On the impact origin of Phobos and Deimos III: resulting composition from different impactors

Abstract

The origin of Phobos and Deimos in a giant impact generated disk is gaining larger attention. Although this scenario has been the subject of many studies, an evaluation of the chemical composition of the Mars' moons in this framework is missing. The chemical composition of Phobos and Deimos is unconstrained. The large uncertainty about the origin of the mid-infrared features, the lack of absorption bands in the visible and near-infrared spectra, and the effects of secondary processes on the moons' surface make the determination of their composition very difficult from remote sensing data. Simulations suggest a formation of a disk made of gas and melt with their composition linked to the nature of the impactor and Mars. Using thermodynamic equilibrium we investigate the composition of dust (condensates from gas) and solids (from a cooling melt) that result from different types of Mars impactors (Mars-, CI-, CV-, EH-, comet-like). Our calculations show a wide range of possible chemical compositions and noticeable differences between dust and solids depending on the considered impactors. Assuming Phobos and Deimos as result of the accretion and mixing of dust and solids, we find that the derived assemblage (dust rich in metallic-iron, sulphides and/or carbon, and quenched solids rich in silicates) can be compatible with the observations. The JAXA's MMX (Martian Moons eXploration) mission will investigate the physical and chemical properties of the Maroons, especially sampling from Phobos, before returning to Earth. Our results could be then used to disentangle the origin and chemical composition of the pristine body that hit Mars and suggest guidelines for helping in the analysis of the returned samples.

arXiv commentAccepted for publication in ApJ (13/12/2017)

References in corpus (14)

• The chemical composition of the Sun
• The Compositional Diversity of Extrasolar Terrestrial Planets: I. In-Situ Simulations
• Origin of water in the inner Solar System: Planetesimals scattered inward during Jupiter and Saturn's rapid gas accretion
• A Possible Carbon-rich Interior in Super-Earth 55 Cancri e
• Formation of Phobos and Deimos via a Giant Impact
• Chemistry of Impact-Generated Silicate Melt-Vapor Debris Disks
• On the Impact Origin of Phobos and Deimos I: Thermodynamic and Physical Aspects
• The cool and distant formation of Mars
• A colossal impact enriched Mars' mantle with noble metals
• On the Impact Origin of Phobos and Deimos II: True Polar Wander and Disk Evolution
• 2D condensation model for the inner Solar Nebula: an enstatite-rich environment
• Reconceiling the orbital and physical properties of the martian moons
• Dust Processing and Mineralogy in Protoplanetary Accretion Disks
• The effect of the regular solution model in the condensation of protoplanetary dust

Cited by in corpus (7)

• Lava Worlds: From Early Earth to Exoplanets
• The Sands of Phobos: The Martian moon's eccentric orbit refreshes its surface
• Transport of impact ejecta from Mars to its moons as a means to reveal Martian history
• On the Impact Origin of Phobos and Deimos IV: Volatile Depletion
• Giga-Year Dynamical Evolution of Particles Around Mars
• Using Mars co-orbitals to estimate the importance of rotation-induced YORP break-up events in Earth co-orbital space
• Mixing model of Phobos' bulk elemental composition for the determination of its origin: Multivariate analysis of MMX/MEGANE data