like ▁first ▁stage ▁ ▁Some ▁T ST O ▁designs ▁compr ise ▁an ▁air plane - like ▁first ▁stage ▁and ▁a ▁ro cket - like ▁second ▁stage . ▁The ▁air plane ▁elements ▁can ▁be ▁wings , ▁air - bre ath ing ▁engines , ▁or ▁both . ▁This ▁approach ▁appe als ▁because ▁it ▁transform s ▁Earth ' s ▁atmosphere ▁from ▁an ▁obst acle ▁into ▁an ▁advantage . ▁A bove ▁a ▁certain ▁speed ▁and ▁alt itude , ▁wings ▁and ▁sc ram jets ▁ce ase ▁being ▁effective , ▁and ▁the ▁ro cket ▁is ▁deployed ▁to ▁complete ▁the ▁trip ▁to ▁orbit . ▁ ▁Sa enger ▁( space craft ) ▁was ▁among ▁the ▁first ▁concepts ▁of ▁this ▁type . ▁ ▁While ▁not ▁an ▁orb ital ▁vehicle , ▁the ▁successful ▁private ▁Space Sh ip One ▁sub orb ital ▁space craft ▁developed ▁for ▁the ▁Ans ari ▁X ▁Prize ▁demonstrated ▁that ▁a ▁two - stage ▁system ▁with ▁a ▁wing ed ▁aircraft ▁as ▁the ▁" lower ▁half " ▁can ▁reach ▁the ▁edge ▁of ▁space . ▁The ▁team ▁behind ▁Space Sh ip One ▁has ▁built ▁and ▁flow n ▁a ▁commercial ▁sub - orb ital ▁launch ▁system ▁— ▁Space Sh ip Two ▁— ▁based ▁on ▁this ▁technology . ▁ ▁The ▁Peg as us ▁ro cket ▁while ▁air plane ▁launched , ▁is ▁not ▁a ▁two - stage - to - or bit ▁system ▁because ▁the ▁ro cket ▁component ▁itself ▁is ▁composed ▁of ▁multiple ▁stages . ▁ ▁References ▁ ▁Category : Ch inese ▁invent ions ▁Category : Space ▁access ▁Category : Space craft ▁prop ulsion ▁ 2