Martian moon may have come from impact on home planet, new study suggests

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 in the Journal of Geophysical Research: Planets, a publication of the American Geophysical Union. 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. “The fun part for me has been taking a poke at some of the ideas out there using an old dataset that’s has been underutilized,” said Tim Glotch, a geoscientist at Stony Brook University in New York and the lead author of the new study. Marc Fries, a planetary ...