▁the ▁Earth ' s ▁gravit ational ▁field ▁and ▁tid al ▁forces ▁to ▁keep ▁the ▁space craft ▁aligned ▁in ▁the ▁desired ▁orientation . ▁ ▁The ▁gravity ▁of ▁the ▁Earth ▁decre ases ▁according ▁to ▁the ▁inverse - square ▁law , ▁and ▁by ▁extending ▁the ▁long ▁axis ▁per pend icular ▁to ▁the ▁orbit , ▁the ▁" lower " ▁part ▁of ▁the ▁orbit ing ▁structure ▁will ▁be ▁more ▁attract ed ▁to ▁the ▁Earth . ▁ ▁The ▁effect ▁is ▁that ▁the ▁satellite ▁will ▁tend ▁to ▁align ▁its ▁axis ▁of ▁minimum ▁moment ▁of ▁in ert ia ▁vert ically . ▁ ▁The ▁first ▁experimental ▁attempt ▁to ▁use ▁the ▁technique ▁on ▁a ▁human ▁space fl ight ▁was ▁performed ▁on ▁September ▁ 1 3 , ▁ 1 9 6 6 , ▁on ▁the ▁US ▁Gem ini ▁ 1 1 ▁mission , ▁by ▁att aching ▁the ▁Gem ini ▁space craft ▁to ▁its ▁A gen a ▁target ▁vehicle ▁by ▁a ▁ ▁t ether . ▁The ▁attempt ▁was ▁a ▁failure , ▁as ▁ins u fficient ▁gradient ▁was ▁produced ▁to ▁keep ▁the ▁t ether ▁t aut . ▁ ▁The ▁technique ▁was ▁first ▁successfully ▁used ▁in ▁a ▁near - ge os ynchronous ▁orbit ▁on ▁the ▁Department ▁of ▁Def ense ▁Gra vity ▁Ex periment ▁( DO D GE ) ▁satellite ▁in ▁July ▁ 1 9 6 7 . ▁ ▁It ▁was ▁first ▁used ▁for ▁low ▁Earth ▁orbit ▁and ▁tested ▁un success fully ▁for ▁ge os ynchronous ▁orbit ▁in ▁the ▁App lications ▁Technology ▁Sat ell ites ▁A TS - 2 , ▁A TS - 4 ▁and ▁A TS -