Latest Mercury Flyby Could Change Theories

"NASA's latest flyby of Mercury upset theories
about the planet's composition and volcanic
history, even though the probe shut down
about halfway through because of an unexpected
power problem.

Closeup imagery from the Sept. 29 pass of the
Mercury Surface, Space Environment,
Geochemistry and Ranging spacecraft
(Messenger) revealed signs of volcanic activity
much more recently than planetary geologists
had thought possible, while neutron spectroscopy
showed much higher concentrations of iron and
titanium at the planet's surface than can be
explained by today's theories of Mercury's
formation."

See:

http://www.aviationweek.com/aw/gener...&channel=space