The orbit of Phobos lies within the Martian Roche Cavity. Why, then, does it exist as a whole cosmic body?

Elastic stresses arising in the satellite’s body due to the action of tidal forces are less than the ultimate strength of its substance.

Remember: The process of learning a person lasts a lifetime. The value of the same knowledge for different people may be different, it is determined by their individual characteristics and needs. Therefore, knowledge is always needed at any age and position.