This week, a survey will begin to map the underground hydrothermal features of Yellowstone National Park for the first time.

The U.S. Geological Survey (USGS), in collaboration with the Aarhus University in Denmark and the University of Wyoming, will use a helicopter carrying electromagnetic technology that resembles a giant hula hoop to record tiny voltage signals.

The data will be able to tell the scientists if they are flying over solid earth, “rotten” sulfuric rock, or water. Carol Finn, one of the scientists on the surveying team, said she has been looking forward to this for ten years.

“This is really kind of a last frontier if you will, in Yellowstone, of being able to look at a large part that’s underground that people that people have not looked at,” said Finn. “This survey can visualize the geology and the water down to about 500 meters, so 1500 feet.”

The goal of the project is to fill in the gaps of knowledge about what causes geysers like Old Faithful and hydrothermal explosions by locating where all that heated water flows underground.

“There’s just a lot we don’t know and this survey is really exciting because it’s going to be the first view of a large portion of the groundwater system, of the water underground that feeds all of these thermal features,” said Finn.

The survey will also provide information that could help the park in the future by locating unstable ground. The researchers will fly the helicopter along the Mammoth-Norris corridor and take at least four weeks to complete.