Source: Sci News

If your favorite radio station has ever jammed or been replaced by another station, a likely cause are layers of plasma in the ionosphere.

Forming suddenly and lasting for several hours, these layers act like giant mirrors in the sky, causing radio signals from far away to bounce over the horizon where they can interfere with local transmissions, like two people trying to talk over one another.

The layers also can cause interference with radio communications by aircraft and shipping, and can blind military radar.

“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,” said Dr. Glyn Collinson, a researcher at NASA’s Goddard Space Flight Center, the University of California, Berkeley, and the Institute for Astrophysics and Computational Sciences at the Catholic University of America.

“Who would have thought one of the best ways to understand them is to launch a satellite 300 million miles to Mars?”

At Earth, the layers form at an altitude of 100 km (62 miles) where the air is too thin for an aircraft to fly, but too thick for any satellite to orbit.

The only way to reach them is with a rocket, but these missions last only tens of minutes before falling back to Earth.

“We’ve known they exist for over 80 years, but we know so little about what goes on inside them, because no satellite can get low enough to reach the layers, at least, no satellite at Earth,” Dr. Collinson said.

Dr. Collinson and colleagues analyzed MAVEN data from the dayside ionosphere of Mars and identified 34 sporadic ‘layer’ candidates.

Contrary to expectations from Earth, in addition to the expected sporadic ‘layers,’ the spacecraft also encountered numerous ionospheric density voids consistent with sporadic ‘rifts.’

At each event, the abrupt change in the density of ionospheric plasma was recorded by three MAVEN instruments: the Suprathermal and Thermal Ion Composition (STATIC) instrument, the Neutral Gas and Ion Mass Spectrometer (NGIMS), and the Langmuir Probe and Waves (LPW) instrument.

“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 former MAVEN project scientist Dr. Joe Grebowsky, of NASA’s Goddard Space Flight Center.

The results were published in the journal Nature Astronomy.

Source: Sci News