Two of the Moon’s Grand Canyons Were Formed in Just Ten Violent Minutes, New Study Suggests

It didn’t take long for the moon to get its grand canyons.

Vallis Schrödinger and Vallis Planck are two long channels near the lunar south pole. The canyons, each more than 160 miles long and around two miles deep, might have been formed in a stunningly quick and violent rain of debris following a powerful impact 3.8 billion years ago. Astronomers detailed this idea in a study published last week in the journal Nature Communications.

“They truly are extraordinary in scale,” says David Kring, a scientist at the Lunar and Planetary Institute and lead author of the study, to Kenneth Chang at the New York Times. “These things were carved in less than ten minutes when the Grand Canyon [in Arizona] took five to six million years to carve. I mean that illustrates the energy of an impact event.”

“The landscape of the south polar region of the moon is so dramatic,” Kring adds to Science News’ Lisa Grossman. “If it occurred on Earth, it would be a national or international park.”

Kring and his team suggest the two canyons formed after a 15-mile-long comet or asteroid rammed into the moon, setting off a pair of high-energy streams of rock that crashed down in lines. “They landed in a staccato fashion, bang-bang-bang-bang-bang,” says Kring to Science News.

The researchers built a mathematical model to show how the canyons were formed by the barrage. They used images obtained by NASA’s robotic Lunar Reconnaissance Orbiter spacecraft and computer modeling to calculate the speed and direction of the rocks. The impactor, they found, would have crashed into the lunar surface with 130 times the energy stored in the entire global inventory of nuclear weapons.

“When the impacting asteroid or comet hit the lunar surface, it excavated a tremendous volume of rock that was launched into space above the lunar surface before it came crashing back down,” explains Kring to Will Dunham at Reuters. “Knots of rock within that curtain of debris hit the surface in a series of smaller impact events, effectively carving the canyons. Adjacent to the canyons, the debris would have covered the landscape.”

While the results are promising, Mark Burchell, a scientist at the University of Kent in England who was not involved in the study, tells New Scientist’s Matthew Sparkes that more research will be needed to confirm its findings. “The ultimate proof would be someone bringing back a rock from one of these canyons, or some rocks,” says Burchell. “Then you just cut them up and there will be grains of minerals in there which have been shocked [by impacts], and some of them have changed their structure as a result.”

The team also asserts that the original impactor did not land in the center of the Schrödinger basin crater near the two massive canyons. Instead, by extending the lines of Vallis Schrödinger and Vallis Planck to a point where they would intersect, the scientists suggest the comet or asteroid hit south of the crater’s middle. It would have pummeled the moon at an angle, sending debris flying to the north.

This finding is helpful to NASA’s Artemis program, which aims to return humans to the moon around the lunar south pole. The Schrödinger impact basin is located within about 77 miles of the planned exploration zone for the upcoming Artemis 3 mission.

“Because debris from the Schrödinger impact was jettisoned away from the lunar south pole, ancient rocks in the polar region will be at or close to the surface, where Artemis astronauts will be able to collect them,” says Kring to Reuters. “Thus, it will be easier for astronauts to collect samples from the earliest epoch of lunar history.” From there, they could use those samples to test the team’s hypothesis.

Sara Hashemi | READ MORE

Sara Hashemi is a science writer and fact-checker currently based in New York City. Her work has appeared in Sierra, The Body, Maisonneuve magazine and more.