On Aug. 21, the moon will move in front of the sun, dissolving daylight into night for mere moments. For the first time in 99 years, a total solar eclipse will cross the entire country from the Pacific to the Atlantic, giving scientists and engineers a chance to conduct research on systems we rely on for communication, safety, and even transportation.

During the total eclipse, Greg Earle, a Virginia Tech professor of electrical and computer engineering, and a team of College of Engineering faculty, staff, and students will study the effects of the eclipse on systems we use every day – such as over-the-horizon radar, amateur radio, and even the global positioning system (GPS) that helps guide us through traffic.

Earle and his team will be stationed across the United States in Bend, Oregon; Holton, Kansas; and at the Shaw Air Force Base in Sumter, South Carolina, using custom-designed ionosodes, instruments that use radio waves to look up into the ionosphere and measure its height and density.

When the eclipse occurs, the moon will turn off the ionosphere’s source of extreme ultraviolet radiation, and this region of the Earth’s upper atmosphere will go from daytime conditions to nighttime.

Funded by NASA and the National Science foundation, Earle and his team will study how the ionosphere responds to changes in sunlight, along with a host of other changes in the upper atmosphere that have an impact on radio propagation – the behavior of radio waves as they travel from one point to another.

Understanding the effects of varying conditions on radio propagation has many practical applications, from choosing frequencies for international shortwave broadcasters, to designing reliable mobile telephone systems, to radio navigation and operation of radar systems.

“Radio wave propagation is affected by the electrical part of the atmosphere and during the eclipse.” said Earle, research member with Virginia Tech’s Center for Space Science and Engineering Research group. “We really have the opportunity to collect data and learn more about the impact of these changes on systems we’ve come to rely on.”

The Virginia Tech team plans to gather data from a variety of sources, including radar systems, transceivers, satellites, ham radio, and GPS receivers, in order to analyze the effects of the solar eclipse on the conductive region of the atmosphere. 

“Whether military radar or consumer GPS signals, the eclipse is going to have effects on the medium that we would like to understand better so that we can either mitigate them or use them to our advantage,” said Earle. 

Their measurements will be combined with data from a nationwide network of GPS receivers and signals from the Ham Radio Reverse Beacon Network, both of which are sensitive to the state of the ionosphere. The team will also utilize data from Virginia Tech’s SuperDARN radars, two of which have been placed along the eclipse path in Christmas Valley, Oregon, and Hays, Kansas.

By combining all the captured data, Earle and his team will be able to improve models of the ionosphere, while understanding and explaining the overall impact of the eclipse on systems we use everyday.

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