Capture origin scenario for Phobos

There are two satellites on Mars, Phobos and Deimos. There are two theories on the origin of these satellites: the capture scenario, which suggests that they were captured by the gravity of Mars; and the giant impact scenario, which suggests that they were formed by the accumulation of small objects that collided with Mars and scattered debris. It is still unclear which theory is correct, but we are particularly interested in the capture theory. Small objects captured on Mars evolve their orbits due to the dragging effect of the Martian atmosphere. When a celestial object is dragged, its orbit shrinks and it falls to Mars. We have been studying to reproduce the orbital evolution of Phobos including the drag effect and to evaluate whether the capture was possible or not.

(Master’s course 1st, Kohei Fujita)

Image: http://cosmos.isas.jaxa.jp/were-going-to-the-martian-moons/