The space bridge appears in several universes. The exact properties of the space bridge vary, but typically they serve as a more convenient means of moving Transformers from one planet to another than the traditional means of space travel.
Space bridges are nonetheless distinct from Transwarp, in that their primary function is movement through space, not time, though the time taken to traverse a space bridge seems to depend on the technology used.
Generation One cartoon continuity
Generation One cartoon
The space bridge was apparently first conceived by Shockwave in 1984, as a means of transport back to Cybertron for the Decepticons stranded on Earth, and to allow them to ferry energon cubes to revitalize the planet .
The Cybertronic end of the space bridge is a fixture in Shockwave's command center, where it takes the form of a cylindrical tube, the top of which projects outside of the center's dome; it is through this open end that transportees enter or depart amid a gyser of energy. The Earth-based end of the space bridge is decidedly more flexible - the Decepticons frequently constructed new space bridges in various locations, normally in the form of large metal rings. The earth end of the space bridge appears as a silver metal ring in the ground.
In early uses of the space bridge, the dimensional portal could only remain open and stable for a maximum of 11 minutes. Early Space Bridge travel likewise proved somewhat unstable, and required the use of a small vehicle to safely transport any cargo. The vehicle was rolled into the ring on a railed structure, and then had to be piloted along "a beam of light." Some Decepticons displayed pronounced horror at being chosen for this unenviable task, as not staying on the light beam would cause the pilot and cargo to "cease to exist". In the very first practice run of the mechanism, the villains opted to use the captive Spike Witwicky, rather than risk any of their number.
After being knocked into the bridge by accident, Megatron proved able to traverse the bridge without a craft. Several Autobots likewise survived the trip in their vehicle forms. After this, the need for the craft seems to have been removed, as many Transformers and various cargoes would travel by space bridge with no vessel and no difficulties. On one occasion, two humans in a convertible even made the trip with no ill effects. The process could, however, still go wrong, as it did when the Decepticons attempted to convert a baseball field into a new space bridge site, and a malfunction blasted a small group of Transformers to an alien world of giants.
It's never made clear exactly how the space bridge works. Typical activation sequences show what appears to be a dimensional portal in the sky above the bridge, opened up by a blast of energy from the bridge ring; the bridge's contents (along with a great deal of rock and detritus) were then drawn into the portal, which then closed with a large discharge of energy. On the Cybertron end, the arrival is marked by a beam or gusher of energy arriving from deep space.
The space bridge technology was taken to its ultimate extent when the Decepticons constructed three colossal pylons that would generate a "space pyramid", the apex of which extended to Cybertron's location in another galaxy. Using this, Cybertron was transported into Earth's orbit for a brief period.Cybertron was later removed from Earth's orbit by an explosion; though never explicitly addressed, this event by rights should have left Cybertron much closer to Earth, possibly accounting for the ease of travel between the two planets thereafter.
The space bridge was used for planetary transportation once more when the Combaticon Onslaught wired his missile guidance systems into it and used its powers to redirect the orbit of Earth, intending to send it spiraling into the sun, only to be stopped by an Autobot-Decepticon team-up.
The space bridge fell into disuse when the Autobots reclaimed Cybertron in 2005, and throughout 2006, both they and the Decepticons were shown to rely on more mundane means of space travel (shuttles, self-propelled flight) in addition to space bridge-like devices called "warp gates" located throughout space.
The Headmasters cartoon
By the year 2011, the Autobots had studied and duplicated the space bridge technology for their own use. They developed their own space bridge network, allowing transport between Cybertron, Earth and the planet Athenia, with fixed space bridge receptors in each base (the transport beam was, of course, now the traditional Autobot orange, as opposed to the Decepticons' iconic purple). They did not, however, destroy the original Decepticon space bridge, as the Decepticons were unable to use it to travel to the planet due to Vector Sigma maintaining an Autobot balance of power. This proved to be a mistake, however, when the Matrix's energy was released in 2010 to cure the Hate Plague; this caused Vector Sigma to become destabilized, and the Decepticons were able to exploit this to use the space bridge to invade Cybertron.
When Mars was destroyed by Scorponok, the gravimetric balance of the solar system was disrupted, making space bridge travel to Earth unstable. This soon ceased to be an issue, however, when the Decepticons headed off on an interplanetary energy raid; in order to slow the Autobots down, Sixshot destroyed the Earth-based space bridge, causing a chain reaction that detonated the entire network.
The destruction of the space bridge left the only means to travel to Earth as the Trainbots and Battleship Maximus. This reduced ability to travel to Earth is one of the reasons for the heavy human involvement in the following battles, since Transformers are mostly unable to join the battle on Earth themselves.
Marvel Generation One comics
The space bridge was built by Lord Straxus's Cybertronic Decepticons, in response to the discovery that Megatron's lost group of Decepticons were alive and had set up operations on Earth. The bridge, which resembles a normal Earthen suspension bridge when not in use, has two halves; one which which remains stationary on Cybertron, and another which teleports to Earth. Passing through the bridge's central arch transports objects across vast distances, instantly and painlessly. Although a properly functioning space bridge is a far more pleasant mode of transportation than the more fuel-efficient Autobot version, the Trans-Time Dimensional Portal, an improperly calibrated space bridge will annihilate any object or being who attempts to pass through its arch. Lord Straxus illustrated this fact when Blaster sent him over the edge during transit.
The original space bridge was built from the vast body of Spanner, a neutral scientist who had been captured by Straxus's forces and forced to design the Bridge. After the space bridge was almost completely destroyed, a new Bridge was built to replace it.
Robots in Disguise cartoon
The Autobots used a complex network of hidden tunnels, bridges, and most notably, transwarp portals to travel to any location on Earth in a matter of minutes. This was called the Global Spacebridge.
Dreamwave Generation One comics
The space bridge was developed by the Decepticons as a means of exploring (and presumably conquering) other worlds far away from Cybertron. These bridges were
stargates small portals that could only be programmed for a certain number of people. Megatron himself underwent the first test of the space bridge. However, Optimus Prime collided with him before he entered. As it had been only programmed to accept one, the space bridge exploded, and both leaders were presumed dead. In actuality, they had survived, and been transported to Quintessa, where they remained for several millennia.
Space bridges are the main mode of traveling in the Unicron Trilogy. Unlike their Generation One counterparts, they do not appear to need the use of a fixed device at both ends.
They appear to change in variation from series to series, although this is likely simply due to art direction. In Armada, the Transformers are 'stretched' into warp gates, while in Energon and Cybertron, space bridges tend to appear as a large hole in the sky that may or may not have a clear ramp leading into it, although in Cybertron, there are examples of it being a simple series of invisible bridges between planets.
Movie (2007) continuity
Revenge of the Fallen film
After remembering his mission and seeing the All Spark symbols scratched out onto the ground by Sam Witwicky, Jetfire opened up a space bridge without warning his passengers what he was doing, and used it to teleport the group to Egypt where he explained the story of the Fallen and the other Six Primes, having taken them there because it was close to where he deciphered the Matrix of Leadership to be. It is possible that The Fallen uses space bridges as well as he is seen to teleport from place to place.
There is a network of space bridge terminals scattered across the galaxy, with the furthest from Cybertron being the Mars terminal, constructed by Thundercracker while the other Decepticons were on Earth.
Dark of the Moon film
Sentinel Prime creates a network of hundreds of space bridge Pillars to supposedly transport the Autobots to another planet, but in reality to bring Cybertron to Earth so they can rebuilt it together using Earth's natural resources and a human slave force.
After the Ark crashes on Earth's moon, the Decepticons take all but five of the Pillars, including the Control Pillar. The five Pillars and Sentinel are recovered decades later by Optimus Prime and Ratchet before being taken into NEST base. However, after Sentinel is revived, he eventually reveals his true colors and uses the Pillars to summon an invasion force of hundreds of Decepticons to Earth. Later, it is used to bring Cybertron to Earth, but the process is interrupted when Optimus knocks over the Control Pillar with Shockwave's laser cannon. The process is reinitalized by Dylan Gould who is then killed by Sam Witwicky by pushing him into the Pillar electrocuting him to death. The Control Pillar is destroyed by Bumblebee, causing all of the other Pillars to draw the Decepticon ships into Cybertron which then collapses on itself as it wasn't brought fully to Earth.
Transformers Animated cartoon
Space bridges are used to travel around the galaxy. This incarnation takes the form of a large, forked structure and works by generating a sphere of energy between the two prongs. The AllSpark was thrown into one to keep it out of Decepticon hands. Optimus Prime and his small band of Autobots were put in charge of repairing space bridges.
These and the AllSpark were apparently the key to the Autobots winning The Great War.
Back on the Energon farm Bulkhead had lots of time to study space bridge schematics and later passed his space bridge aptitude test with flying colors. His life long dream was apparently to become a Space bridge technician, a dream which many 'bots laughed about. Sentinel however remarked he was "a 'bot who knows his place." Bulkhead acheived this dream and was very happy about it.
Megatron plans to use some schematics to build his own with some help. With some additional help he completes it, but, as often is the case with Decepticon plans, it doesn't end well. During the Decepticon Uprisings, Team Chaar attempted to use a space bridge in order to travel to the Space bridge nexus on Cybertron but were stopped by Shockwave who was waiting for Megatron's signal to begin the attack. The network was later shut down by the Cybertron Elite Guard.
Blackarachnia used components from a transwarp generator in order to create a teleportation pod which she used to transform Wasp into a Technorganic being, however, after its use the chamber exploded.
The space bridge appears to have been constructed from a hollowed out asteroid as most of the outer edges are made of rock. The device itself takes the form of a giant ring where the green vortex is generated within. It was apparently constructed by the Decepticons and required a huge amount of Energon to function.
Megatron used the Space Bridge to launch a large crystal of Dark Energon though to Cybertron and re-awake Cybertron's dead to serve as his legion. However, before the horde of undead could exit the vortex, the Autobots were able to cause the bridge to self destruct, killing all of the Terrorcons in the vortex and heavily damaging Megatron in the process.
According to Ratchet, essential components of a space bridge include: a phase conductor, a plasma injector, a neutron shield, a tessaract, and an ample power source.
Fall of Cybertron
It is depicted as a huge tower with several prongs crowning the top of it, much like a rook in chess. It works by generating a portal that "rips the fabric of space and time" and so connects two potentially distant points of the galaxy together for a brief time in order to decrease traveling time and conserve fuel.
The portal it generates functions much like a singularity (a black hole) and is very unstable when the controls are destroyed. Any ships that approach it run the risk of being torn apart by the gravitational shear. Once opened, the portal will slowly destabilize until the point that it closes all together.