NASA has published new photos taken by its venerable Mars Rover Opportunity, which after 14 Earth years and 5,000 Sols – Martian days – continues its scientific mission on the planet Mars. In the ancient valley called Perseverance Valley it found a soil with a texture that resembles certain very particular rock strips on some mountain slopes on the Earth. These formations can be created by cycles of freezing and thawing of moist soil or wind, downhill transport or other processes.
The Mars Rover Opportunity arrived at the entrance to Perseverance Valley at the beginning of May 2017 and began its scientific activities aimed at understanding the origin of that valley. From the beginning, features found in the soil could indicate an origin linked to the presence of water but could also have been generated by other processes.
Ray Arvidson of the University of Washington in St. Louis, one of the Opportunity mission’s investigators, stated that Perseverance Valley is a special place, like having again a new mission 14 Earth years after the rover’s landing on the planet Mars. This strange valley is different from the other places studied during the mission and more surveys are needed to try to solve its origin’s mystery.
For now, the Mars Rover Opportunity has found formations that look like rock stripes. They can also form in not so particular conditions, such as near the peak of the Mauna Kea volcano in Hawaii, where the ground freezes every night but is often dry. Basically, those formations are found where the temperature and ground conditions are suitable. Certain types of soil retain a greater amount of water that expands them when freezing pushing upwards larger particles.
It’s not the first time that an area that seems similar to Hawaii is found on Mars: as early as 2012, a soil similar to the basaltic one of volcanic origin at the Hawaii islands was identified by the Mars Rover Curiosity, which operates in a region very far away from Opportunity. It remains to be seen if the similarities are accidental.
In Perseverance Valley’s case, winds could play an important role due to the erosion they generate. The Martian atmosphere is much thinner than the Earth’s but winds are very fast and together with the dust in the air are more than enough to cause erosion. The debris produced by impacts that generated craters in relatively recent times increase the geological complexity of the area.
The mobility of the Mars Rover Opportunity has long been limited by wheel problems so its movements must be programmed with caution. This makes the Perseverance Valley survey more difficult, although “Oppy” keeps on collecting data. These latest photos published by NASA were taken on January 4, 2018: the image above shows the area of the valley from the north on the left to east-southeast on the right with the rock in the lower right corner around 28 centimeters (11 inches) wide while the image below shows a small area near the rover with the stone near the robotic arm about 5 centimeters (2 inches) wide.