▁scient ist ▁who ▁acts ▁as ▁Earth ' s ▁amb assador ▁to ▁them . ▁ ▁Philip ▁K . ▁Dick ▁expl ores ▁this ▁theory ▁in ▁his ▁VAL IS ▁tr il ogy , ▁where in ▁race ▁of ▁ancient ▁astr onaut s ▁is ▁thought ▁to ▁have ▁placed ▁an ▁information - stream ing ▁satellite ▁in ▁orbit ▁around ▁Earth . ▁ ▁James ▁P . ▁Hog an ▁wrote ▁of ▁an ▁al ien ▁race ▁which ▁inhab ited ▁a ▁destroyed ▁fifth ▁planet ▁between ▁Mars ▁and ▁Jup iter ▁and ▁are ▁discovered ▁in ▁the ▁h ulk ▁of ▁an ▁abandoned ▁space craft ▁on ▁Gan ym ede ▁in ▁his ▁five - volume ▁Gi ants ▁series . ▁( 1 9 7 7 - 2 0 0 5 .) ▁ ▁Douglas ▁Adams ▁used ▁a ▁sat ir ical ▁version ▁of ▁the ▁theory ▁in ▁his ▁H itch h iker ' s ▁Guide ▁to ▁the ▁Gal axy ▁series ▁( 1 9 7 9 – 1 9 9 2 ). ▁ ▁B uzz ▁Ald rin ' s ▁and ▁John ▁Bar nes ' ▁novel , ▁Enc ounter ▁With ▁T iber ▁( 1 9 9 6 ), ▁de als ▁with ▁the ▁discovery ▁of ▁ancient ▁al ien ▁enc oun ters ▁on ▁Earth ▁and ▁Mars , ▁with ▁human ity ▁util izing ▁recovered ▁al ien ▁technology ▁to ▁advance ▁the ▁space ▁program . ▁ ▁In ▁David ▁Br in ' s ▁U pl ift ▁Un iverse ▁series , ▁all ▁known ▁species ▁were ▁brought ▁to ▁s api ence ▁through ▁the ▁direct ▁inter vention ▁of ▁a ▁known ▁gal actic ▁" pat ron ", ▁except ▁for ▁the ▁f abled ▁first ▁sent ient