Observatoire de Paris Institut national de recherche scientifique français Univerité Pierre et Marie Curie Université Paris Diderot - Paris 7

Laboratory investigations of Phobos spectral simulants : effects of porosity and geometry

mardi 31 octobre 2023, par Antonin Wargnier, doctorant du pôle planétologie

Lundi 6 novembre 2023 à 16h30 , Lieu : Salle de confĂ©rence 207 du bâtiment 16

The origins of Phobos and Deimos – the two martian moons – remain uncertain. Two main hypotheses are currently suggested to explain their formation. The first proposes that Phobos and Deimos could have been formed by a giant impact between Mars and a protoplanet. The other hypothesis posits that Phobos and Deimos may be captured asteroids.

JAXA Martian Moon eXploration (MMX) mission – will be crucial in this context to unveil Phobos and Deimos origins. MMX will be the first sample return mission dedicated to the biggest martian moon, Phobos. The composition of Phobos will also be studied, by the infrared spectrometer MIRS. In particular, MIRS will be able to observe Phobos at 3.4 µm organics (0.9-3.6 µm). Detectability of this feature is expected in the case of captured asteroid hypothesis.

In support of the MMX mission, we searched to develop a Phobos visible, near- and mid-infrared spectroscopic laboratory simulant. We studied the detection of organic compounds in a Phobos simulant to support the interpretation of future MIRS observations. Furthermore, surfaces of small bodies are generally covered by fine-grained porous regolith. Therefore, we conducted laboratory experiments to analyze the spectroscopic effects of porosity on a Phobos simulant, by creating porous samples with sublimation of water ice mixed with grains of the Phobos simulant. This presentation will show the results of our laboratory investigations on Phobos simulants.