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Messenger Spies Iron on Mercury

from BBC News Online

Mercury is even more of an "iron planet" than scientists had previously supposed. Richer concentrations of iron and titanium have been seen on Mercury's surface by Nasa's Messenger probe. Previous Earth and spacecraft-based observations had detected only very low amounts of iron in the silicate minerals covering the innermost world.

Because of its immense density, scientists have already assumed much of Mercury's interior contains iron. Messenger sees the surface iron bound up in oxides with titanium.

The mission's principal investigator, Sean Solomon, said the new observations would keep theoreticians busy. "The iron is in a form that we don't normally encounter in other planetary situations and so it's going be a volley back to our geochemists and petrologists to come up with a scenario that's consistent with everything we are measuring now at Mercury," he told reporters.