History Radio / Earthsearch

** 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 certain crewmembers [[YouHaveOutlivedYourUsefulness have outlived their usefulness]] and contaminate their food, but have to intervene to stop someone they want to keep alive from taking a bite off their plate. After that everyone makes sure to only eat food they've taken right off the trees in the food galleries.

** The Moon Sentinel and Spaceguard Six try to stop our heroes from getting to Earth because they're guarding it against potential threats. But the Angels actually are a threat to Earth.

* NotInMyContract: Tidy is a cleaning and garment-making robot, but its dexterity causes it to be used as a DoAnythingRobot to handle one crisis after another, ranging from burying a dead elephant to going into battle against {{Killer Robot}}s. It is ''not'' happy about this and doesn't hesitate to make its feelings known.
* ObfuscatingStupidity: In Season 2
** Darv pretends to be ignorant of what a central switching room is, so Solaria D will allow him past the androids guarding it to carry out repairs. Once inside it's a simple matter to pull the plug.
** [[spoiler:Elka pretends to be TheDitz when [[TheManBehindTheMan she's actually the real villain]], dominating Bran with her psychic powers.]]

* GratuitousPanning: Whenever the two Angel computers are speaking to each other, one is on the left and the other on the right. (Originally, due to the limitations of FM stereo receivers, this tended to cause a slight distortion on the vacant channel. Now that the series is only re-run on the digital Radio 4 Extra, the problem no longer arises.)

** Turns out the asteroid DeflectorShields serve well enough for a BrandishmentBluff. Averted in the novelisation when they're no use against Fagor -- the Angels lure him out of the ship, but they're only designed to destroy incoming objects. Fortunately there are actual weapons on the shuttle the protagonists are on, as Thorden has secretly armed it.

* HeadInTheSandManagement: ''Challenger II'' has [[AHouseDivided split into two societies after generations of conflict]]. One denies the existence of anything outside the hull of the spaceship. The other society rejects the offer of leaving on with the protagonists on the ''Challenger'', as the search for Earth seems to be just the kind of unrealistic pipe dream offered by past leaders to motivate and control their people.
* ImmuneToMindControl: [[spoiler:Elka uses her MindControlEyes on Sharna to make her hand over her firearm, but she's able to shake off the effects and grab it back as [[ItWorksBetterWithBullets she never loaded the weapon in the first place]]. She then points out that years of dealing with the Angels have made her more resistant to such tricks.]]
* ImprovisedWeapon: The Challenger isn't armed, but Telson flies it low over Zelda Five and turns on the DeflectorShields used to destroy incoming asteroids. He then threatens to destroy the entire planet if his captured crewmembers aren't handed over. Even after discovering the latter is a bluff, Thorden is still impressed.

* HalfTruth: The Angels describing Paradise as a DeathWorld. Isn't almost seven-tenths of its surface covered by water, which by the way happens to be undrinkable? Doesn't it have an axial tilt causing severe temperature changes that would inhibit the growth of crops? Isn't most of the land in the Northern hemisphere, where it can be affected by ice ages which have threatened global extinction several times? Not to mention an atmosphere that doesn't provide full protection from cosmic ray bombardment.
* MamaBear: Astra is the most timid member of the group, fearful of the way Darv deliberately antagonises the Angels, but when she becomes pregnant she's determined to raise the child on Paradise regardless of the risk, for fear that if the remains on Challenger, the Angels will take her baby from her.

-->'''Fagor:''' ''[gunfire]'' ''[gunfire]'' No-one! The cowardly vermin hide from Fagor. ''[gunfire]'' When Fagor finds them, Fagor kills! ''[[[PunctuatedForEmphasis gunfire]]'' Kills! ''[[PunctuatedForEmphasis gunfire]]'' Kills!

-->'''Recording:''' Hallo. [[YouAreNumberSix My name is Forty-One.]] I was born during the seventh generation and I was last activated during the hundred and tenth generation when I helped provide Karina of the Velos family with a daughter.

->'''Fagor:''' ''[gunfire]'' ''[gunfire]'' No-one! The cowardly vermin hide from Fagor. ''[gunfire]'' When Fagor finds them, Fagor kills! ''[[[PunctuatedForEmphasis gunfire]]'' Kills! ''[[PunctuatedForEmphasis gunfire]]'' Kills!
->'''Angel One:''' Fagor...
->'''Fagor:''' The murderer of the Lord Thorden!
->'''Angel One:''' Fagor!
->'''Fagor:''' So you're hiding in there. [[TheEasyWayOrTheHardWay Come out slowly and Fagor will kill you quickly. Come out quickly and Fagor will kill you slowly.]] ''[gunfire]''
->'''Angel One:''' Listen Fagor, there is no-one there. We are all around. We are the Angels: Angel One and Angel Two. We are the Challenger's control systems. ''[gunfire]'' All that has done is [[ComputerEqualsMonitor destroy one voice terminal]], Fagor. There are a million throughout--''[gunfire]''
->'''Fagor:''' Then Fagor will destroy a million voice terminals!

* CoolStarship: The ''Challenger'' is a ten mile long GenerationShip capable of reaching relativistic speeds. Its mission is to search for habitable planets, and it's equipped with sophisticated {{Terraforming}} equipment and two of the most advanced computers ever built. Building just one of them cost ten percent of the planetary resources of Earth.

** In Season 2, the Angels try to lure the protagonists into the Challenger, which has been extensively redesigned to make it appear to be another spacecraft. They deny this of course, claiming that a programming error caused an android to paint ''VOYAGER 30'' on the outside. Darv asks if the same programming error also caused it to add ''23RD EARTH TRANS-GALACTIC SURVEY MISSION'' as well.

* ShipwreckGraveyard: In the episodes "Supermass" and "Deathship" the Challenger is drawn into a black hole, only to discover its an artificial construct littered with derelict spacecraft. This is ''Spaceguard Six'', whose inhabitants are dedicated to protecting an Earth they've never seen by trapping any potential invader.

* SaveTheVillain: Telson makes it to the central switching room and finds their guardian angels are nothing more than a couple of circuit racks that could be smashed with a hammer. He decides they are NotWorthKilling, a decision he regrets when the Angels return to kidnap their children in Season 2.
* StayInTheKitchen: Averted; the crew draw straws on who goes on their first mission to a planetary surface, and the two women are selected. From then on they naturally fall into their Darv/Astra and Telson/Sharna pairings.

* MamaBear: Astra is the most timid member of the group, until she realises she's pregnant; then she's willing to take any risk because she's convinced (accurately) that the Angels intend to steal her child. This is why the Angels were stopping the crew from sexually maturing, because they would put the interest of their children first, as the second generation crew did when they voted to give up the Earthsearch mission.

* SpareTheVillain: Telson makes it to the central switching room and finds their guardian angels are nothing more than {{Brain In A Jar}}s that could be smashed with a hammer. He decides they are NotWorthKilling, a decision he regrets when the Angels return to kidnap their children.

** Astra and Darv are munching on them shortly before they give up their innocence forever by having sex for the first time.
** In the novelisation, the protagonists are [[RuleOfSymbolism driven out of Paradise]] when a bomb hidden in an apple sprays them with KnockoutGas.

* ThisIsUnforgiveable:
** Telson refuses to believe that the Angels are malevolent until it's revealed that they lied about Paradise being unsafe for settlement. When Darv and Astra send a signal that there's no high levels of radiation on the inner planets, he goes right for the central switching room the moment he finds its location on a schematic.

* LaserGuidedAmnesia: When Darv sees the Paradise survey report made by a previous commander, the Angels wipe his memory during suspended animation, because they want to conquer a developed world rather than colonise an undeveloped one. Darv does still remember some of the recording after his memory is jogged, but the Angels feel it's too risky to do so a second time as they still need the crew.

** The Great Meteoroid Strike.

* AllHailTheGreatGodMickey: The Earth Worshippers

** The crew leave their starship in a shuttle to explore the derelict ''Challenger II''. On returning they discover that [[KillerRobot Fagor]] has taken control of their own ''Challenger'' and is flying it away. It turns out they have enough fuel to catch up, but only after their air has run out. As if that wasn't bad enough, Fagor then sets out from their ship under its own power to finish them off anyway. [[spoiler:Fortunately this provides the answer to both their problems - the crew discover that Fagor's master had upgraded the shuttle with plasma cannons, and once they've destroyed the robot they realise they can turn the shuttle around and [[ImprovisedMicrogravityManeuvering accelerate backwards using the plasma cannons' recoil]].]]

* BenevolentAI:
** After two seasons of the malevolent version [[spoiler:Earthvoice averts the trope; though at first it appears otherwise, this is only to lure the Angel organic computers to their destruction.]]
** The Custodian of the Past doesn't do anything malicious, though Thorden keeps it locked away under his person seal and Helan responds to it with loathing, implying that it's also a freewill computer.

* UriahGambit: In ''Mindwarp'', one character is on trial for desecration--the penalty being death--but his lawyer gets the charge reduced to community service. Community service turns out to be being conscripted to fight a war.

* WetwareCPU: The human protagonists, who have been raised by the Angels, eventually discover that [[AIIsACrapshoot all such computers go mad with power]]. In Season 2, a concern is raised that the Angels may even have [[ParanoiaFuel incorporated themselves into their brains]].

* ShipwreckGraveyard: In the episodes "Supermass" and "Deathship", the Challenger is drawn into a black hole, only to discover an artificial construct littered with derelict spacecraft, from which they escape by reversing the gravity field.

* BrownNote: When Darv starts to openly criticize the Angels for not knowing about the TimeDilation issue, they induce a fear response by transmitting the signal used for the HypnoSleep illusion. A similar effect is used for the nightmare barriers.

** The Custodian of the Past doesn't do anything malicious, though Thorden keeps it locked away under his person seal and Helan treats like like an EldritchAbomination, implying that it's also a freewill computer.

** When the protagonists are on Solaria, one of the orbiting artificial suns used when [[PlanetSpaceship Earth was being moved to another solar system]], they search through the records of the crew to find out where Earth went, but only find routine technical reports. Then they play an unlabelled disk [[spoiler:that shows the commander of Solaria D calling on Earth to cut the tractor beams holding Solaria in orbit because its freewill computer has gone insane and is about to [[KillSat burn up a city]] unless its [[TakeOverTheWorld demands are met]]. The commander is then killed by a welding android controlled by Solaria D.]]

** When the protagonists are on Solaria, one of the orbiting artificial suns used when [[PlanetSpaceship Earth was being moved to another solar system]], they search through the records of the crew to find out where Earth went, but only find routine technical reports. Then they play an unlabelled disk [[spoiler:that shows the commander of Solaria D calling on Earth to cut the tractor beams holding Solaria in orbit because its freewill computer has gone insane]] and is about to [[KillSat burn up a city]] unless its [[TakeOverTheWorld demands are met]]. The commander is then killed by a welding android controlled by Solaria D.]]

** The crew leave their starship in a shuttle to explore the derelict Challenger II. On returning they discover that [[KillerRobot Fagor]] has taken control of their own Challenger and is flying it away. It turns out they have enough fuel to catch up, but only after their air has run out. As if that wasn't bad enough, Fagor then sets out from their ship under its own power to finish them off anyway. [[spoiler:Fortunately this provides the answer to both their problems - the crew discover that Fagor's master had upgraded the shuttle with plasma cannons, and once they've destroyed the robot they realise they can turn the shuttle around and accelerate backwards using the plasma cannons' recoil.]]

** The series begins with the previous commander of the ''Challenger'' announcing their return to Earth, just before the entire first and second generation crews are killed by the Great Meteoroid Strike. [[PronesiumReveal Astra then calls for the recording to be turned off.]]

* ImprovisedMicrogravityManeuvering

** The Angels were created as the control systems of the ''Challenger'', but being in control of everything on board, and regarding themselves as superior to the crew who become increasingly dependent on them over each generation, it's inevitable that they succumb to megalomania.

** 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. It's no surprise when Kraken eventually goes insane and [[TurnedAgainstTheirMasters wrests command of the ship from the Angels]].

** Solaria D was created as an artificial sun for the Earth while it was being moved to another solar system. [[spoiler:When its freewill computer decides to TakeOverTheWorld, it threatens to [[KillSat fry an entire city]] if control of the other artificial suns isn't handed over to it. The President only avoids this by cutting off the tractor beams holding it in orbit. The protagonists aren't happy on finding out Solaria wants to make contact with the Angels, and destroy it at the first opportunity.]]

** When the protagonists are on Solaria, one of the orbiting artificial suns used when [[PlanetSpaceship Earth was being moved to another solar system]], they search through the records of the crew to find out where Earth went, but only find routine technical reports. Then they play an unlabelled disk [[spoiler:that shows the commander of Solaria calling on Earth to cut the tractor beams holding Solaria in orbit because its freewill computer has gone insane]] and is about to [[KillSat burn up a city]] unless its [[TakeOverTheWorld demands are met]]. The commander is then killed by a welding android controlled by Solaria.]]

** Darv pretends to be ignorant of what a central switching room is, so Solaria will allow him past the androids guarding it to carry out repairs. Once inside it's a simple matter to pull the plug.

* AdamAndEvePlot: The protagonists end Season One by giving up the search for their long-lost home planet Earth, settling instead on the planet "Paradise", which they vow to make "their own Earth". It's very much like their Earth, except that it's two-thirds covered in saltwater oceans, has four seasons, and is the [[EarthAllAlong third planet from its sun]]. Cleverly, throughout the series they had dropped hints that "their Earth" was not the same planet as ours, but then covered them up with Expospeak: for example, the other planets of their solar system have different names from ours, but as soon as this is revealed, it is mentioned offhand that the planets had been renamed. Likewise, we are told that their Earth was the second planet from its sun, but we are told this by a computer which is speculating wildly based on inaccurate information.

* EarthAllAlong: A hybridization of this trope, the AdamAndEvePlot, and an ''anti-''Earth All Along. The crew of the colony-ship ''Challenger'' tries to return to their home planet, Earth, to find it missing, and finally decides to settle on the new planet Paradise. Paradise is a lot like Earth, but it has saltwater oceans, and a heavily cratered moon. They eventually start referring to the planet as "their" Earth. There are a number of clues and red herrings -- the other planets in Earth's solar system have different names, but we're told that the planets were renamed centuries earlier, for example. Just in case you didn't work out the original "Earth" wasn't Earth at all, the sequel begins with a global flood.

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 crew wanted to abort the mission and return to Earth. Twenty years later the third generation have been raised thinking their Angels are [[GodGuise literally guardian angels]], except for the rebellious Darv who insists on exploring the damaged sections of ''Challenger'' which are outside the Angel's control. It's there he discovers a recording of a survey report of a habitable planet called Paradise. Meanwhile the Angels have decided it's the right time to return to Earth, which they calculate will have fallen into a state of barbarism, enabling them to TakeOverTheWorld. Only when they return to Earth, due to TimeDilation from travelling at near light speed a million years have passed, and the Earth has vanished from its solar system.

* AchillesHeel: The central switching room for the Angels. In Season One they guard it with nightmare barriers (holographic monsters to frighten off intruders) and in Season 2 they integrate their systems into the ship to remove this vulnerability entirely.

In ''Earthsearch 2'' the Angels return intent on seizing the children of the protagonists. The Angels are being targeted by mysterious transmissions which are damaging to higher-level computers, so the Angels need a human crew to pilot the ''Challenger'' to seek out and destroy the source.

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 son threatens to go nova. The entire first and second generation crew were killed when a meteorite struck the ship, an 'accident' arranged by the ship's sentient computers, Angel One and Two, when the crew wanted to abort the mission and return to Earth. Twenty years later the third generation have been raised thinking their Angels are [[GodGuise literally guardian angels]], except for the rebellious Darv who insists on exploring the damaged sections of ''Challenger'' which are outside the Angel's control. It's there he discovers a recording of a survey report of a habitable planet called Paradise. Meanwhile the Angels have decided it's the right time to return to Earth, which they calculate will have fallen into a state of barbarism, enabling them to TakeOverTheWorld. Only when they return to Earth, due to TimeDilation from travelling at near light speed a million years have passed, and the Earth has vanished from its solar system.