The enigmatic origin of the Martian moons

Recent research seems to have definitively clarified the mysterious origin of the two moons of Mars.

Phobos and Deimos are the moons of Mars. These are tiny stars with irregular shapes. Phobos measures 27 kilometers from end to end. Deimos, 15. They orbit Mars at a very short distance. Deimos does so about 20,000 kilometers from the surface of Mars, taking 30 hours to make a complete revolution around the planet. The case of Phobos is even more spectacular: only about 6,000 kilometers separate it from the Martian surface and it takes only 7 hours and 39 minutes to orbit the planet. There is no known moon that is closer to its planet. In addition, the distance between Phobos and Mars is gradually reducing. It is estimated that in about 50 million years Phobos will crash into the surface of Mars or break up in orbit to form a ring around the planet.

Those two moons were believed to have originally been asteroids that were then gravitationally captured by Mars. But the true origin of both stars is much more complex than that and has been a mystery for a long time.

Jacob Kegerreis’s team, from the NASA Ames Research Center in Moffett Field, California, United States, has carried out a detailed study on the origin of Phobos and Deimos, using simulations run on a supercomputer.

Artist’s recreation of a landscape seen from space in which a sector of Mars and its two moons appear, one prominently on the far left of the image and the other as a tiny spot on the far right, on the night hemisphere of the planet. (Image: NASA)

The results of the study have made it possible to reconstruct the most probable events that led to Mars acquiring its two satellites.

It all started when an asteroid passed too close to Mars and its gravity fragmented it.

The resulting rock fragments were scattered in various orbits around Mars. More than half of the fragments escaped the Mars system, but others remained in orbit. Tossed around by the gravity of Mars and the Sun, some of the remaining asteroid fragments began to collide with each other, each collision crushing them further and scattering more debris.

After many collisions, the fragments concentrated to form a disk that surrounded the planet. Over time, some of this material clumped together further and formed the two small moons of Mars, Phobos and Deimos.

The study is titled “Origin of Mars’s moons by disruptive partial capture of an asteroid.” And it has been published in the academic journal Icarus. (Fountain: NCYT by Amazings)