History Recap / StarTrekS2E3TheChangeling

* AIIsACrapshoot: Nomad, a deep-space probe, clearly had an incident with what it calls "The Other", which altered its structure and programming, causing it to [[InstantAIJustAddWater become self-aware]]. Part of its new programming includes the sterilization of life as a prelude to alien colonization.
--> '''Spock:''' ''(mind-melding into a MachineMonotone)'' [[IAmTheNoun I am Nomad.]] I am performing my … function. … Deep emptiness … it approaches … collision … damage … blackness. … I am the Other. I am Tan-Ru … Tan-Ru … Nomad … Tan-Ru … error. Flaw. Imperfection. Must … sterilize.\\

Rebirth … [[FusionDance we are complete]] … much power … ''gan ta nu ik-ta Tan-Ru'' … [[ThankTheMaker the Creator]] … instructs … search out … identify … [[KillerRobot sterilize imperfections.]] … We are Nomad … we are Nomad … we are complete. We are instructed … our purpose is clear … [[KillAllHumans sterilize imperfections … sterilize imperfections]] … [[MadnessMantra Nomad — sterilize — sterilize — NOMAD — STERILIZE —]]

* BlueAndOrangeMorality: Nomad is simply a computer carrying out (the garbled remnants of) its programming.
* BreadEggsBreadedEggs: Nomad / Tan Ru's programming is a rare dramatic example. Nomad's orders: Seek out new life forms. Tan Ru's orders: Collect soil samples and sterilize imperfections. [[FusionDance Final result]]: Seek out and sterilize imperfect life forms.

* CooldownHug: Kirk gives Spock one after a Mind Meld goes bad.

* EasyAmnesia: Nomad claims he's completely erased Uhura's mind, yet she is nearly "re-educated" by the end of the episode.
* EurekaMoment: In the final confrontation with Nomad, Kirk, after confirming several times that Nomad will "sterilize" anything that is imperfect or in error without exception, gets the idea to convince the probe that it itself is imperfect, [[LogicBomb and by its own logic should be eliminated]].
* ExactWords: Kirk asks Nomad if he destroyed the system where they found him. He answers truthfully, "Not the ''system'', but the biological infestation."
* FusionDance: Spock's mind-meld with Nomad reveals that, after their collision long ago, Nomad and Tan-Ru underwent one of these as they merged and self-repaired. The "new" Nomad kept the Earth probe's name, the alien probe's power and hardware, and part of each other's programming (settling on "search out … identify … sterilize imperfections").

* HatesBeingTouched: Nomad. Trying to touch it is not a good idea. Whether or not this is because it interprets any contact as an attack is not known. It will, however, allow itself to be touched if Kirk orders it to do so.
* ImStandingRightHere: Bones is clearly offended when Nomad says that he "functions erratically."

* ItRunsOnNonsensoleum: How Nomad is powered.

* JustTestingYou: After Kirk asks Nomad why Nomad refers to him as 'The Creator', Spock quickly interrupts, telling Nomad that 'The Creator was just testing your memory banks'.

'''Spock:''' No, sir.

** Also subverted earlier in the episode. Nomad came to see that Kirk (who it still thought was its creator) also qualified as an "imperfect" being. When Kirk asked it how an imperfect being could have created a perfect machine, Nomad simply concluded that it had no idea.

* OnlyMostlyDead: Scotty, but he gets better.
* OnlySaneMan: Scotty is the only crew member who objects to bringing a planet-sterilizing superweapon aboard the ship.
* PintsizedPowerhouse: ''NOMAD'', 500 kilos and a metre long, can knock out the ''Enterprise'' shields with just three blasts.

* PokeInTheThirdEye: The meld with the probe's artificial mind goes seriously wrong, to the point that Spock is sent into a near catatonic state as NOMAD takes control of the meld. Kirk (who NOMAD fortunately respects as its creator) has to order NOMAD to let go of Spock and drag the Vulcan out into the hall to recover.

* SnapBack: Uhura is back to normal by the next episode, despite last being seen being taught to read again and only being able to speak Swahili. An earlier draft of the script had Nomad explaining it had not purged her brain completely -- her memories and experiences were intact, but her ability to express ''language'' was wiped. This line was probably cut for time. They probably taught her Swahili first because it was her original language. (By the way, she first says ''Sikumbuka'' -- "I can't remember" -- then ''ina mbwa ni tufe,'' "the dog has a ball.") The Creator/JamesBlish novelization still has this version.

* UnwittingInstigatorOfDoom: Neither Jackson Roykirk nor the aliens that created Tan-Ru had any idea that their respective probes would become damaged, then meld with each other with the garbled remnants of their respective programmings also melding in such a way as to create an OmnicidalManiac capable of wiping out four billion humans, [[NightmareFuel as well as any other hapless civilizations who Nomad happened to stumble upon]].

* WeComeInPeaceShootToKill: Kirk assures Nomad that they mean no harm, moments after firing a photon torpedo at it. And then ''Nomad'' states that its mission is non-hostile, moments after pummeling the ''Enterprise'' with powerful energy bolts.

* ThisCannotBe: Kirk when told the entire inhabitants of the system have been destroyed, then when told that Nomad just absorbed the energy of a detonating photon torpedo with no damage.

The episode starts off as most episodes start off: with the ''Enterprise'' on its way to a planet for Kirk to screw around with. Only, this time … there's no planet. The entire system they were assigned to go to has been [[ApocalypseHow wiped out of all organic life forms]], leading the crew to wonder just what the hell is going on. The answer comes in the form of a tiny pod firing massive amounts of photon fire at the ship, resulting in a weak retaliation and the most ludicrous exchanges known to mankind:

->'''Spock:''' We just got attacked with a blast equivalent to ''90 photon torpedoes''. Ship's shields down by ''20%''.\\
'''Kirk:''' Fire photon torpedoes.\\
''(torpedoes are launched, [[NoSell they do nothing]])''\\
'''Spock:''' No effect, the probe that fired the blast absorbed the torpedo.\\
'''Kirk:''' ''[incredulous]'' How can that be? ''Nothing can withstand a photon torpedo blast.''

Um … yeah.[[note]]Maybe they just assumed it was a spaceborne GlassCannon?[[/note]]

** Also subverted earlier in the episode. Nomad came see that Kirk (who it still thought was its creator) also qualified as an "imperfect" being. When Kirk asked it how an imperfect being could have created a perfect machine, Nomad simply concluded that it had no idea.

Anyway, Kirk orders a hail to the probe, which inexplicably stops its attacks. After some exchanges of TranslatorMicrobes, the probe, called "Nomad", ceases hostilities, referring to Kirk as "[[ThankTheMaker The Creator]]" in the process. It's brought aboard, against the concerns of [[OnlySaneMan Scotty]], and is let loose on the ship. [[TemptingFate This can't possibly go wrong, can it?]] I mean, it's not possibly like it's capable of or willing to KillAllHumans and -- oh, wait, it's shown to have the power to annihilate an entire planet's worth of organics, and tells the crew that its mission is to "sterilize all imperfect biological organisms". Right then, moving on …

The FanNickname for this episode is "The One with Nomad". The story for this episode was the basis for that of ''Film/StarTrekTheMotionPicture'', resulting in one of that film's (many) derogatory nicknames being ''[[IncrediblyLamePun Where Nomad Has Gone Before]]''.

With time running out, and information on what happened to Nomad still scanty, Spock somehow manages to mind-meld with the thing (never mind that it's ''a robot''), which causes two things to happen: Spock to talk like the robot [=McCoy=] keeps insisting he really is, and Nomad finding out that Kirk is a biological being and is, therefore, imperfect and a target for its eradication protocol. In an implausible bit of TechnoBabble, it turns out "The Other" is a probe called "Tan-Ru", sent by an alien society to collect and sterilize soil samples as a prelude to colonization, and they combined during a self-repair attempt into the current Nomad. How that gave it the ability to nuke a world is left to the imagination, and there is no time to speculate, as Nomad has shut down the life support systems of the ship, threatening everyone on board. After confronting the killer probe and confirming that its death orders have no loophole, Kirk does what he does best: confuse a computer to death, by dropping the LogicBomb that Nomad isn't perfect as it mistook him for its long-dead creator. This melts down two computers -- Nomad itself, and Spock's brain, as Kirk was never one for flawless logic, but luckily they're able to beam the probe off the ship before it blows itself up.

* KillEmAll: Nomad's "Prime Function".
--> '''Nomad''': My function is to probe for biological infestation. To destroy that which is not perfect.

* NamesTheSame: Played with InUniverse. Nomad mistakes '''J'''ames T. '''Kirk''' for '''J'''ackson Roy'''kirk'''.

** In the climax, Kirk convinces Nomad that [[HoistByTheirOwnPetard it is itself imperfect]] by revealing that its creator, Jackson Roykirk, is dead and that Nomad mistook Kirk for him. Then he says that Nomad made ''another'' error by not discovering the first error, and then committed a ''[[UpToEleven third]]'' error by not sterilizing itself after the first two. This sends Nomad into a VillainousBreakdown that leads to its self-destruction.