'Chinese-made' Space Debris to Collide with the Moon on the 4th... "Will the Moon Become a Trash Dump?" [Reading Science]

Moon crater. Photo source='Nature'

[Asia Economy Reporter Kim Bong-su] On the 4th, a large piece of space debris will 'accidentally' collide with the Moon for the first time in history. This is the first case of a human-made object unintentionally crashing onto the Moon. Scientists are raising concerns that the Moon could become a dumping ground for space debris in the future and are calling for the establishment of international agreements for systematic management.

According to the international academic journal Nature and the space news outlet SpaceNews on the 2nd, around 9:25 PM (Korean time) on the 4th, a large piece of space debris weighing about 4 tons is expected to fall onto the far side of the Moon, specifically the Hertzsprung crater, creating an impact crater over 20 meters in diameter. This lunar collision with space debris is attracting scientific attention as it is the first case where a human-made object 'accidentally' falls under the Moon's gravity without human intention.

There have been about 58 cases of artificial objects crashing or landing on the Moon since the Soviet Union launched the Luna 2 lunar probe in 1959. However, all of these involved human intent. Most were deliberately crashed after satellites or probes completed their missions in lunar orbit or on the surface and ran out of fuel. For example, China deliberately crashed the Chang'e 5 lander’s transport rocket onto the Moon after completing surface exploration and sending collected samples back to Earth in 2020. There were also scientific purposes. For instance, NASA deliberately crashed parts of the massive Saturn V rocket used in the Apollo missions between the 1960s and 1970s onto the Moon to study the seismic waves generated by the impact on the lunar surface. In 2009, the U.S. intentionally crashed a probe into a crater near the lunar south pole to investigate the possible presence of ice buried in the lunar soil, successfully detecting water molecules in the dust.

However, this is the first case where an artificial object has drifted in space for over seven years and then been drawn by the Moon’s much weaker gravity than Earth’s, resulting in a collision. Scientists are concerned about the problem of space debris orbiting between Earth and the Moon. According to the European Space Agency (ESA), since the launch of the Soviet Union’s Sputnik satellite in 1957, about 12,000 artificial satellites have been launched into Earth orbit over 60 years, with only 5,100 still operational. Additionally, more than 36,000 pieces of space debris larger than 10 cm are orbiting at an incredible speed of 7 km/s. Lunar orbit is much cleaner in comparison. According to research by the Astronomy Department at the University of Arizona, about 150 artificial objects orbit the Moon, with at least 90% estimated to be space debris.

[Image source=Yonhap News]

The identity of this space debris has not yet been confirmed, but it is suspected to be the booster of the Long March 3C rocket that carried the Chang'e 5 T-1, launched by China in 2014 for a lunar landing experiment, into lunar orbit. China denied this on the 21st during an official briefing by the Ministry of Foreign Affairs, stating that the large piece of space debris is not a rocket booster they discarded. However, NASA and private astronomers are confident otherwise. Bill Gray, an American astronomer who first predicted the large space debris collision in January, initially suspected it was the Falcon 9 rocket used by SpaceX in 2015 to launch NOAA’s climate observation satellite but corrected his position after receiving different observational data from NASA, concluding it was the upper stage of China’s Long March 3C rocket launched in 2014. This was based on NASA data showing that SpaceX’s rocket never came near the Moon. He also refuted claims based on U.S. Space Force observations that debris from the Long March 3C rocket re-entered the atmosphere and burned up a year later, stating, "That is only an estimate based on limited early launch data." Professor Vishnu Reddy of the University of Arizona said on the 23rd to SpaceNews, "Optical observations comparing the shape of this space debris with rockets from China and SpaceX matched the Chinese rocket," adding, "This is currently the most likely evidence."

Accordingly, scientists are calling for enhanced monitoring capabilities of lunar orbit and systematic management through international agreements. Currently, the U.S. Space Force tracks space objects only up to geostationary orbit, about 38,500 km from Earth, while lunar orbit observations are limited to private astronomers using ground-based telescopes. Professor Alice Gorman of Flinders University in Australia told Nature, "The information currently known to the public about the large space debris collision on the Moon did not come from governments but was confirmed privately," adding, "While it is commendable that people can monitor the space environment themselves, there are concerns about reliability." Holger Krag, ESA Director, also stated in a recent press release, "This lunar collision incident clearly illustrates the need for a comprehensive regulatory system in space," emphasizing, "It should apply not only to popular orbits around Earth but also to lunar orbit."