The Psyche Topography and Geomorphology Investigation

Abstract

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 Global Shape, Gravity Field, and Libration of Enceladus

“…Importantly, the “coverage” approach to scoring (instead of the discrete “buckets” such as those described in Jaumann et al. (2022)) is ambivalent to the clock angle of the measurements. For example, two images with camera azimuth angles of 89° and 91° would get credit for two buckets in the binned approach, while our algorithm considers those measurements as nearly the same and would be scored significantly lower.…”

“…The general criteria used for evaluating an SPC data set depend primarily on the imaging geometry (Jaumann et al., 2022). The specific imaging angle criteria that we have implemented for assessing the SPC dataset are summarized in Table 4; however, the discrete binning method has significant drawbacks.…”

The Psyche Gravity Investigation

“…If Psyche was instead substantially disrupted and/or was never molten, it will likely have a more heterogeneous density structure. Correlation of its gravity field with surface topography (Jaumann et al 2022) via transfer function techniques of admittance and coherence, would indicate spatial regions where the density structure is not consistent with simple azimuthally symmetric models. Gravity and shape combined with magnetometry (Weiss et al 2022) and surface compositional data (Bell et al 2022;Lawrence et al 2022), will be collectively required to constrain the structure and degree of azimuthal symmetry, including the possible disruption of the body into a rubble pile (Elkins-Tanton et al 2022).…”

“…The spatial resolution of gravity noted above, combined with that of topography (50 m pixel −1 ; Jaumann et al 2022) dictates that regional density variations across Psyche's shallow subsurface, including in association with large craters (Marchi et al 2022) can be mapped. And combined with surface observations to provide geophysical information to support geological context based on observations from other Psyche sensors (Jaumann et al 2022;Lawrence et al 2022;Marchi et al 2022).…”

“…Gravity will also contribute towards interpretation of spatially large structural features of the asteroid, and provide linkage between surface and subsurface processes. Secondarily, the gravity investigation, in coordination with topography (Jaumann et al 2022), improves global positioning and the reference frame, increasing the ease of integration of all the Psyche mission data sets.…”