Orbiting landing tracks.

Payloads would be launched from earth with just enough fuel to loft them above the atmosphere and keep them hovering for a few minutes. Then they would electromagnetically couple to a long horizontal structure in low orbit, picking up velocity (or "losing" it, depending on the frame of reference) until they are orbiting at the same rate.

Electrically driven thrusters (e.g. vertical electrodynamic tethers which push against the earth's magnetic field) would be used to replenish the lost momentum. At any given time, the payload would be a fraction of the total track mass, but since it could be new track material this would permit (fairly rapid) bootstrapping.