NASA’s Curiosity rover finds strange bedrock on Mars
As NASA’s Mars Science Laboratory rover Curiosity nears her third anniversary on Mars, it has discovered a geological feature unlike anything it has studied before – an area of bedrock with surprisingly high concentrations of silica. Silica is a chemical compound containing silicon and oxygen that is frequently found on Earth as quartz. High levels of silica could indicate good conditions for the preservation of ancient organic material if it was present. The area was just downhill from a geological contact zone that Curiosity had been studying near “Marias Pass” at a low point on Mount Sharp. The contact zone was an area where pale mudstone met with darker sandstone. Curiosity reached this area after a steep climb up a 20-foot (6-meter) hill.
“We found an outcrop named Missoula where the two rock types came together, but it was quite small and close to the ground. We used the robotic arm to capture a dog’s eye view with the MAHLI camera, getting our nose right in there,” said Ashwin Vasavada, the mission’s project scientist at NASA’s Jet Propulsion Laboratory in Pasadena, California. MAHLI is short for Mars Hand Lens Imager.
Near the top of the hill, the rover fired its laser at a rock target named “Elk” and took a spectral reading of its composition.
The Curiosity team wound up backing up the rover 151 feet (46 meters) from the contact zone in order to do further study of Elk. The decision to double-back was made after the analysis of data from two scientific instruments: the laser firing ChemCam and the Dynamic Albedo of Neutrons (DAN), both showed high amounts of silica and hydrogen.
“One never knows what to expect on Mars, but the Elk target was interesting enough to go back and investigate,” said Roger Wiens, the principal investigator of the ChemCam instrument from the Los Alamos National Laboratory in New Mexico.
ChemCam is nearing its 1,000th rock target and has already fired is laser over 260,000 times since Curiosity landed on Mars on August 6, 2012. The instrument can determine a rock’s chemical composition at a distance of up to 25 feet (about 7 meters).
“ChemCam acts like eyes and ears of the rover for nearby objects,” said Wiens.
After returning to the area near Elk, Curiosity found another target for further study – a rock fragment dubbed “Lamoose”. The rover studied Lamoose with its Mars Hand Lens Imager (MAHLI) and the arm-mounted Alpha Particle X-ray Spectrometer (APXS). Lamoose is about 4 inches (10 centimeters) across and is fine-grained. Like Elk, it possesses unusually high concentrations of silica.
The Curiosity team conducted an engineering test of the rover’s sample-collecting drill on July 18 in order to better understand the intermittent short circuits in the drill’s percussion mechanism, in preparation for drilling in the area where Curiosity has been working for the last two months. Because the most recent test on the drill yielded no short circuits, the team will conduct further tests, performed on the science targets themselves. Curiosity is currently preparing to drill a target designated “Buckskin”, which is in the area of rocks containing high levels of silica.
Jim Sharkey is a lab assistant, writer and general science enthusiast who grew up in Enid, Oklahoma, the hometown of Skylab and Shuttle astronaut Owen K. Garriott. As a young Star Trek fan he participated in the letter-writing campaign which resulted in the space shuttle prototype being named Enterprise. While his academic studies have ranged from psychology and archaeology to biology, he has never lost his passion for space exploration. Jim began blogging about science, science fiction and futurism in 2004. Jim resides in the San Francisco Bay area and has attended NASA Socials for the Mars Science Laboratory Curiosity rover landing and the NASA LADEE lunar orbiter launch.