Curiosity rover has done it again – found even more evidence for soaking, seeping, swirling waters on Mars. We’ve seen earlier images of water-rolled pebbles and sedimentary outcrops, but this week NASA shared a new set of photos from the Yellowknife Bay site showing alternating, thin layers of rock that could only have formed in a stream bed. Other pictures show mineral veins deposited by flowing water in rock fractures. What’s remarkable it how similar these rocks look to their counterparts on Earth.
Scientists have been studying Yellowknife through Curiosity’s eyes looking for an ideal spot to test the rover’s drill for the first time. If engineers deem it safe, the rover will inch up to “John Klein”, a flat-lying expanse of bedrock laced with pale mineral veins, and fire up its drill sometime in the next few days. The location is named after former Mars Science Laboratory deputy project manager John W. Klein who died in 2011.
The first powdered rock samples will be used to scrub the drill clean of any earthly contamination. Later samples will be fed into Curiosity’s miniature chem lab to analyze the rock’s mineral and chemical makeup. Thanks to a zap from the rover’s ChemCam laser, we already know one of the veins contains high levels of calcium, sulfur and hydrogen, likely from the mineral calcium sulfate, better known as gypsum.
Not only has the robot returned photos of cross-bedded outcrops (layers of sediments deposited by rivers) and mineral veins, but using the closeup camera, scientists have found grains of sandstone the size of “peppercorns” in other rock formations nearby.
“Still others are siltstone, with grains finer than powdered sugar. These differ significantly from pebbly conglomerate rocks in the landing area,” according to the NASA release. Siltstones were originally layers of mud that were later compressed into rock by geological forces.
All these signs point to a much wetter past on the Red Planet. Pouring over the new pictures, it doesn’t take much imagination to envision the floor of Gale Crater crossed by streams and dotted with small lakes. For water to be stable on the surface of Mars long enough to build the rocks we’re now finding, the planet must have had a much thicker atmosphere and warmer temperatures in the past. A denser atmosphere provides pressure needed to prevent water from boiling away.
Transport yourself to a remote time when the brown Martian sky was blue and the air almost humid. At your feet a stream swirls along, carrying away tiny pebbles and grains of sand. While oxygen may only have been present in trace amounts in the ancient Martian air, you could listen to the sound of running water and maybe even hear one of Mars’ many volcanoes rumbling in the distance. Tell me this wasn’t a world ripe for microscopic life.