real6
03-03-2008, 09:15 PM
http://dsc.discovery.com/news/2008/03/03/mars-water-gullies.html
March 3, 2008 -- With great excitement, scientists in 2006 unveiled photographs of recently carved gullies on Mars, believing that a burst of underground water may have left its mark.
Not so, say researchers with the University of Arizona, who have been using topographical data derived from new images of Mars and running them through computer models.
Turns out the gullies bear more similarity to channels carved from dry granular debris, such as sand or gravel, said Jon Pelletier, a lead author of a paper on the findings appearing in this month's issue of Geology.
"It rules out pure liquid water," Pelletier said.
In December 2006, Michael Malin, with San Diego-based Malin Space Science Systems, and colleagues published an article in Science theorizing that bright streaks found in two Martian gullies which appeared since 1999 "suggest that liquid water flowed on the surface of Mars in the past decade."
The images, taken by Mars Global Surveyor in 2006, showed an area of Mars that had changed since the spacecraft's first photographs in 1999. The new research is based on imagery from NASA's new sharp-eyed Mars Reconnaissance Orbiter.
"I started off thinking we were going to prove it's liquid water," Pelletier said. "I was surprised."
NASA has embarked on a science strategy of finding where and when water flowed on Mars, as liquid water is believed to be key to the development of life.
In May, scientists are expecting to get their first direct samples of Martian water when the Phoenix probe lands near the planet's north pole and drills down into the frozen soil in an attempt to reach underground ice.
Pelletier and his colleagues designed computer models that resembled how fluids would flow on Mars, then compared the results with stereoscopic imagery generated by Mars Reconnaissance Orbiter.
"We hoped to rule out the dry flow model -- but that didn't happen," said Alfred McEwen, the lead scientist for MRO's camera.
The research doesn't rule out the possibility that the gullies were carved by a thick, grainy mud with the consistency of molasses or hot lava.
"There are other ways of getting deposits that look just like this one, that do not require water," Pelletier said.
Followup studies of bright deposits on other Martian slopes are underway.
March 3, 2008 -- With great excitement, scientists in 2006 unveiled photographs of recently carved gullies on Mars, believing that a burst of underground water may have left its mark.
Not so, say researchers with the University of Arizona, who have been using topographical data derived from new images of Mars and running them through computer models.
Turns out the gullies bear more similarity to channels carved from dry granular debris, such as sand or gravel, said Jon Pelletier, a lead author of a paper on the findings appearing in this month's issue of Geology.
"It rules out pure liquid water," Pelletier said.
In December 2006, Michael Malin, with San Diego-based Malin Space Science Systems, and colleagues published an article in Science theorizing that bright streaks found in two Martian gullies which appeared since 1999 "suggest that liquid water flowed on the surface of Mars in the past decade."
The images, taken by Mars Global Surveyor in 2006, showed an area of Mars that had changed since the spacecraft's first photographs in 1999. The new research is based on imagery from NASA's new sharp-eyed Mars Reconnaissance Orbiter.
"I started off thinking we were going to prove it's liquid water," Pelletier said. "I was surprised."
NASA has embarked on a science strategy of finding where and when water flowed on Mars, as liquid water is believed to be key to the development of life.
In May, scientists are expecting to get their first direct samples of Martian water when the Phoenix probe lands near the planet's north pole and drills down into the frozen soil in an attempt to reach underground ice.
Pelletier and his colleagues designed computer models that resembled how fluids would flow on Mars, then compared the results with stereoscopic imagery generated by Mars Reconnaissance Orbiter.
"We hoped to rule out the dry flow model -- but that didn't happen," said Alfred McEwen, the lead scientist for MRO's camera.
The research doesn't rule out the possibility that the gullies were carved by a thick, grainy mud with the consistency of molasses or hot lava.
"There are other ways of getting deposits that look just like this one, that do not require water," Pelletier said.
Followup studies of bright deposits on other Martian slopes are underway.