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    NASA scientists searching for clues of “ancient water” on Mars now feel they have photographic evidence of recent water flow in some of the gullies （冲沟）that lace the planet’s surface.

    The changing appearance of gullies on Mars over the last seven years suggests that liquid water flowed recently on the Red Planet and may still seep out in brief bursts, researchers said Wednesday.

    New images of known gullies on Mars show evidence of new flows and deposits, pointing to explosive events in which some form of water burst from crater（弹坑） walls and ran down their slopes and support what researchers call “the squirting gun” theory.

    “We’ve had this story of ancient water on Mars,” researcher Kenneth Edgett, who participated in the Mars gully study, said during a news briefing at NASA’s Washington headquarters. “Today we’re talking about liquid water that is present on Mars right now.”

    Edgett and colleagues utilized images from NASA’s Mars Global Survivor to study regions earlier this year where gullies, depressionlike landforms on the Red Planet’s surface, were found in 2000.