After exploring Mars' Vera Rubin Ridge for more than a year, the NASA Rover Curiosity recently moved on. With a new 360 video, the public can view the last Curiosity well on the crest, an area nicknamed "Rock Hall." The video was made from a panorama that the rover had taken on 19 December. It contains images of the next target – an area the team calls "sound recordings" and has recently named "Glen Torridon", as well as the bottom of Gale Crater, home of Mount Sharp, the geological feature the rover has climbed since 2014 ,
Although the rover has left the ridge, Curiosity's team is still bringing the story together. While there are a number of clues, no one fully explains why the crest has resisted erosion compared to the surrounding rock. However, the research of the rover revealed that the rocks of the ridge, which were formed as sediment, settled in an ancient lake, similar to the rock layers below the ridge.
"We've had many surprises," said Abigail, a member of Curiosity's science team, Fraeman, from NASA's Jet Propulsion Laboratory in Pasadena, California. "We're leaving the ridge with a different perspective than before."
A NASA orbiter investigating the ridge had previously identified a strong signal of hematite, an iron-rich mineral that often forms in the water. The curiosity confirmed the presence of hematite along with other signs of ancient water like crystals. These signs appeared in spots, so the team suspected that groundwater influenced other parts of the ridge differently than others over time. Another discovery was that the Hatsit signatures depicted on Curiosity did not always correspond to the view from space.
"The whole traverse helps us understand all the factors that affect how our orbiters see Mars," said Fraeman. "Seeing up close with a rover enabled us to find much more of these hematite signatures, showing how orbiter and rover science complement each other."
The crest also served as a backdrop for a roller coaster year: the curiosity's drill again active only to be braked by surprisingly hard rocks. Nevertheless, the team managed to obtain samples of the three most important rock types of the ridge. To work around a problem with the memory, the engineers also swapped out the Rovers' computers (the spacecraft was designed with two to continue operation in the event of a failure). While the problem is still being diagnosed, the operations continued with little impact on the mission.
Glen Torridon, Rover's new home, is located in a valley between Vera Rubin Ridge and the rest of the mountain. This region was referred to as a clay containing unit because the orbiter data show that the rock strata contain phyllosilicates – clay minerals that form in the water and that could tell the scientists more about the ancient lakes that have been present throughout the history of the Gale Craters.
"In addition to suggesting a previously humid environment, clay minerals are known to capture and preserve organic molecules," said Curiosity Project Scientist Ashwin Vasavada of JPL. "This makes this area particularly promising and the team is already exploring the area for the next drilling site."
Curiosity has found both clay minerals and organic molecules in many of the rocks it has drilled since landing in 2012. Organic molecules are the chemical building blocks of life. If both water and organic molecules were present when the rock was formed, the clay-bearing unit could be another example of a livable environment on ancient Mars – a place that can sustain life, if it ever exists.
Curiosity says goodbye to Vera Rubin Ridge of Mars