On the Impact Origin of Phobos and Deimos IV: Volatile Depletion

Abstract

Recent works have shown that Martian moons Phobos and Deimos may have accreted within a giant impact-generated disk whose composition is about an equal mixture of Martian material and impactor material. Just after the giant impact, the Martian surface is heated up to $\sim 3000-6000$ K and the building blocks of moons, including volatile-rich vapor, are heated up to $\sim 2000$ K. In this paper, we investigate the volatile loss from the building blocks of Phobos and Deimos by hydrodynamic escape of vapor and radiation pressure on condensed particles. We show that a non-negligible amount of volatiles ($>10\%$ of the vapor with temperature $>1000$ K via hydrodynamic escape, and moderately volatile dusts that condense at $\sim 700-2000$ K via radiation pressure) could be removed just after the impact during their first signle orbit from their pericenters to apocenters. Our results indicate that bulk Phobos and Deimos are depleted in volatile elements. Together with future explorations such as JAXA's MMX (Martian Moons eXploration) mission, our results would be used to constrain the origin of Phobos and Deimos.

15 pages, 8 figures. Accepted for publication in ApJ

References in corpus (5)

• On the Impact Origin of Phobos and Deimos I: Thermodynamic and Physical Aspects
• On the Impact Origin of Phobos and Deimos II: True Polar Wander and Disk Evolution
• On the impact origin of Phobos and Deimos III: resulting composition from different impactors
• Reconceiling the orbital and physical properties of the martian moons
• Implantation of Martian materials in the inner solar system by a mega impact on Mars

Cited by in corpus (9)

• Scaling laws for the geometry of an impact-induced magma ocean
• Transport of impact ejecta from Mars to its moons as a means to reveal Martian history
• Assessment of the probability of microbial contamination for sample return from Martian moons II: The fate of microbes on Martian moons
• Exploring the recycling model of Phobos formation: rubble-pile satellites
• Modification of the composition and density of Mercury from late accretion
• Origin of Mars's moons by disruptive partial capture of an asteroid
• 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