12:00 PM - 12:15 PM
[PPS02-30] Martian Moons eXploration (MMX): connecting small bodies with habitable planets
Keywords:Phobos, Deimos, martian satellites , Mars, MMX
On the origin of Martian moons, there are two leading hypotheses, “Captured volatile-rich primordial asteroid” and “Giant impact”. Current observational facts such as orbital properties and surface reflectance spectra are individually supportive of either hypothesis but insufficient to judge which is true. MMX project aims to collect samples from a Martian moon to conclude this discussion through in-depth sample analyses in combination with close-up observations of the moons. Depending on the conclusion, we will further extract information and constraints on material distributions and transports at the outer edge of the early inner solar system as well as on planetary formations.
If the capture hypothesis is true, the Martian moons may serve as an anchor to estimate chemical properties of primitive asteroids and their original formation environments possibly near the Jovian orbit. The dynamics of transportation across the snow line to the circum-Martian orbits would also be constrained, which improves our understanding of building blocks and circum-planetary environments of Mars and the other terrestrial planets during accretion. Acquisition of constraints on the delivery of water and other volatile to Mars is particularly important because these are difficult to be deduced from observations of Mars alone that has experienced differentiation and volatile escape.
Recent numerical simulations of Martian moon accretion from giant impact ejecta suggest that the moons may be constituted from a mixture of nearly equal proportion of impactor and proto-Mars materials. Ejected materials may experience weak impact-induced heating, avoiding severe homogenization due to melting and vaporization before agglomeration. It would therefore be possible to estimate the material properties of impactor and proto-Mars, separately, from returned regolith samples if the giant impact hypothesis is true. This would provide unique constraints for the physico-chemical state of proto-Mars as well as for the material supply to Mars. These constraints are clues to understand the surface environment of Mars where chemical evolution toward life expectedly proceeded under the presence of liquid water.