Seasonal Dark Streaks on Mars

What is causing these dark streaks on Mars? A leading hypothesis is flowing
-- but quickly evaporating -- water. The streaks, visible in dark brown near
the image center, appear in the Martian spring and summer but fade in the
winter months, only to reappear again the next summer. These are not the first
markings on Mars that have been interpreted as showing the effects of running
water, but they are the first to add the clue of a seasonal dependence. The above
picture, taken in May, digitally combines several images from the the HiRISE
instrument on the Mars Reconnaissance Orbiter (MRO). The image is color-enhanced
and depicts a slope inside Newton crater in a mid-southern region of Mars.
The streaks bolster evidence that water exists just below the Martian surface in
several locations, and therefore fuels speculation that Mars might harbor some
sort of water-dependent life. Future observations with robotic spacecraft orbiting
Mars, such as MRO, Mars Express, and Mars Odyssey will continue to monitor
the situation and possibly confirm -- or refute -- the exciting flowing water hypothesis.