Echoes

"Echoes" is the twelfth episode of the third season of Stargate: Atlantis.

Synopsis
Teyla Emmagan starts seeing "ghosts" of Ancients wandering Atlantis, and soon other people start seeing them also. The visit from a group of Flagisallus are related, when they use the "ghosts" to warn the expedition of a Coronal mass ejection.

Previously on Stargate: Atlantis
Dr. Rodney McKay is trapped in the back of a sinking Puddle Jumper and encounters a Flagisallus. The creature leads Lt. Colonel John Sheppard and Dr. Radek Zelenka's rescue Jumper to McKay's location and they are able to rescue him.

Plot
Dr. Radek Zelenka, Ronon Dex, and Lt. Colonel John Sheppard are in a Puddle Jumper returning from an expedition on the mainland to document and hunt local fauna. As they return, Zelenka notices that Atlantis does not appear on the sensors properly. After adjusting their direction by forty degrees they are on the proper course towards Atlantis again.

Teyla Emmagan begins to see repeat visions of Ancients on Atlantis. First she is assumed to be under stress, but after a while other people in the city begin to see the same visions. Meanwhile, Dr. Rodney McKay and Sheppard notice a sea creature which McKay has named "Sam" (after Lt. Colonel Samantha Carter), because he believes it to be the same one that led Sheppard and Zelenka to rescue McKay from a damaged Jumper on the ocean floor. After using Atlantis' sensors to find another of the sea creatures, much larger than "Sam", they decide to take a Puddle Jumper to investigate closer. During a close encounter with the sea creatures, Sheppard and McKay develop intense headaches and McKay falls unconscious.

In the infirmary, Zelenka explains that the sea creatures emit a low frequency pulse and an electromagnetic field which, in combination, are very dangerous to humans. Very soon, most of the city is affected by this. Many victims are transported to the Daedalus, now orbiting the planet, but there are too many in the city to all be relocated.

During his recovery, McKay uses his tablet to locate an Ancient Bio lab dedicated to studying the native marine life and manages to translate what the whales are saying. The Lantea whales are warning that the Lantean Star is about to send out a gigantic coronal mass ejection (similar to a solar flare) straight at the Lantean planet and although the shield will protect Atlantis, the radiation wave will kill all plant and animal life on the planet and destroy the atmosphere, thereby depleting any breathable oxygen. The whales are congregating underneath Atlantis' shield for protection.

The visions that people have been seeing are a genetic memory that the whales have of this catastrophe, which happens every 15,000 years. The Lanteans were experimenting with communicating with these creatures when this traumatic event occurred. An Ancient ship named Adaris was near to the sun when the ejection began and most of its crew were killed immediately by the radiation. The pilot managed to jump to hyperspace and overtake the radiation wave before it reached Atlantis and warn the people there.

Now knowing what is happening, the team consult the Atlantis database and discover that the last time this happened the Ancients managed to temporarily expand the city's shield to encompass a large percentage of the planet's surface. Unfortunately, with only one functioning Zero Point Module, McKay is only able to expand the shield by a radius of a few kilometers.

In order to save Atlantis as well as the planet, Sheppard comes up with the idea to transfer the ZPM to the Daedalus and move the ship into position between the sun and the planet. When the coronal mass ejection begins, the shields aboard the Daedalus (boosted by the ZPM) successfully deflect the emission away from the planet, with the Daedalus sustaining only minor thermal damage in the attempt.

Notable Quotes
(Ronon's first meditation lesson)

Teyla: Feel your mind clearing, open to all that surrounds you. Embrace the silence.

Ronon: (snores)

Teyla: Ronon?

Weir: And how do you know he's a "he"?

McKay: Oh, because I cross referenced the renderings in the database with the whale outside and you'll see...the males have a rather prominent-

Weir: Uh, that's okay, nevermind...I'll take your word for it.

Sheppard: So these whales, did the Ancients say they're good eating?

McKay: Oh, you wouldn't.

Sheppard: I would.

Beckett: Their eardrums have been perforated.

Weir: How?

Zelenka: The whales are emitting an intense low-frequency-pulse, like a sonar, as well as an EM field. The combination is very dangerous to humans, particularly in such close proximity.

McKay: (yelling) It's the whales.

Beckett: (of the yelling to Weir) Hearing's been impaired. It should heal soon.

McKay: (still yelling) It's their echolocation. It's creating very powerful vibrations. The closer we got, the worse it became.

Zelenka: (yelling back) Yes. Yes. Rodney, we know.

McKay: Oh.

Sheppard: (yelling) What?

Beckett: They should rest.

Weir: Agreed.

Sheppard: The pain's going away; I think my hearing is getting better too. (to McKay) How 'bout you? (yells) Rodney!

(McKay gives no response)

Sheppard: Canadian Football League's a joke. Celine Dion is overrated. (yells) Zelenka is smarter than you are!

McKay: (yelling) Hey! I found mention of a bio-lab in the database! Ancient scientists used it to study animal life, we should check it out!

Sheppard: Okay...Meredith.

Ronon: How are you feeling?

Teyla: Much better.

Ronon: I walked the whole way over here and didn't see one ghost.

Teyla: Nor did I.

Ronon: Mind if I join you?

Teyla: (pointing at Ronon) If you fall asleep one more time...

Ronon: (bangs a wooden sword into the wall and gives it to Teyla) Hit me with that.

Goofs

 * When talking about the plan to intercept the stream Dr. Rodney McKay asks why the Ancients didn't think of it, Lt. Colonel John Sheppard answers that the Ancients here in the middle of a war: earlier in the episode they state that the previous event happened 15.000 years ago, whereas the war against the wraiths ended 10.000 years ago after one century of war, which means they were not at war during the previous event
 * Mckay explains that the mass expulsion will travel at 4000km/s, and that once it starts it will take less than an hour to reach Atlantis, which would mean that Lantea is less than 1.4400.000km from it's sun, which is closer than mercury to our sun, therefor Lantea would be too close to its sun to be able to sustain life, which could be slightly inconvienient for Atlantis