Orbiter finds layers of ice, dust at Mars’ north pole BY JOHN JOHNSON JR. Los Angeles Times
Mars’ north pole, like a French parfait, comes in layers. Scientists analyzing radar images from NASA’s Mars Reconnaissance Orbiter spacecraft have found up to seven distinct layers of ice and dust beneath the north pole. Roger J. Phillips, a scientist with the Southwest Research Institute in Boulder, Colo., said the layering probably was caused by changes in the planet’s orbit over the past 4 million years. When the planet tilts strongly on its axis, the surface ice withers and is covered by a layer of dust mixed with ice, Phillips said. Then, “every million years or so,” he said, the planet tilts less, meaning less sunlight falls directly on the pole. At that point, a layer of clean ice is laid down. The discovery, published Friday in the journal Science, comes as NASA’s Phoenix spacecraft closes in for a May 25 landing in the far north. Phoenix carries a drill to dig into the surface ice. The radar aboard the Mars Reconnaissance Orbiter also shows the weight of the ice cap has not deformed the underlying Martian crust, Phillips said. For this to be true, the hard crust layer must be more than 200 miles thick. “This means the inside of Mars is colder than we thought it was,” Phillips said. That has implications for any rudimentary forms of life that might exist on Mars. Despite the planet’s hostile surface, some scientists have speculated that bacteria or some other primitive life forms might be able to survive underground, where heat from the planet’s core could produce layers of liquid water. Based on this new research, any such life forms must be deep underground, close to the core.
Mars soil test brings ‘flabbergasting’ result BY JOHN JOHNSON JR. Los Angeles Times
The first chemistry results from Mars’ northern plain reveal an environment more hospitable to life than some scientists had predicted, one that might allow future colonists to grow crops as familiar on Earth as asparagus and green beans. Strawberries, though, might be tougher, Phoenix mission scientists said Thursday. “We’re flabbergasted by this data,” said Sam Kounaves, the lead scientist on the wet chemistry experiment for the Phoenix spacecraft, which landed on Mars on May 25. “We’ve found nutrients that could support life.” A sample of soil about the size of a sugar cube was delivered to the lab by the lander’s nearly 8-foot long robotic arm and mixed with water brought from Earth. Analysis shows that the soil is alkaline, with a pH between 8 and 9, Kounaves said. This came as something of a surprise, at least to the many scientists who have argued that Martian soil was likely too acidic to support life. With that level of alkalinity, “you might be able to grow asparagus very well,” Kounaves said. Strawberries, on the other hand, require more acidic soils. The test also turned up magnesium, sodium, potassium and chloride, all of which are useful in organic processes. The test did not turn up the prize that the $420 million mission was sent to find: complex organics that would indicate Mars once was, or still might be, habitable. Organic compounds, made up of carbon in combination with nitrogen, hydrogen and other elements, are necessary to build the elaborate chemical scaffolding of life, at least as we know it on Earth. Further, even though the soil chemistry would provide some nutrients for life, any future crops would have to be grown underground, because the meager Martian atmosphere lets in too much of the sun’s destructive ultraviolet rays. “A lot of people predicted the soil would be acidic,” Kounaves added. “We’re showing at this location it appears to be alkaline. But we’re only looking at a tiny area.” Still, the scientists said Thursday in a briefing, the early results are encouraging. “There’s nothing about [the soil] that would preclude life,” Kounaves said. “Some types of life would be happy to live in these soils.” In fact, the Martian soil looks very similar to soils on Earth, only without the organics. Fuller answers to the habitability question are expected from Phoenix’s other major laboratory, the Thermal and Evolved Gas Analyzer, which contains eight tiny ovens to “bake and sniff” the soils, as well as the ice that is lying only inches beneath the lander. Sometime in the next few weeks of the three-month mission, the scientific team will attempt to bore into the hard-as-cement ice layer.
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