Astronomers left baffled by unexplained plumes on Mars' surface

The mysterious plumes observed on Mars' surface has left astronomers studying the atmosphere on the Red Planet baffled.

On two separate occasions in March and April 2012, amateur astronomers reported definite plume-like features developing on the planet. The plumes were seen rising to altitudes of over 250 km above the same region of Mars on both occasions. By comparison, similar features seen in the past have not exceeded 100 km.

The features developed in less than 10 hours, covering an area of up to 1000 x 500 km, and remained visible for around 10 days, changing their structure from day to day.

None of the spacecraft orbiting Mars saw the features because of their viewing geometries and illumination conditions at the time. However, checking archived Hubble Space Telescope images taken between 1995 and 1999 and of databases of amateur images spanning 2001 to 2014 revealed occasional clouds at the limb of Mars, albeit usually only up to 100 km in altitude.

But one set of Hubble images from 17 May 1997 revealed an abnormally high plume, similar to that spotted by the amateur astronomers in 2012.

Scientists are now working on determining the nature and cause of the plumes by using the Hubble data in combination with the images taken by amateurs.

The jury was still out on the nature and genesis of these curious high-altitude martian plumes. Further insights should be possible following the arrival of ESA's ExoMars Trace Gas Orbiter at the Red Planet, scheduled for launch in 2016.