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Doubts About Future GPS Reliability

Posted by Zonk on from the ground-control-to-major-tom dept.

loped_index writes "IT Week reports that the U.S. GPS system is in a delicate state, and that full coverage could be lost if older satellites fail faster than the current rate. From the article: 'The system relies on a network of satellites, which cannot be repaired once launched and have a limited lifespan. Sixteen of the present 28 satellites were built to last seven and a half years, but are now between eight and 14 years old. Twenty-four satellites are required for full coverage.'"

2 of 213 comments (clear)

  1. GPS Constellation status, with launch dates by Anonymous Coward · · Score: 5, Informative

    From: ftp://tycho.usno.navy.mil/pub/gps/gpstd.txt

    A. BLOCK II/IIA/IIR/IIR-M INDIVIDUAL SATELLITE STATUS

    SVN PRN
    15 15 Launched 01 OCT 1990; usable 15 OCT 1990; operating on Cs std
    24 24 Launched 04 JUL 1991; usable 30 AUG 1991; operating on Cs std
    25 25 Launched 23 FEB 1992; usable 24 MAR 1992; operating on Cs std
                        Scheduled unusable 20 Oct 0130 to 1330 UT for repositioning
                          maintenance (NANU 2005131/14 OCT)
    26 26 Launched 07 JUL 1992; usable 23 JUL 1992; operating on Rb std
    27 27 Launched 09 SEP 1992; usable 30 SEP 1992; operating on Rb std
    29 29 Launched 18 DEC 1992; usable 05 JAN 1993; operating on Rb std
    30 30 Launched 12 SEP 1996; usable 01 OCT 1996; operating on Rb std
    31 31 Launched 30 MAR 1993; usable 13 APR 1993; operating on Rb std
                        Unusable 14 Apr 1634 UT and will remain unusable until
                          further notice (NANU 2005055)
    32 01 Launched 22 NOV 1992; usable 11 DEC 1992; operating on Cs std
    33 03 Launched 28 MAR 1996; usable 09 APR 1996; operating on Cs std
    34 04 Launched 26 OCT 1993; usable 22 NOV 1993; operating on Rb std
    35 05 Launched 30 AUG 1993; usable 28 SEP 1993; operating on Cs std
    36 06 Launched 10 MAR 1994; usable 28 MAR 1994; operating on Rb std
    37 07 Launched 13 MAY 1993; usable 12 JUN 1993; operating on Rb std
    38 08 Launched 06 NOV 1997; usable 18 DEC 1997; operating on Cs std
    39 09 Launched 26 JUN 1993; usable 20 JUL 1993; operating on Cs std
    40 10 Launched 16 JUL 1996; usable 15 AUG 1996; operating on Cs std
    41 14 Launched 10 NOV 2000; usable 10 DEC 2000; operating on Rb std
    43 13 Launched 23 JUL 1997; usable 31 JAN 1998; operating on Rb std
    44 28 Launched 16 JUL 2000; usable 17 AUG 2000; operating on Rb std
    45 21 Launched 31 MAR 2003; usable 12 APR 2003; operating on Rb std
                        Unusable 13 Oct 0217 to 0905 UT due to repositioning
                          maintenance (NANUs 2005129, 2005130/13 OCT)
    46 11 Launched 07 OCT 1999; usable 03 JAN 2000; operating on Rb std
    47 22 Launched 21 DEC 2003; usable 12 JAN 2004; operating on Rb std
    51 20 Launched 11 MAY 2000; usable 01 JUN 2000; operating on Rb std
    53 17 Launched 26 SEP 2005
                        For more information about PRN17/SVN53, see:
                          http://www.spaceflightnow.com/delta/d313a/
    54 18 Launched 30 JAN 2001; usable 15 FEB 2001; operating on Rb std
    56 16 Launched 29 JAN 2003; usable 18 FEB 2003; operating on Rb std
    59 19 Launched 20 MAR 2004; usable 05 APR 2004; operating on Rb std
    60 23 Launched 23 JUN 2004; usable 09 JUL 2004; operating on Rb std
    61 02 Launched 06 NOV 2004; usable 22 NOV 2004; operating on Rb std

  2. Working at the GPS hub by iamweezman · · Score: 5, Informative
    As an active duty Air Force tech controller I work almost daily with the satellite operators that "fly" the GPS satellites. Some of their systems are more than antiquated, but still function with adequate redundancy built in. Although the lifespan might have been eclipsed the telemetry data recieved by the operators give them the state of health of the satellites which allows them to plan for future launches.

    In fact, a newer GPS satellite was just launched weeks ago. As stated before, the DOD has a special spot in their hearts for GPS. The GPS operators get treated extra special because of the US military's reliance on them. There are already plans in place for each satellite to be super-orbited when the time comes and for a new launch to follow.

    In other words, if the military isn't worried about it, neither should we be.