You don't need a telescope to know that the moon is littered with craters. A few of the biggest are sometimes visible to the naked, Earth-bound eye [source: King].
Altogether, our planet's natural satellite has thousands of these depressions. So, after the Apollo program was founded in 1961, NASA decided to get its astronauts used to crater-laden terrain. But how? While meteorite impact craters are a dime a dozen on the moon, they're few and far between here on Earth [source: NASA].
Fortunately, the agency had a good-sized crater right in its own backyard. Around 50,000 years ago, a meteorite smacked into what's now northern Arizona. The result was one gigantic hole in the ground with a depth of 570 feet (173.7 meters) and a width of 4,100 feet (1.25 kilometers). Simply known as "Meteor Crater," the indentation's been of great use to NASA. During the Apollo era, future astronauts conducted mapping and surveying drills in and around the crater. It's still a field trip destination for NASA trainees today [source: Davis].
For would-be moonwalkers, isolated craters are great places to carry out some exercises. But a whole field of them would be even better. To that end, in 1963, NASA and the U.S. Geological Survey mapped out a section of the moon's surface. Then they used dynamite — lots and lots of dynamite — to make a few hundred replica craters in a dry expanse near Flagstaff, Arizona. When the site (known as "Cinder Lake") was all prepared, Apollo astronauts got to test-drive rovers across the terrain. Soil sampling drills were also carried out there [source: Northern Arizona University].