Mars landers finds soil with Earth minerals

With a little help, soil imported from Mars could support green beans, turnips, and asparagus.

That's one implication of this week's announcement that scientists had found several water-soluble minerals common to soils on Earth. The soil sample analyzed by the Phoenix Mars Lander at the far northern reaches of the planet also displays alkalinity levels similar to those found in soils in the Dry Valleys of Antarctica.

If the single soil sample analyzed so far is any indication, at least this patch of Mars "seems very friendly" to simple forms of life – at least below the surface, says Samuel Kounaves, a Tufts University chemist who heads the team interpreting the results from the lander's wet-chemistry lab.

By turning the soil into a mini-martian mud pie then stirring it, the lab liberated magnesium, sodium, potassium, chloride, and other ingredients of salts that initially require water to form them. They represent the kind of nutrients that many microbes on Earth crave.

The notion of what constitutes a habitable environment "has become very broad in the past 10 years," Dr. Kounaves adds. The discovery of Earth-like soils hundreds of million miles away means the subsoil environment could have the potential to host a wide range of simple organisms – not to mention string beans.

More broadly, the finding adds one more piece to a growing mountain of evidence that the fourth rock from the sun isn't so out of this world, after all. The more researchers explore the red planet with orbiters and rovers, the more Mars reveals its kinship with Earth.

"The amazing thing about Mars is not that it's an alien world, but that it's actually very Earth-like in a lot of aspects," Kounaves says.

So far, the lander is roughly a third of the way through it's primary mission. Researchers are still analyzing the evidence from the first soil sample that went through a shake-and-bake process to determine other aspects of its composition. One of eight small ovens heated the sample to 1,000 degrees C (about 1,800 degrees F.), revealing traces of carbon dioxide and water that had been bound up in the soil's minerals.

The international mission, spearheaded by the National Aeronautics and Space Administration, also has a clear learn-as-you-go aspect to it. One housekeeping detail pleased the research team: It found that the scoop can deliver portions of the same soil sample to different instruments, rather than delivering a unique sample to each. This allows them to make a broader range of tests to the same batch of soil, allowing them to draw more-confident conclusions about the samples they study.