Study: Mars gully was wet just one million years ago

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Tuesday, March 10, 2009

The “serendipitous discovery” of a million-year-old gully on Mars by Samuel Schon GS may indicate that water was present on the Red Planet more recently than researchers previously thought.

Funded by NASA, the research was published in the current issue of Geology, an influential earth sciences journal. Images from HiRISE – the High Resolution Imaging Science Experiment – were analyzed and provided key photos of gullies scattered throughout Mars. Schon, along with Postdoctoral Research Associate Caleb Fassett and Professor of Geological Sciences James Head, sifted through the data and found a gully located in eastern Promethei Terra which they were able to date to 1.25 million

years ago.

Schon said he and his colleagues had not set out to find this specific gully.

“It’s a lot of geologic good luck,” Schon said. The team simply stumbled upon the gully, which was probably created by the accumulation of melted water that originated from ice deposits nearby. The original crater is thought to be the result of a high-impact meteor crash.

Using a technique that involved measuring the frequency and size of craters and the boundary of the gully, Schon said he and his team were able to pinpoint the date of origin of the site.

According to the study, the gully is located in a crater and consists of multiple lobes – the components of the gully’s depositional fan – which have been determined to be of varying ages due to their appearance. The outer lobes – unblemished by meteor impacts – indicate that the melted water that shaped them was a more recent phenomenon.

“We learned something really exciting,” Fassett said, adding that “just being able to add our knowledge” to the body of geological research was the highlight of finding the age of the gully.

Fassett said the gullies point to the existence of transient water and demonstrate that multiple factors led to the prevailing climate. The discovery will also aid in studies of snow and ice deposition on Mars.

“It fits into the broader study of the water cycle,” Fassett said.

But Schon and Fassett added that the discovery is only marginally applicable to future research because it is limited to young craters.

Due to the specific nature of the million-year-old gully, the team will not continue research on that area but will continue with the analysis of the general presence of gullies and the existence of water on Mars, Schon said.

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