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Nine places on Earth that mimic Mars terrain

Scientists say that Mars went through three ages, and the first age may have been habitable for life as we know it. Each stage on Mars can be found at nine different locations around the planet Earth today.

By Charles Q. ChoiAstrobiology Magazine contributor / December 10, 2010

Valle de la Luna, San Pedro de Atacama, Chile



There is no place on Earth that is a perfect copycat of Mars as it is now, or as it was at any specific point in the past. But scientists suggest Earth has little versions of Mars as it might have been over decades.

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These places could help scientists develop a timeline of the Red Planet's history.

By providing insights on how Mars has changed over time, these terrestrial mimics could help us better understand the results of past and current missions to Mars. They also could help researchers plan future expeditions to look for signs of life on Mars. In addition, investigating these extreme sites on Earth could shed light on the limits of life.

IN PICTURES: Spirit rover's view from Mars

Astrobiologist Alberto Fairen at the SETI Institute and NASA Ames Research Center and his colleagues identified three stages Mars went through.

In the first, cold, wet age, enough liquid water and energy was present to make Mars potentially habitable. In the second "Snowball Mars" age, conditions became extremely challenging, and the liquid water that could have made life possible became scarce.

In the current hyper-arid age, conditions on the surface have become largely uninhabitable, save perhaps some isolated niches.

"We have tried to assign every analog to a specific time in Mars' geological history, so we can study the evolution of Mars in Earth environments," Fairen explained. "This will be the only way to ask ourselves the right questions." Their research was detailed in the November issue of the journal Astrobiology.

First age of Mars — Cold and wet

The first 700 million to 900 million years of the Red Planet are what the researchers dub the first age of Mars. Back then, although temperatures overall were cold, it appears liquid water was probably abundant on the surface. The planet also possessed a thicker atmosphere and a global magnetic field that could have protected against hostile radiation, helping provide the most hospitable conditions for life as we know it in the entire history of Mars. [Videos: What Went Wrong on Mars?]

Most of the water-linked features and mineral deposits seen to date on Mars stem from this first age. The largest part of the surface was composed of volcanic rocks and related soils, which the surface waters reacted with to generate a variety of minerals. These include phyllosilicates, which are typical products of the weathering of volcanic basalt, and evaporites, deposits that form after the upwelling and evaporation of groundwater.

Four sites on Earth mimic rocks from this age on Mars. They could yield insights not only into the chemistry that dominated the surface of the Red Planet back then, but also into the potential for both life and the preservation of traces of life.

The North Pole Dome area, which covers some 230 square miles (600 square km) in the 3.5-billion-year-old Pilbara region of Western Australia, is an excellent analog for Martian phyllosilicate formation, the researchers noted. It also contains evidence of Earth's earliest biosphere in the form of stromatolites and possible microfossils more than 3 billion years old, and therefore could shed light on how any Martian fossils might have been preserved or degraded over time.

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