The case of the mysterious moon crash is now conclusively closed, a brand new study reports.
On March 4, 2022, a rocket body slammed into the moon’s far side, blasting out a weird double crater about 95 feet (29 meters) wide. The crash didn’t come as a surprise; astronomers had been tracking the rogue rocket for weeks and predicted, with impressive accuracy, where and when it could slam into the lunar surface.
The mystery involved the identity of the impactor, which astronomers designated WE0913A. Initial observations suggested it may be the upper stage of the SpaceX Falcon 9 rocket that launched the Earth-observing DSCOVR satellite in February 2015. But, after further work, astronomers soon settled on a special candidate: The third and uppermost stage of the Long March 3C rocket that lofted China’s uncrewed Chang’e 5-T1 mission across the moon in October 2014.
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Considered one of the teams that got here to that conclusion last yr — a gaggle based on the University of Arizona (UA) — has now strengthened it to the purpose of confirmation.
“On this paper, we present a trajectory and spectroscopic evaluation using ground-based telescope observations to point out conclusively that WE0913A is the Long March 3C rocket body (R/B) from the Chang’e 5-T1 mission,” the researchers, led by Tanner Campbell, a doctoral student within the UA’s Department of Aerospace and Mechanical Engineering, wrote in a study that got here out Thursday (Nov. 16) within the Planetary Science Journal.
These two lines of evidence — how the item was moving and what it was manufactured from — leave little doubt about WE0913A’s provenance, Campbell and his colleagues report.
China, nonetheless, has attempted to sow doubt. Greater than that, actually: Chinese officials have said that the Long March 3C’s upper stage burned up in Earth’s atmosphere shortly after the launch of Chang’e 5-T1, which tested technology ahead of the Chang’e 5 moon sample-return mission in 2020. But that assertion was denied by U.S. Space Command, which said last yr that the item never reentered.
The brand new study also sheds further light on the distinctive crater that resulted from the March 2022 moon crash.
The researchers compared WE0913A’s light curve — the change in its brightness over time — with those of 1000’s of hypothetical space objects, generated via computer simulations. They usually found interesting differences.
“Something that is been in space so long as that is subjected to forces from the Earth’s and the moon’s gravity and the sunshine from the sun,” Campbell said in a press release. “So you’ll expect it to wobble somewhat bit, particularly while you consider that the rocket body is a giant empty shell with a heavy engine on one side. But this was just tumbling end-over-end, in a really stable way.”
Probably the most plausible explanation for this behavior, team members said, is a dumbbell-like object — one with considerable mass at each end.
One such mass was the upper stage’s two engines, which weighed a combined 2,400 kilos (1,090 kilograms) without fuel here on Earth. The mass at the opposite end of the rocket stage was probably in that ballpark as well, given how stably WE0913A was tumbling and the character of the outlet it gouged out of the lunar surface, Campbell said.
“That is the primary time we see a double crater” in a moon impact, he said. “We all know that within the case of Chang’e 5 T1, its impact was almost straight down, and to get those two craters of in regards to the same size, you would like two roughly equal masses which are aside from one another.”
The mystery mass is just too big to be just the usual instrument deck carried by the Long March 3C’s third stage, which Campbell said likely weighed about 60 kilos (27 kg) or so. But that is just in regards to the only inference we are able to make.
“Obviously, we’ve no idea what it may need been — perhaps some extra support structure, or additional instrumentation or something else,” Campbell said. “We probably won’t ever know.”