Iris - SCIFIPEDIA

Iris

<span class="SFPTagline"> From SCIFIPEDIA </span>

The Iris, is a titanium and trinium shield that covers the stargate in the series Stargate SG-1. In Stargate Atlantis, a similar energy barrier covers the gate but is referred to as a shield. The iris protects Stargate Command and Earth from unexpected and unwanted entrance through the stargate by hostile forces. When travelers dial a stargate protected by an iris, they are required to send a code through, identifying them as a permitted traveler. The SGC uses a GDO (Garage Door Opener) for this purpose.

Matter does not remain whole while traveling through a wormhole; rather it is broken down into monoatomic and subatomic particles. One of the functions of the stargate is to reassemble these into the original object upon arrival at the destination gate. Placing an object mere microns in front of the event horizon of the stargate prevents this reintegration process.

The iris is composed of many interlocking metal leaves that can be easily positioned in front of the event horizon in order to easily destroy any incoming object before reconstitution. At the push of a button, the leaves retract out of sight providing clear access to the event horizon of the wormhole.

The original iris was composed of titanium, which functioned well until it was sucked through the stargate by the gravity well of a black hole and destroyed. The current iris is composed of a titanium/trinium alloy, as are the ones on off world bases. The stargate in Atlantis was fortunate enough to come equipped with an iris of sorts, using a force field rather than mechanical components.

While the iris is generally effective, it has exhibited several vulnerabilities. A device possessed by the Tollan grants them the ability to pass through solid matter, and the iris, without harm. Small, high energy particles have also been able to materialize with the iris in place by appearing in the miniscule space between the iris and the event horizon. Prolonged exposure to these particles can damage the iris, which is why a particle accelerator was once used against it.

Numerous forms of radiation, electromagnetic and otherwise, have been shown to penetrate the iris. The gravity effects of a blackhole, and its temporal distortion also pass through the iris with ease. Radio waves of many frequencies also pass through the iris, which is vital to offworld communication.

The types of holograms used by Anubis, and presumably the The Asgard and Ancients, can be projected through the iris, and have been in the past. While the Goa'uld do not regularly protect their stargates, they have been known to shield certain gates. An energy shield was used on the planet Erebus in the episode "Orpheus." Erebus was a prison camp where slaves and traitors were sent as punishment to mine naquadah. The shield was deactivated by a specific coded energy signal.