A Liquid Apogee Engine (LAE), or apogee engine, refers to a type of chemical rocket engine typically used as the main engine in a spacecraft. The name apogee engine derives from the type of manoeuvre for which the engine is typically used i.e. an in-space delta-v change made at the apogee of an elliptical orbit in order to circularise it. For geostationary satellites, this type of orbital manoeuvre is performed to transition from a geostationary transfer orbit and place the satellite on station in a circular geostationary orbit. Despite the name, an apogee engine can be used for a range of other manoeuvres such as end-of-life deorbit, earth orbit escape, planetary orbit insertion and planetary descent/ascent.