Its tests and calibrations complete, NASA's Curiosity rover will soon switch to a long-distance mode to reach its main objective — a towering mound of layered sediments — several months from now.
Have you ever dashed off to the grocery store, planning to just grab some milk and eggs, and then you get sidetracked by all the tempting fresh fruit and bakery goodies?
That's basically the situation mission scientists for NASA's Mars Science Laboratory (MSL) find themselves in. It's been 10 months since Curiosity touched down inside Gale crater. The rover's ultimate destination is Aeolis Mons (widely known as "Mount Sharp"), a massive mound that rises 3 miles (5 km) high from the crater's broad floor. This stack of layered sediments likely holds the key to why, when, and how Mars morphed from a clement world gurgling with liquid water in its youth to the stark, frigid, and inhospitable place it is today.
But Curiosity isn't there yet — and likely won't arrive until next year. For the past six months, the rover has been poking around "Glenelg," an area no bigger than a football field with many intriguing geologic outcrops. Since Curiosity is more capable — and more complicated — than any previous interplanetary lander, its handlers have been executing a carefully paced sequence of operations to test all the instruments and mechanisms thoroughly.
Last February ground controllers commanded the craft to drill into an exposure of soft mudstone nicknamed "John Klein." A month later, after instruments had analyzed finely powdered samples of the tailings, scientists reported that this rock contains abundant smectite, a group of clay-like minerals that forms in the presence of water. Also, the presence of calcium sulfates imply that the water probably had a relatively neutral pH and was not strongly salty. It was all good news on the habitability checklist.
Last month Curiosity drilled into a second outcrop, called "Cumberland", then fired its ChemCam laser several times to analyze the powdered tailings. Everything went smoothly, though the analysis of the elements and minerals those contain is ongoing.
But no further drilling is planned before Curiosity starts rolling in earnest. In a few weeks engineers will shift gears to a distance-driving mode that covers more ground and involves fewer sightseeing stops, since the big mound's lower slopes lie about 5 miles (8 km) to the southwest.
The roving geology laboratory would have wrapped up its work in Glenelg sooner, but there were two delays. Earlier this year an electronic glitch halted science activities for about a month, and then communications were suspended for a few weeks when Mars passed very near the Sun as seen from Earth.
"The trip to the Glenelg region has been well worth it," says Joy Crisp, MSL's deputy project scientist at the Jet Propulsion Laboratory. "The science team is very pleased with the results that we've gotten."
"We don't know when we'll get to Mount Sharp," comments project manager Jim Erickson in a NASA press release issued Wednesday. "This truly is a mission of exploration." He speculates that it'll take at least 10 months to a year — and that assumes no sightseeing along the way. Yet even now the mission's scientists and engineers are compiling a list of choice spots that they'll have the rover check out in the months ahead.