Camp Century
A thermal drill is seen at Camp Century in Greenland in 1966. National Achives via NASA

A team of NASA scientists made an astonishing discovery while using a high-tech, airborne radar system to probe Greenland's massive ice sheet — an abandoned U.S. military base hidden 100 feet below the surface.

"We were looking for the bed of the ice and out pops Camp Century," said Alex Gardner, a cryospheric scientist at NASA's Jet Propulsion Laboratory, who helped lead the project. "We didn't know what it was at first."

Known as the "city under the ice," Camp Century is a Cold War relic that was built in 1959 by the Army Corps of Engineers and became buried under snow and ice after it was abandoned in 1967, according to NASA.

The sprawling, $8 million nuclear-powered complex got its name because it was intended to be located 100 miles from the edge of Greenland's ice sheet, according to the Atomic Heritage Foundation.

Officially promoted as a "remote research facility" where the first studies of ice cores were conducted, its real purpose was to provide cover for a military project codenamed "Iceworm" to potentially position ballistic missiles under the ice, according to the foundation.

The site has previously been detected by conventional ground-penetrating radar, which points down and produces a two-dimensional image that made Camp Century look like a blip in the ice, according to NASA.

But the April 2024 surveys that led scientists to accidentally rediscover it involved NASA's more advanced Uninhabited Aerial Vehicle Synthetic Aperture Radar system.

It's mounted to the belly of an aircraft and looks down and to the side, producing maps with greater dimensionality.

"In the new data, individual structures in the secret city are visible in a way that they've never been seen before," said NASA cryospheric scientist Chad Greene, who was aboard a Gulfstream III jet carrying the radar when Camp Century was detected.

The NASA flights were conducted to test the radar system's ability to measure the thickness of ice sheets and help predict how climate change will affect sea levels.

"Without detailed knowledge of ice thickness, it is impossible to know how the ice sheets will respond to rapidly warming oceans and atmosphere, greatly limiting our ability to project rates of sea level rise," Gardner said.