US team says Chinese rocket booster hit the moon with secret payload, leaving ‘very unusual’ crater

“You would expect it to wobble a little bit, particularly when you consider that the rocket body is a big empty shell with a heavy engine on one side,” according to Tanner Campbell, a doctoral student at the University of Arizona and the study’s first author.

“But this was just tumbling end over end, in a very stable way,” Campbell said in a statement released by the university.

In other words, the rocket booster must have had a large mass mounted to the top end to balance the two engines at the bottom, which weighed about 544kg (1,200lbs) each without fuel. However, the two known instruments on the booster only weighed about 27kg, according to Campbell.

Chinese scientists developing AI algorithms to dodge space junk

The researchers compared the collision to Apollo missions, which deliberately let rocket debris hit the moon for research purposes, leaving behind either round or oblong depressions – and never a double crater.

“To get those two craters of about the same size, you need two roughly equal masses that are apart from each other,” Campbell said.

“Obviously, we have no idea what it might have been – perhaps some extra support structure, or additional instrumentation, or something else. We probably won’t ever know,” he said.

In January of last year, paper co-author Bill Gray of the Maine-based Project Pluto found the space junk was about to crash into the moon. He initially thought the object was from a SpaceX Falcon 9 rocket launched in early 2015 to carry a Nasa satellite. But he later realised the space junk was much more likely to be part of the Long March 3C rocket from the Chang’e-5 T-1 mission.

On March 4 of last year, the object dashed towards the far side of the moon, blasting out two craters measuring 16m (52 feet) and 18m across.

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China’s Chang’e 5 lunar lander finds water on the moon, but not as much as they hoped

China’s Chang’e 5 lunar lander finds water on the moon, but not as much as they hoped

Using ground-based telescopes, the researchers examined the object’s trajectory and reflections and determined “conclusively” that the space junk was from the Long March 3C rocket booster China used for its 2014 Chang’e-5 T-1 mission.

According to the team – made up of researchers from the University of Arizona, the Planetary Science Institute, the Jet Propulsion Laboratory and Project Pluto – the work illustrates the growing need to keep track of defunct space hardware after it has served its purpose.

In February 2022, Chinese foreign ministry spokesman Wang Wenbin denied that the Long March rocket had hit the moon, saying that monitoring showed the upper stage of the Chang’e-5 mission rocket had safely entered Earth’s atmosphere and burned.

However, observers speculated that Wang had confused the Chang’e-5 mission with the earlier Chang’e-5 T-1 test mission the scientists now believe caused the lunar impact.