Mercury's surprising core and landscape curiosities
(PhysOrg.com) -- On March 17, the tiny MESSENGER spacecraft completed its primary mission to orbit and observe the planet Mercury for one Earth-year. The bounty of surprises from the mission has completely altered our understanding of the solar system's innermost planet. As reported in one of two papers published today on Science Express, scientists have found that Mercury's core, already suspected to occupy a greater fraction of the planet's interior than do the cores of Earth, Venus, or Mars, is even larger than anticipated. The companion paper shows that the elevation ranges on Mercury are much smaller than on Mars or the Moon and documents evidence that there have been large-scale changes to Mercury's topography since the earliest phases of the planet's geological history.