That sounds very viable, although it's going to be very frustrating to implement in javascript, which doesn't copy objects without a fight. I like the fact that it's calculating the trajectory gradually, I actually think that could be a fun in-game upgrade factor. Maybe your ship computer starts out being able to project 2 future frames per real frame, but you could upgrade that ratio in-game to much more so that you can more quickly see your projected trajectory. This has the added benefit of gating a potential performance bottleneck behind optional upgrades, so even if I can't afford 100 frames / frame of prediction on some devices, it's only an issue if a user on a slow device chooses to heavily upgrade that particular stat.