spacetoday.net: Evidence for flowing water spotted on Mars

Posted: Fri, Aug 5, 2011, 10:11 AM ET (1411 GMT)
Martian streaks possibly created by water (NASA/JPL)

Dark streaks that form seasonally within a Martian crater could have been created by flowing, salty water, scientists announced Thursday. The dark streaks, no more than five meters across but hundreds of meters long, stretch down some Martian slopes during local spring summer, fade away in the winter, and reappear the following spring. Scientist speculate that the streaks are caused by flows of salty water, whose freezing point is lowered enough to allow it to flow as a liquid on the surface for brief periods during the warmest parts of the Martian year. The dark streaks are not dark because they're wet, but likely because the flowing water rearranged grain patterns in the Martial regolith to make it appear darker. Scientists have not directly observed liquid water, they emphasized. Scientists found the streaks in images taken by a camera on the Mars Reconnaissance Orbiter spacecraft, and their results appear in the latest issue of the journal Science.