"Wardens" are computer controlled robots required to check out and activate probes, travel around the parent craft, check leaks and other system failures and rectify them.
Because they operate far beyond the ability of remote control from Earth, they must have their own decision making and control capability built into them. Each Warden would be a self-contained spacecraft, weighing around 10 tons and powered by an on-board reactor, the Wardens would also deploy probes to investigate the interstellar environment during the cruise phase of the flight.
Smaller craft called 'Dustbugs' would be used to travel to a point up ro 200km ahead of the spacecraft, where they would create a cloud of cigarette-sized particles to intercept oncoming debris that could impact the ship. The cloud would be continually 'seeded' and maintained during the encounter with the target system.