The moon may have far more lunar craters than previously known

Using artificial intelligence, Chinese scientists have estimated that there are more than 100,000 craters on the moon, according to a study published Tuesday in the journal Nature Communications. That is far more than the 9,137 officially recognized by the International Astronomical Union and largely detected manually using altitude information and images, the study said.

The researchers, using data on 7,895 previously identified craters and 1,411 dated craters, were able to apply machine learning to train a deep neural network. With information from China’s first and second lunar orbits – Chang’e 1 and Chang’e 2 – the network identified 109,956 new craters. The two unmanned spacecraft were launched in 2007 and 2010 respectively.

Using artificial intelligence, Chinese scientists identified over 109,000 previously unknown lunar craters on the moon's surface.  The moon appears here, seen from Buenos Aires on December 21st.

“Impact craters are the most diagnostic features of the moon’s surface. This is in stark contrast to the Earth’s surface. It is very difficult to trace the Earth’s history of being affected by asteroids and comets over the last 4 billion years,” Chen Yang, from the College of Earth Sciences at Jilin University and the Key Laboratory of Lunar and Deep Space Exploration at the Chinese Academy of Sciences.

“Earth and the moon have been affected by the same impact population over time, but large lunar craters have experienced limited degradation over billions of years. Therefore, lunar craters can track the evolution of the Earth,” she said via email.

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The craters on the moon lack water, an atmosphere and tectonic plate activity – three forces that erode the earth’s surface, meaning that all but the latest meteor impacts are not visible.

On the moon, there are virtually no dents anywhere. The dusty footprints of astronauts who walked on the moon during the Apollo missions are still there today.
According to the Lunar Planetary Institute, approx. 80% of the earth’s surface is less than 200 million years old, while over 99% of the moon’s surface is more than 3 billion years old. The age of a large crater can also be determined by counting how many small craters there are inside it.

This latest study is not the first to implement machine learning to detect lunar craters, said Mohamad Ali-Dib of the Institute for Research on Exoplanets at the University of Montreal.

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He was part of a team at the University of Toronto Scarborough that used data from a laser altimeter, a device used on board satellites orbiting the earth, to map terrain instead of optical images used by the Chinese team, to detect craters. The UT team identified about 6,000 previously unidentified craters on the moon in research published in 2018.

“Machine learning can be used to detect craters on the moon,” he said via email. Craters are “a window into the dynamic history of the solar system.

China became only the third country in the world to successfully collect rocks from the moon when the unmanned Chang’e-5 mission returned to Earth in mid-December with the country’s first lunar samples.