Odds of asteroid 2024 YR4 hitting the moon may rise to 30 per cent

Astronomers are running out of time to decide whether asteroid 2024 YR4 should be prevented from colliding with the Moon in 2032. A small observing window with the James Webb Space Telescope opens in February, and new data could show that the probability of impact will increase by more than 30 percent, putting satellites or future lunar infrastructure at significant risk.

2024 YR4 was discovered late last year and was immediately given the highest probability of impacting Earth of any known asteroid. In the most dangerous case, the probability of impact with Earth in 2032 was 1 in 32. Further observations reduced the likelihood impact with Earth is effectively reduced to zero, but there remains a 4 percent chance that an asteroid will crash into the Moon, which could result in thousands of critical satellites appearing around it. the planet is in danger from lunar shrapnel.

This risk is much higher than from any other asteroid, but the level of risk and uncertainty has not yet prompted the world's space agencies to act, although NASA researchers believe that possible deviation scenariosincluding the explosion of a nuclear bomb near an asteroid.

The asteroid had now moved out of Earth's telescope's field of view, meaning astronomers believed they had no chance of gathering more information about its trajectory until it returned to view in 2028, which may not be enough time to plan and launch a deflection mission.

But it now appears that the James Webb Space Telescope (JWST) will be able to take a look at 2024 YR4 in February 2026, which would be the last good chance to decide on a deflection mission, he says. Andrey Rivkin at Johns Hopkins University in Maryland. “It's going to be very, very close by 2028, and so getting it early in 2026 instead gives extra time,” Rivkin says.

JWST's unique Earth orbit and vantage point allows it to see 2024 YR4 where other ground-based telescopes cannot, but it will still be an extremely difficult observation due to how dim the asteroid will be, even for JWST's extremely sensitive detectors. Two narrow observation windows will be open on February 18 and 26.

Rivkin and his colleagues calculated how these observations could change our understanding of the asteroid's position and speed. They found that there was an 80 percent chance that the chance of a lunar impact would drop to below 1 percent, and a 5 percent chance that the risk would increase to more than 30 percent. In 2027, JWST will have another chance to repeat these observations, but that will leave less time to make a decision, Rivkin says.

But whether space agencies will decide to plan a mission if the risk increases remains an open question. “Whether planetary protection extends to the Moon is a completely new question, and different agencies may have different answers,” says Rivkin. “If a company owns a lot of satellites, it may be motivated to push for one.”

Richard Moissle The European Space Agency says there are currently no asteroid deflection or reconnaissance missions planned in the agency's budget for this year, but if observations next year increase the likelihood of an impact, it will consider its options. “We decided to definitely wait until next year… to give ourselves time to sort out our options,” Moissl says.