Tether

A tether is a thin cable that connects two portions of a spacecraft. The applications of tethers include propulsion, power, and artificial gravity.

Possibly the simplest and most elegant use of tethers is for space propulsion, using the method of momentum exchange by tethers. It has an advantage over mass driver in that it is bidirecitonal, and a single tether can be used to soft land payloads as well as depart. If the energy imparted by the cargo is balanced, the tether would require little if any energy input and minimal propellant usage.

A mass driver is theoretically bidirectional, but in practice to use a mass driver to decelerate an incoming payload requires that the payload be precisely aligned with the input of the mass driver within a few inches, which is not possible in practice.