CBS has given a 13-episode second-season pickup to suspense thriller Salvation to air in summer 2018. There is no decision yet on CBS’ other summer drama series, Zoo. Salvation, which had a decent freshman performance by summer ratings standards and is owned by CBS, centers on Liam Cole, an MIT grad student, and Darius Tanz, a tech superstar, who bring Pentagon official Grace Barrows a staggering discovery – that an asteroid is just months away from colliding with Earth…