▁that ▁these ▁six ▁were ▁the ▁short est ▁of ▁the ▁group ▁of ▁ 2 0 . ▁ ▁In ▁July , ▁shortly ▁after ▁re location ▁to ▁Star ▁City , ▁two ▁of ▁the ▁six ▁were ▁replaced ▁on ▁medical ▁grounds . ▁First ly , ▁during ▁a ▁cent rif uge ▁test ▁of ▁ 8   g , ▁K art ash ov ▁experienced ▁some ▁internal ▁damage , ▁causing ▁minor ▁hem or rh aging ▁on ▁his ▁back . ▁Despite ▁G ag arin ' s ▁requests ▁for ▁him ▁to ▁stay , ▁the ▁do ctors ▁decided ▁to ▁remove ▁K art ash ov ▁from ▁the ▁group ▁of ▁six . ▁Later ▁in ▁July , ▁Var lam ov ▁was ▁involved ▁in ▁a ▁sw imming ▁accident . ▁During ▁a ▁d ive ▁into ▁a ▁lake ▁near ▁the ▁training ▁center , ▁he ▁hit ▁his ▁head ▁on ▁the ▁bottom , ▁disp la cing ▁a ▁cer v ical ▁verte bra . ▁So ▁by ▁the ▁end ▁of ▁July , ▁the ▁V angu ard ▁Six ▁were : ▁G ag arin , ▁By kov ski y , ▁N ely ub ov , ▁Nikol ay ev , ▁Pop ov ich , ▁and ▁Tit ov . ▁ ▁By ▁January ▁ 1 9 6 1 , ▁these ▁six ▁had ▁all ▁finished ▁par ach ute ▁and ▁recovery ▁training , ▁as ▁well ▁as ▁three - day ▁reg imes ▁in ▁sim ul ators . ▁On ▁January ▁ 1 7 , ▁the ▁six ▁participated ▁in ▁their ▁final ▁ex ams , ▁including ▁time ▁spent ▁in ▁a ▁sim ulator , ▁and ▁a ▁written ▁test . ▁Based ▁on ▁these ▁results , ▁a ▁commission