How an ancient asteroid strike carved out two grand canyons on the moon

A recent study indicates that an asteroid impact on the far side of the moon billions of years ago created two massive canyons. This discovery is good news for scientists and NASA, as NASA plans to send astronauts to the lunar south pole, which is located on the near side and was unaffected by the impact, preserving ancient rocks in their original state.

Scientists from the United States and the United Kingdom used photographs and data from NASA's Lunar Reconnaissance Orbiter to map the area and calculate the trajectory of the debris that formed these canyons approximately 3.8 billion years ago. Their findings were published in the journal *Nature Communications* on Tuesday (Wednesday, Australian Eastern Time).

According to the study, the incoming asteroid grazed the lunar south pole before impact, creating a massive basin and ejecting vast amounts of rock at speeds approaching one kilometer per second. These fragments landed like missiles, carving out two canyons comparable in size to the Grand Canyon in Arizona in just 10 minutes, while the latter took millions of years to form.

"This was a very violent, very dramatic geological process," said lead author David Kring of the Lunar and Planetary Institute in Houston. Kring and his team estimate that the asteroid was 25 kilometers in diameter, and the energy required to form the two canyons would be more than 130 times the energy of the world's current nuclear weapons stockpile.

Kring stated that most of the ejected debris was thrown away from the south pole. This means that the area NASA plans to explore near the south pole on the near side of the moon will not be buried by debris, exposing ancient rocks dating back more than 4 billion years for lunar explorers to collect. These ancient rocks can help us understand not only the origin of the moon, but also the origin of the Earth.

Kring stated that it is currently unclear whether the two canyons are permanently shadowed like some craters at the lunar south pole. "This is something we obviously need to revisit," he said. Permanently shadowed regions at the lunar bottom are believed to contain large amounts of ice, which future lunar explorers could convert into rocket fuel and drinking water.

NASA's Artemis program, a follow-up to the Apollo program, aims to send astronauts back to the moon within this decade. The plan is to send astronauts into lunar orbit next year, followed by the first astronaut landing since the Apollo program approximately one year later.