Curiosity Marks 5,000 Martian Days and a New Elevation Record

NASA's Curiosity rover passed two milestones in late August: it climbed more than 1,000 meters (0.62 miles) in elevation from its landing site on the floor of Gale crater, and on Aug. 29 it marked 5,000 Martian days, or sols, since touching down — more than 5,137 Earth days, since a Martian day lasts 24.6 hours. By comparison, NASA's earlier Spirit rover climbed just 106 meters to the top of Husband Hill in Gusev crater in August 2005, wrote William Farrand, a senior research scientist at the Space Science Institute who was on the Spirit team.

During the milestone week, Curiosity examined a wind-formed, long, narrow ripple the team has named "Chocolatal," to help determine whether it qualifies as a "transverse aeolian ridge," or TAR — a type of wind-sculpted feature seen across Mars in orbital images, whose long axis lies perpendicular to the local prevailing wind direction. Because this particular ridge sits higher on the slopes of Mount Sharp than earlier examples, scientists want to know whether it is made of the same granular material as TARs found lower down, or has different grain sizes or layering.

The rover used its ChemCam laser instrument to analyze dark-toned coatings on nearby rocks and sand at the base of Chocolatal, took high-resolution Mastcam mosaics of the ridge and surrounding buttes, and drove one wheel into the ridge before backing off to allow contact science within the resulting trench. Close-up mosaics from MAHLI (the rover's hand-lens camera) of the trench wall, taken to check for layering and grain-size variation, were named in honor of the late Paul Geissler, a leading expert on Martian TARs who had been working with the MAHLI team before his death earlier this year.

The team also planned chemical measurements with APXS (an instrument that analyzes rock and soil composition) on the ripple's coarse-grained surface, and additional ChemCam laser shots on top of Chocolatal, on a dark band along its flank, and at the back of the trench, as it continues investigating how the ridge formed, whether it is still active, and how it may have migrated or stabilized over time.