Before Mars Rover Curiosity can begin its third-ever drilling mission into the Martian surface, some smaller “test drills” were in order. Drilling into the sand stone area known as “Windjana,” the prognosis looks good: Curiosity is now just days away from the real-deal drilling mission.

Though the previous two drilling sites bored into mudstone, Windjana’s sand stone is a first for curiosity. Upon uncovering the area with a wire brush, operators noted that the uncovered bedrock was a very different color than the traditionally red surface.

“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,” said Curiosity science team member Melissa Rice of the California Institute of Technology, Pasadena. “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.”

The mudstone slabs explored earlier suggested the presence of an ancient lake bed, which itself suggests the area may have been hospitable biological organisms. Specifically, the chemical makeup of the rock leads scientists to believe the site may have once hosted microbial life.

NASA isn’t sure what they expect to find as Curiosity bores into Windjana. Once it begins exploring with the primary drill, it will extract powdered rock and sediment and transfer it to on-board laboratory equipment for analysis.

NASA’s Mars Science Laboratory Project is using Curiosity to assess ancient habitable environments and major changes in Martian environmental conditions. NASA’s Jet Propulsion Laboratory, a division of Caltech, built the rover and manages the project for NASA’s Science Mission Directorate in Washington.

For more information on Curiosity, click here.