Warp collar

Interstellar Propulsion Module

Also known as the "warp collar" and "warp donut".

In the early days of interstellar exploration (the Alpha Centauri series), the warp apparatus -- power system and warp modules or pods -- were too massive to build into a spacecraft capable of landing on and taking off again from an Earthlike planet. The compromise was the warp collar, a unit comprising both the fusion reactor power source (originally based on a Chinese tokamak design, hence the "donut") and the pods for the warp modules. This interstellar propulsion module surrounds the landing craft (a chemical-propellant, SSTO-based design) to generate the field for warp travel, and could be undocked for the lander to make planetfall.

Like any unmanned spacecraft, the warp collar has its own systems for limited maoeuvering and stationkeeping. It can be controlled either from the lander or any other (authorized) ship or control center to which control has been transferred. Since the unit never enters atmosphere, there is no particular need for streamlining or aerodynamic shape, and the final integration of the module's components is performed in space.