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

这时可以「免费」在近生推力，渐渐将的高度提。

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

在施以推力，会将近由同步轨道内提到同步轨道外。