A spent SpaceX Falcon 9 upper stage, left drifting in space for 18 months after delivering two lunar landers, is set to crash into the Moon on Wednesday, producing a debris cloud that may be visible from Earth through a telescope. Researchers say the event offers a rare opportunity to study the risks that space debris and impact events pose to future lunar bases, as NASA, China and other nations plan crewed and uncrewed missions to the Moon in the coming decades.

The 4-metric-tonne rocket stage, which lacked the fuel to return to Earth or enter a stable orbit, is expected to strike near Einstein Crater on the Moon's near side at around 6:34am UTC, travelling at roughly 5,400mph. With no atmosphere to slow it, the impact will release energy equivalent to about 3 tonnes of TNT, gouging a crater up to 27 metres wide and 5 metres deep. It follows a similar accidental impact by a Chinese rocket stage in March 2022, and scientists including Bill Gray and Benjamin Fernando say tracking such events helps assess the "multi-modal hazards" that debris, seismic flashes and ejected material could pose to astronauts and infrastructure once permanent lunar bases are built.