LOS ANGELES -- The face of Mars is dotted with a maze of channels, pointing to possible ancient megaflood episodes.

Now scientists peering below the surface have uncovered the first evidence of underground channels apparently created by flooding -- a finding that's expected to further illuminate the role of water in Mars' history.


Besides the contributions from rovers and landers, "Our view of the red planet has largely been restricted to looking at the surface" from orbiting spacecraft, said lead researcher Gareth Morgan, a planetary scientist at the Smithsonian Institution.




The latest 3-D maps, painstakingly pieced together from radar data collected by numerous spacecraft passes, have already changed scientists' notions: The channels are deeper than expected, a sign that flooding was more extensive than generally believed.


Brown University Mars expert John Mustard called the new work "totally cool and significant."

"It shows a completely new dimension for considering the evolution of Mars," Mustard, who was not part of the study, said in an email.