Evidence of liquid flowing water on Mars?

TUCSON, Aug. 4 (UPI) -- A NASA probe orbiting Mars has captured images suggesting the possibility of flowing water on the red planet during its warmest months, the space agency says.

In observations recorded by the Mars Reconnaissance Orbiter, dark, finger-like features appear and extend down some Martian slopes during the planet's late spring through summer, fade in winter, and the return during the next spring, a NASA release said Thursday.

These seasonal changes have been seen on several steep slopes in the middle latitudes of Mars' southern hemisphere, scientists say.

"The best explanation for these observations so far is the flow of briny water," Alfred McEwen of the University of Arizona says.

McEwen is the principal investigator for the orbiter's High Resolution Imaging Science Experiment.

Flows of liquid brine fit the features' characteristics since saltiness lowers the freezing temperature of water while pure water would freeze at the observed temperatures.

The observations are the closest scientists have come to finding evidence of liquid water on the surface of Mars today, although frozen water has been detected near the surface in many middle to high-latitude regions of the planet, NASA says.