SpaceX rocket stage set to crash into Moon on Wednesday in rare accidental impact

A discarded SpaceX rocket stage is expected to slam into the Moon on Wednesday, August 5, in a rare, accidental collision that astronomers around the world hope will unlock new insights into lunar science and the growing problem of space debris. The object, a 3,900-kilogramme Falcon 9 upper stage, has been drifting through space since launching two lunar landers in January 2025. Unable to return to Earth or maintain a stable orbit, it has gradually been pulled onto a collision course with the Moon by gravitational forces. Scientists predict it will strike the lunar surface at around 06:35 UTC, 9:35 am (EAT), at a speed of approximately 8,700 kilometres per hour (5,400 mph), which is more than seven times the speed of sound. The impact will occur near Einstein Crater, close to the boundary between the Moon's near side and far side, on terrain illuminated by sunlight. While the collision poses no threat to Earth or future lunar missions, researchers say it presents a once-in-a-generation scientific opportunity to observe a known artificial object striking another celestial body in real time. A rare experiment that cannot be recreated easily Unlike meteorite impacts, whose timing and location are difficult to predict, scientists know almost exactly when and where this Falcon 9 stage will hit. That certainty has prompted an international observing campaign involving professional observatories, space agencies and amateur astronomers. Researchers hope to capture the impact flash, the expanding cloud of lunar dust and the newly formed crater. NASA's Lunar Reconnaissance Orbiter and South Korea's Danuri lunar orbiter are expected to photograph the impact site before and after the collision, allowing scientists to compare the surface and measure the size of the crater created by the rocket. The event will also help researchers refine methods for locating future impacts on the Moon, an important capability as more spacecraft head to the lunar surface. What will happen when it hits? Because the Moon has virtually no atmosphere, the rocket stage will not burn up the way space debris entering Earth's atmosphere does. Instead, it will strike the lunar surface intact before instantly vaporising on impact. Scientists estimate the collision will release energy roughly equivalent to three tonnes of TNT, excavating a crater between 20 and 30 meters wide and sending a plume of dust and rock high above the lunar surface. Computer simulations suggest the ejecta curtain could rise 15 to 20 kilometres above the surface, while a central dust plume may reach as high as 75 to 100 kilometers, remaining visible long enough for telescopes and lunar orbiters to study its evolution. Unlike Earth, where wind and weather quickly erase evidence of impacts, the Moon has no atmosphere. As a result, the crater and scattered debris are expected to remain preserved for millions of years. Can people watch it from Earth? The impact itself is unlikely to be visible to the naked eye. Astronomers say only observers using sufficiently powerful telescopes, and with favourable viewing conditions, may have a chance of detecting a brief flash or the expanding dust plume. Visibility is also complicated because the collision will occur on the Moon's sunlit surface near its eastern limb, making the flash harder to distinguish against the bright background. Even if the impact is not seen live, orbiting spacecraft are expected to provide detailed before-and-after images in the weeks and months that follow. A warning about the growing problem of space junk Beyond its scientific value, the impact has renewed concerns about the increasing amount of human-made debris in space. The Falcon 9 upper stage is one of thousands of discarded rocket bodies and defunct satellites orbiting Earth. While most eventually re-enter Earth's atmosphere and burn up, some are sent into deep space or left in unstable orbits that can lead to unintended collisions. As governments and private companies accelerate plans to establish permanent lunar bases and conduct more frequent missions to the Moon, researchers warn that unmanaged space debris could become a significant hazard. Scientists say understanding how discarded spacecraft interact with the lunar environment will help engineers design safer landing sites, protect future habitats and improve international guidelines for disposing of spacecraft after missions end. Why scientists are excited Although accidental, the collision offers a controlled experiment that would otherwise be impossible to conduct. Researchers hope the event will improve understanding of: How impact craters form on the Moon. How lunar dust behaves after high-speed collisions. The risks posed by artificial space debris. How future lunar seismic instruments could pinpoint impact locations. How spacecraft disposal practices should evolve as lunar exploration expands. The accidental collision may therefore leave behind more than just another crater; it could.