You’ve seen it looming in the background of so many photo for more than two years. Finally, we’re there. NASA’s Curiosity rover rolled up to Mount Sharp in Gale Crater. With a peak 2.7 miles (4.4 km) high, Mt. Sharp stands more than a half mile higher than Mt. Ranier in Washington.
The mountain is built of layer upon layer of stratified rocks deposited by water and wind after the massive impact that excavated Gale Crater more than 3 billion years ago. From orbit, scientists have detected clays in some of the layers, an indication that water flowed here in the past.
As Curiosity begins its trek up the mountain’s slope, it will first trundle across the Pahrump Hills, a region of layered rocks that’s part of the Murray Formation. At some point within this broad expanse of soft rock, the rover will drill a sample and analyze it before continuing upslope. Several miles later, it will encounter a ridge of hematite-bearing rocks. Hematite is a gray version of iron oxide (rust) that precipitates in hot springs or in pools of standing water.
An intriguing layer of clay-bearing rocks that lies further upslope and offers the best opportunity of finding organic, carbon-containing minerals. A region containing sulfates, found earlier by Curiosity in the form of gypsum (calcium sulfate) extends beyond the clay layer higher yet. Gypsum is the same material used to make drywall back on Earth.
Scientists hope to study the transition between the two. Sulfates point to a time when the ancient, more watery Mars evolved from a wet, fresh-water climate to a drier one with acidic waters that favored the formation of sulfates instead of clays.
We all hope Curiosity’s wheels, poked and torn by sharp rocks, will be up for the long journey ahead.
“In late 2013, the rover team realized a region of Martian terrain littered with sharp, embedded rocks was poking holes in four of the rover’s six wheels. This damage accelerated the rate of wear and tear beyond that for which the rover team had planned. The team altered the rover’s route to a milder terrain, bringing the rover farther south, toward the base of Mount Sharp”, according to NASA.
Curiosity has already fulfilled its initial goal of determining whether Mars ever offered an environment suitable for the formation and development of early life. Clay-bearing rocks in the Yellowknife Bay site revealed an ancient lakebed that once lapped with fresh water and contained the key elemental ingredients for life - sulfur, nitrogen, hydrogen, oxygen, phosphorus and carbon – as well as a sulfate energy source potential life could use to thrive.