I enjoy a lot your paper ! Well written very clear and synthetic. You can improve by explaining why we're doing all those research. Why are we investigating mars inner composition ? To improve our field of knowledge in order to prepare the future human missions to Mars, exploring landing site, and conditions at the surface and under. Lavatube are one of main option consider to set up a human base there to protect us from the radiation. Mars has no magnetosphere, the human body is not ready to receive that level of radiation. Know well the martian earthquake, and be able to predict them will be helpful if we go this way. Also Mars is very similar to earth, understand Mars history work as studying a witness of earth history.
There is the JPL map of rovers and landers landing sites, that express that main interest research points and our research for the best landing site for future man mission.
RE: 4 "mysteries" of Mars that will investigate NASA's Mars InSight probe