Surely the best person to fly this thing is not a race car driver but an astronaut... trained in this kinda thing. When the space programme started, they didn't choose people who were just used to travelling at speed. They chose people who were intelligent and exceptional pilots... key word is pilots. Just because the driver is used to going fast doesn't mean he can fly, so why would anyone think he was a better choice than the leading astronaut at that time? Someone who can fly and is also used to speed and has had psychological training to deal with such a situation. A race car driver just makes no sense to me at all.
You're telling us they must induce a second ice-age... but why? To what end. That's the goal. Why does a second ice age need to be induced bearing in mind that most plants and animals on earth will die?!
I stand by my previous thoughts on light speed travel. If light speed is possible, then everything changes. Everything is possible at that point unless you're adding to what we currently know about light speed travel. If that's the case, we NEED that information to understand how this could work.
I think the idea that we will all be destroyed by Mother Nature is a good inciting incident BUT what your characters seem to do about it makes very little sense right now. There needs to be something that grounds it in reality even if it is a SciFi. How would light speed travel induce an ice age??