“Grand Canyons” On The Moon Were Carved Out In Ten Catastrophic Minutes

The Schrödinger Impact Basin, named for noted quantum physicist and hypothetical cat murderer Erwin Schrödinger, is an impressively big crater located within the larger South Pole-Aitken basin on the far side of the Moon. As one of the youngest basins that we know of, it is well-preserved, making it a tempting target for anyone wishing to learn about basin formation processes.

In the new study, David Kring, Danielle Kallenborn, and Gareth Collins attempted to do just this, and explain the giant canyons that surround the ~320-kilometer (~199-mile) in diameter basin. The canyons studied, Vallis Schrödinger and Vallis Planck, are comparable to the Earth’s Grand Canyon in size. Vallis Schrödinger is ~270 kilometers (~168 miles) long, and ~2.7 kilometers (~1.7 miles) deep, whereas Vallis Planck is ~280 kilometers (~174 miles) long and ~3.5 kilometers (~2.2 miles) deep. 

How these canyons formed has been uncertain. In the study, the team looked at photographs taken of the Moon’s far side and created maps to help them calculate the trajectory of debris ejected during the impact event that formed the basin. Modeling the impact, they noted key differences in the formation of the Grand Canyon and the canyons on the Moon.

“Whereas Arizona’s Grand Canyon was carved by water over the last 5 to 6 million years and from integrated paleocanyons that formed over 70 million years, the Moon’s Vallis Schrödinger and Vallis Planck were carved by streams of impacting rock in less than 10 min,” the team wrote in their study.

According to the analysis, the canyons were formed in about the time it takes to microwave a frozen lasagna, in an impact that sent debris flying at between 0.95 kilometers per second (0.59 miles per second) and 1.28 kilometers per second (0.8 miles per second). While pinning down the exact energy involved is tricky, the impact was certainly a big one.

“The energy to produce the grand canyons on the Moon are 1200–2200 times larger than the nuclear explosion energy once planned to excavate a second Panama Canal on Earth, more than 700 times larger than the total yield of US, USSR, and China’s nuclear explosion tests, and about 130 times larger than the energy in the global inventory of nuclear weapons,” the team explained.

While you may file this under “cool to know”, NASA may want to take a closer look at the results. According to the team, it could have several implications for the upcoming crewed Artemis mission.

“The asymmetric ejecta distribution implied by Schrödinger’s crater rays suggests there is less Schrödinger impact ejecta covering candidate landing sites and, thus, astronauts and robotic assets will find it easier to sample SPA [South Pole-Aitken] and underlying primordial crust samples.”

As well as this, the team suggests that aging samples from the basin could test the “lunar impact cataclysm hypothesis”, which suggests the Moon underwent an “enhanced period” of bombardment around 3.8 billion years ago, among other ideas.

“Where craters puncture the SPA ejecta blanket, they can expose primordial crust. Excavated SPA material and any primordial crust can be used to test the lunar magma ocean hypothesis for planetary differentiation and the giant impact hypothesis for the origin of the Earth-Moon system, among many other objectives,” they explain. “Because the Schrödinger impact event dispersed the bulk of its ejecta away from Artemis candidate landing sites, those objectives are more likely to be met.”

The study is published in Nature Communications.