Main Question or Discussion Point
Why is it that if an orbiting space station is observed to remain always vertically above the same point on Earth then the observer must be on the equator of Earth?
I am not sure what this person is talking about. There's some misleading info here.The thesis is wrong. The orbit of the space station will always around the core of the Earth but not neccesarily around the equator. You will see the space station always above you if it has the same angular velocity as the Earth. For example telecommunication satellites work like this. They are put into orbit by high powered rockets so that they have angular velocity the same as that of the Earth.
In order for the space station to remain vertically above the same point on the Earth (this is a given condition), the space station must be in an equatorial geosynchronous orbit (i.e., a geostationary orbit). There are no other orbits that satisfy this given condition.The thesis is wrong. The orbit of the space station will always around the core of the Earth but not neccesarily around the equator.