The Curiosity rover has captured a farewell 360-degree panorama of the Gediz Vallis, a region it has explored over the past year. On its territory, it found a mysterious rock composed of pure sulfur.
Mystery of the Martian sulfur
Curiosity’s primary mission is to find evidence that ancient Mars had the necessary ingredients to support microbial life. During this mission, it has spent the past year studying the Gediz Vallis. It is a channel at the foot of the 5-km-long Mount Sharp, formed by water that once flowed there.
The Gediz Vallis has interested scientists because of its relative youth. While the older layers on the mountain were already formed in a dry climate, the channel suggests that water still periodically flowed through the area. How the channel formed so late, at a time when Mars was already beginning to dry up, is one of the big questions for the science team. Another mystery is the field of white sulfur rocks that the rover discovered during the summer.
In the images taken from orbit, the field looks like an unremarkable section of light-colored terrain. The rocks are simply too small to be photographed by MRO. So the mission specialists were extremely intrigued to discover them when the rover reached the site. They were even more surprised when Curiosity rolled over one of the rocks and smashed it, revealing yellow crystals inside.
The rover’s scientific instruments confirmed that the rock was pure sulfur, something never before seen on Mars. The team doesn’t have a ready explanation for the formation of sulfur there. On Earth, it is associated with volcanoes and hot springs, but there is no evidence at Mount Sharp to indicate such processes.
Scientists are also still trying to unravel the processes that led to the formation of other features in the channel, including a debris mound called Pinnacle Ridge. It can be seen in a farewell 360-degree panorama taken by Curiosity before it left the valley for the next destination of its journey. Rivers, debris flows and avalanches seem to have left their mark here. The science team is now building a timeline of events based on Curiosity’s observations.
Web on Mars
Curiosity, which has traveled about 33 kilometers since landing in 2012, is now moving along the western edge of Gediz Vallis. It will take a few more panoramas to document the region before moving on to the so-called boxwork formations.
In images taken from orbit by the MRO spacecraft, these structures look like spider webs stretching across the surface. It is believed to have formed when minerals carried by recent water flows from Mount Sharp settled in cracks and then solidified. When some of the rock weathered away, only minerals remained, forming spider web-like boxwork structures.
On Earth, boxwork formations are found on rock slopes and in caves. But the boxwork structures of Mount Sharp stand out among them, both because they formed during the disappearance of water on Mars and because they are so extensive, covering an area of 10 to 20 kilometers.
Scientists say these ridges contain minerals that crystallized underground, where it was warmer and salty liquid water flowed. Early Earth microbes could survive in a similar environment. This makes the site very interesting for astrobiological research.
Provided by NASA
