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

Ryuki Hyodo, Hidenori Genda, Sébastien Charnoz, Francesco C. Pignatale, Pascal Rosenblatt
(Submitted on 24 Apr 2018)

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 ∼3000−6000 K and the building blocks of moons, including volatile-rich vapor, are heated up to ∼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 ∼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.

Comments:    15 pages, 8 figures. Accepted for publication in ApJ
Subjects:    Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as:    arXiv:1804.08889 [astro-ph.EP] (or arXiv:1804.08889v1 [astro-ph.EP] for this version)
Submission history
From: Ryuki Hyodo
[v1] Tue, 24 Apr 2018 08:14:56 GMT (1514kb)
http://xxx.lanl.gov/abs/1804.08889