Miguel Larsen has dedicated his career to measuring and interpreting upper atmospheric winds in the ionosphere, a dynamic region about 60 miles from the Earth’s surface. Perhaps his biggest discovery was that wind speeds in this region are significantly stronger than what conventional scientific models expected.
His findings have helped scientists devise better models of the electromagnetic regions of space, which can damage satellites and disrupt radio communications. They have also helped explain how ash and particles from volcanic eruptions are transported around the world so rapidly.
“What became apparent is there are very large winds in this region, and they produce a very rapid global transport,” Larsen says.
In the process of making these measurements, Larsen, professor emeritus of physics and astronomy in Clemson’s College of Science, has become one of the world’s leading authorities on using sounding rockets and luminescent vapor trails to record the winds. He has also developed triangulation techniques to accurately determine wind profiles and their evolution over time.
The rockets, which fly for about 10 minutes, release into the upper atmosphere tiny amounts of illuminating agents similar to the elements used in standard fireworks displays. These vapor tracers produce a colorful three-dimensional grid in the night sky. Teams of researchers at three locations on the ground then capture high-resolution video and still images of the bright display. From there, researchers are able to calculate the wind speed.
Larsen has demonstrated that intense shears from large amplitude winds were causing mysterious quasi-periodic radar echoes observed in the lower ionosphere at night, a phenomenon that had puzzled researchers for decades.
During his prolific career, Larsen has designed and built experiments that were flown on 100 NASA sounding rockets launched at high, mid- and low latitudes. Research colleagues from around the world regularly seek his counsel and expertise.
Larsen was the lead investigator on NASA’s Cusp-Heating Investigation mission, which launched in December 2019 off the coast of northern Norway. The mission measures the flow of plasmas and gases in the northern polar cusp, a region where satellites, GPS and spacecraft could encounter problems. It is one of three missions that make up the Grand Challenge Initiative – Cusp, a series of nine sounding rocket missions exploring the polar cusp.
In August 2019, NASA recognized Larsen with its Distinguished Public Service Medal — the highest honor the space agency bestows to nongovernment personnel — for his “pioneering research to measure vertical profiles of the Earth’s upper atmospheric winds and leading over 100 NASA sounding rockets during 40 years of research.”