The fission power reactor will be attached to the aft end of the main truss behind a thermal reflector. This shield will protect the cryogenic fuel from the heat generated by the drive as well as the reactor. The rear end of the reactor will incorporate a flange for mounting fusion drive. This connector will contain pyrotechnic elements to separate the drive system once the spacecraft reaches Alpha Centauri.
The fusion drive system was described in the Propulsion section. It will serve the additional function of providing attach points for the after particle shield and the chemical upper stages. The rear shield is needed during the deceleration phase of the flight when the spacecraft is flying backwards.
A weight table is included in the appendix as well a diagram of the structure.
