On: Starlink – SpaceX’s broadband internet system

[DarmokJalad1701]

And what happens to the rocket from the reaction force from the spring?

[ceejayoz → DarmokJalad1701]

Nothing, because you used a spring to launch the other satellite on the other side of the payload at the same time.

Or, you just use thrusters, like the ones that launched from the Shuttle did.