The Woman Who Alerts the World When an Asteroid Could Hit Earth

Aarti Holla-Maini, a British lawyer with a background in the satellite business, is the director of the UN's Office for Outer Space Affairs (Unoosa). She is responsible for alerting the UN secretary general if a large asteroid is on a possible collision course with Earth.

On 27 December 2024, a robotic telescope in Chile spotted a distant rock, asteroid 2024 YR4, which was initially estimated to be the size of a small building. As the asteroid's impact probability increased, Holla-Maini's team drafted a letter to the UN secretary general, triggering the first global notification since the UN established a planetary defence collaboration in 2013.

The asteroid's size and speed meant an impact could release energy comparable to hundreds of times the power of the Hiroshima bomb, potentially wiping out a city or region. The asteroid reached level three on the Torino Impact Hazard Scale, indicating a threat to human civilization.

Holla-Maini's team worked with the International Asteroid Warning Network and other experts to track the asteroid. Although its impact probability peaked at more than 3% in February 2025, it has since dropped to a negligible level. The asteroid scare served as a useful test for Unoosa's role in planetary defence.

Unoosa plays a critical role in registering satellites launched into Earth's orbit and acts as an informal 'hotline' for potential satellite collisions. Holla-Maini's small team of 35 employees punches well above its weight, managing a massive remit as governments and businesses increasingly operate in space.