so that it safely misses the Earth at its next rendezvous. However, the probability that this will be necessary remains minimal.

(mho)