Psawhn posted:

I am bad at gifs.

Anyway, I have a very nerdy and question about the final -esque action scene in the book. The better audience for this is probably the spaceflight thread, but I didn't want to CIA document FOIA with black bars over everything over there.

On their missed rendezvous to Watney they were going to miss him with a relative velocity of 11 m/s at a closest approach distance of 68 km, 39 minutes after the Ares 4 MAV finished its burn. They had about 30 m/s dV of RCS fuel and an unlimited dV (for our purposes) of ion engine at 2 mm/s/s. My experience tells me that that kind dV for the rendezvous is plenty, especially because they're traveling on an escape trajectory out of a planet 5x bigger than Kerbin so orbital mechanics doesn't come into play. At the very least, they could cancel out the 11 m/s relV at closest approach, then use the remaining 20 m/s of remaining RCS fuel to inch closer to Watney, arriving an hour or so later.

But the best way to adjust rendezvous is to burn as early as possible, as soon as they realize how badly they're going to miss. I mathed out that a 15 m/s RCS burn immediately, (at an angle 59.6 deg away from Watney), followed by turning on the ion engine for 43.35 minutes, then turning the ion engine around and firing the other way for the remaining 43.35 minutes, then a braking RCS burn of 11.8 m/s (at an angle of 51.1 deg away from relative velocity), will rendezvous Hermes to Watney at 0 m/s relV, only about 48 minutes after the book does. Is my math correct? Is the main reason Andy Weir wrote the existing sequence of events (complete with blowing the airlock for ~30 m/s dV) because he doesn't play KSP enough?