NASA’s Perseverance rover found strange green spots in Martian rock, potentially indicating a past interaction with liquid water.
Nearing its fourth year of operation on the Martian surface, NASA’s Perseverance rover has been studying old habitats, gathering samples, and determining whether our reddish neighbor may have ever been home to microbiological life.
Perseverance used its SHERLOC WATSON camera to capture a mosaic image of the Malgosa Crest abrasion patch at night, at a site known as the “Serpentine Rapids,” as part of its most recent results. Surprisingly, the photograph showed white, black, and greenish patches inside the rock. Although the makeup of these rocks is yet unknown, the surprising discovery has scientists eager to see what other undiscovered treasures Perseverance may discover in the future.
In order to obtain photos from inside the rock, Perseverance created an abrasion area in an outcrop known as “Wallace Butte.” The huge green spot visible in the upper left corner of the picture is about two millimeters (about 0.08 inches) in diameter, while the abrasion patch is five centimeters (about two inches) in diameter. On August 19, Martian day 1,243 of the Mars 2020 mission, the photograph was taken.
Oxidized iron, the same kind of iron that gives our blood its red hue and is comparable to the oxidized red rust you may see on your automobile, is usually the source of color in rocks on Earth that match the red Martian rocks under study. When liquid water percolates through sediment before solidifying into rock, it creates the green patches seen in Perseverance’s latest image, which are also frequently found in red rocks on Earth. This procedure facilitates a chemical reaction that turns oxidized iron into its reduced form, giving the rock its green color.
On Earth, bacteria occasionally contribute to this process, but decomposing organic debris can also produce the ideal environment for the reduction reaction. Without the aid of microbes, sulfur and iron can also interact chemically to promote iron-reduction processes.
However, there was not enough space for the rover to securely position its arms carrying the SHERLOC and PIXL instruments right on top of the green area, thus it will remain unclear exactly what kind of reaction caused the green spots seen in Perseverance’s photograph. This prevented a closer view of the robotic explorer. To further understand what kinds of chemical interactions are creating these features in the rock, the team expects Perseverance will find something similar in the future.
Perseverance’s next goal is to climb to the edge of the Jezero Crater, which will require it to traverse severe terrain. After that, it will eventually emerge from the crater where it has spent the past two years.