6 ▁astr onaut ▁to ▁receive ▁a ▁potential ▁flight ▁assignment . ▁ ▁Mus gra ve ▁participated ▁in ▁the ▁design ▁and ▁development ▁of ▁all ▁Space ▁Sh utt le ▁extra - ve h icular ▁activity ▁equipment , ▁including ▁spaces uits , ▁life ▁support ▁systems , ▁air lock s ▁and ▁Mann ed ▁M ane u ver ing ▁Units . ▁From ▁ 1 9 7 9 ▁to ▁ 1 9 8 2 , ▁and ▁ 1 9 8 3 ▁to ▁ 1 9 8 4 , ▁he ▁was ▁assigned ▁as ▁a ▁test ▁and ▁ver ification ▁pilot ▁in ▁the ▁Sh utt le ▁Av ion ics ▁Integr ation ▁Labor atory ▁at ▁J SC . ▁ ▁Mus gra ve ▁served ▁as ▁a ▁C AP COM ▁for ▁the ▁second ▁and ▁third ▁Sk yl ab ▁miss ions , ▁ST S - 3 1 , ▁ST S - 3 5 , ▁ST S - 3 6 , ▁ST S - 3 8 ▁and ▁ST S - 4 1 . ▁He ▁was ▁a ▁Mission ▁Special ist ▁on ▁ST S - 6 ▁( 1 9 8 3 ), ▁ST S - 5 1 - F / Sp ac el ab - 2 ▁( 1 9 8 5 ), ▁ST S - 3 3 ▁( 1 9 8 9 ), ▁ST S - 4 4 ▁( 1 9 9 1 ), ▁and ▁ST S - 8 0 ▁( 1 9 9 6 ); ▁and ▁the ▁Pay load ▁Commander ▁on ▁ST S - 6 1 ▁( 1 9 9 3 ). ▁ ▁A ▁veter an ▁of ▁six ▁space