Probe Unlocks Mercury's Secrets

Mercury is anything but the boring "burnt-out cinder" scientists once believed it was, say researchers analyzing data from NASA's Messenger orbiter. The spacecraft has now spent 88 days—one Mercurian year—circling the planet, and has sent back about 20,000 new pictures that strongly suggest that ice coats parts of the permanently shadowed craters near the planet's poles, reports the Los Angeles Times.

Messenger's readings have revealed that the planet has 10 times as much sulfur in its crust as the Earth or moon, suggesting it was formed from very different building blocks than what scientists had expected (and pointing, perhaps, to evidence of volcanism). Its magnetic field is stronger in its northern hemisphere, suggesting something strange in the structure of its core. Messenger, which is only a quarter of the way through its mission, is casting many of the old theories about Mercury "into the dustbin of science," the project's chief scientist tells the Christian Science Monitor. (More Mercury stories.)