NASA’s Mars Science Laboratory Curiosity rover has returned images to earth of Martian geological features that are completely “unexpected” say mission scientists at the agency’s Jet Propulsion Laboratory in Pasadena.

A mosaic of high-definition images of Mount Sharp, the central peak dominating the landing site at Gale Crater, reveals tilted strata never before seen on Mars. The strata dip downwards at an angle close to that of the slope of the foothills of the 18,000-ft. tall mountain within which they are formed.

“The cool thing is the cameras have discovered something we were unaware of,” says mission chief scientist John Grotzinger. “This thing jumped out at us as being very different to what we expected,” he adds. Lying in the low-lying foothills beyond the dune field between the rover and the base of Mount Sharp, the inclined layers are a “spectacular feature” that could not be seen from orbit.

NASA is not yet willing to speculate in detail on the mechanics of the processes which created the landform. On earth such features are typically formed by tectonic, volcanic, sub-aqueous or wind-driven processes. The JPL team plans to use Curiosity’s stereoscopic mast cameras (Mastcam) to measure the precise angle of the dipping strata after a short 10-meter drive scheduled for Aug. 28, says Grotzinger. The new images were collected by the rover’s 100-millimeter telephoto lens and 34mm wide-angle lens.

“Then we’ll start driving and will execute a series of increasingly long drives in excess of 100 meters,” Grotzinger says. This will be “well away from the area we think was affected by the thrusters, and then we’ll head east as quickly as possible.” The rover has successfully demonstrated its ability to maneuver during a series of short moves around its present site, which was dubbed ‘Bradbury Landing’ by NASA as a tribute to the science fiction author Ray Bradbury who died earlier this year.

Mission planners also conducted the first science drive on Aug. 27 to study the bedrock exposed by the impingement made by one of the sky-crane’s thrusters as it lowered the rover to the surface. Although the science team initially expressed concerns about potential contamination from rocket chemical and heating effects, the scoured-out depression will be sampled with Curiosity’s Dynamic Albedo of Neutrons (DAN) instrument. This will fire neutrons into the ground to a measurable depth of around 20 in. below the rover in search of hydrogen atoms, and therefore signs of water. The results will be compared with readings already taken by the DAN over soil-covered areas in the Bradbury Landing area.

Preparations also continue for taking the first sample of the Martian atmosphere. “We are the nose of Curiosity” says SAM (Sample Analysis at Mars) principal investigator Paul Mahaffy. During initial check out tests of SAM, scientists discovered the amount of air from earth’s atmosphere remaining in the instrument after launch was more than expected. As a result, a difference in pressure on either side of tiny pumps led SAM operators to stop pumping out the remaining air as a precaution. The pumps subsequently worked, and a chemical analysis was completed on a sample of earth air.

“As a test of the instrument, the results are beautiful confirmation of the sensitivities for identifying the gases present,” says Mahaffy, who adds the initial indication of methane caused a brief flurry of excitement until the terrestrial origins of the gas were recognized. Mahaffy, who is based at NASA’s Goddard Space Flight Center, says “a few Sols down the road we’re looking forward to getting our first sniff of Mars atmosphere.”

The SAM is a key tool in Curiosity’s search for signs of life, past or present, and is more sensitive and sophisticated than the sensors on the Viking lander which came up negative for organics. The system is designed, for example, to examine a wider range of organic compounds and can therefore check a recent hypothesis that perchlorate - a reactive chemical discovered by the Phoenix Mars Mission – may have masked organics in soil samples taken by Viking.