PASADENA, Calif. -- NASA's Mars Reconnaissance Orbiter has provided images allowing scientists for the first time to create a 3-D reconstruction of ancient water channels below the Martian surface.Google Image Search: Channeled Scalands, which has nice pix of this geological feature. I provided the links to prevent this from being photo-heavy....and to evade the effort to make it photo-heavy. Please go see them.The spacecraft took numerous images during the past few years that showed channels attributed to catastrophic flooding in the last 500 million years. During this period, Mars had been otherwise considered cold and dry. These channels are essential to understanding the extent to which recent hydrologic activity prevailed during such arid conditions. They also help scientists determine whether the floods could have induced episodes of climate change.
The estimated size of the flooding appears to be comparable to the ancient mega-flood that created the Channeled Scablands in the Pacific Northwest region of the United States, in eastern Washington.
Outflow channels on Mars are interpreted as the product of gigantic floods due to the catastrophic eruption of groundwater that may also have initiated episodes of climate change. Marte Vallis, the largest of the young martian outflow channels (<500 Ma), is embayed by lava flows that hinder detailed studies and comparisons with older channel systems. Understanding Marte Vallis is essential to our assessment of recent Mars hydrologic activity during a period otherwise considered to be cold and dry. Using the SHARAD sounding radar, we present a three-dimensional (3D) reconstruction of buried channels on Mars and provide estimates of paleo-hydrologic parameters. Our work shows that Cerberus Fossae provided the waters that carved Marte Vallis, and extended an additional 180 kilometers to the east prior to the emplacement of the younger lava flows. We identify two stages of channel incision and determine that channel depths were more than twice that of previous estimates.More from the NASA page
The channels lie in Elysium Planitia, an expanse of plains along the Martian equator and the youngest volcanic region on the planet. Extensive volcanism throughout the last several hundred million years covered most of the surface of Elysium Planitia, and this buried evidence of Mars' older geologic history, including the source and most of the length of the 620-mile-long (1000-kilometer-long) Marte Vallis channel system. To probe the length, width and depth of these underground channels, the researchers used the Mars Reconnaissance Orbiter's Shallow Radar (SHARAD).I am most interested in the fact this 'catastrophic flooding' was occurring within the past 500 million years as opposed to being remnants of processes more than 2 billion years old.
Marte Vallis' morphology is similar to more ancient channel systems on Mars, especially those of the Chryse basin. Many scientists think the Chryse channels likely were formed by the catastrophic release of ground water, although others suggest lava can produce many of the same features. In comparison, little is known about Marte Vallis.
With the SHARAD radar, the team was able to map the buried channels in three dimensions with enough detail to see evidence suggesting two different phases of channel formation. One phase etched a series of smaller branching, or "anastomosing," channels that are now on a raised "bench" next to the main channel. These smaller channels flowed around four streamlined islands. A second phase carved the deep, wide channels.
"In this region, the radar picked up multiple 'reflectors,' which are surfaces or boundaries that reflect radio waves, so it was possible to see multiple layers, " said Lynn Carter, the paper's co-author from NASA's Goddard Space Flight Center in Greenbelt, Md. "We have rarely seen that in SHARAD data outside of the polar ice regions of Mars."
The mapping also provided sufficient information to establish the floods that carved the channels originated from a now-buried portion of the Cerberus Fossae fracture system. The water could have accumulated in an underground reservoir and been released by tectonic or volcanic activity.
That would seem to be reason to suspect there may still be underground water on Mars.....somewhere.