The Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft found structures in the planet's ionosphere similar to atmospheric structures that are known to cause problems with radio communications on Earth.
MAVEN uncovered two types of structure in the Martian ionosphere: layers and rifts. These structures also occur in the Earth's ionosphere, where they can interfere with local and long-distance transmissions. (Related: Mysterious Mars: Methane "burp" previously detected on Mars "seems to have disappeared.")
Electrically charged layers in the ionosphere
What the scientists call "layers" are areas where electrically charged plasma -- or electrically charged gas -- builds up in the uppermost region of the ionosphere, an electrically charged zone of the upper atmosphere. These formations form suddenly and persist for hours, reflecting radio signals the way light reflects off mirrors. They can cause radio signals from far away to bounce over the horizon, interfering with local transmissions.
However, they don't just interfere with radio stations: they can also block radar signals that can be used to detect aircraft and ballistic missiles.
Scientists have known of the existence of these layers in the Earth's atmosphere for over 80 years. But at 60 miles high, they exist at an altitude that makes them inconvenient to study. Here, the air is too thin for aircraft but too thick for satellites to remain in orbit.
In an attempt to study these layers, scientists use sounding rockets, which fly for a few minutes before falling back to Earth, but this approach is hardly satisfying, as it can't gather as much data.
Mars has a thinner atmosphere than Earth. This permits MAVEN to orbit at a lower altitude and see the layers from a closer vantage point. The spacecraft is able to see spikes in plasma in certain spots in the Martian ionosphere, similar to what has been recorded on Earth during sound rocket flights.
Lead author Glyn Collinson, a research associate at the National Aeronautics and Space Administration (NASA)'s Goddard Space Flight Center in Maryland, said in a NASA statement, "The layers are so close above all our heads at Earth, and can be detected by anyone with a radio, but they are still quite mysterious. Who would have thought one of the best ways to understand them is to launch a satellite 300 million miles [482 million km] to Mars?"
"The low altitudes observable by MAVEN will fill in a great gap in our understanding of this region on both Mars and Earth, with really significant discoveries to be had," said co-author Joe Grebowsky, a former MAVEN project scientist at Goddard.
Rifts previously thought impossible on Mars
What scientists call "rifts" happen in zones where plasma is less abundant. MAVEN is the first to find such rifts on Mars, and the discovery overturns past models that suggest they cannot exist in the planet's atmosphere.
The presence of the rifts as well as the mechanisms behind them are still poorly understood. That said, one thing that was observed was that Martian rifts last longer than those on Earth.
MAVEN's observations have already overturned many of our existing ideas about the layers and rifts phenomena that gave scientists a better understanding of the fundamental processes regarding the layers. Future exploration at Mars can also allow scientists to build better models on how they form.
Much like the weather, there is no way to stop the layers and rifts from forming. But new insights from Mars may help forecast their existence on Earth for better and more reliable radio communication.
“MAVEN has already explored more of these at Mars than we have ever explored on Earth. It’s giving us a place where we can finally study this thing that’s happening right above us all the time that you wouldn’t know about unless your radio starts speaking Portuguese," says Collinson.
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