High above Earth, thin veils of metallic haze drift through the edge of space. Known as sporadic E layers, these high-altitude “clouds” form from the vaporized dust of burnt-up meteors, earning their name from the unpredictable way they emerge and then dissipate. Now, new results from a NASA sounding rocket — a suborbital research rocket — that flew five detectors through one of these layers simultaneously reveal unexpected complexity in the layer for the first time.
Though invisible to the eye, sporadic E layers make their presence known to the radio signals we rely on for long-distance communication. When present, sporadic E can send those signals ping-ponging off in unexpected directions, rendering the technology temporarily unreliable.
Scientists have long sought a fuller understanding of these radio-disrupting clouds, but until recently, they had only sampled them one narrow slice at a time. The rocket, called the sporadic E Electrodynamics Demonstration, or SpEED Demon for short, launched from NASA’s Wallops Flight Facility in Virginia on Aug. 24, 2022, and demonstrated the first concurrent, multi-point view inside sporadic E. Its results, from a team led by Embry-Riddle Aeronautical University, are described in a new study in the Journal of Geophysical Research: Space Physics.
Sporadic E layers form in the ionosphere, a region of the upper atmosphere beginning around 40 miles (60 kilometers) up where the neutral gases begin to transform into plasma, or ionized gas. Some of the particles there come from meteors, which burn up and leave behind traces of iron, magnesium, and other metals. These metals occasionally clump into dense, cloud-like sheets — the sporadic E layers — that reflect radio waves.
