简介：OneofthemostdaringclandestineoperationsofWorldWarIIwasthe1944sinkingoftheNorwegianferryHydrowithitscargoof"heavywater"destinedfortheNazis'secretatomicbombproject.Althoughthemissionwasdeclaredasuccess,nooneeverestablishedifthespecialshipmentwasactuallyonboard.Inthisprogram,NOVAdescends1,300feetbeneatharemoteNorwegianlaketofindtheanswer. Exploringthepristinelakebottomwitharemotelyoperatedvehicle,theexpeditionteamlocatestheremarkablywell-preservedship,alongwithevidenceofamysteriouscargoinsteeldrums.Analysisofthecontentsofoneofthosedrumswillsolveasix-decade-longmysteryabouttheroletheAlliesplayedinpreventingaNazinuclearbomb. TheprogramfeaturesparticipantsintheHydroaffair,includingamemberoftheNorwegianResistancewhoslippedaboardthevesselonthenightofFebruary21,1944,andhelpedplantexplosivesinthebowthatweretimedtogooffthefollowingdaywhentheferrywasoverthedeepestpartofLakeTinn.IntelligencehadindicatedthattheHydrowouldbetransportingrailroadflatcarsloadedwithbarrelsofheavywaterproducedbythenearbyNorskhydroelectricplant,whichatthattimewastheworld'slargestpowerstation.TheGermanshadconqueredNorwayearlyinthewarandimmediatelyorderedtheNorskplanttodoubleitsoutputofheavywater. CrucialtotheNazinuclearprogram,heavywaterwasextractedfromordinarywaterbyusingelectricitytobreakapartordinarywatermoleculesandconcentratingthesolutionuntilallthatremainedwastherare,heavierformoftheliquid.Withabigger,"heavier"nucleusthanordinarywater,heavywaterwasanidealsubstanceforslowingneutronsinanuclearreactor,akeystepintriggeringachainreaction(seeDangerousWater). Withasufficientsupplyofheavywateranduranium,theGermanscouldusereactorstoproducebomb-gradematerialfornuclearweaponsthatwouldrendertheThirdReichinvincible.FearofthatoutcomesparkedtheAlliestoundertaketheirowncrashprogram.ThisbecametheManhattanProject,whichultimatelyproducedthefirstatomicbomb. TheNorwegianpartisanshadnoinklingofthereasonfortheirmission.AlltheyknewwasthatithadtoppriorityfromtheircontactinLondonandthatinnocentNorwegiancivilianswerelikelytobeaboardonthelast,fatalvoyageoftheHydro.(ToreadactualtelegramssentbetweenthesaboteursandtheirchiefsinLondon,gotoSeetheSpyMessages.) NOVAinterviewsoneofthecivilianswhosurvivedthesinkingandwhoremembersseeingbarrelsfloatingamongthedebris.ThesebarrelswereimmediatelyrecoveredbytheGermansandshippedtoBerlin.However,hadtheybeenfilledwithheavywatertheyshouldhavesunk,notfloated.ThisisjustoneofthemysteriesNOVAsolvesbysnaringabarrel,bringingittothesurface,andseeingjustwhat'sinside.…