NASA Rocket Finds Radio-Reflecting Upper-Atmosphere Clouds Are Far From Flat

A NASA sounding rocket has offered scientists their first simultaneous look at several points inside a sporadic E layer, a short-lived metallic cloud high above Earth that can interfere with radio signals. The mission, known as the sporadic E Electrodynamics Demonstration—or SpEED Demon—sent four small probes away from the rocket while it passed through one of the layers. Along with instruments on the main payload, the probes measured the ionized gas in five locations at the same time. NASA reported that the mission launched from Wallops Flight Facility in Virginia in August 2022. The article identifies Aug. 24 as the launch date, while an accompanying caption gives Aug. 23. The findings, led by researchers at Embry-Riddle Aeronautical University, appear in the Journal of Geophysical Research: Space Physics. Sporadic E layers form in the ionosphere, beginning roughly 40 miles above Earth, where gases become plasma. When meteors burn up, they leave behind metals including iron and magnesium. Those materials can gather into dense sheets that reflect radio waves. The reflections may cause long-distance signals to travel in unexpected directions. NASA said air traffic controllers and marine radio users can receive distant transmissions as if they were nearby, while radar systems may detect false targets beyond the horizon. Sporadic E can also add to uncertainty in phone-based GPS measurements. Before SpEED Demon, sounding rockets could sample these layers only along a single flight path. The new dropsondes expanded that narrow view and showed that the layer was not a smooth, pancake-like sheet. Instead, the measurements indicated an uneven, structured formation affected by turbulent winds in the surrounding neutral atmosphere. During the rocket’s descent, the layer separated into two distinct peaks. Researchers said the shape was consistent with Kelvin-Helmholtz billows, curling atmospheric instabilities that can resemble breaking waves. However, because the mission did not directly measure the local winds and electric fields, NASA described that explanation as plausible rather than confirmed. The successful probe system has since been adapted for other rocket missions, including flights during the 2023 and 2024 solar eclipses and a 2025 mission launched from Kwajalein Atoll in the Marshall Islands. Further papers from those missions are still being prepared.