Slick sands in Hidden Valley have delayed the Mars rover Curiosity's planned ascent of a nearby mountain. With suboptimal traction between the valley floor and the rover's tires, engineers are being forced to consider alternative routes

A little more than a year ago, Curiosity headed out from Yellowknife Bay with its sights set on Aeolis Mons, also known as Mount Sharp, a major Red Planet peak that rises from the center of Gale Crater. Mount Sharp has been Curiosity's most coveted destination since even before it landed in 2012. But the rover has skidded into a bit of slippery situation, thwarting its preferred route to the mountain's base.

"We need to gain a better understanding of the interaction between the wheels and Martian sand ripples, and Hidden Valley is not a good location for experimenting," Curiosity Project Manager Jim Erickson said in a news release.

Since Curiosity left Yellowknife Bay, its traversed more than five miles, stopping along the way to drill rock and collect samples. It has two miles left to Mount Sharp's base, but having reversed course out Hidden Valley's slippery sand flats it will now have to find an alternative passage.

Before Curiosity heads off to ascend the foothills of Mount Sharp, NASA scientists want the rover to drill a rock known as "Bonanza King." The slab lies at the northeastern end of Hidden Valley, not far from the rover's current location. Researchers say it could offer context clues as to the geological history and evolution of Gale Crater and the Red Planet.

The valley is roughly the length of a football field, but the slippery sands look like they will force Curiosity to make its way to the mountain by driving north and around the valley to the other side. The pit stop to drill Bonanza King -- its fourth drilling specimen of the mission -- will give NASA engineers time to chart out a new course to Mount Sharp.

"This rock has an appearance quite different from the sandstones we've been driving through for several months," Curiosity project deputy scientist Ashwin Vasavada said. "The landscape is changing, and that's worth checking out."