San Diego ? NASA scientists announced Wednesday that they had found evidence that water still flows over the surface of Mars – sporadic gushers that increase the possibility that the Red Planet could harbor some form of life.

Using images obtained by the Mars Global Surveyor spacecraft, the researchers concluded that geologic changes in the shapes and sizes of gullies cut into the walls of two Martian craters were likely made by flowing water.

The team looked at two sets of images taken several years apart. In both cases, the second set of images revealed a light-colored substance several hundred yards long that had not been there before, indicating that something had erupted from the ground and apparently sloshed toward the bottom of the basin.

NASA’s two rovers, Spirit and Opportunity, which are on the surface of the planet, found evidence that water covered large areas of Mars billions of years ago.

“Today, we’re talking about liquid water being present on Mars right now,” said Ken Edgett, a staff scientist at Malin Space Sciences in San Diego, which built the camera that took the pictures released Wednesday.

“You have all heard of a smoking gun,” he said. “This a squirting gun.”

This combination of photos released by NASA show two views of a crater in the Centauri Montes region on Mars taken by NASA's Mars Global Surveyor. The image on the right, taken in 2005, shows an area with changes to the surface, suggesting that water occasionally flows on the frigid surface of Mars, raising the possibility that the Red Planet is hospitable to life. The image on the left shows the same view of that crater taken in 1999.

The findings, to be published in the journal Science, pose more issues for scientists to grapple with. “The big questions are: how does this happen? And does it point to a habitat for life?” said Michael Meyer, lead scientist for NASA’s Mars Exploration Program.

The answers will not come soon. The two rovers, which could investigate further, are both hundreds of miles away from the gullies described Wednesday.

Still, the discovery, if confirmed, would give the search for extraterrestrial life a new focus.

“Liquid water is one of only three things required by all life on Earth,” the Planetary Society, a Pasadena-based organization of space advocates, said in a statement.

“If there is liquid water on Mars, that makes it even more compelling to search for life on Mars.”

In another major finding, members of the science team said they found 20 new impact craters, ranging from 7 feet to 486 feet across, in other images from Global Surveyor. The scientists said the number of new craters indicated impacts from meteors could be a hazard if astronauts tried to establish a base on the planet.