A European spacecraft is uncovering the secrets of the strange long cloud which has appeared again and again in the Mars heavens for years.
The Arsia Mons Elongated Cloud is a peculiar feature of Mars: a long, clear cloud of water ice that stretches across the Martian surface and over the planet’s Arsia Mons volcano to the volcano Olympus Mons, the highest mountain in the solar system. The strange phenomenon reappears every year in the southern solar eclipse of Mars, with the cloud fading daily on the Red Planet for 80 or more days.
Although the cloud is not a new presence, it is a challenge to observe in its entirety due to the changing Martian atmosphere and the difficulty of observing from an orbit. Still, the European Space Agency Mars Express orbiter managed to get an in-depth look at the strange cloud using a special tool: the Visual Monitoring Camera (VMC), perhaps better known by the nickname Mars Webcam.
In a new study, astronomers using this data pick up new details about the long cloud, including how big it can really get and details about the complex dynamics that play out in the climate system around it.
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The VMC was originally installed to Beagle 2-lander, a British Marslander who was declared lost and is speculated to have crashed.
“However, the VMC was recently reclassified as a camera 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 long-term study. project studying the cloud, said in a statement.
“Through the reconstitution of the VMC, we have successfully enabled us to understand this transient cloud in a way that would not otherwise be possible,” ESA Mars Express project scientist Dmitry Titov said in the same statement.
The tool allows scientists to “detect clouds, monitor dust storms, study cloud and dust structures in the Martian atmosphere, study changes in the planet’s ice sheets, and more,” Titov added.
For this study, astronomers used both the VMC observations and data from other Mars Express instruments, in addition to data from other missions, including NASA’s Mars Atmosphere and Volatile Evolution (MAVEN). Mars Exploration Orbiter (MRO), the Viking 2 missions and the Indian Space Research Organization Mars Orbiter Mission (MA).
“We were especially excited when we dug into the Viking 2’s observations from the 1970s,” Bernal said. “We have found that this enormous, fascinating cloud has been partially imaged so long ago – and now we are examining it in detail.”
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Cloudy clues
The researchers found that the cloud, at its largest, is about 1,800 kilometers long and 150 kilometers wide. The cloud is ‘orographic’, meaning that it arises when wind is pushed upwards by surface features such as mountains (in this case, Arsia Mons), and is the largest cloud of its kind ever seen on the planet.
The cloud is also very dynamic, finding and forming them before sunrise and then expanding rapidly for two and a half hours. It can grow at an astonishing speed of over 373 mph (600 km / h) before stopping expanding. It then leaves from where it formed and is stretched even more before evaporating late in the morning. On Earth, orographic clouds are never as large as this Mars cloud and also not as dynamic, which makes it especially strange.
Now that the researchers are better able to handle the life cycle and patterns of these phenomena, it will enable them to aim and observe the cloud more easily.
‘Many Mars orbits cannot even begin to observe this part of the surface in the afternoon due to the properties of their orbits, so this is the first detailed examination of this interesting feature – and this is made possible by not only the diverse range of instruments of Mars Express does not. , but also his orbit, “co-author Agustin Sánchez-Lavega, the science leader for the VMC and a professor of physics at the University of the Basque Country, said in the same statement.
This work was first published December 20 in a study in the Journal of Geophysical Research and was released in March 2021 in Volume 126 of Issue 3.
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