Project Barrier

The first starship to Centauri could only carry 120 lb. Of human being, yet required three specialist crewmen to handle it.

The solution was radical but relatively simple. Take a twelve-year-old girl weighing 100 lb., and impress the personalities of three ideal crew members on her mind.

These "shadow" crewmen then took the ship - with the girl - to the stars. Quite naturally the four became close friends - which would make for a decidedly complex problem when they returned.

From the psychiatrists's point of view he's merely restoring the girl's sanity. But from the crew's point of view it's murder!