In orbit

Now when you feel like you’re falling, keeping a straight forward path, and what’s pulling you down is always the same way away. Then you’re in orbit; neither going towards nor away from the centre, but, moving, facing one way. Newton’s law of universal gravitation would hint that you pull much less weight than the object you’re orbiting does.

Inertia relates to the tendency to stay the same; to remain as one is, in motion or stationary. Newton’s first law of motion says that a body or person at rest remains so (inertia), or if moving with an unchanging velocity, similarly remains so (inertia) unless acted upon by an external net force. When such force is applied, what results is a change of motional (or perhaps, emotional) state along the direction of the force, and directly proportional to it (Newton’s second law). That is, the person/object might gain or lose momentum in a particular path.

To change or leave orbit needs a change of momentum, a new impulse, whether through a change in the mass of character or rapidity of movement. Both, enabled by wisdom—or science if you prefer.

Newton’s third law of motion says that action produces a response that is equal and opposite to it. So we may note that force experienced is a repercussion, or produces one. The effect of which may be a change of inertial state. A stationary aeroplane starts moving when its engines push back hard enough so that it moves forward. Thus, if you fire your rockets hard enough and long enough away from that pull, gravity, you will escape into free space—freedom.

Other definitions:
Space is that expanse with everything inside it. At least every thing of physics, chemistry, and biology; every physical thing.
A body at rest (a stationary entity) is a special case of a body moving, with no speed/velocity.
Velocity is speed in one direction.