TARDIS

A TARDIS, ( Time And Relative Dimensions (or Dimension) In Space), is the vessel which the Doctor and other Time Lords use to travel through space and time. The "D" in the name may stand for either "dimension" or "dimensions"; depending on who is asked. Susan, the Doctor's granddaughter, said that she coined the name TARDIS. By popular usage, the name has come to mean any Time Lord time ships ("The Pilot Episode," "An Unearthly Child," "Lungbarrow"). However, some Time Lords, such as Castellan Spandrell and Romana have referred to the TARDIS as an "S/T capsule," with "S" presumably standing for "Space," and "T" standing for "Time." ("The Deadly Assassin," "The Pirate Planet"). The First Doctor often referred to the TARDIS simply as "the ship."

Transport
A properly piloted and working TARDIS is capable of transporting its occupants to (almost?) any point in space and time. It can hover or fly through space like a aircraft or spacecraft or "dematerialize" (vanish) and traverse the Vortex which connects disparate points in time and space until it "rematerializes" into another time and space. While it may, under certain circumstances, venture outside this universe, generally a TARDIS is confined to travel within this one. The Doctor's TARDIS, generally referred to as the TARDIS, is a Type 40 Mark I.

Protection of Occupants
TARDISes have many defensive devices, designed not only to protect the occupants, but also the ship itself.

These include items such as the HADS (Hostile Action Displacement System) ("The Krotons", " The Keeper of Traken"), which causes the TARDIS to dematerialise in the event of immediate danger and rematerialise close by, removing itself from the danger zone whilst still remaining available to its crew.

A TARDIS is also capable of "anchoring" itself onto another ship to not only stabilise itself, but also to allow the occupants to escape in the event of terminal instability ("break-up") (" Terminus") This is invoked by an automatic safety cut out.

Also mentioned in the classic series episode " The Daleks" is the concept of multiple locks within the single TARDIS lock presented to the outside world. There are a total of 21, and insertion of the key into the wrong lock will cause the entire assembly to melt, barring access to the TARDIS entirely. This idea was discontinued and no longer referenced in later years when posession of the TARDIS key was granted to several companions as well as the Doctor himself.

Certainly one of the best-known defense mechanisms a TARDIS possesses is the Chameleon Circuit, which allows the outer plasmic shell of the TARDIS to assume any form whatsoever in order to blend in with the surrounding environs.

Power Systems
TARDISes draw their power from a variety of sources, but their primary source of power is a dimensional link to the nucleus of an artificial black hole created by the legendary Time Lord Omega. Each TARDIS's individual link, and the nucleus itself, is known as the Eye of Harmony. ("The Deadly Assassin," "Doctor Who: The TV Movie")

Type 40 TARDISes also have an ancillary power station, which on the Doctor's TARDIS exists in the form of an art gallery, the exhibited works apparently being converted from matter into raw energy when needed. ("The Invasion of Time") The TARDIS's architectural configuration controls, in addition to rearranging the almost infinite number of rooms inside the TARDIS, can also delete them, apparently converting them and their contents into raw energy which is then dumped into the reactor core. This action can often give the TARDIS the added thrust it may need to escape from areas of gravity strong enough to otherwise defeat the TARDIS's helm controls. ("Logopolis," "Castrovalva") Both these systems appear to act on a very sophisticated application of the energy-mass equation formulated by Albert Einstein as E=mc2, which among other things, demonstrates that energy and matter are different forms of the same substance, and one can be converted into the other.

Vital Components

 * Before a TARDIS is fully functional, it needs to be primed with the biological imprint from the symbiotic nuclei of a Time Lord's cells. Known as the Rassilon Imprimatur, this gives them a symbiotic link to their TARDISes and allows them to survive the physical stresses of time travel. Without the Imprimatur, molecular disintegration would result, a safeguard against misuse of time travel, even if the TARDIS technology were copied. Once a time machine is properly primed, however, and the imprint stored on a component (a briode nebuliser), it can be used safely by any species. ("The Two Doctors")


 * Elements needed for the proper functioning of the TARDIS and requiring occasional replenishment include mercury used in its fluid links (The Daleks, The Wheel in Space) and the rare ore Zeiton 7. ("Vengeance on Varos").


 * The Doctor has on a number of occasions described his TARDIS as at least partially sentient and alive. Therefore some empathy must exist between the user and the machine.

The Doctor's TARDIS
The Doctor's TARDIS is an obsolete Type 40 Mark I that he borrowed "unofficially" when he departed his home planet of Gallifrey. All the other Type 40s have long since been (officially) decommissioned and replaced by new, improved models, although the Master does possess a Mark II Type 40 TARDIS, and the Monk's TARDIS also appears to be a Type 40. The changing appearance of the primary console room over the years implies that the Doctor does upgrade the TARDIS's systems every now and then. The TARDIS may also be capable of  periodically changing its own interior appearance ("The Invisible Enemy"). The TARDIS also has a secondary control room, and possibly more control rooms within its vast interior.

The Doctor's TARDIS appears from outside to be an ordinary 1950s style blue British police box (a phone booth designed for police communications). Although it is only slightly larger than a telephone box on the outside, the TARDIS is extremely large inside with a vast number of rooms and corridors. This is because the TARDIS is "dimensionally transcendental", meaning that its exterior and interior exist in separate dimensions. The Fourth Doctor once explained this to his companion Leela by using the analogy of how a larger cube can appear to be able to fit inside a smaller one if the larger cube is further away, yet immediately accessible at the same time. This application of transdimensional engineering was "a key Time Lord discovery ("The Robots of Death")."

Although it is supposed to blend inconspicuously into whatever time or environment it turns up in, the Doctor's TARDIS invariably shows up in the police box shape. This is due to a malfunction in the ship's chameleon circuit, the mechanism which is responsible for changing the outside appearance of the ship in order to fit in with its environment. Despite his considerable ingenuity in other fields and his ownership of a sonic screwdriver, the Doctor has been unable to fix this problem completely; the occasional temporary success has always been followed by a return to the status quo. The Doctor sometimes uses a "splinter" of the TARDIS which has the outward appearance of a jade pagoda ("Iceberg").

The Doctor's TARDIS has at least two console rooms, including a white-walled, futuristic one, and a secondary one which has wood panelling and a more antique, Edwardian feel to it. The cavernous, steampunk-inspired console room used by the Eighth Doctor and the more organic one used by the Ninth Doctor may be reconfigurations of either of these rooms or other console room entirely. (The author of this sentence prefers to believe that the Eighth Doctor's console room was merely a redecoration of the previous one, but that this was destroyed in the Time War and due to the telepathic nature of the TARDIS (and the fact that the Master is actually inside it) the ship regenerated, Time Lord-style, giving it an organic appearance.) The main feature of the rooms, in any of the known configurations, is the TARDIS console that holds the instruments that control the ship's functions. The appearance of the primary TARDIS consoles may vary widely but share common details; hexagonal pedestals with controls around the periphery and a moveable column in the center that bobs rhythmically up and down when the TARDIS is in flight. The secondary console was smaller, with the controls hidden behind wooden panels, and had no central column. The entrance to the TARDIS can be locked and unlocked from the outside with a key, which the Doctor keeps on his person.

A distinctive architectural feature of the TARDIS interior is the "roundel," a circular decoration that adorns the walls of the rooms and corridors of the TARDIS, including the console room. Some roundels conceal TARDIS circuitry and devices ("The Wheel in Space," "Logopolis (TV story)", "Castrovalva," "Arc of Infinity," "Terminus"). The design of the roundels may vary and include a basic circular cut-out with black background, roundels resembling washing-up bowls stuck to the wall, recessed wood paneling with a few decorative ones in what appeared to be stained glass, translucent illuminated discs, and hexagonal shapes with nodes in the center. Because the Doctor's TARDIS is so old, it is inclined to break down. The Doctor is often seen with his head stuck in a panel carrying out maintenance of some kind or another, and he occasionally has to give it "percussive maintenance" (a good thump on the console) to get it to start working properly. Efforts to repair, control, and maintain the TARDIS were frequent plot devices throughout the show's run. This creates the amusing irony of a highly-advanced space-time machine which is at the same time an obsolete and unreliable piece of junk.

The TARDIS is possessed of telepathic circuits, although the Doctor prefers to pilot it manually. Its controls are said to be isomorphic, that is, only the Doctor can operate them ("Pyramids of Mars"). However, various companions have been able to operate the TARDIS and even fly it. The Time Lords are also able to pilot the TARDIS by remote control, usually, as the Doctor once bitterly noted, so he may take care of "some dirty work they don't want to get their lily-white hands on ("Colony In Space," "The Brain of Morbius")." The Second Doctor once used a portable Stattenheim remote control given to him by the High Council to summon his TARDIS to him ("The Two Doctors"). The Rani also uses a Stattenheim remote control to summon her TARDIS, though the Master's compliment to her on this point in indicates she developed hers before the Time Lords on Gallifrey did ("Mark of the Rani" ). The TARDIS is also vulnerable to diversion or relocation by the Guardians, Eternals, and other immensely powerful beings.

Some of the TARDIS's other functions include the Hostile Action Displacement System (HADS), which can teleport the ship a short distance away if it is attacked ("The Krotons"). The cloister room on the TARDIS sounds the cloister bell when disaster is imminent. The interior of the TARDIS also exists in a state of "temporal grace", which is supposed to ensure that no weapons can be used inside its environs. This last function is also inconsistent in its application ("Earthshock").

At times the TARDIS also appears to have a mind of its own. It is heavily implied that the TARDIS is intelligent to a degree, and has a bond with those who travel in it. The Eighth Doctor once called the TARDIS "sentimental" (Doctor Who: The TV Movie"). The Doctor once even met a TARDIS which "died" after its Time Lord master had passed away (" Omega").

Other TARDISes
The Time Scaphe was a TARDIS precursor developed on Gallifrey during the reign of the last Pythia, shortly before Rassilon, Omega, and the Other seized power. The first true TARDISes were developed by this triumvirate ("Cat's Cradle: Time's Crucible"). During his attempt to steal the Fifth Doctor's positive matter form, Omega built his own TARDIS ("The Arc of Infinity").

The Master has his own TARDIS, with at least one other kept in reserve, which are more advanced models than the Doctor's and whose chameleon circuits function perfectly. Once, the Master tricked the Doctor into materializing his TARDIS around the Master's, creating a dimensionally recursive loop (" Logopolis") - repeating a situation that had previously occurred accidentally ("The Time Monster"). In his first encounters with the Doctor, the Master used a Type 40 Mark II.

Other Time Lords with TARDISes include the Monk and the Rani. The War Chief provided dimensionally transcendent time machines named SIDRATs to the alien race known as the War Lords. Gallifreyans have employed Battle TARDISes which fire "time torpedoes" that freeze the target in time.

Note on the Abbreviation TARDIS
Susan explained to Ian and Barbara that TARDIS stood for Time and Relative Dimension in Space. (An Unearthly Child.) A later adventure (The Time Meddler) revised this to Time and Relative Dimensions in Space. Most Doctors have since used the second, plural, definition, but the Ninth Doctor preferred to use the singular form.