Following the Asuran invasion of Atlantis in 2006 and the city's subsequent recapture by the Atlantis expedition, the Daedalus was sent to periodically fly over Asuras to collect intelligence. On one such flyby, it was discovered that the Asurans had begun building a massive fleet of ships capable of posing a significant threat to Atlantis and Earth. In response to this, a plan was devised by military leaders on Earth to launch a first strike again the Asuran replicators as to prevent an attack. (SGA: "The Return, Part 2", "First Strike")
First strike on the AsuransEdit
The Apollo's first mission was to fly to Atlantis to use the new Horizon weapons platform in a first strike to destroy the Asuran's new ships. Colonel Abraham Ellis assigned Dr. Rodney McKay and Dr. Radek Zelenka to prepare the Horizon, consisting of six Mark IX Nuclear warheads and four decoys, for deployment. The Apollo exited hyperspace very close to the planet, and launched the Horizon. The six warheads were able to obliterate all the known shipbuilding facilities.
However, in retaliation, Oberoth launched a Stargate satellite over Lantea, and started to attack Atlantis. Because of the strength of the beam emanating from the satellite, Atlantis' shield would be depleted in a matter of days and the city would be destroyed. So, the expedition planned to submerge the city to allow the water to attenuate the beam intensity. However, the water did not stop the beam, it only slowed it down. Eventually, McKay and Lt. Colonel John Sheppard were able to devise a way for Atlantis to evacuate Lantea and fly to M12-578 through hyperspace by engaging the city's Stardrive. To enact this plan, a squadron of F-302 fighter-interceptors was sent to pull a large asteroid from the system to block the beam, which allowed Atlantis to lower its shield, activate the Stardrive, and leave the planet. However, the beam grazed the central control tower before the shield could re-close completely. Because of this, the city exited hyperspace far too early in the middle of nowhere, with only 24 hours of power left. (SGA: "First Strike")
Atlantis Adrift and ZPM raidEdit
With Atlantis adrift in space, the city was very low on power. In order for Atlantis to reach its new home planet, the expedition needed to obtain a Zero Point Module and, as the only known ZPMs were are on Asuras, they came up with a plan. Using a hyperdrive generator prototype developed by Dr. Rodney McKay equipped on a Puddle Jumper, they were able to reach the planet, using up a lot of power in the process.
Meanwhile, in the Midway space station, Colonel Samantha Carter and Dr. Bill Lee were contacted by Colonel Abraham Ellis. He informed her that Atlantis did not arrive on M12-578. Ellis had taken the Apollo to the nearest planet with a Stargate in order to inform Carter of the situation. Ellis then decided to head back to 578 and dial back in one hour. When Carter and Lee later arrived on a planet in the Pegasus galaxy, Carter contacted the Apollo, which quickly beamed them both on board. Assuming that Atlantis dropped out of hyperspace early, Carter devised a plan where they would have to power up the Apollo's sensors to extend their range significantly. They would follow Atlantis' original path, making a short hyperspace jump, scanning the area, and then jumping to the next area.
They descended onto the planet and landed on top of a building housing a ZPM hub. In order to prevent capture, Dr. Elizabeth Weir, and her reactivated replicator nanites, guided Lt. Colonel John Sheppard and Ronon Dex to the ZPM, avoiding an encounter with a replicator on the way.
The mission was successful, however, McKay discovered a disabled line in the Asuran base code that would force them to attack the Wraith. However, the only way to reprogram them was to update their computer core manually. Risking everything, Sheppard and Ronon went back into the city. They formed an Anti-Replicator field around the core, using the Jumper's cloaking field, to buy them some time and began trying to reactivate the code. Unfortunately, the process took too long and the Asurans managed to counter the field. With hundreds of Replicators heading toward the core, Weir left the Jumper in an attempt to stop them. Ignorant of her true purpose, McKay attempted to disable the nanites and kill her, but the command failed to work.
She confronted Oberoth and made physical contact with him, connecting herself to the Asuran network. She used her access to freeze all of the Replicators and fool Oberoth into thinking he had captured the team to give them time to escape. Sheppard, not wanting to leave Weir behind, went to search for her. However, Oberoth began to resist her control over the network and managed to physically grab her arm. She pleaded for Sheppard to run and leave her behind. Sheppard was forced to run back to the Jumper and escape without her. (SGA: "Adrift", "Lifeline")
Escape from AsurasEdit
Frantically trying to interface the Zero Point Module with the Puddle Jumper in order to open a hyperspace window, an Asuran cruiser appeared in front of them. Fortunately, they were saved when the Apollo arrived, weapons firing, having found Atlantis and came to help once they learned of the team's plan. The Apollo distracted the Asuran cruiser pursuing them long enough for the Jumper to land in one of the 302 Bays and then jumped to hyperspace without either ship suffering any major damage. (SGA: "Lifeline")
Back in Atlantis, they were able to install the Zero Point Module, and the city became fully powered. McKay found them a new home planet, M35-117, a planet with a large ocean, like Lantea. He purposely left out a group of planets during earlier considerations, so the Asurans could probe Dr. Elizabeth Weir's mind and still never find Atlantis. The city jumped into hyperspace, and arrived over M35-117. Lt. Colonel John Sheppard then went into the Control chair, where he could pilot and land the city. After a rough re-entry and landing, Atlantis was safely on the ocean with plenty of power left in the ZPM. Atlantis would remain on its new planet until 2009, when it would leave for its first home: Earth. (SGA: "Lifeline", "Enemy at the Gate")