The Price Of Space Is Friendship
It's an exciting time in the history of human exploration. We're only just beginning to probe outside our biosphere. Low-orbit, long-term space inhabitation like that seen on the ISS has been the norm for many years now. As of the time of writing, 7 people were in space. Our long term goals seem set on permanent outposts on Mars.
Orbital re-entry of crewed spacecraft is a complicated dance of physics. You ever do that challenge where you have to build a cage out of straws and cardboard to protect an egg from a fall? Well, it's like that on steroids. Generally, if you are coming in from another interstellar body you will be going very fast. You can't decelerate over around 90m/s/s (or 9gs) or let the interior of the ship get too hot without killing your crew. You've got an enormous amount of kinetic energy to disperse, and the best way to do that is by braking in the atmosphere at a relatively shallow angle of descent. This means that reentry maneuvers cover a lot of airspace. You will likely either orbit the earth entirely or a large portion of it before you finally reduce your velocity enough to land.