Reusable orbital propulsion exchange and Earth–Mars transportation system.
Hypothetical concept — not an existing SpaceX system
Ship forward. Collar. Boom. Shadow shield. Reactor and nozzle aft. The ship’s chemical engines stay mounted.
Starship-class ship does Earth to orbit, and Earth return.
The station performs the propulsion exchange.
The nuclear tug does the deep-space transfer.
The tug returns to Earth orbit and is reused.
The reactor stays on the tug. It is never loaded into the ship.
Study geometry, not a flight vehicle. Ship-class 9 m × 50 m. Booster-class 9 m × 71 m. Boom 130 m. Reactor aft of a shadow shield, about 200 m from the crew compartment. Planets are context, not to scale.