Published online 27 June 2008 | Nature | doi:10.1038/news.2008.920

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Penguins on Mars?

Phoenix chemistry set discovers that Mars's soil is like Antarctica's.

Mars samplePhoenix's robotic scoop has snagged some surprisingly fertile soil (inset).NASA/JPL-Caltech/University of Arizona/Max Planck Institute

Should we be looking for penguins on Mars, rather than little green men? Just a week after finding definitive signs of water ice just beneath the surface, news of another remarkable scientific discovery has been beamed back to Earth by the Mars lander Phoenix.

This time it’s about muck. The soil under the lander was scooped up into its onboard chemistry lab just a few days ago, and subjected to a round of prodding, poking and other analysis.

And the results? Martian soil is like Antarctic soil. “This soil appears to be a close analogue to surface soils found in the upper dry valleys in Antarctica,” says Sam Kounaves of Tufts University in Medford, Massachusetts, leader of the 'wet chemistry' portion of the Phoenix mission.

The team hasn’t yet finished looking through the results of the analysis by the microscopy, electrochemistry and conductivity analyzer (MECA), but already MECA scientists have worked out that soil on Mars is salty and alkaline. They found traces of magnesium, sodium, potassium and chloride ions – constituents of salts. The pH of the soil taken from an inch under the surface is high – 8 or 9 — making the soil quite basic. “The alkalinity of the soil at this location is definitely striking,” says Kounaves.

Worth its salt

The salts are more evidence for water on the planet, he says.

“I've come to the conclusion that the amazing thing about Mars is not that it's an alien world, but that in many aspects, like mineralogy, it's very much like Earth,” says Kounaves.

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He has also been reported as saying that the soil has all the characteristics needed to support life, although there's no chance of finding anything alive there today – despite the apparently fertile soil, the planet’s atmosphere is too harsh and thin for anything to grow.

Phoenix is carrying the necessary kit to do three more chemistry tests in the remainder of its three-month mission. In the coming weeks, the lander will be busying its other instruments, including the thermal and evolved-gas analyzer (TEGA), which has been baking soil samples at 1,000 °C. 

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