Once again the world is abuzz about water on Mars. Sure, we already
that there's a plentiful supply of water ice at the Red Planet's poles; we
that approximately 2 percent of the Martian regolith (at Mars rover Curiosity's location in any case) is composed of water; we also
that ancient Mars was a wet world, possessing rivers, lakes and even seas -- according to the sedimentary rock and minerals that could have only been formed in an abundance of liquid water.
But now NASA has found pretty solid evidence that the seasonal short-lived, dark channels seen on steep slopes are formed by salty liquid water gushing over the apparently barren Mars surface
MORE: Mystery Solved: Water DOES Flow on Mars
Shown here is a 3-D map of the slopes of Hale Crater which is based on observations by the High-Resolution Imaging Science Experiment (HiRISE) camera on board NASA's Mars Reconnaissance Orbiter. The dark channels running down the slopes are known as "recurring slope lineae," and they could be one of the biggest hints yet that some form of basic, yet extreme, microbe may use that water as a means to eke out an existence just below the surface.