▁with ▁ces ium ▁clock s , ▁started ▁to ▁go ▁into ▁orbit ▁on ▁June ▁ 2 3 , ▁ 1 9 7 7 . ▁ ▁By ▁ 1 9 8 5 , ▁the ▁first ▁ 1 1 - s at ellite ▁G PS ▁Block ▁I ▁const ell ation ▁was ▁in ▁orbit . ▁ ▁Sat ell ites ▁of ▁the ▁similar ▁Russian ▁GL ON ASS ▁system ▁began ▁to ▁be ▁put ▁into ▁orbit ▁in ▁ 1 9 8 2 , ▁and ▁the ▁system ▁is ▁expected ▁to ▁have ▁a ▁complete ▁ 2 4 - s at ellite ▁const ell ation ▁in ▁place ▁by ▁ 2 0 1 0 . ▁ ▁The ▁European ▁Space ▁Agency ▁expects ▁to ▁have ▁its ▁Gal ile o ▁with ▁ 3 0 ▁sat ell ites ▁in ▁place ▁by ▁ 2 0 1 1 / 1 2 ▁as ▁well . ▁ ▁Integr ated ▁bridge ▁systems ▁Electron ic ▁integrated ▁bridge ▁concepts ▁are ▁driving ▁future ▁navigation ▁system ▁planning . ▁Integr ated ▁systems ▁take ▁inputs ▁from ▁various ▁ship ▁sens ors , ▁electron ically ▁display ▁position ing ▁information , ▁and ▁provide ▁control ▁signals ▁required ▁to ▁maintain ▁a ▁vessel ▁on ▁a ▁pres et ▁course . ▁The ▁navig ator ▁becomes ▁a ▁system ▁manager , ▁choosing ▁system ▁pres ets , ▁interpre ting ▁system ▁output , ▁and ▁monitoring ▁vessel ▁response . ▁ ▁See ▁also ▁ ▁Air ▁navigation ▁Aust ron esian ▁navigation ▁Cel est ial ▁navigation ▁Gal ile o ▁position ing ▁system ▁Ge od etic ▁system ▁Great - circle ▁distance ▁explains ▁how ▁to ▁find ▁that ▁quantity ▁if ▁one ▁knows ▁the ▁two ▁lat itudes ▁and ▁longitude