Curiosity Investigates Petrified Martian Sand Dunes, Contemplates Next Drill Campaign

Large-scale crossbedding in the sandstone of this ridge on a lower slope of Mars’ Mount Sharp is typical of windblown sand dunes that have petrified. NASA’s Curiosity Mars rover used its Mastcam to capture this vista on Aug. 27, 2015, Sol 1087. Similarly textured sandstone is common in the U.S. Southwest. Credits: NASA/JPL-Caltech/MSSS
See Sol 1100 mosaic below [/caption]

NASA’s SUV-sized Curiosity rover has arrived at a beautiful Martian vista displaying a huge deposit of magnificently petrified sand dunes that look remarkably like some commonly found on Earth and native to the deserts of the U.S. Southwest.

The dunes are keenly fascinating to Red Planet researchers as the NASA robot celebrates 1100 fabulous Sols of exploration and discovery on Mars and contemplates plans for the next drill campaign later this month. See dune mosaic above and our Sol 1100 mosaic below.

The petrified sand dunes were discovered amongst an area of dark sandstone along a ridge at the lower slope of Mars’ Mount Sharp. They are now being explored in detail by the six wheeled rover in a geologic feature dubbed the Stimson unit.

“The team is considering where to drill next within the Stimson sandstone and we are looking for the best light toned areas to check for mineralogical signs of water-rock reaction,” says John Bridges, rover team member from the University of Leicester, England, in the latest mission update from today, September 12, 2015.

Curiosity also discovered large-scale crossbedding in the sandstone that were formed by the action of Martian winds.

“This sandstone outcrop — part of a geological layer that Curiosity’s science team calls the Stimson unit — has a structure called crossbedding on a large scale that the team has interpreted as deposits of sand dunes formed by wind,” according to the rover team.

So Curiosity was commanded by her handlers back on Earth to capture an array of high resolution imagery as part of detailed investigation of the area for up close and contact science.

Dozens of images were taken with the pair of high resolution Mastcam color cameras on the robots mast and combined into the panoramic scene show above and another shown below with a scalebar the length of a tall human, 6.6 feet or 200 centimeters.

The images were taken on Aug. 27, 2015, corresponding to Sol 1087 of the rover’s work on Mars, using both the 34 millimeter-focal-length lens and the 100 mm millimeter-focal-length telephoto Mastcam camera lenses that function as Curiosity’s left and right eyes.

The panorama spans the Martian terrain looking from the east, at left, to the south-southwest at right.

“Some of the dark sandstone in the area …. shows texture and inclined bedding structures characteristic of deposits that formed as sand dunes, then were cemented into rock” say officials.

“Sets of bedding laminations lie at angles to each other.”

Since taking the panorama in late August, the team has driven Curiosity around the area to collect more measurements with her state of the art science instruments.

Later this month, Curiosity will drill into an outcrop at the Stimson unit sandstone for collection and feed it for analysis into the pair of on board chemistry labs – SAM and CheMin- located inside the rover’s belly.

Curiosity already carried out initial contact science in the area by extending the robotic arm to rock targets for investigation with the arm mounted instruments, including the MAHLI camera and APXS spectrometer.

Curiosity “investigated an outcrop of the Stimson unit … and conducted successful contact science,” says Lauren Edgar, Research Geologist at the USGS Astrogeology Science Center and an MSL science team member, in a mission update.

Scientists will select the Stimson drill target soon.

Why explore outcrops at Stimson?

“The Stimson unit overlies a layer of mudstone that was deposited in a lake environment. Curiosity has been examining successively higher and younger layers of Mount Sharp, starting with the mudstone at the mountain’s base, for evidence about changes in the area’s ancient environment.”

Curiosity’s prior drill campaign was recently conducted at the “Buckskin” outcrop target in early August 2015. Buckskin was very notable for being the first high silica rock drilling target of the mission.

Stimson and Buckskin sit at the base of Mount Sharp, a huge layered mountain that dominates the center of the 96 mile-wide (154 kilometers-wide) Gale Crater landing site.

Exploring the sedimentary layers of Mount Sharp, which towers 3.4 miles (5.5 kilometers) into the Martian sky, is the primary destination and goal of the rovers long term scientific expedition on the Red Planet.

Curiosity recently celebrated 1000 Sols of exploration on Mars on May 31, 2015 – detailed here with our Sol 1000 mosaic by Marco Di Lorenzo and Ken Kremer also featured at Astronomy Picture of the Day on June 13, 2015.

As of today, Sol 1102, September 12, 2015, she has driven some 6.9 miles (11.1 kilometers) kilometers and taken over 268,000 amazing images.

Curiosity has already accomplished her primary objective of discovering a habitable zone on the Red Planet – at the Yellowknife Bay area – that contains the minerals necessary to support microbial life in the ancient past when Mars was far wetter and warmer billions of years ago.

Stay tuned here for Ken’s continuing Earth and planetary science and human spaceflight news.

Ken Kremer