Along with the other suggestions, there's also "Rogue System" which is a sort of "hard sci-fi" simulator/game. However, development has unfortunately stopped due to the developer suffering an injury.
Kerbal does sound like it'd be a good match for what you are asking though; It's not perfectly realistic but probably the best (only?) combination of all aspects - from building to launch to space manoeuvres to re-entry - and there are plenty of mods for making things more hardcore-realistic (planet gravity wells, reaction wheel saturation, angular momentum, signal delay, life-support, better aerodynamics).
Kerbal does sound like it'd be a good match for what you are asking though; It's not perfectly realistic but probably the best (only?) combination of all aspects - from building to launch to space manoeuvres to re-entry - and there are plenty of mods for making things more hardcore-realistic (planet gravity wells, reaction wheel saturation, angular momentum, signal delay, life-support, better aerodynamics).