Muddying the Water? Orbiter drains confidence from fluid story of Mars
By Ron Cowen
Evidence for liquid water on some parts of Mars—now or in the past—looks leakier than researchers had supposed, according to an analysis of the sharpest images ever taken of the Red Planet from orbit. But in other places, the new images bolster the case that water once flowed.
High-resolution pictures and infrared spectra recorded by NASA’s Mars Reconnaissance Orbiter (MRO) indicate that fresh, bright streaks on two steep gullies don’t signify a recent flow of water, as scientists suggested just a year ago (SN: 12/23/06, p. 416). MRO’s instruments neither detected minerals that might have been left behind as salty groundwater evaporated from those regions nor found changes in the shapes of the deposits since the gullies were last imaged 15 months ago. Such changes could have occurred if the bright deposits were frost created by an underground supply of water rushing to the frigid surface in recent years or months.