The modern civilizations of the Third Imperium and its interstellar neighbors have had control of gravity for almost 10,000 years. Gravity control was discovered by the Vilani just prior to the development of Jump drive in the minus ninth millennium. The Solomani did not reach this level of discovery until the minus twenty-four hundreds. No civilization has achieved mastery of jump technology independently without first discovering gravity control, since this is a related technology.
Gravity control devices encompass four different applied technologies, all of which are used on a starship. The first is artificial gravity technology. The second acceleration compensation. The third, contragravity, or the attenuation of the effect of natural gravity fields. The last is the densitometer. The first three are discussed here. The last will be described in the sensors section.
Artificial gravity is produced through the use of gravity plates. A gravity plate produces a field of artificial gravity which is controlled by a local computer processor. Acceleration compensation is effected through the use of gravity plates and computer processing power. Gravity plates are installed directly beneath the decking. Support devices, such as the power couplings and control assemblies, are installed beneath the grav plates in the spaces between decks. A central inertial compensation detector (CICD) feeds information to the individual LCPs to adjust the gravity plates to counteract the acceleration effects of the maneuvering engines. The CICD can determine the actual orientation of the ship in real space. It also receives an input from the maneuvering engines and from external detectors that quantify resident natural gravitational fields. Each environmental compartment will have at least one LCP that regulates the gravity in the compartment. Larger spaces, like cargo bays or hangars, may have zoned gravity control, with more than one LCP for the whole compartment. Individual staterooms also sometimes have individual gravity control, allowing gravity in them to be set for the comfort of the inhabitants.
Grav plates operate independently of local natural gravitational fields. This allows a ship to maintain a gravity reference field in any direction, even perpendicular to the natural gravitational field of a planetary surface.
The 6 G limit of present inertial compensation systems is a result of the technology used to merge the gravitational fields of adjacent grav plates under the control of the CICD. No doubt future improvements in this technology, perhaps as soon as the next century, will allow ships capable of higher accelerations to be safely designed.
Some tinkers have attempted to use a ship's computer to override the CICD so as to produce quickly varying gravitation fields in specific compartments. This is generally done as a deterrent to boarders. The problem with this modification is that it requires overriding safety protocols. Unless care is taken to restore all safety subroutines, failure of the safeties at a later time can cause unexpected malfunction of the grav plates. The best defense against this kind of "grav pong" is to destroy the LCP. The gravity plates themselves can also be rendered inoperative, but this typically requires damaging the decking above the grav plates. Removing power from the compartment is also generally effective in smaller ships. Larger ships are likely to have a separate distribution system for gravity control. Most also have local emergency backup powercells installed to help maintain gravity even during a power outage.
Failure of the CICD or disconnection of the grav plate from the ship's control system results it the gravity plate 'sticking' at its present setting. This can result in a residual gravity field at a high level or odd orientation dependent upon acceleration conditions when the failure occurs.
Contragravity units produce 'lift'. Unlike a balloon a contragravity unit does not transmit its lift to the vehicle structure through its supporting structure. A contragravity system will shield the vessel from the effects of gravity by producing a field effect. In the absence of an artificial gravity field persons in the vessel would feel the effects of the loss of gravity. In a vessel with full gravity compensation the passengers and crew will notice no effect at all, since the artificial gravity field will insulate the interior of the vessel from the effect to the natural gravity field.
Contragravity components must be as carefully designed into a craft as its reactionless drives. They cannot generally be added later, without massive refitting of the vessel. Like the reactionless thrusters, the contragravity unit is generally controlled from the bridge, by the pilot. On truly large ships both systems are sometimes controlled from an auxiliary bridge during landing. Often this auxiliary bridge has a sophisticated viewing system specially designed to give the pilot a 3 dimensional display of the exterior of the ship to allow a better view of the landing area.
The unit itself consists of the Gravity Core, a chamber where the fields that counteract the effect of gravity are centered. The Core is attached to the structure of the vessel. On large ships a number of cores are often installed. A computer coordination system evens out the effects of the various cores allowing the pilot to set trim on the units to smoothly control the lift of the vessel.
The contragravity system CCU both receives and transmits information to the CICD. The CCU also receives input from the pilot's control console and sends the resulting control signals to the LCP attached to each Gravity Core.
Nested Gravity Devices
Gravity control devices can be made to shield the gravitational fields of other natural and artificial gravity fields. This characteristic of gravity control technology is obvious to anyone who has ever seen a 300 meter long vessel drift skyward, unfettered by the pull of gravity, or who has ever crossed the threshold of a ship and felt the unnerving jolt of a sudden realignment of "down". What does not occur to many laymen is that gravity effect devices can be nested, like the venerable egg within an egg, to produce the amazing technological marvels that are so common in a modern technological society.
A prime example of such technology is the gravitational lens. Modern space based laser weaponry would be impossible without this device, which consists of nested gravitational focal points, allowing immense gravitational forces to be concentrated in a very small area to create a gravity field so large even highly energetic X-rays can be bent and focused into a tight beam. The application of this effect to gravitational weapons, or even more effective inertial dampers has so far been unsuccessful, as the effect is very localized.
Nested gravity systems can also be used to shield artificial gravity fields and so prevent their detection. Military gravitic devices are commonly shielded in this way, making the use of any so called "gravity detectors" fairly useless for detecting military grade units. Since the desired effect is the dissipation, or rather screening, of active gravity fields, rather than their concentration, these devices have not experienced the technical difficulties associated with focusing nested fields and are a proven technology with a record for reliability stretching back to the First Imperium.
On board ship nested gravity fields are used for everything from the ubiquitous inline gravity pump, to the lift.