Asgard deceleration drive
A vitally important component of Asgard motherships, located on the ventral side of Asgard vessels. Like its name, the deceleration drive allows Asgard motherships to decelerate from high interstellar velocities. With the drive disabled, a ship would go plummeting out of control.
The deceleration drive is protected from direct attack by shield emitters which extend around the ship, but it is vulnerable to any explosive devices already bypassing the protective barrier of the shield.
Nemesis - Teal'c plants BF-8 against the Beliskner's deceleration drive which detonates some time later, spinning the ship out of control, into the atmosphere of Earth.