Unlike on other moons, what caused the hardening of the ridges into these large designs is a big mystery, as well as why they were hardened in this particular place, director of NASA Jet Propulsion Laboratory Curiosity project scientist Ashwin Vasavada said in a NASA Jet Propulsion Laboratory update.
Curiosity, the NASA rover, has been maneuvering its way on a landscape within the Gale Crater on the lower slopes of Mount Sharp, which less resembles a hillside and more a collection of broken lattices being piled across the surface. At an orbit it is as though a web had been thrown over some pallid bedrock; at the height of the rover it is a maze of low walls and shallow depressions, some ridges rising to a height of roughly 6 feet. These are called the “boxwork” and have been observable by Mars Reconnaissance Orbiter cameras since the surface images first started reaching Earth.
The problem of engineering presents itself instantly: boxwork is no level plain, but rather a skeleton of ribs of mineral-hard materials interlaced with one another, and broken sand and fissured bedrock. NASA operations systems engineer Ashley Stroupe, in a statement by the JPL, said “it was nearly like a highway upon which the rover could drive on,” and that the rover had to repeatedly penetrate the hollows in which traction and steering are more challenging. The path finding is important since the reward of Curiosity is not a solitary photogenic ridge, but the narrative embedded within the cement that caused these patterns to be durable as the rest of the rock was being eroded by the wind.
Earth Boxwork is frequently a buried phenomenon that is discovered only at a later time: groundwater flows in a series of cracks, it deposits minerals, and mineral fillings are now as hard as the parent rock. When the softer material has been worn away, the mineralised fissures become protruded in form of ridges. The boxwork of Mount Sharp is being analyzed by this team of Curiosity as a form of a similar type of “negative fossil” evidence of water, water that remained long after the surface lakes in the Gale Crater already vanished. That time is important as Curiosity is traversing successive beds which record changing conditions: the earlier deposits are made of clay and are deposited in a wetter environment, and the later ones are made more and more of salts, which grow as the water is evaporated.
In this case, the rover is in a bed of magnesium sulfates minerals that are found in dried lands. But the boxwork in itself presupposes that, though the surface grew rougher, there was water flowing below, along fissures, and leaving mineral cementations. Curiosity has already bored and analyzed a sample belonging to a target named “Altadena” to feed powdered rock into its own laboratory to check its minerals. Those observations have been useful in determining clay minerals in the ridges, an indication of the nature of the water that used to seep here and of the conditions under which the mineral network was able to develop and to persist.
Circumstances continue to puzzle why the kind of groundwater signature would be so elevated on Mount Sharp to begin with one of the most enduring puzzles. Mission scientists have indicated that the elevation of boxwork at this height indicates a groundwater table that was previously high than expected indicating a larger or more extensive system of subsurface water. It is important in the case of astrobiology since mineral cements are able to serve as a sort of vault that entombs remnants of the ancient environments and (had there ever been any) chemical fingerprints associated with the existence of microbial habitats.
New shocks have come to the information between the ridges. Curiosity has discovered many slender and gleaming veins of calcium sulfate slicing through neighborhood bedrock, a character of mineral-saturated fluids flowing through cracks. That is quite unexpected, said Curiosity deputy project scientist Abigail Fraeman, as such veins had been widespread as the rover descended the mountain to lower on Mount Sharp, but had since been mostly lost to view as the rover penetrated the sulfate-bearing layers-until now. The team is exploiting them by returning their familiar vein networks, and the unique chemistry of the surrounding bedrock, to determine whether the boxwork story is a single episode of mineralisation or a more complicated sequence of fluid events.
Curiosity will proceed on, leaving this webbed surface to her he is to have passed over Mount Sharp with all of its sulfate history of a drying planet. They are still in the ridges, silent and geometric, showing where the ground water used to flow in invisible fissures and where a rover, by a step taken every turn, may still read what that water wrote in stone.
