>>23548652But science fiction gives justification, and depending on whether it's hard or soft, goes as far to make the justification downright accurate to modern science fact.
A perturbation maneuver is a possible and implemented movement when spacecraft travel.
That DOES exist, and (for example) 2001: A Space Odyssey uses this exact thing as a plot device.
In the case that you want to argue that since it is still a 'what if' situation, then in that case, all fiction, ever, is fantasy.
And while that is true by the definition of fantasy, it isn't true by what defines something as being part of the fantasy genre.