A four-tonne upper stage of a SpaceX Falcon 9 rocket is believed to have unintentionally crashed into the Moon on Wednesday, a collision expected to leave a new crater on the lunar surface.
The impact was expected to occur at around 0635 GMT near the Einstein Crater in the Moon's northern hemisphere at a speed of about 8,690 kmph.
There was no danger to Earth.
There was no immediate official confirmation of the impact. NASA's Lunar Reconnaissance Orbiter and South Korea's Pathfinder Lunar Orbiter are expected to image the impact site, although it may take several days for the data to become available.
Scientists had hoped to observe the plume of dust and debris created by the collision. Benjamin Fernando of the Los Alamos National Laboratory said researchers were interested in determining how bright the ejecta plume would be and studying the impact's effects.
The Falcon 9 rocket was launched in January 2025 carrying two lunar landers. While the rocket's booster returned to Earth, its upper stage remained in space after placing the landers on their trajectory.
According to SpaceX, the upper stage was initially manoeuvred in accordance with safety requirements after the mission. However, the combined effects of solar activity and gravitational forces later altered its trajectory, putting it on a collision course with the Moon.
NASA said it had been tracking the rocket stage for training purposes and would study the impact site for scientific research.
Researchers said the event would provide an opportunity to study impact dynamics, lunar dust behaviour and the potential hazards posed by artificial space debris.
The Moon is regularly struck by natural meteoroids, but impacts involving human-made objects are relatively rare. NASA intentionally crashed spacecraft into the Moon during the Apollo programme in the 1970s to collect seismic data.
According to the European Space Agency, more than 46,000 pieces of space debris weighing about 17,000 tonnes are currently in orbit around Earth. Some experts have warned that the growing amount of orbital debris could increase the risk of cascading collisions in space.