You're right, it's a fine line. I think it falls on the engineering side of the line because the hypothetical and the consequences in the Martian are pretty mun

You're right, it's a fine line. I think it falls on the engineering side of the line because the hypothetical and the consequences in the Martian are pretty mundane when you remove the setting and price tags. Imagine the same story but about a character abandoned at McMurdo Station in the present day. It would be a largely similar story with largely similar consequences. I think you might agree that it wouldn't be sci-fi. The world isn't really any different for the hypothetical of Watney getting stranded on mars. It's just an event that happens. A hypothetical like -what if Mars were already inhabited by aliens or -what if we could launch items to space for less than $.10/kg using X technology would be more on the sci-fi side of hypotheticals to me. The latter because it would open up the question of how the world would develop differently, even though it's just a simple question of technology. Edit: I should make it clear I loved The Martian, I'm just making the argument it could be called not sci-fi.