Scientists who want to study the moon can’t just go there… but the Arizona desert has the next best thing: a crater stamped out by an asteroid 50,000 years ago.
The desert rises to what seems like an ordinary hill until you hike to the edge and see the mile-wide hole in the ground.
Two Canadian geologists, Sharini Kanni Suresh Babu and Ashka Thaker, stand on the crater’s edge.
"We are looking at a lot of white stones, which are shocked Kaibab," Kanni Suresh Babu explains. "We are on top of that right now, and the view here is great."
The stones are "shocked" because they got pummeled by an asteroid that screamed in at an estimated 30,000 miles per hour. Plenty of asteroids have hit the Earth, but the craters tend to get erased by wind and water.
Thaker says Barringer Meteor Crater is the best preserved on the planet, "and it looks strikingly similar to what we see on the moon, so that’s one of the reasons why it makes a really good study space."
She would know — her job is to study images of the lunar surface. They’re hard to interpret without actually standing on the moon — hence today’s fieldwork. It’s a test of a portable mapping instrument called LIDAR.
"You just carry the LIDAR on your backpack and walk around," Kanni Suresh Babu explains, before Thaker interrupts and points to the crater's opposite rim:
"You can see them right over there, two little ant people."
The "two little ant people" are Sahank Vanga and Catherine Neish of the University of Western Ontario. It takes a long while for them to make their way around the crater's rim.
Vanga carries the whirring, 30-pound LIDAR on his back.
"It shoots out a bunch of pulses of infrared light, and you can measure how long the light took to bounce off the surroundings and return to the sensor," he explains.
The result is a detailed three-dimensional map that picks up fractures in the rocks — as long as the person carrying goes at a steady clip, says Neish.
"It was exhausting!" she laughs. "We couldn’t stop walking, so we were going at a brisk pace over uneven ground for a mile without stopping in the 30-degree Celsius heat [around 85 Fahrenheit]."
Scientists will use the map to understand what they see in pictures of lunar craters. But they also want to know what’s underground. For that, they need a different instrument called a ground-penetrating radar.
Kristian Chan of Johns Hopkins University describes its appearance as "a lawnmower — except it doesn't cut grass."
He and his colleagues push the gently beeping radar over rocks, shrubs, and old cowpies.
"You can kind of look at what's underneath without having to dig down," Chan says.
What’s underneath Meteor Crater is weirdly folded and smushed-up rock. On the Moon, the hope is to find ice.
Wes Patterson leads the radar instrument team at Johns Hopkins University.
"Looking for ice on the moon is crucial for human exploration and the future of human exploration," Patterson says. "If it’s there, we don’t have to bring it."
Water ice is all over the solar system. It’s on Mars, Saturn’s rings, and even on scorching-hot Mercury hidden inside the everlasting shadows cast by deep craters. But the moon is dry, and that’s a mystery.
"We as scientists ask ourselves the question, how did it get to Mercury and why is it not at the moon?" Patterson asks.
It’s one of many unanswered questions. Some scientists here today don’t have any desire to go to the moon themselves, among them, Ashka Thaker.
"I love space and I love everything space has to offer, but I hope it’s offered to me either in the form of samples, while I’m here comfortably on Earth, or satellite images," she says.
But their research may guide astronauts on the planned Artemis missions. And it’s shaped by the same landscape where Apollo astronauts trained half a century ago.
"You can understand, right, why astronauts would train out here," Neish says. "It really does look like the moon. If you put a greyscale filter on here, you can imagine yourself walking on the moon."
It’s part of Meteor Crater’s allure — how easy it is to imagine an alien landscape and rehearse a visit to another world, without ever leaving the Earth.
