Extract from ABC News
Vallis Schrödinger can be seen here as a dark line cutting through Sikorsky Crater (centre). (Supplied: NASA/Johnson Space Center.)
In short:
Two giant lunar valleys, Vallis Schrödinger and Vallis Planck, formed in less than 10 minutes, researchers say.
Rocky debris ejected by an asteroid or comet impact 3.81 billion years ago bombarded the crusty surface to form the valleys in two straight lines.
What's next?
Understanding debris patterns will aid sampling efforts for the next human-crewed mission to the Moon, scheduled for no earlier than 2027.
Jutting off in straight lines from a massive crater like two bilby ears near the Moon's South Pole, is a pair of valleys similar to the Grand Canyon in size.
But while the Grand Canyon was etched from the landscape over millions of years, these Moon valleys were carved in less than 10 minutes, according to a new study in Nature Communications.
Around 3.81 billion years ago, an asteroid or comet smashed into the lunar surface, creating a 320-kilometre-wide crater at the bottom of the Moon as we see it in the Southern Hemisphere.
Following the secondary impact rays that formed Vallis Schrödinger and Vallis Planck back to Schrödinger Crater reveals the potential point of first impact when they formed. (NASA/JPL-Caltech: Eyes On The Solar System)
Streams of rocky debris, ejected by the impact, gouged out two valleys: the 270km-long, 20km-wide and 2.7km-deep Vallis Schrödinger and, stretching discontinuously over 860km, Vallis Planck.
"It was a dramatic impact event," study lead author and US Lunar and Planetary Institute geologist David Kring said.
"Having measured the canyons and the series of small craters that produce the canyons, we were able to then calculate the flight time of debris ejected from the crater."
The Grand Canyon was formed over 5 to 6 million years as the Colorado River carved through a plateau in Arizona. (Flickr: Hannes Flo, Grand Canyon, CC BY 2.0)
Debris travelled at speeds of 0.95 to 1.28 kilometres per second (up to 4,608kph).
The biggest chunks were 5.2km wide. That's the length of Brisbane's Story Bridge.
The energy needed to excavate the two valleys was around 130 times the blast generated by the world's entire nuclear stockpile exploding at once.
Dr Kring's previous work has linked the buried Chicxulub Crater to a mass extinction event 66 million years ago, at the end of the Cretaceous period, which wiped out most dinosaurs.
He said studying the Moon's craters helped untangle evolution of life on Earth since both went through a shared history of bombardment.
Shadows shift and reveal the Schrödinger Crater. (NASA: Ernie Wright) (GIPHY)
Avoiding a rocky landing
Planetary scientist Marc Norman, an emeritus at the Australian National University who was not part of the study, said the main new finding was that the projectile that formed the initial impact crater came in at a fairly shallow angle from the south.
"This produced an asymmetric distribution of ejecta [material thrown up by an impact] that is directed away from the lunar South Pole," he said.
He also said the study helped resolve some lingering questions about possible complications this rocky debris could have at proposed landing sites for China's robotic Chang'e 7 mission next year, and the US Artemis III mission to return humans to the Moon in 2027.
NASA has identified 13 landing options around the South Pole for the human-piloted surface mission, the first since 1972 and Apollo 17.
Understanding debris patterns from nearby craters will help focus material collection efforts.
A topographic map of Schrödinger crater shows where impact debris smashed into the surface at a low angle to carve out Vallis Planck and Vallis Schrödinger. (Supplied: United States Geological Survey)
This will be the first time astronauts land at the South Pole of the Moon, which is located in its oldest impact crater: the South Pole-Aitken basin.
The South Pole-Aitken basin formed 4.2 billion years ago. It is 2,500km wide and up to 8.2km deep. The Moon itself is thought to have formed 4.51 billion years.
An illustration of what it might look like when humans return to the moon for the Artemis III mission which is slated to be no earlier than 2027. (Supplied: NASA)
By sampling rocks from the South Pole-Aitken basin, scientists hope to test theories like whether the Moon ever had a magma ocean, or if it formed after a giant impact with Earth.
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