Low-flying planes over northeast Iowa this fall are mapping the earth below, federal officials say

Residents across northeastern Iowa may notice low-flying airplanes in November and December, and federal officials say there is nothing suspicious about them: the aircraft are doing "earth mapping" flights to gather geologic data, KWWL reported Friday. The flights are part of the U.S. Geological Survey's Earth Mapping Resources Initiative, a collaborative effort with the Iowa and Minnesota geological surveys. The aircraft carry equipment to "image geology" using airborne geophysical technology, and magnetic surveys create images of the different magnetic properties of rocks, allowing instruments to see underground without digging. Data will be collected along north-south flight lines spaced 1,310 feet apart at a nominal height of 330 feet above ground, rising to 1,000 feet over populated areas. The region being mapped contains rock types that may host undiscovered deposits of critical minerals such as nickel, copper, platinum group elements and cobalt, officials said. The USGS has contracted with Dewberry and Sander Geophysics Ltd. to collect the data. Their fixed-wing aircraft are equipped with an elongated "stinger" that extends from the main cabin and houses the sensors. Officials said the instruments are completely passive, with no emissions that pose a risk to humans, animals or plant life, and that no photography or video data will be collected.