How do you do the turret part in dead space?

Answer 1

There are two turret objectives in Dead Space, the first is in Chapter Four when you have to destroy asteroids and keep the ship's health up for about one minute so that captain Hammond can turn on the Ship's defence system.

The other turret mission comes later in Chapter Eight when you battle a slug type alien boss and you have to dismember its limbs to kill it while blowing up the debris that it throws at you to keep the ship's health up. The slug boss is a little easier.