A piece of human-made space junk slammed into the far side of the moon last year, initially leaving scientists stumped. After some astronomical detective work, new research argues that it was most likely a Chinese booster rocket – with an unknown object attached to it.
On March 4, 2022, a mysterious object known as WE0913A crashed into the lunar surface, leaving behind an unusually shaped double-crater. While it was initially suspected to be part of a SpaceX Falcon 9 rocket, later evidence suggested it was a booster as part of the Chang’e 5-T1 lunar mission. China, however, denied any involvement.
Now, scientists at the University of Arizona, California Institute of Technology, Project Pluto, and the Planetary Science Institute hope to put the mystery to bed.
They mapped the object’s trajectory using ground-based telescope observations and concluded that WE0913A is part of a Chinese Long March rocket body from the Chang’e 5-T1 mission that launched in 2014.
On top of this, they also found evidence that the abandoned rocket stage likely carried an “undisclosed, additional payload.”
The unusual twin crater appears to be the result of a rocket booster that impacted the moon in March 2022.
Image Credit: NASA/Goddard/Arizona State University
The team made this claim with two lines of evidence. Firstly, the object did not appear to wobble as it fell to the lunar surface, but rotated in a fairly organized rolling tumble. They argue that this shows that the rocket stage was balanced out with a significantly sized counterweight to the two engines, each of which weighs 544 kilograms (1,200 pounds).
“Something that’s been in space as long as this is subjected to forces from the Earth’s and the moon’s gravity and the light from the sun. So 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. But this was just tumbling end-over-end, in a very stable way,” Tanner Campbell, first study author and a doctoral student at the University of Arizona Department of Aerospace and Mechanical Engineering, said in a statement.
“We know the booster had an instrument deck mounted to its top end, but those weigh only about [27 kilograms] 60 pounds or so. We performed a torque balance analysis, which showed that this amount of weight would have moved the rocket’s center of gravity by a few inches – it wasn’t nearly enough to account for its stable rotation. That’s what leads us to think that there must have been something more mounted to the front,” he added.
Secondly, the researchers were also struck by the strange overlapping craters it formed, made of an eastern crater about 18 meters (59 feet) in diameter and a western crater about 16 meters (52 feet) in diameter.
“This is the first time we see a double crater,” Campbell explained. “We know that in the case of Chang’e 5 T1, its impact was almost straight down, and to get those two craters of about the same size, you need two roughly equal masses that are apart from each other.”
As for what the undisclosed payload was, Campbell and the team aren’t holding out for any answers.
“Obviously, we have no idea what it might have been – perhaps some extra support structure, or additional instrumentation, or something else,” he said.
“We probably won’t ever know.”
Dr. Sarah Adams is a scientist and science communicator who makes complex topics accessible to all. Her articles explore breakthroughs in various scientific disciplines, from space exploration to cutting-edge research.
