This figure shows the major-element composition of representative rocks and soils from Earth, Moon, and Mars as displayed on a graph of the ratio by weight of aluminum over silicon versus that of magnesium over silicon. The newly measured major-element composition of Mercury's surface materials are also depicted on the same graph, as measured by the MESSENGER XRS. Mercury has lower Al/Si and higher Mg/Si than typical lunar surface materials and terrestrial basalts, indicating a lower fraction of the common mineral plagioclase feldspar.

The MESSENGER spacecraft is the first ever to orbit the planet Mercury, and the spacecraft's seven scientific instruments and radio science investigation are unraveling the history and evolution of the Solar System's innermost planet. Visit the Why Mercury? section of this website to learn more about the key science questions that the MESSENGER mission is addressing.

Date Presented: June 16, 2011, at a NASA press conference
Instrument: X-Ray Spectrometer (XRS)

These images are from MESSENGER, a NASA Discovery mission to conduct the first orbital study of the innermost planet, Mercury. For information regarding the use of images, see the MESSENGER image use policy.