REPLICATORS

Technologically advanced "bugs," Replicators are programmed by the creators with only one objective: self replication. Anything and everything that interferes with this plan of infestation, annihilation and duplication is immediately at risk.The world where the Replicators originated is actually in our own Milky Way galaxy. A corrupt and childlike android, Reese, created the Replicators to be her "toys," but also capable of defending her from threats. As their creator, she also passed on to them her own design flaw. As the inhabitants of her world feared the toys, and tried to destroy them, she ordered them to "replicate at all costs." She quickly lost control, and the Replicators annihilated her civilization, and her own creator in the process. After the Replicators left, Reese went into a deep depression and deactivated herself.Replicators are composed of hundreds of individual blocks, which are comprised of whatever substance the original Replicator has consumed. It is unclear how many blocks make up a standard Replicator, but two Replicators are required to make a third, and thus exponential growth. It takes only a few blocks to replicate new blocks, and in a few hours Replicators can breed from a handful into hundreds.There are different kinds of Replicators, depending on what the creatures require to achieve their goals. The most common is the "spider" Replicator, with four legs and wing-like flippers on its dorsal side. Another Replicator is much larger and insect-like, appearing in the general shape of a giant fly. It also has four legs, but enormous "wings" allowing it to roll on its back when it lands on the floor, then righting itself. It can also leap great distances.A third type of Replicator is an assemblage of many thousands of Replicator blocks, which comprise a single, story-tall mother Replicator, capable of siphoning, regulating and energizing an enormous amount of power. Logically, the mother Replicator may also coordinate the activities of all other Replicators.Replicators generally operate in groups, but it is unclear how their social structure is organized, and there seems to be no apparent means by which they transmit and receive information to and from one another. Despite this absence of information, they are very effective at cooperating with each other to achieve their objectives.

If need be, Replicator blocks can simply form a "wall" to block aggressors who would impede their objectives. Goa'uld and other energy weapons are incapable of stopping Replicators, though the sheer force of such a blast does "halt" them for less than a second. Human weapons, which launch projectiles, are much more effective, causing the blocks to break apart from one another. However, this can only solve problems for a few moments; the Replicators reassemble with a vengeance and come again. Once shot a second time, the blocks do not tend to reorganize. Generally, Replicators will not attack unless they are threatened. They can, in fact, clamor over and past an individual without a hint of malice; but once they are fired upon, a vengeful subroutine in the Replicator makeup emerges, and the creature becomes a serious threat. Their highly acidic "spray," used to help break down metal alloys to create new blocks, is deadly.Replicators have been a serious threat to the technologically advanced Asgard empire, which has exhausted all unilateral options within their arsenal of ships and weapons. The Asgard have, on more than one occasion, come to Earth seeking help. Recently the Asgard, through studying the android Reese, located an additional command within her: "Come forth." The Asgard used this command on every known Replicator throughout the galaxies, and once they were all gathered in one place (the Asgard home planet, Halla), the Asgard intended to activate a time-dilation device and trap the Replicators in a time bubble. Unfortunately, the Replicators reversed the device before it could be activated, allotting themselves hundreds of years (in a matter of normal days, relatively speaking) to consume every technological component on the planet and conserve energy -- evolving into humanoid forms, made up of microscopic nanites rather than blocks. SG-1 infiltrated this world and successfully reversed the device with help from the Replicator Fifth, but not before billions of Replicator blocks were forged, covering the entire surface of Halla, perhaps miles beneath as well. The fate of the Replicators is still unknown, but the Asgard now theoretically have hundreds of years to solve their malfunction, as the Replicators remain trapped in a temporal bubble, inside which time is moving very slowly.

SIEGE OF ATLANTIS (II), THE
A second attack by the Wraith on the city of Atlantis, drawn out over a period of several days, and the first faced by the expedition from Earth. (The first siege took place some 10,000 years earlier, when the Ancients still occupied the city.) Originally three Wraith hive ships were detected, but that number would escalate after the city received aid from Earth. The battle would end with an ingenious plan that could conceivably prevent the Wraith from ever returning.

LONG-RANGE SENSORS
A single Wraith Dart arrives in the city and begins scanning its structures. Dr. Elizabeth Weir orders the population confined to their quarters. Puddle Jumpers are deployed to deal with the threat and one is destroyed, killing officers Markham and Smith. After it completes its scans the Dart transmits a message into deep space and self-destructs -- but, unbeknownst to the expedition team, the pilot is beamed safely into the city. Dr. Zelenka scans that region and locates three Wraith hive ships. If they maintain course and speed they will be over the planet in two weeks.

RECONNAISSANCE
Zelenka calculates at least three hyperspace "pit stops" the hive ships must use, either because their hyperdrive technology is limited or they must gather food to sustain their journey. Major Sheppard and Teyla fly a Puddle Jumper through a nearby planet's Stargate to gather intelligence on the threat. When they arrive they are forced to witness the culling of that world, but the Jumper is able to save a few inhabitants before returning to Atlantis.

A TELEPATHIC MESSAGE
Realizing Teyla is able to communicate with the Wraith's telepathic network, Dr. Heightmeyer instructs her to think back to the time when she and her father were captured. But during two of the sessions a Wraith manages to take control of her instead, to deliver a message: "Nothing can stop us." But she is able to ascertain that the Wraith are more interested in getting to Earth than taking Atlantis. Meanwhile, the Atlantis Alpha Site's location is discovered by the Wraith.

THE SATELLITE
With hive ships in range of the Atlantis system in 49 hours, Dr. McKay deduces their last hyperdrive stop will be in range of the last remaining Ancient defense satellite at the far end of the solar system. Because its power cells have been depleted for 10,000 years they won't see it as a threat, but a single naquadah generator can at least partially charge the weapon, which when powered should be able to destroy the ships. McKay, Dr. Grodin, and Miller are sent to reconfigure the satellite. After one successful shot the rerouted circuit pathway fries. The two remaining hive ships and their escorts destroy the satellite (with Grodin aboard), but they also briefly halt their approach to rethink their strategy.

DART ASSAULT
Before the hive ships reach orbit they send out multiple squadrons of Darts to attack the city at night. At this point, reinforcements have arrived through the Stargate from Earth, including multiple troops with advanced rail gun weaponry. A command chair in the city is manned by Major Sheppard, who launches the remaining Ancient drone weapons against the attackers to fight off the ships.

NEGOTIATING FOR WEAPONRY
Dr. Weir travels to the Genii homeworld to meet with Prenum, hoping to negotiate for some of their weapons. Meanwhile troops are deployed throughout Atlantis to eliminate Wraith soldiers that were beamed down via the darts. Dr. McKay, Dr. Zelenka and Dr. Beckett use the command chair to try and automate Puddle Jumpers so that the Genii weapons can be placed within them and sent into the bellies of the hive ships without the loss of pilots.

THE SECOND WAVE
When the hive ships enter orbit they release a second wave of darts that rain down upon the city. The command chair is not allowing Sheppard to interface with the Jumper remotely, so he is forced to take the Jumper into the hive ship himself, armed with one of the Genii nuclear warheads.

DAEDALUS ARRIVES
Just before Major Sheppard sacrifices himself he de-cloaks the Jumper and Asgard beams transport him aboard the Daedalus, which has finally arrived. The Jumper detonates, taking out the second hive ship. Colonel Caldwell, commander of the Daedalus, orders the Z.P.M. beamed to Atlantis. Using the Asgard beams to transport nuclear weapons into the hive ships, the last carrier is successfully destroyed. The Wraith cruisers hyperspace away and all remaining darts make a kamikaze run. Fortunately the Z.P.M. is connected and powers the city shield,

COUNTER-ATTACK
With deep-space sensors returned, 12 more hive ships are detected. The Daedalus is sent to stop them at their next hypderspace stop, and the Asgard beams are successful at depositing warheads inside of two of the ships before the Wraith engage countermeasures preventing any more. With ten vessels remaining and no way to win the fight the Daedalus returns to Atlantis.

THE SIEGE
The Daedalus returns to Atlantis in time to land on the East pier just before the ten remaining ships arrive, pelting the city with energy weapons fire. With the intensity of the hits the Z.P.M. will only maintain the shield for a matter of days. The senior staff gathers in the situation room to come up with a plan and realize that if the Wraith thought that Atlantis was destroyed, there would be no reason to remain. The coordinates to Earth would be lost and they would depart.

DETONATION 'FLASH'
Teyla links telepathically with the Wraith to greater affirm this ploy. Surprised at the sudden change in strategy, and not wishing to aid the Atlanteans by destroying the city they are attempting to access, they cease fire. The Daedalus drops a nuclear warhead just above the city's shield, which detonates, and Atlantis switches from the shield to a Puddle Jumper's integrated stealth device, cloaking the city-ship.

AFTERMATH
The ploy works. Believing Atlantis has been destroyed, the hive ships and their escorts depart. Preliminary accounts estimate the casualties at 40 losses, perhaps more. The injured are sent through the Stargate to Earth, and with the threat long-gone, Atlantis de-cloaks again.