▁used ▁in ▁these ▁orb iter ▁configurations ▁was ▁destroyed ▁in ▁the ▁Columbia ▁accident . ▁ ▁E DO ▁Pal let ▁ ▁The ▁Ext ended ▁D uration ▁Or b iter ▁Cry ogen ic ▁k it ▁( ED O - pal let ▁or ▁C RY O ) ▁was ▁a ▁ ▁equipment ▁assembly ▁which ▁attached ▁vert ically ▁to ▁the ▁payload ▁bay ▁rear ▁bulk head ▁of ▁an ▁orb iter , ▁and ▁allowed ▁the ▁orb iter ▁to ▁support ▁a ▁flight ▁of ▁up ▁to ▁ 1 6 ▁days ▁duration . ▁The ▁equipment ▁included ▁cry ogen ic ▁t anks , ▁associated ▁control ▁pan els , ▁and ▁av ion ics ▁equipment . ▁Although ▁Atl ant is ▁was ▁partially ▁upgrad ed ▁to ▁accommod ate ▁the ▁E DO , ▁only ▁Columbia ▁and ▁Ende av our ▁actually ▁fle w ▁with ▁the ▁pal let . ▁ ▁The ▁pal let ▁made ▁its ▁debut ▁on ▁ST S - 5 0 , ▁and ▁was ▁lost ▁on ▁ST S - 1 0 7 . ▁ ▁Initial ly , ▁NASA ▁considered ▁adding ▁a ▁second ▁E DO ▁pal let ▁to ▁Ende av our , ▁placed ▁in ▁front ▁of ▁the ▁first , ▁for ▁a ▁total ▁of ▁th ir teen ▁tank ▁sets , ▁that ▁would ▁have ▁allowed ▁an ▁orb iter ▁to ▁remain ▁in ▁space ▁for ▁ 2 8 ▁days , ▁but ▁man agers ▁decided ▁against ▁it ▁when ▁the ▁International ▁Space ▁Station ▁assembly ▁began , ▁and ▁instead ▁removed ▁the ▁E DO ▁cap ability ▁from ▁the ▁orb iter , ▁to ▁reduce ▁its ▁weight ▁and ▁allow ▁it ▁to ▁carry ▁more ▁cargo ▁to ▁the ▁I SS . ▁ ▁No