If Newton's first law is only applicable for the Inertial frame of reference, do we think of a spacecraft following the law when it's in outer the space where there is no gravity? How long can it move without fuel then?

Question

If Newton's first law is only applicable for the Inertial frame of reference, do we think of a spacecraft following the law when it's in outer the space where there is no gravity?  How long can it move without fuel then?

anonymous · Answer

inertial frame means the body is at rest or MOVING WITH UNIFORM VELOCITY
so it can move right?

anonymous · Answer

once a spacecraft has fixed itself in orbit, it needs very little fuel to keep itself there.
In fact if there is no resistance (even at those altitudes there is a tiny miny bit of air you see...), it could going forever
Its like the moon going round the earth

anonymous · Answer

ya space crafts  get original kinetic energy to force them into their orbits 
and  centripetal force from earth provides necessary orbital velocity for its movement