1,2,3,4,6- 1NASA Goddard Space Flight Center, Greenbelt MD, USA (andy.lopez-oquendo@nasa.gov)
- 2Northern Arizona University, Flagstaff, AZ, USA
- 3Southwest Research Institute, Boulder, CO, USA
- 4University of Oxford, Oxford, UK
- 5Lowell Observatory, Flagstaff, AZ, USA
- 6University of Maryland, College Park, MD, USA
On November 1, 2023, NASA’s Lucy spacecraft successfully imaged the Main-Belt asteroid (152830) Dinkinesh and its moon, Selam. Dinkinesh is an S- or Sq-type asteroid with multiple geologic features (i.e., craters, central ridge, and trough) [1]. The Dinkinesh system is complex, with satellite that itself is a contact binary [1]. Broadband visible (0.35-0.95 µm) and near-IR (0.97-3.95 µm) hyperspectral images collected by the L’Ralph instrument showed absorption features near 1-, 2-, and 3-µm [2, 3].
The vibrational absorption between 2.6 and 3.3 µm in asteroid spectra has generally been interpreted as OH and H2O (i.e., hydration). This ~3.0 µm band, has been a crucial tool of characterization to understand the degree of hydration on the surface of asteroids [4]. Detection of hydration or volatile-rich materials on S-type objects is surprising due to the expected high temperature at which these bodies formed in the main-belt and presence of anhydrous silicates. Ground-based facilities have provided crucial detections and insights about the 3.0 µm band on S-type asteroids [5,6], yet much remains unknown about its origin. Dinkinesh’s close approach by Lucy offers a fortuitous opportunity to better understand the hydration of these bodies and assess any spatial variation on the surface that might be related to geologic features.
The Lucy L’Ralph Dinkinesh observations can help differentiate the source of hydration. For example, exogenous material (e.g., carbonaceous or cometary material) is expected to appear in discrete areas associated with specific surface features such as craters [7]. Alternatively, solar wind implantation on asteroids occurs when high H+ fluxes doses from the Sun interact with surface minerals, embedding hydrogen atoms and potentially leading to the formation of OH or H2O in the regolith [8]. We will report on the spectral analysis of Dinkinesh, with a focus on the shape model registration of hyperspectral images from the L’Ralph Multi-spectral Visible Imaging Camera (MVIC) and Linear Etalon Imaging Spectral Array (LEISA). We will present colors, spectral slopes, and band depth to look for possible spectral heterogeneities associated with geologic morphologies.
Results: We registered the digital shape model of Dinkinesh to the L’Ralph instrument detectors. Figure 1 shows a preliminary example of the MVIC panchromatic filter frame during the close approach registered to the respective incidence angle backplane obtained using SpiceyPy [9]. Figure 2 shows an example of a LEISA-calibrated frame (e.g., I/F) registered to Dinkinesh’s shape model. After registration, the 3 µm absorption feature is analyzed for each facet by computing the absorption strength (e.g., band depth) and looking for correlations with surface morphologies provided by stereophotogrammetry of L’LORRI images. Similarly, we obtained MVIC color maps and overlayed them on the shape model. Our preliminary analysis suggests a 3 µm detection across the entire imaged surface, showing variabilities in band depth. We will further explore such variability to find its possible relationship with surface morphologies, local color variations, and illumination geometry.
Figure 1. MVIC panchromatic frame of Dinkinesh overlayed with the SpiceyPy incidence angle backplane.
Figure 2. Left: Dinkinesh shape model with overlayed LEISA cross-track I/F frame 700 during close approach.
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abstract #1474. Houston, TX: Lunar and Planetary Institute.
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How to cite: López-Oquendo, A. J., Kaplan, H. H., Simon, A. A., Reuter, D. C., Emery, J. P., Protopapa, S., Howett, C., Grundy, W. M., and Sunshine, J. M.: Spectral Imaging Analysis of Asteroid (152830) Dinkinesh by the Lucy Mission, EPSC-DPS Joint Meeting 2025, Helsinki, Finland, 7–12 Sep 2025, EPSC-DPS2025-744, https://doi.org/10.5194/epsc-dps2025-744, 2025.
