Global major-element maps of Mercury from four years of MESSENGER X-Ray Spectrometer observations

• Published in: Icarus (New York, N.Y. 1962) Vol. 345; p. 113716
• Main Authors: Nittler, Larry R., Frank, Elizabeth A., Weider, Shoshana Z., Crapster-Pregont, Ellen, Vorburger, Audrey, Starr, Richard D., Solomon, Sean C.
• Format: Journal Article
• Language: English
• Published: Elsevier Inc 15.07.2020
• Subjects: Mercury, composition; Mercury, surface; X-ray spectroscopy; Mercury, composition; Mercury, surface; X-ray spectroscopy
• ISSN: 0019-1035; 1090-2643
• DOI: 10.1016/j.icarus.2020.113716

The X-Ray Spectrometer (XRS) on the MESSENGER spacecraft provided measurements of major-element ratios across Mercury's surface. We present global maps of Mg/Si, Al/Si, S/Si, Ca/Si, and Fe/Si derived from XRS data collected throughout MESSENGER's orbital mission. We describe the procedures we used to select and filter data and to combine them to make the final maps, which are archived in NASA's Planetary Data System. Areal coverage is variable for the different element-ratio maps, with 100% coverage for Mg/Si and Al/Si, but only 18% coverage for Fe/Si north of 30° N, where the spatial resolution is highest. The spatial resolution is improved over previous maps by 10–15% because of the inclusion of higher-resolution data from late in the mission when the spacecraft periapsis altitude was low. Unlike typical planetary data maps, however, the spatial resolution of the XRS maps can vary from pixel to pixel, and thus care must be taken in interpreting small-scale features. We provide several examples of how the XRS maps can be used to investigate elemental variations in the context of geological features on Mercury, which range in size from single ~100-km-diameter craters to large impact basins. We expect that these maps will provide the basis for and/or contribute to studies of Mercury's origin and geological history for many years to come. •We present global maps of Mg/Si, Al/Si, S/Si, Ca/Si, and Fe/Si on Mercury derived from MESSENGER X-ray fluorescence data.•Procedures used to filter data and generate maps are described in detail.•Areal coverage and spatial resolution are improved over previous maps.•New maps used to investigate elemental variations in the context of geological features on Mercury over wide range of size.