History Radio / Earthsearch

** The Angel computers use BedtimeBrainwashing to make Darv forget about the Paradise survey recording, by associating it with a [[YourWorstNightmare childhood nightmare]] to make his subconscious mind afraid of remembering the recording. Later when Darv gets insolent they induce a fear response by transmitting a subliminal signal to remind him of the nightmare. The 'nightmare barriers' guarding the Angel's central switching room use this in combination with holograms of monsters.

* TemptingFate

* YourWorstNightmare: [[BedtimeBrainwashing While he is asleep]] Angel One sends Darv a memory of a childhood nightmare, promising to save Darv if he forgets the Paradise recording.

* AncientKeeper: Several ArtificialIntelligence versions with the Moon Sentinel and the Custodian of the Past in Season 1, and Earthvoice in Season 2.

* ForbiddenZone: The uncontrolled zones that the [[BigBrotherIsWatching Angel's monitoring systems can't cover]]. [[ConstantlyCurious Darv]] keeps disobeying to explore them, and eventually discovers a hologram recording in the cabin of the previous commander about the discovery of Paradise, a habitable planet.

-->'''Telson:''' Tidy, a job for you. You're to stay by the entrance. If that door tries to close, you're to [[LivingDoorstop jam it with your body]] and yell.
-->'''Tidy:''' Thanks. I'm glad to be of use!

* ScienceFictionWritersHaveNoSenseOfScale: Averted; even travelling at near-light speed requires a [[GenerationShip multiple generation crew]] who still have to spend years in [[HumanPopsicle suspended animation]]. Though there's still the occasional ContrivedCoincidence for RuleOfDrama.
* SpannerInTheWorks: The Great Meteoroid Strike causes more damage than the Angels anticipated, removing their control of large parts of the ship and destroying their knowledge of TimeDilation.

* TamperingWithFoodAndDrink
** The Angel computers are secretly putting drugs in the food to repress the crew's puberty to keep them under their control. However Darv and Astra find the food galleries on the spaceship and start eating the food before it's been processed [[TemptingApple because it tastes better]].
** When they are AlmostOutOfOxygen and arguing what to do, Darv [[SlippingAMickey slips a double dose of morphon]] into the other's food so they'll fall asleep and use up less oxygen (and so he can carry out ''his'' plan without argument).
** In Season 2, the Angels decide our heroes [[YouHaveOutlivedYourUsefulness have outlived their usefulness]] and contaminate their food, but have to intervene to [[CantKillYouStillNeedYou stop their children from taking a bite off their plates]]. After that everyone makes sure to only eat food they've taken right off the trees in the food galleries.
* TemptingApple
** Astra and Darv are munching on them shortly before they give up their innocence by having sex for the first time.
** In ''Earthsearch: Deathship'', the protagonists are [[RuleOfSymbolism driven out of Paradise]] when a bomb hidden in an apple sprays them with KnockoutGas. The radio series just has them gassed by a surgical droid.
* TheLastManHeardAKnock: At the start of Season 2, the humans have the entire planet to themselves. Then after one of Astra's children is apparently taken by a shark, Tidy complains of having to clean up the tracks of a strange android who has been going up and down the beach at night. They follow the tracks and find the dead child with a breathing mask on back-to-front (causing him to drown) and marks from an android's manipulator claw. The kicker is when the android is later destroyed, and they realise its PD weapon is identical to their own. Which can only mean the Angels have returned.

* TractorBeam: Taken UpToEleven with an artificial black hole!

Telson, Sharna, Darv and Astra are the only crew members of ''Challenger'', a ten mile-long GenerationShip on a mission to discover a new planet for humanity to settle on after Earth's sun threatens to go nova. The entire first and second generation crew were killed when a meteorite struck the ship, an [[AIIsACrapshoot 'accident' arranged by the ship's sentient computers]], Angel One and Two, when the humans wanted to abort the mission and return to Earth.

** The Great Meteoroid Strike. The Angels become aware of a meteorite on a collision course, so they arrange for the crew to have a group meeting where the meteorite is going to impact, then turn off the sensors and asteroid defense systems for 'routine maintenance'.

* SpannerInTheWorks: The Great Meteorite Strike causes more damage than the Angels anticipated, removing their control of large parts of the ship and destroying their knowledge of TimeDilation.

** The Solarian Empire defeated their own Angels in the [[GreatOffscreenWar First Computer War]] and buried them in a vault on Kyros in case some of the circuits were still active. They're not happy when the protagonists detect a magnetic anomoly and start digging there.

* EnfantTerrible: Bran as a child appears to be a budding psychopath. [[spoiler:Turns out he's being mind-controlled by his sister Elka, committing wicked pranks to make her look good by comparison.]]

** [[spoiler:When Elka and the Angels urge Bran to kill their parents, he refuses. It's the first time he's refused his sister anything and causes him to start throwing off her influence.]]

* HeelFaceTurn: [[spoiler:After a number of BreakTheHaughty moments, Bran finally shakes off the influence of his sister Elka and refuses to go along with the Angel's plan to kill his father.]]

* AlternativeCalendar: When the Sentinel is told the ''Challenger'' left Earth in the year 2090 of the Third Millenium, it replies that the date is meaningless. However they're able to establish the launch date by saying it's 321 years after the first Moon landing, as the Sentinel is maintaining a museum on that historic event.

* HumansArePsychicInTheFuture: [[spoiler:Erika has MindControlEyes that the Angels have taught her to use, but no explanation for this is given in an otherwise hard-scifi series. Though there was a suggestion that the Angels had somehow influenced her in the womb.]]

* AdultFear:
** When the Angels discover that Astra is pregnant, they decide to steal the foetus without her knowledge and raise the child in another part of the ship.
** In Season 2 the Angels send an android to kidnap the children of the protagonists. The attempt only causes the accidental drowning of Astra's son. Then when they're forced to take refuge on the ''Challenger'', the Angels knock out everyone and put the adults in suspended animation for sixteen years while allowing their children to age normally. By the time they are revived, Bran and Elka are adults with unquestioning faith in the Angels.

* AbsurdlyDedicatedWorker: Tidy, to [[TeethClenchedTeamwork everyone's irritation]]. After it loses contact with the Angels after the Great Meteoroid Strike, it continues to clean up its allocated area for decades though there's no-one there to make a mess. When they settle on Paradise it insists on sweeping their footprints off the beach every night, even though the tide is going to do that anyway. On the other hand after they're kidnapped by the Angels, Tidy makes a point of [[UndyingLoyalty checking on their wellbeing every day they're in suspended animation]], for over sixteen years.

** The protagonists are surprised to find the Moon covered in [[DomedCity domed cities]] that are completely deserted, as the Moon has long since been evacuated due to the dangers of radiation from the sun, and returning there is now taboo. The inhabitants of Zelda Five have long since abandoned their own domed cities and now live [[UndergroundCity underground]].

* IndyPloy: Darv's plan for being AlmostOutOfOxygen. Not wanting to go back to ''Challenger II'' and join one of their societies (one which will likely kill them and the other will put him and Telson in PeopleJars), he knocks out Telson and Sharna, then burns the all fuel heading after their spacecraft, hoping to work out how to make up nine hours of missing oxygen on the way.

-->'''Telson:''' Tidy, a job for you. You're to stay by the entrance. If that door tries to close, you're to [[Living Doorstop jam it with your body]] and yell.

-->'''Telson:''' Tidy, a job for you. You're to stay by the entrance. If that door tries to close, you're to jam it with your body and yell.

** In Season 2, the Angels have built Android Surgeon-General Kraken to control the other androids and pilot the ship as they no longer have a human crew. However the Axon disabling beacon also affects Kraken, and it eventually goes insane and [[TurnedAgainstTheirMasters wrests command of the ship from the Angels]].

* OnlyOneName: The protagonists, justified as there's only four of them on the ship, so they don't need more than one name. When they encounter

** In Season 2, Bran loses confidence in the Angels when they hand over control of the ''Challenger'' to his father (who handles the crisis better than the Angels anyway), and Elka when the Angels reveal [[YouHaveOutlivedYourUsefulness just how expendable she is to them.]]

** Bran as an adult is a gun-toting megalomaniac. Unlike Thorden, no-one takes him seriously as they know he's just a puppet for the Angels. [[spoiler:Turns out he's a puppet for Elka, and this is all just an act.]]

* YouKeepUsingThatWord: A black hole is referred to as a hypothetical (which it was back in TheEighties) phenomena, but then Bran says he's observed them before, in which case they're no longer hypothetical.
* YourWorstNightmare: [[BedtimeBrainwashing While he is asleep]] Angel One sends Darv a memory of a childhood nightmare, promising to save Darv if he forgets the Paradise recording.

* AbsentAliens: Although aliens are mentioned (the protagonists are often [[HumanAliens mistaken for them]]) they never encounter any, though alien spacecraft are seen in a ShipwreckGraveyard in Season 2.