Two basic possibilities exist in order to escape the gravitational effect of the Earth or of another heavenly body: reaching the practical gravitational boundary or transitioning into a free orbit. Which possibility will be employed depends on the intended goals.
Thus, for example, in the case of longdistance travel through outer space, it would generally depend on maneuvering in such a fashion that those celestial bodies, in whose range of attraction (gravitational field) the trip
takes place, will be circled in a free orbit suspended in space (that is, only in suspension without power by a manmade force) if there is no intention to land on them. A longer trip would consist, however, of parts of orbits of this nature (suspension distances), with the transition from the gravitational field of one heavenly body into that of a neighboring one being caused generally by power from a manmade force.
If we want to remain at any desired altitude above a celestial body (e.g., the Earth) for a longer period, then we will continuously orbit that body at an appropriate velocity in a free circular orbit, if possible, and, therefore, remain over it in a stable state of suspension.
When ascending from the Earth or from another planet, we must finally strive either to attain the practical gravitational boundary and, as a result, the "total separation" (when foregoing a stable state of suspension) or transitioning into a free orbit and as a result into the "stable state of suspension" (when foregoing a total separation). Or, finally, we do not intend for the vehicle continually to escape the gravitational effect when ascending at all, but are satisfied to raise it to a certain altitude and to allow it to return immediately to Earth again after reaching this altitude (ballistic trajectory).
In reality, these differing cases will naturally not always be rigorously separated from one another, but frequently supplement one another. The ascent, however, will always have to take place by power from a manmade force and require a significant expenditure of energy, whichin the case when an ascending object is also to escape from the gravitational effectfor the Earth represents the enormous value of around 3,200 up to 6,400 metertons per kilogram of the load to be raised. Orwhich amounts to the same thingit requires imparting the huge, indeed cosmic velocity of approximately 8,000 to 11,200 meters per second, that is about 12 times the velocity of an artillery projectile!