Mars has metal in its atmosphere, says a new finding obtained from Maven spacecraft flying near the red planet. The study is published in Geophysical Research Letters.
A metal Mars
Mars is a ‘metal planet’. It has electrically charged metal atoms (known as ions) permanently dancing high up in its atmosphere, more specifically in its ionosphere. This spectacular finding was revealed thanks to Maven spacecraft of NASA’s, marking the first time a planet other than Earth has been shown to have metal ions on a permanent basis in its atmosphere, says study lead author, NASA’s Joseph Grebowsky from the Goddard Space Flight Center.
The lost air of Mars
MAVEN (Mars Atmosphere and Volatile Evolution Mission) was sent by NASA to study the upper atmosphere of the red planet. One of the aims of this mission is to understand the process by which Mars lost its air to space; this is believed to have changed the planet from one that could have sustained life to a barren world. Therefore, gleaning more information about the activities in the ionosphere is hoped to gain more knowledge about the lost air of Mars. This can be achieved by studying the metallic ions: since the latter last for a long period of time, and can be displaced over vast distances from their place of origin by neutral winds and electric fields, they can be used to trace movement in the ionosphere—Grebowsky explains that this is the same method used on Earth to find out in which direction wind is blowing.
Metal from meteoroid rain
Where does this metal come from? According to the authors, it originates from an influx of tiny, high-speed meteoroids constantly being rained down into the atmosphere of Mars. When this rain falls into the Martian air, the meteoroids vaporise, and the metal atoms of this vapour have their electrons are snatched away by other charged atoms in the ionosphere. Thus are metal ions formed from the metal atoms.
Metal ions & other planets
So far, iron, magnesium, and sodium ions have been detected by Maven. The spacecraft used its Neutral Gas and Ion Mass Spectrometer to identify the metals, information collected over the last two years. The authors, thus, concluded that the metal ions are permanently present in the ionosphere. They also theorised that all planets and moons of the solar system having an atmosphere are likely to have metal ions too because of the high prevalence of meteor showers.
As mentioned earlier, Earth also has metal ions in its upper atmosphere. However, the behaviour thereof is different from that of the Martian metal ions. Those on Earth are forced into layers by the planet’s global magnetic field (generated from its interior), and ionospheric winds. On the other hand, Mars having local magnetic fields present in specific regions of its crust only has these metal ion layers in these localised spots, and the distributions of metal ions elsewhere are in stark contrast with those on Earth.
All of this information is hoped to paint a better picture of the ionosphere and atmospheric chemistry of Earth as one can compare and contrast with Earth’s, explains Grebowsky.