A discarded upper stage of a SpaceX Falcon 9 rocket is on course to strike the Moon on Wednesday, with impact expected at 7.35am. The 4,900kg piece of debris will be travelling at 5,400mph — seven times the speed of sound — when it hits the lunar surface on the side facing Earth.
The rocket part comes from a Falcon 9 launched in January 2025. The mission carried two lunar landers and scientific instruments to the Moon, but the 45-foot-tall upper stage was left adrift after its one-way trip and was eventually captured by the Moon's gravity.
Space analyst Bill Gray, who runs Project Pluto software for tracking objects in orbit, said the impact will release the energy equivalent of three tons of TNT and could leave a crater 17 metres in diameter. "It doesn't present any danger to anyone," he said. "Though it does highlight a certain carelessness about how leftover space hardware (space junk) is disposed of." The Associated Press reports that SpaceX did not plan for the dead rocket to hit the Moon. Metro has contacted SpaceX for comment.
Will the Moon be damaged?
The Moon is no stranger to impacts. Unlike Earth, it has no tectonic plates or atmosphere to erase craters, so its surface keeps the scars of past collisions. Dr Ed Bloomer, an astronomer at the Royal Observatory Greenwich, said there is no cause for concern. "In fact, it will likely go unnoticed in the UK," he said. "While the rocket part colliding with the lunar surface is quite a large piece of kit, and it is moving at a fairly impressive speed, it is certainly not going to cause any problems. 'After all, the moon is pretty large and desolate, and we know precisely where and when the collision will occur.'"
Can the impact be seen from the UK?
The collision is likely to be invisible to the naked eye or binoculars. Gray doubts it will even be visible with a professional telescope. The rocket will come down on the lunar limb — the edge of the Moon's sunlit side that appears only occasionally as the Moon wobbles. A sensitive telescope might pick up an ejecta plume or a dim flash of light from the impact, but Gray suspects it will be rather faint. The best vantage points are the eastern United States, eastern Canada and much of South America.
British stargazers might still see the longer-term result. "Afterwards, the moon will have a quite small new crater!" said Dr Bloomer, which should appear in the northwestern region near the Einstein Crater.
Nasa's Lunar Reconnaissance Orbiter will pass over the crash site, according to project scientist Brent Garry. Speaking in June, he said: "We can do some additional targeting about a week after the impact and get some targeting over where the site is."
What exactly is space junk?
The rocket part is an example of space junk, a term Dean Sladen, an aerospace engineer at Accu Components, defines as "any human-made object in orbit, or falling back to Earth, that no longer serves a purpose." The precision engineering components supplier, which tracks and analyses space junk, says that includes "spent rocket stages and dead satellites down to bolts, paint flecks and fragments from old collisions." Sladen noted there are "tens of thousands of trackable objects up there right now, and many more too small to track."
SpaceX is responsible for an increasing share of that debris, since it conducts half of all global launches, according to Accu Component's space race report. Dr Bloomer warned that the skies above Earth are becoming a "stellar dumping ground", and Wednesday's collision will not be the last. This will be the second known accidental crash of a dead rocket into the Moon. In 2022, a Chinese rocket segment left a pair of craters on the far side, sometimes called the dark side, and Nasa's Lunar Crater Observation and Sensing Satellite landed there in 2009. "Although we generally track manmade debris with high precision, even for tiny objects, we continue to add to the swarm of material in the local neighbourhood, astronomically speaking," added Dr Bloomer. "Avoiding further pollution and reducing existing material is a phenomenal technical challenge, but of increasing importance for future spaceflight operations."
