Rover hits 'a jackpot' in quest for signs of water on Mars
White veins of minerals coursing through rocks on the floor of Mars' Gale Crater are providing some of the strongest evidence yet that the rover Curiosity's landing site once was a wetter, warmer place.
The details are still fuzzy. But the composition of the minerals indicate that they precipitated out of water flowing through fissures in the rock, while large grains within the rocks themselves are rounded, suggesting that water might have dulled their sharp edges.
Yellowknife Bay, the rocky expanse Curiosity inhabits, “is literally shot through with these fractures,” said John Grotzinger, a geologist at the California Institute of Technology in Pasadena., Calif., and the mission's chief scientist.
It features abundant, berry-shaped spherules that scientists said are sedimentary concretions formed in and worked over by water.
All together, “basically these rocks were saturated with water,” Grotzinger explained during a briefing this month outlining the rover's latest exploits.
Yellowknife Bay represents “a jackpot unit,” he said. Initially, researchers thought they might have to drive Curiosity up on the shoulders of Mt. Sharp, a towering summit in the middle of the crater, to find such a trove.
Curiosity, a one-ton geochemistry lab on wheels, landed on Mars in August. Its goal is to determine whether the crater at one time could have been hospitable for simple forms of organic life.
A layered, rock outcrop the team has named the Shaler Unit indicates a stream flowed through the area, shifting small sediment dunes on the stream bed in ways that formed the layers. The composition of the white minerals in rock veins is consistent with calcium sulfate, plus a fair bit of hydrogen. The relatively high levels of hydrogen suggest the minerals precipitated out of water flowing through the fissures.
The mineral-filled fissures looked similar to those found in rocks in the Sahara.