Strange plumes in Mars’ atmosphere first recorded by amateur astronomers two years ago have planetary scientists still scratching their heads.
On two occasions in 2012 amateurs photographed cloud-like features rising to altitudes of over 155 miles (250 km) above the same region of Mars. By comparison, similar features seen in the past haven’t exceeded 62 miles (100 km). Back then, no one was certain of the cloud’s nature; it was thought ice crystals or even dust whirled high into the Martian atmosphere by seasonal winds could be the cause.
But a recent paper by scientist Agustin Sanchez-Lavega of the Universidad del País Vasco in Spain explores other possibilities. One problem with dust or ice is altitude – 155 miles is way, way up there where Mars’ atmosphere grazes outer space. Just how clouds could form so high is unknown.
“One idea we’ve discussed is that the features are caused by a reflective cloud of water-ice, carbon dioxide-ice or dust particles, but this would require exceptional deviations from standard atmospheric circulation models to explain cloud formations at such high altitudes,” said Agustin.
Another idea is even more intriguing. The wisps could be Martian auroras linked to regions on the surface with stronger-than-usual magnetic fields.
Once upon a very long time ago, Mars may have had a global magnetic field generated by electrical currents in a liquid iron-nickel core much like the Earth’s does today. In the current era, the Red Planet has only residual fields centered over regions of magnetic rocks in its crust.
Instead of a single, planet-wide field that funnels particles from the Sun into the atmosphere to generate auroras, Mars is peppered with pockets of magnetism, each potentially capable of connecting with the wind of particles from the Sun to spark auroras.
Auroras were first discovered on Mars in 2004 by the European Space Agency’s Mars Express orbiter. NASA’s MAVEN spacecraft, which has been orbiting Mars since last September, is well-equipped to study the planet’s upper atmosphere and auroras, so perhaps we’ll have a more definitive answer soon on the makeup of the mysterious plumes.