NASA’s Curiosity rover is on an ambitious trek across the bottom of Gale Crater on Mars. It has many months to go until it reaches its ultimate goal – the geologically vibrant and elucidating lower layers of Mount Sharp. Curiosity recently reached the first waypoint on its sojourn towards the mountain.
Waypoint 1 is the first of five waypoints along Curiosity’s 5.3-mile journey to Mount Sharp; the five waypoints were mapped by the Mars Reconnaissance Orbiter, and are in a region between an area known as “Glenelg”, where Curiosity spent the first half of 2013, and the lower slopes of Mount Sharp. With a westward drive of 75 feet on September 22, Curiosity departed Waypoint 1, but not before training its instruments on an intriguing rock outcrop.
The outcrop in question has been nicknamed “Darwin”, and Curiosity’s first photographs of the rocks, taken from a distance, showed that it was likely a conglomerate, a type of rock composed of a mixture of smaller grains, such as sand, and larger grains, such as gravel and pebbles. Conglomerates form when grains are transported and deposited by flowing water.
Once Curiosity arrived at the “Darwin” outcrop, the rover used two instruments mounted on its robotic arm: the Alpha Particle X-ray Spectrometer, which characterizes the chemical composition of a sample, and the Mars Hand Lens Imager, which reveals the textures, shapes, and colors of rocks. Curiosity used these devices to examine eight targets on September 19 and 20.
Curiosity’s investigation of “Darwin” revealed a pebbly sandstone with younger granular veins cutting through it, indicating that water once flowed through the location and deposited the sediment that eventually became the rocks of the “Darwin” outcrop. Curiosity’s science team will combine data from “Darwin” and the next four waypoints to connect the geological dots between the “Glenelg” area and the base of Mount Sharp. Curiosity’s most important discovery in “Glenelg” came at a site known as “Yellowknife Bay”, which analysis revealed to be an ancient lakebed that was once hospitable for microbial life.
“We want to understand the history of water in Gale Crater,” explained Dawn Sumner, a member of the Curiosity science team at the University of California, Davis, in a NASA press release. “Did the water flow that deposited the pebbly sandstone at Waypoint 1 occur at about the same time as the water flow at Yellowknife Bay? If the same fluid flow produced the veins here and the veins at Yellowknife Bay, you would expect the veins to have the same composition. We see that the veins are different, so we know the history is complicated. We use these observations to piece together the long-term history.”