GPS Operational Constellation

The GPS Operational Constellation consists of 24 satellites that orbit the earth in 12 hours. Often times there are 26 satellites orbiting earth which are gradually replaced by newer model of satellites. Each satellite is the same every time it makes a round around earth. Orbit altitude is such that every 24 hours satellite completes full circle. There are three minutes laps each day. Satellites equally spaced with 60 degrees apart in six planes. This arrangement allows having access at any given point of time to 7 satellites from any location on the earth.

There were several major overhauls of the Operation GPS in the past decades. They all have known as Blocks. Starting with Block I and ending with the latest Block IIF. Each block is upgraded and improved version in terms of characteristics of the system design as well as improvements in satellite designs.

Following is brief specification outline of the latest satellites which were part of Block II, Block IIR, Block IIRM and Block IIF

Block II/IIA GPS Satellite Characteristics

Total of 28 satellites were procured by Department of Defense and 15 are orbiting earth now (2007)

Launched On: April 14th 1998.
Launched By: Delta II Rocket
Weight: 2,175.00 pounds
Altitude: 10,988 n.m.
Power Supply: Solar Panel
Power Generation: 700 Watts
Width: 5 Feet
Length: 17.5 Feet
Signal: L1, C/A and L1, L2 P(Y)
Lifespan: 7.5 years

Block IIR GPS Satellite Characteristics

Total of 21 satellites were procured by Department of Defense and 12 are orbiting earth now (2007)

Launched On: July 22nd 1997
Launched By: Delta II Rocket
Weight: 2,370.00 pounds
Altitude: 10,988 n.m.
Power Supply: Solar Panel
Power Generation: 1,136 Watts
Width: 5 Feet
Length: 38 Feet
Signal: L1, C/A and L1, L2 P(Y)
Lifespan: 10 years

Block IIR-M GPS Satellite Characteristics

3 are orbiting earth now and 5 more are waiting to be launched (2007)

Launched On: Spetmeber 25th 2005
Launched By: Delta II Rocket
Weight: 2,370.00 pounds
Altitude: 10,988 n.m.
Power Supply: Solar Panel
Power Generation: 1,136 Watts
Width: 5 Feet
Length: 39 Feet
Signal: L1, C/A and L1, L2 P(Y) and adds 2nd civil signal on L2 as well as L1, L2, & M-Code signal
Lifespan: 10 years

Block IIF GPS Satellite Characteristics

12 waiting to be launched (2007)

Launched On: 2008
Launched By: Delta IV and Atlas V Rocket
Weight: 2,370.00 pounds
Altitude: 10,988 n.m.
Power Supply: Gallium Arsenide Solar Panel
Power Generation: 2,900 Watts
Width: 9.6 Feet
Length: 43 Feet
Signal: L1, C/A and L1, L2 P(Y) and adds 2nd civil signal on L2 as well as L1, L2, & M-Code signal plus a 3rd civil signal on L5
Lifespan: 12 years