Lava revealed to have carved some channels on Mars
Discovery weakens theory that water may have existed on the Red Planet.
Mon, Mar 15, 2010 at 05:03 PM
River valley on Mars. (Photo: NASA)
Scientists have debated for years about the source of the channels that carve through the red landscape of Mars. Some say rivers of water formed the landscape, while others say molten lava scarred it. Solving this mystery is important to the space community. The presence of abundant water on an ancient Martian landscape promotes the theory that there was once life there. But Space.com reports that a new discovery indicates that lava may have been the source of some channels.
Last week, NASA researcher Jacob Bleacher spoke before the 41st Lunar and Planetary Science Conference. He revealed a series of images that shows that lava may have created some of the Martian channels.
Channels created by water generally have fine, delicate terrain features. These are called fluvial erosions and have longed been believed to be present on Mars. But lava creates a much different landscape. Bleacher calls to mind the lava flows of Hawaii for a frame of reference. These create big, open channels. According to Bleacher, closer examination of some of the ridges on Mars show that "the channel is actually roofed over, as if it were a lava tube, and lined up along this, we see several rootless vents." Bleacher further explains to Space.com that these rootless vents are openings where lava is forced out of its tube to create small structures.
Bleacher, along with W. Brent Garry and Jim Zimbelman at the Smithsonian Institution in Washington, studied the southwest flank of Mars' Ascraeus Mons volcano, one of three volcanoes collectively known as the Tharsis Montes. Using some of the highest imaging power available, the scientists at first determined that water seemed to be the source of the channels. Islands and secondary channels indicate this. But the other ends of the channel have tubes and ridges that were indicative of lava flow. Rather than assuming one end of the channel was carved by water and the opposite end was lava, Bleacher and his team proposed the entire channel was lava formed.
Bleacher and his team compared images of Mars’ channels with lava flows on Mauna Loa on the Big Island of Hawaii. They found that many of the features caused by this epic 1859 eruption can also be found on Mars. Bleacher elaborates, "We found terraced walls on the insides of these channels, channels that go out and just disappear, channels that cut back into the main one, and vertical walls 9 meters (29 feet) high. So, right here, in something that we know was formed only by flowing lava, we found most of the features that were considered to be diagnostic of water-carved channels on Mars."
Bleacher concludes that this revelation does not rule out water on Mars. Instead, he urges the public to never underestimate how liquid rock will flow, or what it will do to a planet’s surface.
For further reading: Some Mars channels carved by lava, not water