Astronomers had discovered a rocket body heading towards a lunar collision last year and the impact occurred on March 4. NASA’s Lunar Reconnaissance Orbiter has spotted the resulting crater which, surprisingly, was actually two craters: an 18-metre-diameter easter crater superimposed on a 16-metre-diameter western crater.
The unexpected double crater formation indicates that the rocket body had large masses at each end. Usually, a spent rocket has mass concentrated at the motor end with the rest of the rocket stage consisting of an empty fuel tank. Since the origin of the rocket that created the crater remains uncertain, the double nature of the crater could help indicate its identity.
No other rocket body impacts detected so far on the Moon have created double craters. The four craters created by the third stage of the Saturn rockets that powered the Apollo missions (Apollo 13, 14, 15, 17) were irregular in outline and were substantially larger, with most being larger than 35 metres in diameter. The maximum width of the double crater created by the mystery rocket, about 29 metres, was near that of the Saturn rockets.
Before the impact, researchers at the University of Arizona’s Space Domain Awareness lab at the Lunar and Planetary Laboratory had concluded that it was caused by a Chinese booster from a rocket launch in 2014. But NASA is yet to confirm the same.
“We took a spectrum (which can reveal the material makeup of an object) and compared it with Chinese and SpaceX rockets of similar types, and it matches the Chinese rocket. This is the best match, and we have the best possible evidence at this point,” said associate professor Vishnu Reddy, who co-leads the Space Domain Awareness lab, in a university press statement issued in March.
Based on its path through the sky, the booster was initially thought to be a SpaceX Falcon 9 rocket booster from a 2015 launch but the University researchers later concluded that the rocket is a booster for Chang’E 5-T1, launched in 2014 as part of the Chinese space agency’s lunar exploration program. But NASA’s statement about the crater issued on June 24 refers to it as a “mystery rocket”.