NASA’s Curiosity rover finds surprise clues to Mars’s watery past

Amongst different discoveries made by the Curiosity rover, rippled rock textures recommend lakes existed in a area of historic Mars that scientists anticipated to be drier.

When NASA’s Curiosity rover arrived on the “sulfate-bearing unit” final fall, scientists thought they’d seen the final proof that lakes as soon as coated this area of Mars. That is as a result of the rock layers right here shaped in drier settings than areas explored earlier within the mission. The realm’s sulfates—salty minerals—are thought to have been left behind when water was drying to a trickle.

So Curiosity’s group was shocked to find the mission’s clearest proof but of historic water ripples that shaped inside lakes. Billions of years in the past, waves on the floor of a shallow lake stirred up sediment on the lake backside, over time creating rippled textures left in rock.

“That is the most effective proof of water and waves that we have seen in the whole mission,” stated Ashwin Vasavada, Curiosity’s mission scientist at NASA’s Jet Propulsion Laboratory in Southern California. “We climbed by means of hundreds of toes of lake deposits and by no means noticed proof like this—and now we discovered it in a spot we anticipated to be dry.”

Layers of historical past

Since 2014, the rover has been ascending the foothills of Mount Sharp, a 3-mile-tall (5-kilometer-tall) mountain that was as soon as laced with lakes and streams that might have supplied a wealthy surroundings for microbial life, if any ever shaped on the Pink Planet.

Mount Sharp is made up of layers, with the oldest on the backside of the mountain and the youngest on the high. Because the rover ascends, it progresses alongside a Martian timeline, permitting scientists to check how Mars developed from a planet that was extra Earth-like in its historic previous, with a hotter local weather and plentiful water, to the freezing desert it’s as we speak.

Having climbed practically a half-mile above the mountain’s base, Curiosity has discovered these rippled rock textures preserved in what’s nicknamed the “Marker Band”—a skinny layer of darkish rock that stands out from the remainder of Mount Sharp. This rock layer is so laborious that Curiosity hasn’t been capable of drill a pattern from it regardless of a number of makes an attempt. It is not the primary time Mars has been unwilling to share a pattern; decrease down the mountain, on “Vera Rubin Ridge,” Curiosity needed to strive 3 times earlier than discovering a spot comfortable sufficient to drill.

Scientists can be searching for softer rock within the week forward. However even when they by no means get a pattern from this uncommon strip of rock, there are different websites they’re desperate to discover.

Martian clues

Far forward of the Marker Band, scientists can see one other clue to the historical past of Mars’s historic water in a valley named Gediz Vallis. Wind carved the valley, however a channel working by means of it that begins larger up on Mount Sharp is assumed to have been eroded by a small river. Scientists suspect moist landslides additionally occurred right here, sending car-size boulders and particles to the underside of the valley.

As a result of the ensuing particles pile sits on high of all the opposite layers within the valley, it is clearly one of many youngest options on Mount Sharp. Curiosity obtained a glimpse of this particles at Gediz Vallis Ridge twice final yr however may solely survey it from a distance. The rover group hopes to have one other probability to view it later this yr.

Another clue throughout the Marker Band that has fascinated the group is an uncommon rock texture doubtless attributable to some kind of common cycle within the climate or local weather, resembling dust storms. Not removed from the rippled textures are rocks product of layers which might be common of their spacing and thickness. This type of rhythmic sample in rock layers on Earth usually stems from atmospheric occasions taking place at periodic intervals. It is doable the rhythmic patterns in these Martian rocks resulted from related occasions, hinting at modifications within the Pink Planet’s historic local weather.

“The wave ripples, particles flows, and rhythmic layers all inform us that the story of wet-to-dry on Mars wasn’t easy,” Vasavada stated. “Mars’s historic climate had a beautiful complexity to it, very like Earth’s.”