JPL: New Clues Suggest Wet Era on Early Mars Was Global

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New Clues Suggest Wet Era on Early Mars Was Global
NASA JPL | 2010-209 | 24 June 2010

PIA13215: Hydrated Minerals Exposed at Lyot, Northern Mars (Credit: NASA/ESA/JPL-Caltech/JHU-APL/IAS)

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Minerals in northern Mars craters seen by two orbiters suggest that a phase in Mars' early history with conditions favorable to life occurred globally, not just in the south.

Southern and northern Mars differ in many ways, so the extent to which they shared ancient environments has been open to question.

In recent years, the European Space Agency's Mars Express orbiter and NASA's Mars Reconnaissance Orbiter have found clay minerals that are signatures of a wet environment at thousands of sites in the southern highlands of Mars, where rocks on or near the surface are about four billion years old. Until this week, no sites with those minerals had been reported in the northern lowlands, where younger volcanic activity has buried the older surface more deeply.

French and American researchers report in the journal Science this week that some large craters penetrating younger, overlying rocks in the northern lowlands expose similar mineral clues to ancient wet conditions.

"We can now say that the planet was altered on a global scale by liquid water about four billion years ago," said John Carter of the University of Paris, the report's lead author.

Other types of evidence about liquid water in later epochs on Mars tend to point to shorter durations of wet conditions or water that was more acidic or salty.

Water Was Widespread Across Early Mars, But No Oceans
Universe Today | 24 June 2010

Locations of nine exposures of hydrated silicate in northern plain craters. (Image courtesy of Science/AAAS)

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By looking at the mineralogy deep inside craters on Mars' northern plains and comparing it to the makeup of regions in the southern hemisphere, scientists have found that widespread liquid water likely altered the Red Planet's crust about 4 billion years ago. However, the new findings do not support other recent studies that a giant ocean covered Mars' northern highlands. Using the Mars Express OMEGA instrument and the Mars Reconnaissance Orbiter's CRISM instrument, John Carter from Bibring at Université Paris in Orsay, France and a group of scientists from France and the US investigated large craters, and found minerals which could have only formed in the presence of water. "We've detected hydrated minerals in about 10 of these craters," Carter told Universe Today, "and we conclude that the ancient crust was altered in a similar way both in the south and in the north, in a very early environment which was much warmer and wetter than today's."

Carter added that in terms of Mars' water history, this means that liquid water existed near and on the surface of early Mars on a planetary scale, and is not restricted to select areas of the southern highlands.

Detection of Hydrated Silicates in Crustal Outcrops in the Northern Plains of Mars

• Science, Vol 328 No 5986, 25 June 2010, DOI: 10.1126/science.1189013

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Wet Era on Early Mars Was Global
ESA Portal | 25 June 2010

Conditions favourable to life may once have existed all over Mars. Detailed studies of minerals found inside craters show that liquid water was widespread, not only in the southern highlands, but also beneath the northern plains.

ESA’s Mars Express and NASA’s Mars Reconnaissance Orbiter have discovered hydrated silicate minerals in the northern lowlands of Mars, a clear indication that water once flowed there.

The spacecraft have previously discovered thousands of small outcrops in the southern hemisphere where rock minerals have been altered by water. Many of these exist in the form of hydrated clay minerals known as phyllosilicates, and indicate that the planet’s southern hemisphere was once much warmer and wetter than it is today.

However, until this week, no sites with hydrated silicate minerals had been found in the northern lowlands, where thick blankets of lava and sediments up to several kilometres thick hamper efforts to probe the underlying bedrock.

The first hints that there may be hydrated silicates beneath the northern plains were provided by Mars Express’ OMEGA sensor. However, the outcrops were small and more detailed observations were required to confirm their presence. The OMEGA team sifted higher resolution data from a sensor on NASA’s orbiter