on ▁sphere , ▁although ▁D ys on ▁used ▁the ▁term ▁" shell ". ▁D ys on ▁said ▁that ▁he ▁used ▁the ▁term ▁" art ific ial ▁b ios phere " ▁in ▁the ▁article ▁to ▁mean ▁a ▁habitat , ▁not ▁a ▁shape . ▁The ▁general ▁concept ▁of ▁such ▁an ▁energy - trans fer ring ▁shell ▁had ▁been ▁advanced ▁dec ades ▁earlier ▁by ▁author ▁O la f ▁St ap led on ▁in ▁his ▁ 1 9 3 7 ▁novel ▁Star ▁M aker , ▁a ▁source ▁D ys on ▁cred ited ▁public ly . ▁ ▁D ys on ▁tree ▁ ▁D ys on ▁also ▁proposed ▁the ▁creation ▁of ▁a ▁D ys on ▁tree , ▁a ▁gen et ically ▁engine ered ▁plant ▁capable ▁of ▁growing ▁on ▁a ▁com et . ▁He ▁suggested ▁that ▁com ets ▁could ▁be ▁engine ered ▁to ▁contain ▁h ollow ▁spaces ▁filled ▁with ▁a ▁breath able ▁atmosphere , ▁thus ▁providing ▁self - s ust aining ▁habit ats ▁for ▁human ity ▁in ▁the ▁outer ▁Sol ar ▁System . ▁ ▁Space ▁colon ies ▁ ▁D ys on ▁was ▁interested ▁in ▁space ▁travel ▁since ▁he ▁was ▁a ▁child , ▁reading ▁such ▁science ▁fiction ▁class ics ▁as ▁O la f ▁St ap led on ' s ▁Star ▁M aker . ▁As ▁a ▁young ▁man , ▁he ▁worked ▁for ▁General ▁At om ics ▁on ▁the ▁nuclear - power ed ▁Or ion ▁space craft . ▁He ▁hoped ▁Project ▁Or ion ▁would ▁put ▁men ▁on ▁Mars ▁by ▁ 1 9 6 5 , ▁Sat urn ▁by ▁ 1 9 7 0