AGU: Martian Moon May Have Come from Impact on Home Planet

bystander · Post by **bystander** » Tue Sep 25, 2018 3:21 pm

Martian Moon May Have Come from Impact on Home Planet
American Geophysical Union | 2018 Sep 24

Spectral fingerprints of Phobos’ surface support an ancient big crash origin for the Martian moon

Phobos, the larger of Mars’ two tiny satellites, is the darkest moon in the solar system. This dark aspect inspired the hypothesis that the close-orbiting moon may be a captured asteroid, but its orbital dynamics seemed to disagree. A new study suggests Phobos’ composition may be more like the volcanic crust of the Red Planet than it appears, consistent with an origin for the moon in an ancient, violent impact on Mars. (Credit: G. Neukum (FU Berlin) et al / Mars Express / DLR / ESA; Acknowledgement: Peter Masek)
The weird shapes and colors of the tiny Martian moons Phobos and Deimos have inspired a long-standing debate about their origins.

The dark faces of the moons resemble the primitive asteroids of the outer solar system, suggesting the moons might be asteroids caught long ago in Mars’ gravitational pull. But the shapes and angles of the moons’ orbits do not fit this capture scenario.

A fresh look at 20-year-old data from the Mars Global Surveyor mission lends support to the idea the moons of Mars formed after a large impact on the planet threw a lot of rock into orbit, according to a new study ...

The dataset held unplumbed clues to the stuff Phobos is made of, which may be more similar to the crust of the Red Planet than it appears, according to the study’s authors. ...

MGS-TES Spectra Suggest a Basaltic Component in the Regolith of Phobos ~ Timothy D. Glotch et al

Journal of Geophysical Research (online 24 Sep 2018) DOI: 10.1029/2018JE005647 (pdf)