Updated: 20 September 2026 la 12:09. Articolul a fost revizuit pentru a reflecta informațiile disponibile la această dată.
They are not metal clouds in the ordinary sense of the term. At around 100 kilometres above Earth, however, extremely thin plasma layers can form containing ions of iron, magnesium and other metals from meteoric dust that has burned up in the atmosphere. On 2 September 2026, NASA reported that a research rocket had managed to measure the interior of one such layer simultaneously at five points. The key finding was that the structure was not a smooth “sheet”, but a fragmented and dynamic one.
These formations are known as sporadic E layers, or sporadic E. They are invisible to the naked eye, appear and disappear irregularly, and can reflect or refract certain radio waves in unexpected directions. This does not mean mobile phones or the internet suddenly become unusable, but it helps explain why amateur radio operators or radio services can sometimes receive very distant transmitters—and why the ionosphere remains a source of error that must be accounted for in satellite-navigation systems.
What exactly did NASA publish?
The SpEED Demon mission launched from Wallops Flight Facility in Virginia on 23 August 2022. The suborbital rocket passed through a sporadic E layer and released four small probes; together with the main payload, they took plasma measurements along five paths at the same time. Normally, a rocket provides only a narrow “slice” through such a layer.
The analysis, published in August 2026 in Journal of Geophysical Research: Space Physics, is significant precisely because of this multipoint view. The data showed that the layer did not resemble a uniform disk of particles, but had an irregular structure. The team considers the influence of Kelvin–Helmholtz instabilities plausible—ripples that occur when two air flows move at different speeds. The explanation is not yet definitive confirmation: during that flight, the rocket did not directly measure the local winds and electric fields needed to demonstrate the mechanism.
NASA’s report is based on the study “Simultaneous Multi-Point In Situ Plasma Density Measurements of a Mid-Latitude Sporadic E Layer”, by H. C. Valentine and colleagues. The novelty is not the discovery of meteoric metals in the upper atmosphere—these have long been known—but the simultaneous measurements showing how complex such a layer can be.
Where the “metal” comes from—and why it does not fall like dust
Earth continuously passes through tiny particles of cosmic dust. When they enter the atmosphere at high speed, many heat up and vaporise. The process leaves behind metal atoms, including iron and magnesium. At ionospheric altitudes, some of these atoms lose or exchange electrons and become ions—electrically charged particles.
For more science curiosities, see also Earth After 100 Years Without Humans: What Would Remain, Collapse and Not Recover, which provides complementary details on this subject.
Here is the important distinction: these are not droplets or grains of metal suspended as in an industrial cloud. They are an extremely thin, ionised gas, with metal atoms and ions mixed into a plasma. Upper-atmosphere winds and Earth’s magnetic field can temporarily concentrate the ions into dense bands. The image of a “metal mist” is evocative, but it should be treated as a metaphor.
Sporadic E layers occur in the E region of the ionosphere, at around 100 km in altitude. This is an area that is difficult to observe directly: too high for weather balloons and too low for a satellite to orbit for long without atmospheric drag. That is why suborbital rockets remain an essential tool for direct measurements.
How an invisible layer can change the path of radio waves
A radio wave encountering plasma does not always behave as it would in empty space. Electron density can alter its speed and direction, while a sufficiently dense layer can send the signal back towards the ground. In simplified terms, the layer becomes a radio mirror; physically, the phenomenon mainly involves refraction and, under certain conditions, actual reflection.
| Signal type | What a sporadic E layer can do | What should not be assumed |
|---|---|---|
| Shortwave radio, VHF or some specialised communications | It can enable reception of transmitters far beyond the horizon or create interference. | It does not mean every radio frequency will be affected in the same way. |
| Radar, aviation and maritime communications | It can produce unusual reception, overlapping signals or unwanted echoes, depending on the system and frequency. | It is not equivalent to a general communications outage. |
| GPS/Galileo and other GNSS systems | Ionospheric plasma can delay, bend or make the signal unstable, increasing position uncertainty. | Not every GPS error is caused by sporadic E; geomagnetic storms and other ionospheric structures also play an important role. |
NOAA explains that GPS signals pass through the ionosphere and that plasma can bend their path, much as a lens bends light. Receivers use models to compensate for a normal ionosphere, while professional dual-frequency equipment can correct the effect more effectively. During periods of strongly changing ionospheric structure, however, accuracy may decline or a receiver may temporarily lose the signal.
This mechanism differs from the physical route of the international internet, which travels mainly through submarine fibre-optic cables. By comparison, a message crossing the Atlantic via submarine cables is not redirected by these ionospheric layers. Sporadic E matters chiefly for radio propagation through the atmosphere and for satellite-to-ground signals that pass through the ionosphere.
Is this a new risk for Romania?
No. The phenomenon is not new and does not in itself constitute a warning for the public. Romania lies at mid-latitudes, where sporadic E layers can occur seasonally, particularly in summer, but the observable effect depends on frequency, time of day, radio-path geometry, solar activity and local conditions in the ionosphere.
Most likely, an ordinary user will not be able to identify a sporadic E episode simply from the position displayed on their phone. A location error can have many other causes: a weak signal between buildings, urban reflections, few visible satellites, the device’s antenna or the corrections available. For aviation, navigation, precision mapping and specialised radio communications, the ionosphere is already included in monitoring procedures and equipment design.
Why the five-point measurement matters
A model that treats a sporadic E layer as a uniform film can wrongly estimate how waves propagate through it. If the layer has gaps, ridges, two density peaks or ripples, a signal may be affected differently from one path to another. The SpEED Demon mission’s result does not yet provide a daily forecast for these radio “mirrors”, but it shows what must be measured better to get there.
NASA notes that these layers have a seasonal pattern, with peak occurrence in local summer. The next step is not a promise that interference will be eliminated, but the development of better models of their timing, location and shape. That is the real significance of the new data: moving from the observation that “a layer exists” to describing the structure that concretely changes the path of a radio wave.
Frequently asked questions
Are sporadic E layers visible from the ground?
No. They are structures of extremely thin plasma at around 100 km altitude, without the appearance of an ordinary weather cloud.
Are they made entirely of metal?
No. They are concentrations of plasma; metal ions originating from meteoric material are an important component, alongside electrons and other ionised particles.
Can these layers stop mobile internet?
Not directly or generally. They mainly affect certain forms of radio propagation and can contribute to GNSS signal errors. Mobile networks and the internet depend on multiple components, including terrestrial infrastructure and fibre optics.
