Jon D. Pelletier of The University of Arizona in Tucson said topographic data from the High Resolution Imaging Science Experiment (HiRISE) camera on NASA's Mars Reconnaissance Orbiter shows that a bright streak in a gully on the side of a crater is probably not water.
Pelletier, an associate professor of geosciences, said the researchers applied the basic physics of how fluid flows under the conditions on Mars to determine how a flow of pure liquid water would look on the HiRISE images vs. how an avalanche of sand and gravel would look, the university said Friday in a release.
"The dry granular case was the winner," said Pelletier. "I was surprised. I started off thinking we were going to prove it's liquid water."
He said the research does not rule out the possibility that the images show flows of very thick mud containing about 50 percent to 60 percent sediment.
The report will be published in the March issue of Geology.