Aarti Holla-Maini of the UN’s Office for Outer Space Affairs is primed to spot a potential planetary strike – and a year ago, she thought the moment had come

The UN official had trained for this moment. She had run drills and table-top exercises at her offices in Vienna, housed inside a grey and unassuming 1970s concrete tower complex next to the Danube River.

Aarti Holla-Maini, a British lawyer with a background in the satellite business, needed to have at least played out the scenario step by step. As the director of the UN’s Office for Outer Space Affairs (Unoosa), she was required to know exactly what she was expected to do if – and it was a big if – she were informed that a significantly large asteroid was on a possible collision course with Earth. Or, as she says with a laugh: “Armageddon.”

ESA’s Planetary Defence team allays fears 100-metre-wide object could hit Earth’s moon and disrupt satellites

Fears that a 100-metre-wide asteroid could be on course to collide with the moon appear to have been misplaced, according to new observations.

Discovered in December 2024, asteroid 2024 YR4 was briefly considered the “most dangerous asteroid” in decades after scientists initially estimated it had a 3.1% chance of colliding with the Earth in 2032. Closer observations quickly ruled out a “city killer” scenario, but instead astronomers calculated there was a 4.3% chance that the moon lay in the path of impact.