Abstract EANA2024-113

The discussion on the origins of Mars' moons, Phobos and Deimos, provides a unique opportunity for astrobiological research. Two main theories have been suggested to explain their formation: a massive impact on Mars followed by the re-accumulation of debris in analogy of Earth’s Moon [1,2], or the capture of primitive dark carbonaceous asteroids [3,4]. Both Mars and primitive asteroids are well-recognized as fascinating astrobiological target. In the past, Mars may have harboured conditions favourable for the emergence of life. Primitive asteroids, on the other hand, are regarded as pivotal vehicles for transporting and delivering organic materials from the protoplanetary disk to rocky planets, such as Earth and Mars.
To investigate the origin of Martian moons, JAXA will launch in 2024 a new sample return mission, Martian Moons eXploration (MMX) [5], with the ambitious objective to study in detail the Martian system and bring back on Earth a sample from Phobos in 2029. This mission will aim to determine the most probable formation process for Phobos and Deimos but also to investigate the early Solar System evolution in terms of volatile delivery across the snow line to the terrestrial planets having habitable surface environments. To reach such interesting objectives, the spacecraft payload will include a suite of scientific instruments to study the surface of the moons. Among them, the MMX InfraRed Spectrometer (MIRS) [6] will acquire data in the 0.9-3.6 µm wavelength range with a spectral resolution better than 20 nm. This wavelength range is essential for studying volatiles and other key components related to the origin of life, including water, organics, and carbonates. When MMX will arrive in the Martian system and MIRS will start observing the two moons, a substantial amount of data will be collected. In this presentation, we will discuss the preparatory studies and the forthcoming astrobiological investigations that will be conducted using the infrared spectrometer on board the MMX spacecraft. We will present some preliminary results on the UV irradiation of Phobos simulant [7,8]. We focused in particular on the UV stability of the mineral mixture resembling the spectrum of Phobos. Further investigation will use the simulant as a substrate for the absorption of organic molecules and survival studies. Irradiation experiments were performed in the Arcetri Astrobiology Laboratory at the INAF-Astrophysical Observatory of Arcetri using a Newport Xe-enhanced UV 300 W lamp as UV solar simulator, using the expertise of martian studies [9,10]. 

Reference
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