Where Astronauts Learned to Walk on the Moon

Before any astronaut stepped onto the lunar surface, they came to northern Arizona to learn what a geologist was supposed to notice on an alien world. The landscape around Flagstaff offered something no other place in the continental United States could: fresh volcanic cinder fields, impact craters, and basaltic lava flows that resembled, in texture and origin, the terrain waiting for them on the Moon.

The training was organized largely by Eugene Shoemaker, a geologist at the United States Geological Survey who had established the Astrogeology Research Program and spent years convincing a skeptical scientific community that the Moon's craters were mostly of impact origin rather than volcanic. Shoemaker believed the astronauts needed to be field geologists, not just button-pushers, and he ran field trips to Sunset Crater and to Meteor Crater, thirty-seven miles east of Flagstaff.

Meteor Crater is fifty thousand years old, nearly four thousand feet across, and five hundred sixty feet deep, formed when a nickel-iron meteorite roughly one hundred sixty feet in diameter struck the Colorado Plateau at roughly twenty-nine thousand miles per hour. The impactor largely vaporized on contact. What it left behind is the best-preserved impact crater on earth, and it became a classroom for men who would soon stand at the edge of craters on another world.

Shoemaker himself had wanted to be the first geologist on the Moon. A medical condition disqualified him from astronaut training. He poured that ambition into the people he taught instead, and a portion of his ashes was eventually carried to the Moon aboard a spacecraft in nineteen ninety-nine. He made it there after all.