A discarded SpaceX rocket is on a high-speed collision course with the moon

An abandoned SpaceX rocket stage is on course to crash into the Moon on Wednesday in a rare accidental impact that scientists hope will provide valuable insights into lunar geology and the hazards posed by space debris.

The rocket's upper stage, which launched two private lunar landers in January 2025, is expected to strike the Moon at about 8,700 kilometres per hour near Einstein Crater on the sunlit western edge of the lunar surface.

Space-tracking expert Bill Gray predicts the impact will generate energy equivalent to around three tonnes of TNT, creating a crater about 27 metres wide and five metres deep.

Although the collision poses no threat to Earth, scientists say it highlights the growing problem of space debris as increasing numbers of spacecraft are launched into orbit.

"Things are getting crowded up there," Gray said.

Experts noted that the impact could have been avoided had the rocket stage been redirected into an orbit around the Sun after completing its mission.

The crash will mark only the second known accidental collision of a discarded rocket with the Moon. In 2022, a Chinese rocket stage struck the Moon's far side, leaving two craters.

Unlike that incident, Wednesday's impact will occur on the Moon's near side, allowing astronomers to observe the aftermath more easily.

The initial flash from the impact is expected to be too faint to see from Earth, but scientists believe the collision will eject a plume of dust and debris several kilometres into space that could remain visible through telescopes for tens of minutes.

Benjamin Fernando of Los Alamos National Laboratory said the observations would help researchers better understand the risks that debris impacts could pose to future astronauts and lunar infrastructure.

"The gravity on the Moon is low and there is no wind to blow the dust away," he said, encouraging both professional and amateur astronomers to observe the event.

NASA's Lunar Reconnaissance Orbiter and South Korea's Danuri lunar orbiter are expected to capture before-and-after images of the impact site. According to Fernando's team, Danuri will pass within a few kilometres of the rocket stage just two minutes before it strikes the lunar surface.

The discarded rocket stage, measuring about 12 metres long and weighing roughly 4,500 kilograms, launched Firefly Aerospace's Blue Ghost lander and Japanese company ispace's lunar lander on 15 January 2025.

Blue Ghost later became the first privately built spacecraft to achieve a fully successful lunar landing, while the ispace lander crashed during its descent.

Scientists say observing a precisely tracked, human-made impact offers a rare opportunity to study lunar cratering, as natural meteoroid strikes usually occur without warning.

NASA deliberately crashed spacecraft into the Moon during the Apollo programme to conduct seismic experiments and again in 2009, when the LCROSS mission struck the lunar south pole in a search for water ice.

With the United States and China preparing to send astronauts back to the Moon in the coming years, researchers say improving space traffic management and debris mitigation will become increasingly important.

Retired astrophysicist Jonathan McDowell said the latest impact was unlikely to cause any significant problems but warned that similar incidents could become a concern once permanent human bases are established on the lunar surface.

"This impact will not be a problem," he said. "But in a future where there are long-term bases on the Moon, similar impacts would be an issue, and we need not leave rocket stages in chaotic orbits of this kind."