 Why did the man take Craig's picture when he arrived on Terra?
Flight Officer Robert Craig surrendered the tube containing his service record tapes and stood waiting while the bored process clerk examined the seal. "No specific destination," supplied the man as he punched a key on a small instrument, "Air-lock ahead and to your right. Craig obeyed the robot voice and began reluctantly to remove his flight jacket. "Mr. Craig," the psychologist said slowly, "you have my authorization for you to return to Terra as a private citizen of that planet. On the eighth day, two attendants, who showed the effects of massive doses of PON to protect themselves from the centrifugal force, had to carry a man out of the tank.
 The man is a customs official.
 Terran society identifies and monitors everyone.  The man is a customs official.  The photo is for Craig's job ID.  Craig is the first spaceman he had ever seen.