Space weathering is a key process in the interpretation of airless planetary surfaces. As we engage new missions to planetary objects with potentially novel surfaces such as 16 Psyche, there is renewed interest in expanding our knowledge of space weathering effects to a wider variety of analog materials, including the physical/chemical effects of solar‐wind ions on planetary regoliths. We have experimentally simulated the effects of solar ions on two polished thick sections of meteoritic troilite (FeS) via irradiation with 1 keV hydrogen (H+) and 4 keV helium (He+), to investigate effects resulting from different ion species. We detected depletion of sulfur over the course of each irradiation using in situ X‐ray photoelectron spectroscopy. Sulfur depletion rates were surprisingly similar for H+ and He+, interpreted as a function of subsurface ion‐activated diffusion. By comparing XPS‐derived elemental abundances with SDTrimSP computer simulations, we further quantified sulfur diffusion, sputtering yield, and altered‐layer composition with respect to incident‐ion fluence, and accounted for the influence of surface oxidation due to atmospheric sample storage. Using scanning electron microscopy, we detected an increase in nanoscale surface roughness resulting from the irradiation, which we quantified using atomic force microscopy. Based on these results, we estimate that an exposure time of order 103 Earth‐years is required for troilite on Psyche to reach equilibrium sulfur depletion within the first atomic layer.

Detailed mapping of topography is crucial for the understanding of processes shaping the surfaces of planetary bodies. In particular, stereoscopic imagery makes a major contribution to topographic mapping and especially supports the geologic characterization of planetary surfaces. Image data provide the basis for extensive studies of the surface structure and morphology on local, regional and global scales using photogeologic information from images, the topographic information from stereo-derived digital terrain models and co-registered spectral terrain information from color images. The objective of the Psyche topography and geomorphology investigation is to derive the detailed shape of (16) Psyche to generate orthorectified image mosaics, which are needed to study the asteroids’ landforms, interior structure, and the processes that have modified the surface over geologic time. In this paper we describe our approaches for producing shape models, and our plans for acquiring requested image data to quantify the expected accuracy of the results. Multi-angle images obtained by Psyche’s camera will be used to create topographic models with about 15 m/pixel horizontal resolution and better than 10 m height accuracy on a global scale. This is slightly better as global imaging obtained during the Dawn mission, however, both missions yield resolutions of a few m/pixel locally. Two different techniques, stereophotogrammetry and stereophotoclinometry, are used to model the shape; these models will be merged with the gravity fields obtained by the Psyche spacecraft to produce geodetically controlled topographic models. The resulting digital topography models, together with the gravity data, will reveal the tectonic, volcanic, impact, and gradational history of Psyche, and enable co-registration of data sets to determine Psyche’s geologic history.

The article was published bearing incorrect affiliation information for Simone Marchi (coauthor). The affiliation information is as it stands in this correction and the original article has been corrected.