GPS Satellite SVN-15 will celebrate its 16th birthday in space this month, and by next spring it will have circled the earth 12,000 times (roughly twice a day), continuously transmitting navigation signals to us. That’s amazing performance, especially considering that its original orbital life was expected to be 7.5 years. As the last remaining member of the USAF’s early Block II GPS space vehicles, Number 15 is a great tribute to the engineers who designed it. However, its reliability is creating some obstacles for the engineers who designed newer-generation satellites.
The Block IIs were the second generation of GPS satellites, and over time they have been replaced by progressively more advanced Block IIAs, then IIRs and IIRMs. Eventually, even more improved IIF space vehicles will follow, with Block IIIs to come much later. There are 30 satellites of various vintages in the GPS constellation, including one of the new Block IIRMs launched on September 25.
More In Avionics
