The rock target, called Windjana, is at the base of the Mount Remarkable butte. The previous two drillings, elsewhere in Gale crater at Yellowknife Bay, were in mudstone, and provided evidence for an ancient freshwater lake at that location. The conditions at the time would have been ideal for at least microbial life.
Interestingly, the powdered tailings created by the drill are significantly darker in this new drill hole than in the other two. It is thought, therefore, that the composition of this rock slab will be different than what was found in the mudstone. Powdered samples have already been delivered to the rover's on-board laboratory, so it is just a matter of waiting for the first results.
"The drill tailings from this rock are darker-toned and less red than we saw at the two previous drill sites," said Jim Bell of Arizona State University, Tempe. "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!" Bell is also the deputy principal investigator for Curiosity's Mast Camera (Mastcam).
The new drill hole is 0.63 inch (1.6 centimeters) in diameter and 2.6 inches (6.5 centimeters) deep. Another smaller previous test hole can be seen next to it.
Curiosity is searching for organic material preserved in the rocks. Organics can occur either abiotically (without life) or can be the remains of previously living organisms. Only very small quantities have been found so far, but rock outcrops at the base of buttes or mesas are thought to be a better place to look for them. Any old organics near or on the surface in more open places would be destroyed by the harsh ultraviolet light hitting the surface.