Now thrust could be generated (for “free” again) at periapsis, progressively increasing the altitude of apoapsis.

这时可以「免费」在近心点产，渐渐将心点的升。

The repeated thrust applications at apoapsis would raise periapsis from inside to outside the stationary orbit.

重复在心点施以，会将近心点由同步轨道内升到同步轨道外。