Research results that Mars may 'tear with gravity' its moon Phobos

Phobos , the largest satellite of Mars, is a small celestial body with a maximum diameter of about 27 km, and orbits within about 6000 km from the surface of Mars once in about 7 hours and 40 minutes. Such Phobos is known to have radial grooves on its surface, but research results have been announced that these grooves are 'a sign that Phobos is torn by the gravity of Mars.'

Numerical Simulations of Drainage Grooves in Response to Extensional Fracturing: Testing the Phobos Groove Formation Model - IOPscience

Mars may be slowly ripping its largest moon apart | Live Science

Phobos is the closest orbiting object in the solar system, and it orbits faster than Mars rotates. Phobos' orbit is not stable and falls toward the surface of Mars at a speed of about 1.8 m every 100 years, so it will collide with Mars about 40 million years later.

Phobos is characterized by the beautiful striped grooves visible on the surface. The most widely accepted hypothesis for the formation of the ditch is that it was formed by a past asteroid impact that created Stickney , the largest crater on Phobos.


Steve Jurvetson

Other than asteroid impacts, there is a hypothesis that the tidal forces of Mars' gravity pulling on Phobos formed the grooves. However, because Phobos is covered with granular sediment, there was an objection that it was too soft to form such cracks.

Therefore, the research team used computer simulations to investigate the idea that ``there is a relatively hard internal region under the soft sedimentary layer of Phobos.'' As a result, it was found that the striped pattern may have been formed by the sediment falling into grooves created by tidal forces in the relatively hard inner layer.

The research team wrote, ``If you model the interior of Phobos as a mountain of debris covered with a coherent layer, you will find that tidal forces create parallel cracks at regular intervals.'' If the trough on Phobos is formed by tidal forces, Phobos could be torn apart by tidal forces before colliding with Mars, and the fragments could form a ring around Mars like Saturn.

In addition, JAXA, a Japanese space agency, is proceeding with an exploration plan called Martian Moons eXploration (Mars satellite exploration plan) , which plans to land on Phobos and bring back samples.

in Science, Posted by log1h_ik