The Curiosity rover on Mars has drilled into the Windjana sandstone, in its latest investigations of the red planet. This is the third time the drill has excavated a sample of the Martian crust for analysis.

Curiosity is a car-sized rover, launched to Mars in 2011, on a mission to explore the alien world for signs of water, past or present. 

Before now, the rover drilled into two rocks since landing, and both of those were revealed have been created from ancient mud. These formations, dubbed John Klein and Cumberland, provided evidence of an seabed, long dried up in the harsh Martian atmosphere. 

Windjana is believed to be made from sandstone, and was named after a gorge in western Australia. 

NASA decided Windjana should be the third rock formation to be drilled by Curiosity, after analysis by other instruments. The space agency examined the rock using a camera and X-ray spectrometer pair on the craft, called ChemCam. The process involved brushing the surface, and shooting the outcrop with pulses from a laser. This allowed researchers to gather information about the chemical composition of the surface of rocks. Drilling into Windjana provides astronomers and geologists a chance to examine material within the rock. 

"Stay on target! Preparing to drill this sandstone on Mars," mission managers tweeted for the rover just before the sample was taken. 

The sample is being closely scrutinized by the laboratory on-board the interplanetary vehicle. NASA managers hope that material from Windjana will show the composition of the binding chemical in the feature. 

"We want to learn more about the wet process that turned sand deposits into sandstone here. What was the composition of the fluids that bound the grains together? That aqueous chemistry is part of the habitability story we're investigating," John Grotzinger,  Curiosity project scientist, said. 

Curiosity arrived at the Kimberley Waypoint, a region scientists have been wanting to examine, at the beginning of April. Since that time, mission planners have been searching for a geologically-promising place to drill. 

After drilling, samples from Windjana were hammered into dust, and sent through a filter. Material from the alien world is being examined by two on-board experiments, CheMin and SAM. 

The development of mesas around Gale Crater, the landing location of Curiosity, could be studied by understanding why some sandstone features are more resistant to wear than others. It could also explain the formation of Mount Sharp in Gale Crater. 

Since landing in August 2012, Curiosity has traveled 3.8 miles, and taken 143,000 images. The rover is headed to Mount Sharp, 3.4 miles away.