Stargate shield

{{Infobox Technology
|image=Stargate shield.jpg
|name=Stargate shield
|manufacturer=Ancient
|designer=Ancient
|function=Preventing unauthorized travels
|control=Varies
|material=Energy
|size=
|weight=
|power=Varies
|affiliation=
Lanteans
Tau'ri
Goa'uld
}}A Stargate shield is a Ancient shield that fulfills the same role as the metal Iris for Stargate Command. The most famous example of a shielded Stargate is the Atlantis' Stargate|one in Atlantis.

The Atlantis shield
Unlike the Iris protecting the Stargate on Earth, the shield on the Atlantis Atlantis' Stargate|Stargate is translucent; the suppressed Unstable vortex and the impact of objects prevented from rematerializing can clearly be seen. The Atlantis shield has yet to be breached by anything because it is placed so close to the event horizon that it blocks even subatomic particles, unlike Earth's iris which can only block objects larger than an atom. However, a "back-door" previously coded into the shield's control system by Dr. Rodney McKay allowed him to remotely deactivate Atlantis' gate shield from an off world location, preventing anyone else (including anyone using the shield's control panel in Atlantis itself) from reactivating it. {{Cite|SGA|Rising|The Return, Part 2}}


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Garage Door Opener|GDOs and IDCs are still used by both Atlantis' offworld teams and the Athosians, which usually prevents unfriendlies from entering the city via Stargate although that is not always the case. It is unknown what method the original Lanteans used to identify themselves as incoming travelers, but it is possible that the Puddle Jumpers themselves performed this function in some way. {{Cite|SGA|The Storm}}


The Atlantis Stargate shield generator is not built into the gate itself, but is located somewhere else in the control room, or elsewhere on Atlantis. It continued to function when the original gate was destroyed and replaced. {{cite|SGA|The Lost Tribe}}


Notable appearances
While exploring Atlantis' systems, Peter Grodin discovered the shield. While he was excited, Dr. Rodney McKay reminded Grodin that he was using their limited power and Grodin quickly shut it down. The shield was later used to block three Wraith Darts that followed Major John Sheppard's rescue team back through the Stargate from the Wraith homeworld. {{cite|SGA|Rising}}
During the Genii invasion of Atlantis, the Genii are able to penetrate the shield by forcing an Athosian to send his IDC and then faking a Wraith attack on Manaria, causing the Marines on Atlantis to lower the shield. Later, Sheppard manages to raise the Stargate shield as a full company of Genii reinforcements are arriving and locks the controls with his command code. As Ladon Radim is unconscious and with Sheppard's code locking out the shield, Sora Tyrus is unable to lower it and over 60 men die against the shield. {{cite|SGA|The Storm|The Eye}}
When Ladon Radim detonates a Genii A-bomb|nuclear weapon on M6R-867 to kill Cowen and his Elite Guard, Sheppard orders the shield raised. Moments later, the nuclear blast impacts the shield which prevents the blast from harming Atlantis. {{cite|SGA|Coup D'etat}}
When the Taranis Stargate falls into a pool of lava, McKay orders Chuck to raise the Stargate shield in order to prevent the lava from coming through to Atlantis. Some lava impacts the shield before the Taranis Stargate is destroyed and the wormhole disconnects. {{cite|SGA|Inferno}}
When Atlantis is taken over by the Asuran|Replicators, they have control of the Stargate shield along with the city's other systems. However, McKay is able to use a backdoor program he installed to drop the shield, allowing a team made out of himself, Doctor Carson Beckett, Doctor Elizabeth Weir, Lt. Colonel John Sheppard, Teyla Emmagan and Ronon Dex to enter the city and retake it. {{cite|SGA|The Return, Part 1|The Return, Part 2}}
During Michael's invasion of Atlantis, he raises the Stargate shield while in control of the city. Dr. Radek Zelenka is eventually able to gain limited control over Atlantis' systems back, including over the Stargate shield. With the shield under their control, McKay flies a Puddle Jumper from the underwater Jumper bay outside of Atlantis' Control Tower and signals Zelenka who lowers the Stargate shield. With the shield down, McKay uses the Puddle Jumper to dial the Stargate, vaporizing the back of Lastlight|Michael's hijacked Puddle Jumper parked in front of the Stargate. Zelenka is then able to regain full control of Atlantis' systems. This also has the incidental effect of saving the life of Ronon Dex who Michael was moments from killing when the Stargate shield went down and drew his attention. {{cite|SGA|The Prodigal}}
During the Raid on Atlantis, the now-Wraith Doctor Rodney McKay is able to use his backdoor program to lower the shield and allow a Wraith strike team into Atlantis that steals the city's ZPM. To counter this, an iris is installed as well as the shield. {{cite|SGA|Legacy: Allegiance{{!}}
Allegiance}}
Other shielded gates
Some planets, mostly Goa'uld-controlled, use a Stargate shield similar to, but less effective than, the one in place on Atlantis. These shields wrap around the entire Stargate instead of solely against the wormhole, allowing most particles to rematerialize.

Instances of Goa'uld-controlled Stargates protected by a shield include:
Erebus had a Stargate shield which required a signal to deactivate it, similar to Earth's Iris. Stargate Command was able to acquire the signal during a failed attempt by Bra'tac and Rya'c to escape to the Alpha Site, a fact that was witnessed by Dr. Daniel Jackson during his ascension, allowing him to relay this information to the SGC following his return and thus identify the signal based on the Alpha Site's Stargate access records. {{Cite|SG1|Orpheus}}
Tartarus also possessed a gate shield; however, the Kull armor|energy-absorbing suit worn by Kull warriors could easily pass through the shield, eliminating the need for an IDC. {{Cite|SG1|Evolution, Part 2}}
Although unconfirmed, Teal'c stated that Dakara would most likely be shielded. {{Cite|SG1|Threads}}

{{wikipedia|Iris (Stargate)}}

Category:Ancient technology>Category:Ancient technology
Category:Stargate>Category:Stargate
Category:Shields>Category:Shields