Hello Mercury ...

NASA's MESSENGER makes another pass by Mercury. Click here for MESSENGER's Mission page.

Combining observations of Martian crust recorded by MESSENGER and those recorded by Mariner 10 in the 1970s reveals that at least 15 percent of the planet’s surface is covered by a relatively blue, dim compound. Most of it is concentrated in craters and adjacent regions splattered with material excavated from craters. Solomon says the most likely candidate is a titanium-rich oxide that originated one to 10 kilometers below the surface and was exposed when space debris bombarded the planet.

The presence of titanium oxide would suggest that during Mercury’s first 100 million years or so, while the planet was still forming, it was hot enough to generate a magma ocean, with much of the surface and the interior liquid, comments Linda Elkins-Tanton of MIT. Titanium oxide would have been one of the last compounds to solidify, and it might have remained just beneath the surface.

MESSENGER is slated to make another pass of Mercury in September.