Global positioning system Nuclear weapons delivery

during labor day weekend in 1973, meeting of twelve military officers @ pentagon discussed creation of defense navigation satellite system (dnss). @ meeting real synthesis became gps created. later year, dnss program named navstar, or navigation system using timing , ranging.

during development of submarine-launched polaris missile, requirement accurately know submarine s location needed ensure high circular error probable warhead target accuracy. led develop transit system. in 1959, arpa (renamed darpa in 1972) played role in transit.

the first satellite navigation system, transit, used united states navy, first tested in 1960. used constellation of 5 satellites , provide navigational fix approximately once per hour. in 1967, u.s. navy developed timation satellite proved ability place accurate clocks in space, technology required latter global positioning system. in 1970s, ground-based omega navigation system, based on phase comparison of signal transmission pairs of stations, became first worldwide radio navigation system. limitations of these systems drove need more universal navigation solution greater accuracy.

while there wide needs accurate navigation in military , civilian sectors, none of seen justification billions of dollars cost in research, development, deployment, , operation constellation of navigation satellites. during cold war arms race, nuclear threat existence of united states 1 need did justify cost in view of united states congress. deterrent effect why gps funded. nuclear triad consisted of united states navy s submarine-launched ballistic missiles (slbms) along united states air force (usaf) strategic bombers , intercontinental ballistic missiles (icbms). considered vital nuclear-deterrence posture, accurate determination of slbm launch position force multiplier.

precise navigation enable united states submarines accurate fix of positions before launched slbms. usaf, 2 thirds of nuclear triad, had requirements more accurate , reliable navigation system. navy , air force developing own technologies in parallel solve same problem. increase survivability of icbms, there proposal use mobile launch platforms (such russian ss-24 , ss-25) , need fix launch position had similarity slbm situation.

in 1960, air force proposed radio-navigation system called mosaic (mobile system accurate icbm control) 3-d loran. follow-on study, project 57, worked in 1963 , in study gps concept born . same year, concept pursued project 621b, had many of attributes see in gps , promised increased accuracy air force bombers icbms. updates navy transit system slow high speeds of air force operation.the navy research laboratory continued advancements timation (time navigation) satellites, first launched in 1967, , third 1 in 1974 carrying first atomic clock orbit.

another important predecessor gps came different branch of united states military. in 1964, united states army orbited first sequential collation of range (secor) satellite used geodetic surveying. secor system included 3 ground-based transmitters known locations send signals satellite transponder in orbit. fourth ground-based station, @ undetermined position, use signals fix location precisely. last secor satellite launched in 1969. decades later, during years of gps, civilian surveying became 1 of first fields make use of new technology, because surveyors reap benefits of signals less-than-complete gps constellation years before declared operational. gps can thought of evolution of secor system ground-based transmitters have been migrated orbit.