Barton, at the beginning of the short story, is presented as a man who is absolutely committed to his job and is able to live by the logic of the cold equations, even when that necessitates him killing another being. Note what the text reveals when his computer tells him about the stowaway on board the ship:
He would, of course, do it. It was the law, stated very bluntly and definitely in grim Paragraph L, Section 8, of Interstellar Regulations: “Any stowaway discovered in an EDS shall be jettisoned immediately following discovery.”
There is no ambiguity in this statement, and the short sentence at the beginning of this quote highlights the finality of Barton's response. Even after Marilyn is discovered, and Barton realises that his stowaway is no dangerous man, but a teenage girl who is completely ignorant of the repercussions of what she has done, Barton still has to follow the law. However, what is different is the presentation of Barton after he has jettisoned Marilyn. Even though he knows that there is no other possible outcome, and after he has done what he can, he remains a deeply haunted man concerning what he has been forced to do. It is interesting that in the TV version of the short story, Barton is presented in a slightly more sympathetic light, as he even contemplates killing himself in Marilyn's place, only to realise that she lacks the knowledge to fly the shuttle. Barton at the end of the short story is walks with "the slow steps of a man old and weary." He is haunted by what has happened:
It seemed, almost, that she still sat, small and bewildered and frightened, on the metal box beside him, her words echoing hauntingly clear in the void she had left behind her:
I didn’t do anything to die for... I didn’t do anything...
Living life by the cold equations of interplanetary space travel necessitates a brutal, harsh and pitiless approach, and even an experienced pilot such as himself still finds this impossibly difficult to accept.