Resolving the Origin of Deimos: Combining Global and Local Composi-tional Analysis with the small-sat TASTE Mission

Understanding the formation of Phobos and Deimos is critical for decoding the history of Mars and the evolution of the outer Solar System. The scientific debate centers on two models: for-mation via a Martian giant impact or the capture of D-type asteroids. The TASTE – Terrain Analyzer and Sample Tester Explorer mission seeks to resolve the origin of Deimos by com-bining global morphology and elemental composition from close orbit with local surface organ-ic and mineralogical composition acquired via a lander.

TASTE will provide characterization, complementing the expected results of the JAXA MMX mission, which focuses on Phobos. The investigation strategy involves two distinct phases:
• Global Characterization (Orbiter): An hyperspectral camera and a miniaturized X-γ-ray spectrometer will characterize the surface’s elemental composition from a stable Quasi-Satellite Orbit. Additionally, radio science will acquire data on Deimos’ gravity field, providing constraints on its interior structure.
• Local Surface Analysis (Lander): The lander will descend to the surface. Once land-ed, the Surface Sample Analyser will perform detailed chemical analysis. This direct view and analysis is crucial for characterizing the local organic and mineralogical com-position, which holds the key to definitively linking Deimos to either the impact ejecta or carbonaceous chondrite parent bodies.

TASTE, currently in Phase B, uses a 16U CubeSat architecture to perform scientific investiga-tion in a deep-space, low-gravity environment. This talk will present the scientific objectives, the critical role of the mission’s data in the origin debate, and the required measurement synergy.

This work is funded by the Italian Space Agency (ASI) within the Alcor Program, as part of the development of the TASTE mission under contract n. 2024-45-I.0. The project is led by the Italian consortium INAF-Arcetri Astrophysics Observatory, Firenze, As-tronomical Observatory of Trieste and the Politecnico of Milano-DAER, Milano, Italy