Helicopters don’t usually fly 100 to 200 feet above the ground — low enough to startle a herd of cattle, low enough to read a road sign. But that’s exactly what’s happening over Wyoming and northern Colorado, where aircraft are skimming the landscape and towing what looks, from below, like an oversized hula-hoop dangling in the air.
The strange sight is part of a federal scientific mission. The sensor isn’t decorative — it’s listening to the earth, picking up faint electromagnetic signals from deep underground. What those signals reveal about what’s buried beneath this stretch of the American West is the whole point.
A strange sight in the western sky
If you spot a low-flying helicopter over Carbon County or Larimer County in the coming weeks, don’t be alarmed. The aircraft is intentionally skimming terrain at 100 to 200 feet — well below typical flight altitudes — while towing a large, hula-hoop-shaped electromagnetic sensor beneath it. Unusual enough to cause a double take.
Flights operate out of various Wyoming airports, with crews shifting landing areas and routes on short notice to dodge bad weather and cut travel distances. Despite the low altitude, all operations follow Federal Aviation Administration regulations, and ground clearance increases wherever the terrain demands it.
Reading the Earth’s hidden layers
The hula-hoop sensor measures faint electromagnetic signals coming from underground — signals that carry detailed information about what lies beneath the surface. This technique, airborne electromagnetic (AEM) surveying, lets geologists build subsurface images without drilling a single hole.
Flight lines run in pre-planned patterns spaced roughly 6,500 feet (about 2,000 meters) apart, covering Routt, Jackson, and Larimer counties in Colorado, plus Carbon and Albany counties in Wyoming. Together, the data will extend subsurface imaging across a vast corridor stretching from the Cheyenne Belt in Wyoming all the way to the Black Hills in South Dakota — an enormous swath of geology that, until now, has lacked this level of resolution.
Why critical minerals are driving this mission
The project is funded and coordinated through the USGS Earth Mapping Resources Initiative, known as Earth MRI. Launched as part of a national mandate, Earth MRI aims to identify where critical minerals — the raw materials essential for electronics, defense systems, and clean energy infrastructure — may exist across the United States.
The stakes are concrete. Critical mineral supply chains tie directly to U.S. economic competitiveness and national security, and mapping domestic deposits gives policymakers better information while reducing dependence on foreign sources.
Jamey Jones, science coordinator for USGS Earth MRI, put it plainly: “Earth MRI is mapping the critical minerals needed to drive the U.S. economy and bolster national security. Partnering with the state geological surveys of Colorado and Wyoming helps with the work of the nation — and adds to state knowledge crucial to the resource economy, as well as water resources, and natural hazards.”
The collaboration with both state geological surveys means the resulting data won’t sit in a federal archive. It will flow directly to state agencies that can use it for their own planning and research.
Beyond minerals: water and natural hazards
Critical minerals are the headline, but the survey’s usefulness extends further. The same subsurface images that reveal mineral deposits also shed light on underground water resources — a pressing concern across the arid and semi-arid landscapes of Wyoming and Colorado. Subsurface geology influences everything from fault behavior to slope stability, so accurate modern maps make hazard analysis more reliable too.
Foundational geologic maps underpin decisions about where to site infrastructure, how to manage groundwater, and where development may carry hidden risks. Many existing maps for this region are simply outdated. Modernizing them isn’t just scientifically valuable — it’s practically necessary.
A two-year project with long-term consequences
The current flight phase, beginning in February and lasting up to one month, is one chapter in a larger story. Full airborne data collection spans two years and is expected to wrap up in 2026, part of a nationwide push to bring U.S. geological mapping into the modern era.
When complete, the survey will give researchers, state agencies, and planners a far clearer picture of what lies beneath this stretch of the American West — one that could shape mineral extraction decisions, water management strategies, and infrastructure investments for decades.
The helicopter will eventually move on. But the data it collects — invisible signals translated into subsurface maps — will stay useful long after the hula-hoop disappears from the Wyoming sky.