NASA’s Mars rover Curiosity is poised to begin drilling on the planet’s surface for the first time following the selection of an area of flat rock containing a target-rich environment of fractures, veins and mineral concentrations.

Drilling will provide samples that will be used to obtain detailed data about the mineral and chemical composition of the rocks as part of Curiosity’s main mission to investigate whether Mars ever offered an environment suitable for life.

The target area lies within a shallow depression called “Yellowknife Bay,” which lies around 500 meters to the east of the landing site and was originally identified from orbital observations of fractured ground that cooled more slowly each night than nearby terrain.

“The orbital signal drew us here, but what we found when we arrived has been a great surprise,” says Mars Science Laboratory (MSL) Project Scientist John Grotzinger of the California Institute of Technology in Pasadena. “This area had a different type of wet environment than the streambed where we landed, maybe a few different types of wet environments.”

However, despite identifying the target area, preparations for the start of actual drilling will take another few weeks, according to mission specialists. “Drilling is the most significant engineering task we’ve done since landing,” says NASA Jet Propulsion Laboratory MSL project manager Richard Cook. “We will interact with unknown surface terrain and it’s the first time we’ve ever done that.”

Initial targets for drilling in the rock feature, named John Klein for a now-deceased deputy project manager on the Curiosity rover, include a variety of objects such as fractured rock, veins and samples with concretions, or small, spherical concentrations of minerals. As both veins and concretions are geological indicators of the precipitation of minerals from water, “this is why we selected it for drilling,” Grotzinger says. “Water went through these rocks and precipitated chemicals. It’s the first time in this mission we’ve seen something that’s not just an aqueous environment but also one which results in precipitation of minerals.”

Commenting on the potential for contamination of the mineral samples by the parts of the Teflon making up seals within the drill assembly, Cook says “we’ve done a lot of work to understand if Teflon had an impact on the engineering capabilities of the instruments as Curiosity was on its way to Mars and we concluded it would not be the case. Teflon is not a concern [from an engineering perspective].” However, Cook acknowledges there are scientific implications. “While it had a noticeable impact, [the analysis teams] thought they could work around it, essentially. Teflon is a well-characterized substance, and so although it has potential [to contaminate a sample], that’s not very likely since they know what Teflon will do.”

The presence of polytetrafluroethylene (the chemical name for Teflon) and another potential contaminant from the drill, molybdenum disulfide, will be detected and taken into account by the Curiosity’s Sample Analysis at Mars instrument, project scientists say.