The rear-end cap slowly chews its way up the length of the ship, feeding fuel into the engine. The amount of lithium hydride before and behind the living quarters is chosen so the engine uses most of the rear fuel accelerating: then, as the ship nears its destination, the end caps are released and the ship reversed so the forward section (now needed more for fuel than shielding) docks into the engine. The umbrella shield is discarded as excess mass, and will be rebuilt during refueling.
Deceleration poses an interesting problem, since one can hardly put an umbrella shield behind the main engine. But the hot breath of an engine like this should sizzle nearly everything within a light-day of the nozzle into ionic vapors—and the engine’s magnetic fields protect the ship from ions. An arriving ship appears as an enormous dim comet, with tail pointing along its path rather than away from the sun—and like comets of old, it can be an omen of change.