NASA has confirmed the Moon is a bit messier and a mystery has deepened after its Lunar Reconnaissance Orbiter (LRO) spacecraft discovered the double impact crater of a rocket booster that collided with the lunar surface on March 4, 2022. Although the rocket's origin hasn't been confirmed, a Chinese rocket booster remains the prime candidate.
In January, amateur astronomers and astronomical software writer Bill Gray found evidence that a disused rocket booster was on a collision course with the Moon. At first this was thought to be a SpaceX Falcon 9 second stage rocket used to launch the Deep Space Climate Observatory (DSCOVR) probe in 2015, but additional data and calculations later determined that the most likely candidate was the upper stage of a Chinese Long March 3C used to launch the Chang'e 5-T1 lunar flyby mission in 2014.
Because the impact of the Chinese rocket was predicted to take place in the dark on the far side of the Moon, the event couldn't be seen from the Earth, so matters rested there. However, the LRO was in a position to take images of the crash site afterward and send back evidence to confirm the impact near Hertzsprung crater in the Mare Orientale region.
The surprising result was the discovery of not one, but two impact craters at the site. Until now, rocket impacts on the Moon, such as those left by the Apollo mission S-IVB boosters, have been single craters with an irregular outline.
These single craters are created because most of the mass of a rocket is concentrated in the engine at one end, with the rest of the rocket consisting of empty fuel tanks. The new craters measure 18 m (59 ft) in diameter for the eastern crater and 16 m (52 ft) for the western crater. Combined, these two craters are the same width as the single crater left behind by an S-IVB impact.
Exactly why this double crater occurred isn't certain but it suggests the rocket body may have had large masses at each end. Though the Long March rocket is the most likely candidate, information on its exact configuration is still lacking, therefore, so is confirmation it's the culprit.
Source: NASA
