Mercury Mascons for the Cover of JGR Planets

This image appeared on the cover of the December, 2014 issue of Journal of Geophysical Research: Planets. In a lengthy article in the same issue, planetary scientist Erwan Mazarico and his co-authors describe their new and improved gravity map of Mercury, named HgM005. The map is based on a careful analysis of the orbit of the MESSENGER spacecraft. It shows variations in the strength of Mercury's gravity caused by mass concentrations, or mascons — dense lumps of material beneath the surface of the planet. The analysis also led to more accurate values for Mercury's tilt and the length of its day and allowed researchers to find stable near-circular orbits that could be used by future Mercury probes.