periapsis

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

这时可以「免」在近心点产生推力，渐渐将远心点的高度。

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

复在远心点施以推力，会将近心点由同步轨道内到同步轨道外。