Using images captured by NASA’s Mars Reconnaissance Orbiter (MRO) over the last few years, scientists have created a 3-D reconstruction detailing an ancient system of water channels below the surface of the Red Planet—something that has never been done before on a planet other than Earth.
The flood channels are located in the youngest volcanic region of the planet, at an area along the Martian equator known as Elysium Planitia. Extensive volcanism has shaped the geology in this area since before the days of the dinosaurs, and over hundreds of millions of years geologic processes such as lava flows have buried evidence of Mars’ ancient geologic history.
MRO’s imaging focused on the 620-mile-long Marte Vallis channel system, which consists of several elevated channels formed around streamlined islands that feed a deeper and wider main channel. Little is known about Marte Vallis, but MRO’s new research has revealed the estimated depth and width of these channels to be nearly double what scientists had previously believed—some 262 feet deep and 60 miles wide. Scientists theorize these channels formed due to an event known as a mega flood, where a catastrophic release of ground water occurred to form the channels. These ancient flood channels are critical to understanding the extent to which hydrologic activity prevailed over the past 500 million years—a time period that had been considered to be cold, dry, and mostly geologically dead for some three billion years. The channels may also help scientists determine whether the floods could have triggered dramatic episodes of climate change on Mars throughout the planet’s history.
“What we’ve found is that the source of this mega flood was water deep underground that was delivered to the surface through tectonic fractures,” said Gareth Morgan, a geologist at the National Air and Space Museum’s Center for Earth and Planetary Studies in Washington and lead author on the paper. “The source of the water, and the size of the outflow, had been something of a mystery, but the radar allowed us to look below the lava flows and see what existed there before. This work demonstrates the importance of orbital sounding radar in understanding how water has shaped the surface of Mars.”
Researchers used MRO’s Shallow Radar system (SHARAD) to penetrate the martian surface and probe the length, width, and depth of these 3-billion-year-old underground flood channels in three dimensions, revealing details which lava flows buried no more than 500 million years ago. Using the images gathered by SHARAD, researchers mapped the channels with enough detail to show evidence suggesting the floods which formed the channels originated from a now-buried portion of the Cerberus Fossae fracture system. The research also suggests the possibility that water could have accumulated in an underground reservoir and been released as a result of tectonic or volcanic activity, which in turn caused a mega flood that affected an area comparable to the ancient mega flood that created the 2,000-square-mile Channeled Scablands in eastern Washington state.
“Mars is certainly very cold and dry today, but even now it remains dynamic and certainly is not dead,” Morgan said. “There are huge reservoirs of ice beneath the surface and we don’t really know much about its relationship with the surface.”
Launched in 2005, NASA’s Mars Reconnaissance Orbiter is searching for evidence that liquid water was present on the planet’s surface long enough to support a habitat suitable for life. NASA’s rover Curiosity, which is currently on the surface at the base of Gale Crater, recently discovered an area where an ancient fast-flowing stream once came off the crater rim and flowed through the area near the rover’s landing site.
For more information on NASA’s Mars Reconnaissance Orbiter, visit www.nasa.gov/mission_pages/MRO