Space agencies across the world like ESA, NASA, ISRO, etc, have always been in a quest to find out more information about Mars. There had many missions launched only to explore if life ever existed on the red planet or it could exist in the future and its various other aspects.
Among other observations, ESA’s Mars Express has detected a mysteriously long cloud that keeps reappearing over a rapid periodic cycle. The orbiter has now captured images of the elusive cloud when it appeared again. According to ESA, the cloud appears periodically over Arsia Mons, a 20-km high volcano but it is not a volcanic plume. The strange cloud is made up of water ice and can be about 1800 kilometres long. It forms because of the airflow influenced by the volcano’s slope that does not face the wind.
It has been spotted so many times in the past over the Arsia Mons volcano that this time, scientists were waiting for it to happen. Therefore the cloud has been named Arsia Mons Elongated Cloud (AMEC) by the Mars Express team. Scientists have been observing the unusual phenomenon for a while now as part of a study.
The picture of the event was captured by the Visual Monitoring Camera (VMC) on the Mars Express probe on July 17 and July 19. It’s believed that the cloud is formed when dense air near Mars’ surface is forced uphill. At that height, the temperature dips and the moisture condenses around dust particles. However, scientists say that the fog trail is not created by the volcano.
physicist Jorge Hernandez-Bernal, from the University of the Basque Country in Spain, explained that “This elongated cloud forms every martian year during this season around the southern solstice, and repeats for 80 days or even more, following a rapid daily cycle. However, we don’t know yet if the clouds are always quite this impressive”.
The cloud appears only early in the morning during the southern solstice on Mars, the time of year when Sun is in the southernmost position in the martian skies, similar to 21 December on Earth. The cloud grows in size for about three hours after appearing and then quickly disappears again a few hours later.
“Luckily for Mars Express, the highly elliptical orbit of the spacecraft, coupled with the wide field of view of the VMC instrument, lets us take pictures covering a wide area of the planet in the early morning. That means we can catch it!” explained by Planetary scientist Eleni Ravanis, who is working on the Mars Express mission. The Mars Express has a perfect position and perfect tool to observe the cloud and gather data on the mysterious phenomenon.