Curiosity rover sees more evidence of water on Mars

Evidence of water-bearing minerals in rocks near where it had already found clay minerals inside a drilled rock

NASA's rover Curiosity has found evidence of water-bearing minerals in rocks on Mars, providing more proof that water once flowed on the surface of the red planet.

Last week, the rover's science team announced that analysis of powder from a drilled mudstone rock on Mars indicates past environmental conditions that were favourable for microbial life.

Additional findings presented yesterday at a news briefing at the Lunar and Planetary Science Conference in The Woodlands, Texas, suggested those conditions extended beyond the site of the drilling.

Using infrared-imaging capability of a camera on the rover and an instrument that shoots neutrons into the ground to probe for hydrogen, researchers have found more hydration of minerals near the clay-bearing rock than at locations Curiosity visited earlier.

The rover's Mast Camera (Mastcam) can also serve as a mineral-detecting and hydration-detecting tool, said Jim Bell of Arizona State University.

"Some iron-bearing rocks and minerals can be detected and mapped using the Mastcam's near-infrared filters," Bell said.

Ratios of brightness in different Mastcam near-infrared wavelengths can indicate the presence of some hydrated minerals.

The technique was used to check rocks in the "Yellowknife Bay" area where Curiosity's drill last month collected the first powder from the interior of a rock on Mars. Some rocks in Yellowknife Bay are crisscrossed with bright veins.

"With Mastcam, we see elevated hydration signals in the narrow veins that cut many of the rocks in this area," said Melissa Rice of the California Institute of Technology, Pasadena.

"These bright veins contain hydrated minerals that are different from the clay minerals in the surrounding rock matrix," Rice said in a statement.

The findings presented from the Canadian-made Alpha Particle X-ray Spectrometer (APXS) on Curiosity's arm indicate that the wet environmental processes that produced clay at Yellowknife Bay did so without much change in the overall mix of chemical elements present.

The elemental composition of the outcrop Curiosity drilled into matches the composition of basalt. For example, it has basalt-like proportions of silicon, aluminium, magnesium and iron.

Basalt is the most common rock type on Mars. It is igneous, but it is also thought to be the parent material for sedimentary rocks Curiosity has examined.

The sedimentary rocks at Yellowknife Bay likely formed when original basaltic rocks were broken into fragments, transported, re-deposited as sedimentary particles, and mineralogically altered by exposure to water.