NASA’s MAVEN spacecraft, currently in orbit around Mars, has made an interesting discovery of metal ions in its atmosphere. It’s the first time we’ve found such a feature on another planet.
The research was led by Joseph Grebowsky of NASA’s Goddard Space Flight Center in Greenbelt, Maryland. The findings are published in Geophysical Research Letters.
The metal comes from interplanetary dust in the form of meteoroids that is hitting the atmosphere. MAVEN (Mars Atmosphere and Volatile Evolution Mission) detected iron, magnesium, and sodium ions in the upper atmosphere, all with this cosmic origin.
"MAVEN has made the first direct detection of the permanent presence of metal ions in the ionosphere of a planet other than Earth," said Grebowsky in a statement.
As the meteoroids hit the atmosphere, they are vaporized and metal atoms in the vapor trail have their electrons stripped away by the ionosphere (the upper atmosphere), turning the atoms into electrically charged ions.
We already knew these sorts of ions were present in Earth’s atmosphere, forming into permanent layers above our planet. They’re arranged in layers by our global magnetic field, but on Mars things are a bit different.
MAVEN is studying the atmosphere of Mars. NASA's Goddard Space Flight Center
Mars only has localized magnetic fields that are fossilized in certain parts of the crust, having lost its global magnetic field – and most of its atmosphere with it – long ago. But this detection suggests it does also have some permanent ions, but they are mostly disordered except above these local magnetic fields.
MAVEN has been studying the atmosphere of Mars since it entered orbit in September 2014. It has previously found evidence that the solar wind was responsible for stripping away much of the atmosphere after the planet lost its magnetic field. This study, though, suggests it still has some features that are similar to our world.
"Observing metal ions on another planet gives us something to compare and contrast with Earth to understand the ionosphere and atmospheric chemistry better," said Grebowsky in the statement.
Understanding the Martian ionosphere will give us a better understanding of how the Martian atmosphere has been lost to space. And this study hints that other planets and moons with atmospheres will have metal ions like Earth, too.