A European spacecraft is unraveling the secrets of the strange long cloud which has been appearing over and over in the Martian sky for years.
the Elongated Cloud of Arsia Mons is a peculiar feature of Mars: a long, bright cloud of water ice that extends over the Martian surface, extending over the planet’s Arsia Mons volcano to the volcano Olympus Mons, the highest mountain in the solar system. The strange phenomenon has been repeated every year around the southern solstice of Mars, and the cloud forms and fades daily for 80 days or more at a time on the red planet.
However, while the cloud is not a new presence, it is a challenge to observe it in its entirety due to the changing Martian atmosphere and the difficulties of observing from orbit. Still, the European Space Agency Mars Express orbiter has managed to get an in-depth look at the peculiar cloud using a special tool: the Visual Monitoring Camera (VMC), perhaps better known by its nickname the Mars Webcam.
In a new study, astronomers using this data are getting new details about the long cloud, including how big it can actually grow and details of the intricate dynamics at play in the climate system around it.
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The VMC was originally installed to detect the Beagle 2 lander, a British lander on Mars that was declared lost and speculated to have crashed.
“However, recently, the VMC was reclassified as a chamber for science,” said Jorge Hernández Bernal, an astronomer at the University of the Basque Country in Spain and lead author of this new study of the cloud that is also part of a study to long term. project studying the cloud, said in a statement.
“Reusing the VMC has allowed us to successfully understand this transient cloud in a way that would not have been possible otherwise,” ESA Mars Express project scientist Dmitrij Titov said of the VMC in the same statement.
The tool allows scientists to “track clouds, monitor dust storms, probe clouds and dust structures in the Martian atmosphere, explore changes in the planet’s polar caps and more,” added Titov.
For this study, the astronomers used both VMC observations and data from other Mars Express instruments, in addition to data from other missions, including NASA’s Atmosphere of Mars and Volatile Evolution (MAVEN). Mars reconnaissance orbiter (MRO), the Viking 2 missions and the Indian Space Research Organization Mars Orbiter Mission (MOTHER).
“We were especially excited when we delved into Viking 2 observations from the 1970s,” Bernal said. “We discovered that this huge and fascinating cloud had already been partially photographed so long ago, and now we are exploring it in detail.”
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The researchers found that, at its largest point, the cloud is about 1,118 miles (1,800 kilometers) long and 93 miles (150 km) wide. The cloud is “orographic”, which means that it forms when the wind is pushed upward by surface elements such as mountains (in this case, Arsia Mons), and is the largest cloud of its kind ever seen on the planet. .
They found that the cloud is also very dynamic, forming before sunrise and then expanding rapidly for two and a half hours. It can grow at a mind-blowing speed of over 600 kph (373 mph) before stopping to expand. It then sloughs off where it was formed and stretches even further before evaporating in the late morning. On Earth, orographic clouds are never as big as this Martian cloud, nor as dynamic, which makes them especially strange.
Now that researchers have better managed the life cycle and patterns of this phenomenon, it will allow them to target and observe the cloud more easily.
“Many Mars orbiters cannot begin to observe this part of the surface until the afternoon due to the properties of their orbits, so this is really the first detailed exploration of this interesting feature, and it is possible thanks not only to the diverse ensemble. of instruments of Mars Express., but also its orbit “, said in the same statement the co-author of the study Agustín Sánchez-Lavega, scientific director of the VMC and professor of physics at the University of the Basque Country.
This work was published for the first time December 20 in a study in the Journal of Geophysical Research and was published in Volume 126 of Issue 3 in March 2021.
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