In the 1960s, during the Cold War, the U.S. built an Arctic research center in Greenland and called it Camp Century.

Except it was actually a secret military operation—code name: Project Iceworm.

It was intended to drill a network of nuclear missile launch silos in the Greenland Ice Sheet, designed to survive a Russian ‘first strike.’

The first people there were researchers, to test the ice for suitability. They drilled nearly a mile through the ice sheet and 12 feet into the soil below.

Their studies revealed the ice was flowing much faster than expected. The launch tunnels, and the missiles within them, would be crushed within 2 years.

Of the planned 2,500 miles of tunnels, only 2 miles were built before the base was scuttled. Years later, the project and the ice cores they drilled have been declassified.

And they’ve revealed something else. The Greenland soil wasn’t always under ice!

Judging from sediment found with the plants, 416,000 years ago the area was ice-free during a warm interglacial period.

The ground was exposed for more than 10,000 years at this location. Then it froze over when the glaciers returned—and has been buried under ice ever since.

Project Iceworm may not have produced a missile base. But it did yield important evidence for scientists studying Earth's natural glacial and interglacial cycles.