NASA scientists believe they've discovered flowing water on Mars which may have the ability to sustain living organisms. In the middle latitudes of the planet's southern hemisphere, water appears to flow off the edges of craters. Dark, finger-like features appear to extend down some Martian slopes during late spring through summer, before fading in winter and returning the following spring.

An image combining orbital imagery with 3-D modeling shows flows that appear in spring and summer on a slope inside Mars' Newton crater. Note the dark streaks near the bottom of the picture.

Repeated observations have tracked the seasonal changes in these recurring features on several steep slopes. The water is thought to be salty and therefore highly resistant to freezing at normal mid-latitude Martian temperatures. While scientists have had evidence of water on Mars for years, the previous general conclusion was that it was all frozen. This is the first time there is evidence that the water is occasionally flowing.