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 uncertainness 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.

Assessing the Impact of Lean Healthcare on Inpatient Care: A Systematic Review

“…To the best of our knowledge there is not a SR focusing on inpatient care and outcomes related to patient flow and efficiency. Complementarily, different authors have proposed models analyzing the relationship between LH and performance outcomes using structural equation modelling [72][73][74][75] and confirmatory factor analysis [76].…”

Using Mars co-orbitals to estimate the importance of rotation-induced YORP break-up events in Earth co-orbital space

“…Although the thermal YORP mechanism may have spun up Eureka, leading to the formation of the Eureka family, Mars Trojans may also be the results of impacts (Polishook et al 2017). A giant impact (Marinova, Aharonson & Asphaug 2008; may have led to the formation of the Martian moons Phobos and Deimos as well (Citron, Genda & Ida 2015;Hyodo et al 2017aHyodo et al , b, 2018Hansen 2018;Pignatale et al 2018). Separate origins for the known Mars Trojans have previously been suggested by Rivkin et al (2007) and Trilling et al (2007), but see also the discussion in Christou et al (2021).…”

Analytical protocols for Phobos regolith samples returned by the Martian Moons eXploration (MMX) mission

“…In the case of the giant impact scenario, the ingredients of the Martian moons are predicted to be a mixture of both Martian and impactor materials with a mixing ratio depending on the impact angle (Hyodo et al 2017 ). The nature of the impactor is difficult to predict but could be constrained by comparing the composition of returned Phobos regolith samples to the composition expected from condensation of a gas and solids from a cooling melt in the impact-generated disk (Pignatale et al 2018 ), and composition and mineralogy of known Martian meteorites. Because the Martian materials contributing to the Martian moons would originate from regions as deep as ~ 100 km from the Martian surface (Hyodo et al 2017 ), the moons could contain both Martian crust and mantle materials but would be depleted in metals with siderophile elements that had already formed the Martian core (Righter and Chabot 2011 ).…”

“…Based on the matrix mineralogy of the samples, their primitiveness and their degrees of aqueous alteration can be evaluated (Noguchi et al 2017 ). In the case of the giant impact scenario, the mineralogy and petrology of the returned samples can be compared with those expected for condensation from gas and solids from a cooling melt in the impact-generated disk, calculated assuming thermodynamic equilibrium (Pignatale et al 2018 ). The mineralogy and petrology of the samples can be corroborated by remote sensing observations of the Phobos surface (e.g., the presence/absence of absorption at ~ 0.7 and ~ 2.7 μm indicative of hydrated minerals and at ~ 3.4 μm for macromolecular organic solids; Rivkin et al 2002b ).…”