The primary hull (or saucer section or saucer module) is a major component of the overall hull structure of a starship. In many starship designs, the primary hull is usually located above and in front of the secondary hull of the vessel. The primary hull of a starship often contains the most vital systems and facilities that are essential such as the bridge, computer cores, sickbay, science labs, and crew quarters. However, due to safety concerns, the main propulsion systems are usually housed in the secondary hull of a starship.