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Early days on Mars

Mineral maps based on data from Europe’s Mars Express probe are helping scientists piece together a detailed picture of the Red Planet’s history.

Life on Mars was most likely during the planet’s infancy, the data suggest.

Ancient clays bearing telltale signs of standing water indicate the most likely time for life to have developed on Mars was about four billion years ago, before a cataclysmic global change left the planet cold, dry and plagued with acid water, researchers said.

The first era began with the planet’s formation about 4.6 billion years ago and lasted for about 600 million years. Rock from this period lies exposed on the planet’s surface due to meteorite strikes, erosion and underground shifts that formed cracks or faults in the planet’s crust.

This ancient Mars terrain contains clay minerals, such as chamosite and nontronite, which form when water is abundant, temperatures are moderate and acidity is low, conditions that may have been suitable for life.

The planet’s golden years did not last long. Between four billion and 3.5 billion years ago, Mars underwent a dramatic change. The shift may have been triggered by massive volcanic eruptions that spewed sulfur into the atmosphere, which then rained down on the planet’s surface.

Researchers found that minerals formed during this period, such as gypsum and grey hematite, are marked by sulfates, which indicate a dry and acidic environment, one that is not believed to be suitable for life as we know it to form.

The changes stripped away most of Mars’ atmosphere, leaving the world vulnerable to radioactive assaults from the sun, as well as freezing temperatures.

Between 3.2 billion and 3.5 billion years ago, the planet transitioned to its third epoch, one that exists now. Minerals dating to this time were not formed with or altered by liquid water. They are dominated by ferric oxides and other iron-rich minerals and they cover most of the planet.

Scientists plan to refine their mineral maps of Mars with a more powerful instrument aboard the newly arrived Mars Reconnaissance Orbiter. The spacecraft is maneuvering into an orbit suitable for science operations and is scheduled to begin surveys this fall.

posted by: kyawoo at 20:41 | link | comments |
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