Flood Water on Mars Carved Out Channels Half Billion Years Ago

Researchers highlighted an ancient network of underground channels on Mars on a 3D map, discovered by using a radar instrument on NASA's Mars Reconnaissance Orbiter, a spacecraft that beams back images and other information about Mars.

The Shallow Radar instrument on the Mars Mars Reconnaissance Orbiter is used to probe the the surface and subsurface of Mars for evidence of water, and enabled scientists to reconstruct three-dimensional maps of the biggest underground system of flood channels on Mars. The channels sit in the youngest volcanic region on the planet. Until now, the source, scale and structure of the channels have not been well understood because they are buried by lava flows on the planet's surface.

With the ground-penetrating radar they were able to make out the different layers — the channels and the volcanic rock that is covering it — because of their different makeup.

The new findings were published online Thursday, March 7, in the journal Science.

The 1000 kilometer channel system, known as Marte Vallis, is thought to have been carved out 500 million years ago by a major flood. This is unexpected because Mars is thought to have been cold and dry for the past 2.5 billion years. The channels are also twice as deep as originally estimated, with a depth of about 70 meters.

Researchers have also identified the source of the floodwater — a now-buried series of fractures known as Cerberus Fossae.The finding tells scientists how water has shaped Mars, including the surface and climate.

The idea that large amounts of water once flowed on Mars — both on the surface and underground — is not new. Giant craters found on the Red Planet's surface suggest that these depressions used to be filled with liquid water, based on the mineral composition of the crater floor.