Seminar: The story of the moons of Mars

Dr. Pascal Rosenblatt (Royal Observatory of Belgium)

The two moons of Mars, Phobos and Deimos, were first thought to be asteroids captured by the red planet. The remote sensing of their surfaces argue in favor of this scenario but the present near-circular and near-equatorial orbit of the two moons could not fit expected orbits of capture objects. An alternative scenario has been proposed in which the two small moons of Mars were formed after a giant collision occurred more than 4 billions years ago, similarly to the formation of our Moon. But this scenario raises challenges as how to form small moons (and not a big one as for the Earth) and to maintain them in orbit around Mars over billions of years.

A recent work has provided a solution to overcome these problems. It proposes that Mars had bigger moons in the past (now disappeared), which had favored the formation of smaller moons in a disc of debris extending at large distances from the planet. This new scenario will be explained in details after a brief review of previous ideas about the formation of the Martian moons. Eventually, the new missions scheduled by the Japanese (JAXA) and European (ESA) space agencies will be presented. Those missions aim to bring back to Earth sample of the surface of Phobos and are foreseen for launch at around 2024.
Friday September 30th, 13:00, ULB, Building D, Room 5.236 (Location)