On Mars, CuriosityCuriosity getting ready to hit the road again. For several months the rover has been surveying the site called Gediz Vallis, which scientists assume to be the bed of an ancient river. Since last March, Curiosity has been exploring this ancient channel in the hope of finding evidence that liquid water did indeed flow into this region of Gale crater, several billion years ago. This site is also a unique opportunity to observe blocks of rock originating from a higher area of the crater, which unfortunately the small rover will never reach.
Gediz Vallis was indeed an ancient channel with at least temporary water flow
The data collected over the months by the rover suggest that this channel was the site of hydrological activity. The areas strewn with debris and blocks indicate that these rocks were transported during violent episodes, which can perhaps be compared to is madeis made torrential torrents which sometimes flow down the slopes of our mountains during episodes of strong precipitationprecipitation. The researchers thus discovered numerous small geological clues which suggest that these rocks were indeed in contact with liquid water. A confirmation which fuels the hope of finding traces of Martian life.
Pure sulfur discovered inadvertently
These, however, are not the only interesting discoveries that Curiosity has made in Gediz Vallis. On May 30, the rover inadvertently rolled over a stone, reducing it to pieces. And what this debris revealed made scientists jump. Curiosity's cameras have indeed relayed images of yellowish crystals under the crustcrust red and weathered from the fragmented block. A typical signature that geologistsgeologists of the mission were immediately recognized as being sulfur crystals. This is the first time that such a discovery has been made on Mars.
Certainly, before its arrival in Gediz Valllis, Curiosity explored a region rich in sulfates, mineralsminerals containing sulfur and which are formed by evaporation of a water reservoir saturated with this type of salt. In Gediz Vallis, however, it is pure sulfur that the rover discovered.
A major find, because this mineralmineral only forms under very specific conditions… which scientists have not yet managed to correlate with Gediz Vallis. Usually, such sulfur crystals are only found in volcanic environments or at the level of hot springshot springs.
By observing the landscape, it also became clear that this block of sulfur was in no way an isolated element. The researchers in fact realized that Curiosity was in the middle of a field made up of many blocks of the same nature.
On the way to a strange terrain that resembles a spider's web
As researchers ponder the origin of this vast sulfur field in this ancient channel, Curiosity now prepares to continue its ascent. But before setting off again, the rover captured an impressive 360° panorama of Gediz Vallis.
The Curiosity rover leaves the Gediz Vallis channel (360 View). © NASA Jet Propulsion Laboratory
Curiosity's next step is already known. By following the western edge of the channel, the rover should arrive on a very particular terrain, which looks, seen from space, like a spider's web extending over 10 to 20 kilometers. This terrain which still promises us incredible images is supposed to have been formed during the last period when water was present on the surface in this region.
By infiltrating the fractures in the subsoil, the water would have transported minerals which would then have precipitated and crystallized in this network of fractures. The action of ventvent over several billion years would then have gradually eroded the loose materials, revealing this network of cemented fractures in relief. A scenario that Curiosity will of course have to confirm in the coming months!
