A three-tonne rocket part is due to crash into the Moon shortly after midday on Friday, astronomers have said.
The space debris is expected to smash into the far side of the Moon at approximately 5,800mph, creating a crater between 33ft and 66ft wide – enough to fit two double decker buses.
However, the impact – expected to occur at 12.25pm – will not be visible from Earth and may take months to confirm with satellite images.
The Moon
Gareth Milner / GBN
Initially astronomers thought the rocket part had been launched by Elon Musk’s SpaceX programme after the collision course was identified by Mr Gray in January.
But following further analysis, a month later he suggested the object was not actually a SpaceX Falcon rocket upper stage from a 2015 launch, but was likely to be a Chinese rocket launched in 2014 as part of the Chang’e 5-T1 mission.
However, China has denied this.
Debris is a big concern for the space community, not least because a collision with a satellite could wipe out the services people rely on every day, including mobile phones and online banking.
But the discarded rocket is not worrying experts too much, and astronomer Bill Gray, who first identified the collision course, has said the Moon is used much more severe batterings.
Writing on his blog Project Pluto, Gray said: “Keep in mind that this is a roughly four-ton object that will hit at 2.58 km/s.
“The Moon is fairly routinely hit with larger objects moving in the ballpark of 10-20 km/s hence the craters.
“It’s well-built to take that sort of abuse.”
Jacob Geer, head of space surveillance and tracking at the UK Space Agency, said: “Although this particular piece of space junk isn’t likely to cause any significant damage, we are concerned about the growing amount of debris in orbit above the Earth.
“This debris could collide at any time with the satellites we depend upon every day for navigation, banking and communications.
“That’s why the UK is taking action, by funding new technology to track or even remove debris from space and working with international partners, including the UN Office for Outer Space Affairs (UNOOSA) to lead efforts to promote space sustainability.”
According to the European Space Agency, there is around 9,200 tonnes of space debris, with 34,000 objects greater than 10cm in size and 128 million objects measuring from 1mm to 1cm.
It estimates there have been more than 560 break-ups, explosions, collisions or non-typical events resulting in fragmentation.
While rocket launches have placed about 10,680 satellites in Earth’s orbit since 1957, around 6,250 of these remain in space, but only 3,700 are still functioning.
