Curiosity reveals mysterious variety of terrains at Vera Rubin Ridge
NASA’s Curiosity rover has imaged Martian terrain that features an unprecedented variety of colors and textures at Vera Rubin Ridge, a 250-mile-wide outcrop that forms a distinctive layer on Mount Sharp. The rover has been exploring this Martian mountain since its arrival in 2012.
One of four unique terrains on Vera Rubin Ridge contains the iron oxide mineral hematite, a type of rock that typically forms in water and holds clues to the area’s ancient environment. This makes it an ideal site to look for evidence that liquid water once flowed on the Red Planet’s surface.
Approximately eight stories tall, the ridge sits in front of a trough that holds clay minerals.
More than a year after a mechanical problem shut down drilling, mission engineers successfully came up with a new method that allowed drilling to resume earlier this year (2018). Before successfully collecting drill samples last month, Curiosity twice encountered extremely hard rocks that it could not penetrate.
Because scientists have no way of determining the hardness of rock before drilling starts, they need to choose sample sites based on educated guesses.
Both hard and soft rocks have been found at Vera Rubin Ridge. One long ledge is composed of very hard stone that is resistant to wind erosion while an area below it is made up of softer rocks vulnerable to such erosion.
“This ridge isn’t this monolithic thing–it has two distinct sections, each of which has a variety of colors. Some are visible to the eye, and even more show up when we look in near-infrared, just beyond what our eyes can see. Some seem related to how hard the rocks are,” explained Curiosity project scientist Ashwin Vasavada of NASA’s Jet Propulsion Laboratory (JPL) in Pasadena, California.
Stone with a reddish hue in the region seem to be the hardest ones.
Vera Rubin Ridge was chosen for exploration by the rover after NASA’s Mars Reconnaissance Orbiter (MRO) detected the area had a high hematite content.
Scientists are uncertain as to whether variations in the hematite within regions on Vera Rubin Ridge might be the cause of the differing levels of hardness in the area’s rocks.
Collected samples will be pounded into powder form and studied by Curiosity‘s two science laboratories. Mission scientists hope the laboratories’ analyses will point to a substance in the rocks that is hardening them and acting like a type of cement.
Vasaveda suspects the rocks were hardened and strengthened in Mars’s ancient past by groundwater that flowed through the ridge and transported this hardening substance.
Curiosity will conduct two more drillings at Vera Rubin Ridge in September before climbing further up Mount Sharp.
The nuclear-powered rover’s Mast Camera (MastCam) took a panoramic photo of Vera Rubin Ridge in which Curiosity and its latest drill site, named “Stoer” after a Scotland town in which lakebed sediments revealed clues about early Earth life, are visible.
Varied terrains on Vera Rubin Ridge are only the latest of several strange discoveries the rover has made on Mount Sharp. In June, Curiosity‘s Sample Analysis at Mars (SAM) instrument detected organic material in three-billion-year-old sedimentary rocks close to the Martian surface. These molecules could have been produced by either biological or geological processes.
Significantly, the concentration of organic compounds measured by SAM, slightly more than 10 parts per million, match the amounts of these compounds detected in Martian meteorites on Earth.
Data collected by Curiosity indicates a water lake existed several billion years ago inside Gale Crater, complete with the chemical building blocks and energy sources necessary for the existence of microbial life.
SAM also detected seasonal variations in atmospheric methane, with levels increasing during Martian summers and decreasing during winters. These variations could have both biological and/or geological origins.
On August 18, the rover’s cameras imaged a strange stone fragment on the Martian surface that its Chemistry and Camera (ChemCam) instrument found to be a thin piece of rock.
The rover has also been monitoring the global dust storm on Mars, which began in late May and is only just now winding down.
Video courtesy of NASA
Laurel Kornfeld is an amateur astronomer and freelance writer from Highland Park, NJ, who enjoys writing about astronomy and planetary science. She studied journalism at Douglass College, Rutgers University, and earned a Graduate Certificate of Science from Swinburne University’s Astronomy Online program. Her writings have been published online in The Atlantic, Astronomy magazine’s guest blog section, the UK Space Conference, the 2009 IAU General Assembly newspaper, The Space Reporter, and newsletters of various astronomy clubs. She is a member of the Cranford, NJ-based Amateur Astronomers, Inc. Especially interested in the outer solar system, Laurel gave a brief presentation at the 2008 Great Planet Debate held at the Johns Hopkins University Applied Physics Lab in Laurel, MD.