Target rock sample may be good for Curiosity, NASA says

NASA's Curiosity Mars rover completed a shallow "mini drill" test April 29, 2014, in preparation for full-depth drilling at a rock target called "Windjana."

Weeks after NASA announced that Curiosity would soon drill another rock sample -- the third since landing on the red planet in 2012 -- the team operating Curiosity plans to decide on whether to proceed in the coming days.

The third time could be the charm for Curiosity, as it continues its mission to search for evidence of possible habitable past conditions on Mars. The target slab of sandstone -- nicknamed "Windjana," after a gorge in Western Australia -- was examined over the weekend, using a wire-bristle brush to clear away dust from a patch on the rock.

"In the brushed spot, we can see that the rock is fine-grained, its true color is much grayer than the surface dust, and some portions of the rock are harder than others, creating the interesting bumpy textures," Curiosity science team member Melissa Rice, of the California Institute of Technology, Pasadena, said in a press release. "All of these traits reinforce our interest in drilling here in order understand the chemistry of the fluids that bound these grains together to form the rock."

Before the rover could drill deeply enough for a collection of rock-powder sample, the rover had to perform a so-called "mini-drill operation" on Tuesday. The rover then drilled a hole about eight-tenths of an inch deep. If the team of operators decide to continue, the rover's hammering drill will collect a powdered sample from the inside of a rock and analyze, using its laboratory instruments.

Curiosity's first two drilled samples, taken in an area near the rover's landing site -- known as Yellowknife Bay -- provided evidence of an ancient lakebed environment, which would have been favorable to microbes. If the team decides to do so, the third sample could be from the Kimberley, the rover's current location.

It is at the Kimberley -- where multiple types of rocks lie close together -- and at Mount Sharp inside Gale Crater that these solid minerals could be able to provide information about the types of organic elements available on Mars.

The Curiosity rover, originally slated to last two years, could continue to operate years longer, barring any major problems, NASA says.