In hard sci-fi, how is the bombing of hiroshima and nagasaki viewed?
a destructive event
a joyous event
a learning experience
a bitter event
an enraging event

3.) A learning experience

Explanation:

Even though some of the other options might apply as correct in other contexts, when we are speaking about hard science fiction, it is a learning experience.  

The main characteristic of hard sci-fi is that it relies mainly on natural sciences, and it is, using that logical approached that it focuses on every event (and experience) as an opportunity to get an objective lesson, and in an event of such magnitude, to learn, analyzing logically its cause-effect logically based on its consequences, regardless of the social and cataclysmic impact it might have (or even considering them in that logical analysis).

do you have a picture of the cartoon?