NASA's Curiosity rover has completed its drilling assignment with the "Windjana" sandstone slab on Mars' surface and plans to keep a powdered sample for examination.

According to BBC News, the samples could give NASA insight to the chemical composition that lies underneath the Gale Crater's surface. This sample could then help NASA learn more about the environmental history of the area.

The space agency will now send Curiosity back on track to reach Mount Sharp, the rover's ultimate science goal on Mars. The mountain, which lies in the middle of the Gale Crater, Curiosity's landing site more than a year ago, is believed to hold even more environmental clues than the rover has already uncovered.

"We're most interested to find clues as to the aqueous geochemistry which resulted in cementation of the sedimentary rocks," John Grotzinger, a project scientist with NASA's Jet Propulsion Laboratory (JPL) in Pasadena, Calif., told BBC News. "These have all turned out to be much harder than we expected, and if we could get a sense of their mineralogy and chemistry, we might better understand the composition and history of groundwater in the region - also an important type of potentially habitable environment."

Before Curiosity actually extracts the sample, scientists on Earth must determine if it has the right materials to exist in the rover's storage components. If approved, Curiosity will take out "a pinch" of sandstone dust.

"The drill tailings from this rock are darker-toned and less red than we saw at the two previous drill sites," Jim Bell, Curiosity's Mast Camera deputy principal investigator, of Arizona State University, said in a press release. "This suggests that the detailed chemical and mineral analysis that will be coming from Curiosity's other instruments could reveal different materials than we've seen before. We can't wait to find out!"

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