Researchers: Asteroid cut canyons into moon 3.8 billion years ago

CAPE CANAVERAL, Fla. — New research shows that when an asteroid slammed into the moon billions of years ago, it carved out a pair of grand canyons on the lunar far side.

That’s good news for scientists and NASA, which is looking to land astronauts at the south pole on the near, Earth-facing side untouched by that impact and containing older rocks in original condition.

U.S. and British scientists used photos and data from NASA’s Lunar Reconnaissance Orbiter to map the area and calculate the path of debris that produced these canyons about 3.8 billion years ago. They reported their findings Tuesday in the journal Nature Communications.

The incoming space rock passed over the lunar south pole before hitting, creating a huge basin and sending streams of boulders hurtling at a speed of nearly 1 mile a second. The debris landed like missiles, digging out two canyons comparable in size to Arizona’s Grand Canyon in barely 10 minutes. The latter, by comparison, took millions of years to form.

“This was a very violent, a very dramatic geologic process,” said lead author David Kring of the Lunar and Planetary Institute in Houston.

Kring and his team estimate the asteroid was 15 miles across.

Most of the ejected debris was thrown in a direction away from the south pole, Kring said. That means NASA’s targeted exploration zone around the pole mostly on the moon’s near side won’t be buried under debris, keeping rocks from 4 billion-plus years ago still exposed for collection by moonwalkers.

These older rocks can help shed light not only on the moon’s origins, but also Earth’s.