Archive for August, 2009

Last GPS Block IIR Satellite now in Orbit

August 17th, 2009 | Category: Launch

Monday, August 17 at 10:35 GMT, the last Lockheed Martin built Block IIR satellite lifted off.  There were a lot of lasts with this launch:

  • This is the last Block IIR satellite
  • This was the last time the Air Force would use the Delta-II rocket
  • This is the last scheduled launch from pad 17A, in use since the 1950's

SVN 50 (PRN 05) will be located in the same orbital slot as SVN 40 (PRN 10), eventually taking its place.  SVN 40 is on its last clock (of four original clocks) and it also has a reduced navigation payload capability.  It's User Range Error (URE) is not too bad though, as can be seen from these graphs:

PRN10EphemerisError3Days

This plot shows the ephemeris error for SVN 40 (PRN 10) for the last three days.

PRN10Clock3Days

This plot shows the clock error for SVN 40 (PRN 10) for the last three days.

PRN10URE

This last bar chart shows a three day history of the RMS URE for all satellites in the constellation.  PRN 10 is a nice, middle-of-the-road satellite.  I'd expect to to remain in use until it can no longer perform it's duties.  There may even be some benefit in moving it within plane to optimize the Dilution of Precision (DOP) for the entire constellation.

Job well done on the Block II Replenishment satellites!

Next up: Block IIF with the first launch for this new series of satellites scheduled for early 2010.

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