Nine months since it touched down in the vast, yawning bowl of Mars’ 96-mile-wide Gale Crater, the Curiosity rover is gearing up to perform its second rock drilling and sampling exercise. The six-wheeled craft will be directed toward a spot known as “Cumberland,” about nine feet to the west of another rock which Curiosity sampled back in February. This is expected to confirm results from the first drilling, which revealed that the chemistry of a powdered sample from a rock named “John Klein” was much less oxidizing than earlier soil samples. The John Klein work also found evidence of an ancient environment favorable for microbial life—a key goal of the $2.5 billion mission.
Although Cumberland and John Klein are very similar, the former appears to have more of the erosion-resistant granules which cause surface bumps. These bumps are known as “concretions,” or clumps of minerals, which formed when water soaked the rock in Mars’ distant past. Analysis of a sample containing more material from these concretions could yield clues about the variability within the rock layer which includes both Cumberland and John Klein. Yet there is always the risk of cross-contamination with the earlier sample. “For the Cumberland sample,” said Dawn Sumner, a long-term planner for Curiosity’s science team at the University of California at Davis, “we expect to have most of that cross-contamination come from a similar rock, rather than from very different soil.”
On 8 February 2013, Curiosity began the first human-made vehicle to drill into a rock on another world, when it bored a 2.5-inch hole into the sedimentary rock, named in honor of former Mars Science Laboratory (MSL) Deputy Project Manager John Klein, who died two years ago. The location was significant—about a third of a mile west of the rover’s Bradbury Landing site, its conditions were not harshly oxidizing, acidic, or extremely salty, and offered favorable conditions for microbial life—and the drilling identified elevated levels of calcium, sulfur, and hydrogen. Also found were vein-like features and nodules, strongly suggesting that multiple periods of “wet” conditions had been involved in their formation.
After material is drilled and extracted, it is sieved and sampled by Curiosity’s Collection and Handling for In-Situ Martian Rock Analysis (CHIMRA) instrument—which screens out particles larger than about 0.006 inches—and delivered through inlet ports to the Chemistry and Mineralogy (CheMin) and Sample Analysis at Mars (SAM) analysis suite. In the days preceding the John Klein drilling task, the difficulties were apparent. “The drill hardware interacts energetically with Martian material we don’t control,” explained MSL Deputy Project Manager Richard Cook at the time. “We won’t be surprised if some steps in the process don’t go exactly as planned the first time through.”
The second drilling at the Cumberland location comes at the end of a lengthy upgrade of the rover’s software, following a four-week break, during which time the NASA control team did not send any new commands, because Mars and the Sun were positioned in such a fashion that the latter could have blocked or corrupted their transmission. Future plans after this next drilling include a drive towards the base of 18,000-foot-high Aeolis Mons (“Mount Sharp”), which sits inside Gale Crater.
Since its arrival on Mars—with the aid of a revolutionary “Sky Crane”—last August, Curiosity has made significant inroads in our understanding of the Red Planet … and has already begun to tackle the tantalizing question of whether its atmosphere and climate was once suitable for microbial life. This produced a flurry of public and media speculation in November that traces of ancient life had been found, although NASA was quick to admit that nothing conclusive had been identified. In addition to the John Klein drilling, Curiosity has also performed the first-ever X-ray diffraction analysis of the internal structure of a soil sample on another world.
Want to keep up-to-date with all things space? Be sure to “Like” AmericaSpace on Facebook and follow us on Twitter:@AmericaSpace