NASA's Mars rover Curiosity is on the road again, driving toward a flat rock with pale veins that the team says could help shed light on Mars' watery past.
In the next few days, if all goes well, it'll be the first rock to be drilled by the rover for a sample. It's in an area where Curiosity's cameras have revealed a range of unexpected features, including veins, nodules, cross-bedded layering, a lustrous pebble embedded in sandstone and possibly some holes in the ground.
"Drilling into a rock to collect a sample will be this mission's most challenging activity since the landing. It has never been done on Mars," says Mars Science Laboratory project manager Richard Cook.
"The drill hardware interacts energetically with Martian material we don't control. We won't be surprised if some steps in the process don't go exactly as planned the first time through."
Curiosity will first collect powdered samples from inside the rock and use them to scrub the drill. It will then drill and ingest more samples from this rock, which it will analyze for information about its mineral and chemical composition.
The rock chosen for drilling is on flat-lying bedrock within a shallow depression called Yellowknife Bay. The terrain here's different from that of the landing site, a dry streambed about a third of a mile. The spot was picked because orbital observations showed fractured ground that cools more slowly each night than nearby terrain types do.
"The orbital signal drew us here, but what we found when we arrived has been a great surprise," says Mars Science Laboratory project scientist John Grotzingera. "This area had a different type of wet environment than the streambed where we landed, maybe a few different types of wet environments."
One interesting feature of the rock is its light-toned veins, in which Curiosity's laser-pulsing Chemistry and Camera instrument hash found elevated levels of calcium, sulfur and hydrogen.
"These veins are likely composed of hydrated calcium sulfate, such as bassinite or gypsum," says ChemCam team member Nicolas Mangolde. "On Earth, forming veins like these requires water circulating in fractures."