You don't have to be a 'rocket scientist' [=you don't have to be unusually smart] to understand the instructions.
Sales 'rocketed' from 1,000 units last week to 5,000 units this week.
The job is challenging, but it's not exactly 'rocket science'.
(..) - When we throw the switches, how long before the ship blows? - Ten minutes. - No bullshit. - If we ain't outta here in ten minutes... we won't need no rocket to fly through space. We're gonna need coolant for the air support system. You two go down and get all the coolant you can carry. (..)1979 Alien