One of my all time favourite books too.

I'd recommend 2312 by Kim Stanley Robinson if you've not read it - it's in a similar vein / world to the third part of Seveneves.

Thanks so much for the recommendation! I love Kim Stanley Robinson - Aurora and the Red Mars series are some of my all time favorite books - but have had trouble getting into the one of his I'm on right now (The Ministry for the Future). So I'm very pleased to get a different recommendation.