Mars is slowly tearing apart its largest moon

Scientists are trying to solve the mystery of the origin of the furrows that cover the largest satellite of Mars, Phobos. They could be a sign that the Red Planet's gravity is actually tearing the moon apart and eventually destroying it.

Phobos is about 22 kilometers in diameter. The satellite revolves around the Red Planet at a distance of about 6000 km from it and makes a complete revolution three times a day. But the orbit of Phobos is not quite ordinary: the satellite gradually moves in a spiral, thus slowly approaching Mars, passing 1.8 meters every 100 years.

Unlike Deimos , which is half the size and much farther away from Mars, an unusual pattern of parallel, shallow furrows formed on the surface of Phobos. As a rule, they are 100–200 m wide and 10–30 m deep.

Morphological analysis shows that many of the furrows are aligned with the intermediate axis of the satellite (tangent to its orbit), and maintain a mostly parallel orientation within a few degrees over tens of kilometers. The width of the grooves and the distance between them are relatively uniform, and the grooves resemble tensile cracks in a brittle layer of the same thickness.

These furrows were previously considered to be traces of a collision with an asteroid that occurred in the distant past. They are dust-filled canyons and are slowly expanding.

A new study published in The Planetary Science Journal shows that the long, shallow streaks covering the surface of Mars’ moon Phobos are signs that it is being torn apart by extreme gravitational forces emanating from the Red Planet . This happens as the satellite gets closer to Mars.

The idea of ​​the authors of the study is based on the fact that as one body, in this case Phobos, approaches a larger body, such as Mars , the smaller one begins to stretch along the line relative to the larger body. This phenomenon is known as tidal force. In fact, the decay of the orbit leads to the formation of surface grooves on Phobos.

In the case of Phobos, the tidal force acting on the satellite will increase as it approaches Mars. Finally, there will come a moment when the tidal stress becomes greater than gravity , which holds the satellite as an integral object. And at this moment, Phobos will actually be torn apart, and from its fragments, most likely, a small ring will form around Mars, resembling the rings of Saturn .

Previous studies have also suggested that tidal forces caused the furrows to form, but this is doubtful due to the powdery composition of the Martian moon, which is too soft to form such cracks.

At a constant speed, Phobos will complete its “death spiral”, that is, touch the surface of Mars in about 40 million years. However, if the theory outlined in the new study is correct, then the satellite will be completely destroyed much earlier.

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