Last year, not one but two craters unexpectedly appeared on the Moon, leaving us all wondering: what could have caused this?
According to a study published this week, the craters were created by a spent Chinese rocket – with a possible additional payload – that crashed onto the lunar surface.
In March 2022, astronomers warned that a piece of space junk was on its way to hitting the Moon. Some speculated that the object was a leftover from the Chinese National Space Administration’s Long March 3C rocket, which sent the Chang’e 5- T1 around the Moon in 2014.
China’s Foreign Ministry, however, rejected claims that the debris was from its rocket and said the mission’s upper stage disintegrated in Earth’s atmosphere. Confusingly, the representative, Wang Wenbin, ended up referring to another rocket that launched Chang’e-5, a different probe.
It was difficult to confirm exactly what hit the Moon, as space agencies generally don’t monitor debris moving beyond certain altitudes. Some thought it might have been a piece of one of SpaceX’s Falcon 9 rockets. Astronomers were even more intrigued when images from NASA’s Lunar Reconnaissance Orbiter showed that the impact had punched two holes in the lunar surface.
Double trouble… The two recent craters on the Moon. Click to enlarge. Source: NASA/GSFC/Arizona State University.
Now, a team led by scientists from the University of Arizona, USA, claims in a published paper that they have definitive evidence proving that the collision was in fact the upper stage of the Long March 3C launch vehicle behind the Chang’e 5 mission. -T1. Furthermore, the fragment likely carried an unknown extra charge at one end of its body.
“This is the first time we’ve seen a double crater,” said Tanner Campbell, lead author of the paper and a doctoral student at the University of Arizona.
“We know that in the case of Chang’e 5 T1, its impact was almost straight down, and to get these two craters approximately the same size, you need two masses approximately equal and separated from each other.”
Another indication that the object was carrying something extra was the way it fell into space. Instead of wobbling, like a normal rocket booster, it spun in a stable manner. Academics calculate that it carried something to balance the weight of its engines, which reportedly weigh 1,200 pounds (544.3 kg) without fuel.
“We know the booster had an instrument panel mounted on the top end, but they only weigh about 60 pounds or so,” Campbell said.
“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 centimeters – it was not enough to explain its stable rotation. it has been something more assembled at the front”, he added.
What exactly the payload was, however, remains unknown. It may have been built to support the rocket structure or possibly a separate instrument for some other purpose. Experts believe the impact shows how important it is to monitor space debris beyond Earth, especially as the rate of lunar missions increases.
“There is a big push, both governmentally and commercially, to go to the Moon,” said Roberto Furfaro, co-author of the study and professor of Systems and Industrial Engineering at the University of Arizona.
“As we put more and more objects on the Moon, it becomes extremely important that we not only track the object, but also understand what they will do when they get there.” ®