Curiosity's priority switches from driving to science
BY STEPHEN CLARK
Posted: April 15, 2014
Beginning its most extensive scientific survey in a year, the Curiosity Mars rover is employing cameras, mineral-sniffing spectrometers, a rock-zapping laser and potentially its impact drill at a study site named "the Kimberley" on the robot's trek toward Mount Sharp.
Scientists designated the Kimberley site as one of several waypoints on Curiosity's route from Yellowknife Bay, a shallow depression where the one-ton rover's instruments found an environment that was once habitable to microbial life, toward the mission's ultimate objective at Mount Sharp, a three-mile-high mountain believed to harbor layered clay minerals, an indicator of a wetter time on ancient Mars.
Rover managers have focused on driving Curiosity toward Mount Sharp over the last year, eyeing an arrival in the mountain's foothills by the end of the summer.
But the scene at the Kimberley is, at least temporarily, shifting the rover from its overland drive campaign into science mode.
Four different types of rock intersect at the Kimberley, and scientists hope the region contains more clues about Martian environments that may have once been home to life. The Kimberley is named for a region of western Australia fraught with geological riches.
Since arriving at the Kimberley around April 2, Curiosity has toured the research site, taking pictures, beaming rocks with its laser to measure chemical composition, and collecting data for a probable use of the rover's drill.
The hammer drill hasn't been used for more than a year. It works by boring into a rock and gathering fine-grained samples through an auger into a holding chamber, where it awaits delivery to Curiosity's sample analysis instruments, which can examine the material's chemical and mineral composition, plus look for organic compounds.
The initial survey at the Kimberley location revealed stair-like rocky outcrops, but the mineral analysis will take longer to produce a deeper understanding of the region.
"This is the spot on the map we've been headed for, on a little rise that gives us a great view for context imaging of the outcrops at the Kimberley," said Melissa Rice of the California Institute of Technology, science planning lead for Curiosity's research at the Kimberley.
According to a NASA press release, officials expect Curiosity to remain at the Kimberley for several weeks.
At Yellowknife Bay, a shallow depression to which Curiosity detoured soon after landing, the rover drilled into mudstone and found evidence the site was an ancient lakebed. Furthermore, the results showed the lake's water had a neutral pH and contained the right minerals to support simple microbial organisms.
But Curiosity's drill samples from Yellowknife turned up no signature of organic molecules, the building blocks of life scientists hoped to find. The negative result from Yellowknife Bay has prompted the science team to reconsider their strategy for finding organics.
Radiation measurements on Mars indicate cosmic rays could destroy organic molecules, but the material might be preserved within one meter, or about 3.3 feet, of the surface, where soil and bedrock could shield organics from the constant life-destroying radiation bombardment.
Curiosity does not carry an instrument to penetrate that deep into the Martian subsurface, but geologists are on the lookout for potential drill sites where wind erosion has exposed underground layers in the red planet's relatively recent past.
"If you want to find organics, you need to find places where it hasn't been exposed for such a long time," said Robert Wimmer-Schweingruber, a co-investigator for Curiosity's Radiation Assessment Detector, during a press conference in December.
Follow Stephen Clark on Twitter: @StephenClark1.
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