Expected Investigation of the (65803) Didymos–Dimorphos System Using the RGB Spectrophotometry Data Set from the LICIACube Unit Key Explorer (LUKE) Wide-angle Camera

Abstract

The Light Italian Cubesat for Imaging of Asteroids (LICIACube) is part of the NASA Double Asteroid Redirection Test (DART), the first mission aiming to demonstrate the applicability of the kinetic impactor method for planetary defense. The mission was launched on 2021 November 24 to perform the impact experiment on Dimorphos, the small secondary of the binary asteroid (65803) Didymos. The 6U LICIACube, stored as a piggyback of the DART spacecraft, is the first Italian mission operating in deep space managed by the Italian Space Agency that will witness the effects of the DART impact on Dimorphos. On board LICIACube, there is a suite of cameras that will perform imaging of Didymos and Dimorphos to investigate the DART impact effects and study the binary system. Among them, the LICIACube Unit Key Explorer (LUKE), a wide-angle camera coupled to an RGB Bayer pattern filter, will be pivotal to constrain the surface composition and heterogeneity of the binary system due to differences in surface properties linked with possible space weathering effects and/or the presence of exogenous material. Multiband photometric analysis of LUKE data and laboratory experiments in support of data interpretation will provide new insights on the binary asteroid nature and evolution. Moreover, photometric phase curve analysis will reveal the scattering properties of the granular surface medium providing important constraints for the microphysical properties of the Didymos–Dimorphos system. In this work, we will present the state of the art of the LUKE scientific activities with an overview of the instrument setup, science operations, and expected results.

Anticipated Geological Assessment of the (65803) Didymos–Dimorphos System, Target of the DART–LICIACube Mission

“…The geological mapping efforts are greatly aided by the use of color data provided by LICIACube/LUKE. This multicolor image data set will provide clues to the potential variegation in the surface composition of the binary system (see Poggiali et al 2022), similarly to what was achieved for the S-type asteroids Ida and Dactyl (Figure 6), where data were collected during a flyby (Geissler et al 1996). These color data converted into spectrophotometry measurements are related to several surface properties, such as space-weathering alteration (e.g., Murchie et al 2002;DellaGiustina et al 2020;Rizos et al 2021).…”

“…Like LEIA, LUKE images the illuminated portions and nonimpacted sides of Dimorphos and Didymos (Dotto et al 2021). This camera will capture color RGB data in the visible (Poggiali et al 2022). The color information will be at a spatial scale of <10 m pixel −1 (maximum will be ∼4.8 m pix −1 at CA) and follows the same range of phase angles as LEIA, changing rapidly within a few tens of seconds.…”

Spectral Rotational Characterization of the Didymos System prior to the DART Impact*

“…This could indirectly indicate that different regions on Didymos's surface show a local variation on hypersthene and olivine concentrations, with some portions richer in those silicates, while others are more similar to L-chondrite assemblages. While new spectral characterization, ideally in the 2022 apparition (when the system will be brighter than in the last two decades) is required to confirm these interesting results, RGB images obtained by LUKE on board LICIACube (Poggiali et al 2022) would definitely resolve this conundrum.…”

The Unusual Brightness Phase Curve of (65803) Didymos

“…The early evolution of this ejecta plume, as well as the binary system, was observed by the LUKE camera. The optical system consists of a front-illuminated CMOS CMV2000 detector equipped with an RGB Bayer pattern filter (Poggiali et al 2022). The CCD has the characteristic pixel size of 5.5 μm and dimensions of 1088 × 2048 pixels.…”