Martian north pole consists of layers of dust and ice
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 as many as 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 was probably caused by changes in the planet's orbit over the last 4 million years.
When the planet tilts strongly on its axis, the surface ice erodes and is covered by a layer of dust, 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 today in the journal Science, comes as NASA's Phoenix spacecraft closes in for a May 25 landing at the north pole. Phoenix carries a drill to dig into the surface ice.
Scientists analyzing radar images from NASA's Mars Reconnaissance Orbiter spacecraft have found as many as 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 was probably caused by changes in the planet's orbit over the last 4 million years.
When the planet tilts strongly on its axis, the surface ice erodes and is covered by a layer of dust, 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 today in the journal Science, comes as NASA's Phoenix spacecraft closes in for a May 25 landing at the north pole. Phoenix carries a drill to dig into the surface ice.
