Water once existed on Mars

[Avinash]

On March, 2004 NASA scientists presented evidence that some rocks at Opportunity's landing site on Mars were once soaked in liquid water.

They provided the evidence based on the study of the texture and the chemistry of the rocks.

 

Here are some of the clues that water formerly pervaded these rocks:

 

(1) The rover's alpha particle X-ray spectrometer found lots of sulfur in the outcrop. Related clues from that instrument and the miniature thermal emission spectrometer suggest the sulfur is in the form of sulfate salts (similar to Epsom salts). On Earth, rocks containing so much salt either formed in water or, after formation, were soaked in water a long time.

 

(2) The rover's Moessbauer spectrometer detected jarosite, a hydrated iron sulfate mineral that could result from the target rock spending time in an acidic lake or acidic hot springs environment.

 

(3) Pictures from Opportunity's panoramic camera and microscopic imager show many thin, flat holes in an outcrop rock selected for close-up examination. These holes match the distinctive appearance of Earth-rock holes that form where crystals of salt minerals grow inside rocks that sit in briny water then disappear by eroding or dissolving.

 

(4) The cameras have revealed spheres embedded in outcrop rocks. These spheres are not concentrated at particular layers within the rock, as they would be if they originated outside the rock and were deposited onto accumulating layers while the rock was forming. Instead, the spheres are scattered. This means they are probably what geologists call "concretions" that formed from accumulation of minerals coming out of solution inside a porous, water-soaked rock.

 

(5) Some of the spherules in pictures from the microscope appear to have stripes that correspond to layering of the matrix rock around them. This would be consistent with the interpretation that the spheres are concretions that formed inside a wet rock.