Items11The creator’s order
  1. 1Gladys WestGladys WestBorn Oct 27, 1930Modeling the Earth beneath the orbit West worked on mathematical models of Earth’s shape and on satellite geodesy at the Navy’s research facility in Dahlgren. Models from that work were later incorporated into GPS. Her part of the story starts with the ground under the receiver. To use satellite…0
  2. 2Roger L. EastonRoger L. EastonPutting precise time in orbit Easton’s Timation experiments at the Naval Research Laboratory tested navigation using time-synchronized satellites. Timation I went up in 1967. A receiver could use the timed signal to estimate how far away the satellite was, an approach that carried into GPS.0
  3. 3Bradford ParkinsonBradford ParkinsonBorn Feb 16, 1935Making separate ideas work as one system Parkinson led the program that brought earlier approaches together into the GPS design. The job included developing and testing the pieces that had to work together, from spacecraft to receivers. He also pushed for equipment people could use without making…0
  4. 4James SpilkerJames SpilkerBorn Aug 4, 1933Letting satellites share a frequency Spilker helped design the ranging signal for civilian GPS receivers. Different codes let a receiver tell satellites apart even when they use the same frequency. His team also built an early receiver to process the signal, so this story is about what a listener…0
  5. 5Ivan GettingIvan GettingBorn Jan 18, 1912Making the case for a positioning system Getting advocated using satellites to locate moving vehicles. His contribution was in advancing the idea and pressing for a program capable of delivering it. Read his role alongside Parkinson’s to see the difference between making the case for a system and…0
  6. 6Richard Schwartz (engineer)Richard Schwartz (engineer)Making the early GPS satellites last Schwartz managed Rockwell’s GPS satellite program. His team had to protect the spacecraft against radiation in the upper Van Allen belt. The satellites had a three-year design life, and some of the early spacecraft operated for more than nine. That durability…0
  7. 7Hugo FruehaufHugo FruehaufShrinking the clock An atomic clock has to fit on the satellite and survive there. Fruehauf helped develop a radiation-hardened rubidium clock and later worked on a miniature rubidium oscillator that met GPS accuracy requirements. His work shows why proving a clock in the lab and making one that…0
  8. 8William H. GuierWilliam H. GuierTurning the change in pitch into an orbit Guier and George Weiffenbach used the changing frequency of Sputnik’s signal to work out its orbit. Guier later helped derive a model of Earth’s gravity field from tracking data for Transit. Both steps show what careful analysis can recover from signals a…0
  9. 9George C. WeiffenbachGeorge C. WeiffenbachBorn Jun 20, 1921Getting a signal worth measuring Weiffenbach had the receiver and frequency reference that let him and William Guier listen to Sputnik. He found a way to turn their recorded signals into digital data for analysis and continued working on Doppler tracking for Transit. The mathematical idea needed…0
  10. 10Frank T. McClureFrank T. McClureBorn Aug 21, 1916Reversing the tracking problem McClure saw a different use for the method his colleagues had tested. If the satellite’s orbit was already known, the same kind of signal could tell an observer where they were on Earth. That reversal became the basis of Transit.0