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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.'"

4 of 213 comments (clear)

  1. Re:EU's Galileo by theLOUDroom · · Score: 4, Interesting

    So maybe the US will stop its attemps to prevent the European Galileo...


    Actually, it looks like this whole thing may be just misinformation to drum up support for Galileo.

    The satellites are lasting LONGER than expected, and we have plenty of spares. It appears the article may also have the number of necessary satellites wrong.

    As someone else has pointed out:
    Bonnor said launches of new satellites are "only just keeping up" with current losses of around two satellites per year.

    So we HAVE SPARES and we're REPLACING THE SPARES AS WE USE THEM. Sounds like it's working just dandy.

    --
    Life is too short to proofread.
  2. Re:Yada yada by GileadGreene · · Score: 3, Interesting
    The current replacement rate is designed to slowly phase out existing satellites before they hit their (statistical) expected end-of-life. It's not intended to cope with unexpected (i.e. low probability, such as 4 or 5 satellites dying at once) failures. Nor does it have to. The GPS constellation includes a number of "on-orbit spares" (i.e. spare satellites already in the GPS orbits), which can be used to ensure continuous availability in the face of an unexpected failure. AFAIK the typical scenario is something like:
    1. GPS satellite fails
    2. On-orbit spare is activated
    3. New satellite launched some months later becomes a spare
    4. Life goes on
  3. Re:EU's Galileo by theLOUDroom · · Score: 3, Interesting

    The implication is that the failure rate is going to accelerate beyond the replacement rate real soon now.

    So if that *actually* happens they'll increase the replacement rate. Are we now also worried that the US is suddenly only going to be capable of two satellite launches per year?

    My point is that this is all silly sensationalism. If the failure rate doubles, no big deal, we send up a few more. The system would still have 100% uptime.

    For the GPS system to actually become "unreliable", failure rates would have to increase by orders of magnitude. There is no data presented to suggest such an abrupt change might take place.

    --
    Life is too short to proofread.
  4. Re:EU's Galileo by quax · · Score: 4, Interesting

    But don't think that because you do and can that the US government is worse than some other half-baked government out there.

    Sorry, but I think this speaks of lack of real world experience in international settings on your part. The US winner take all election system can produce some really nasty outliers when it comes to the quality of your government. BTW I mean the whole selection process - just imagine McCaine winning the 2000 primaries.

    In the EU all member nations need to compromise to get anything done. This process certainly squashes all brilliance but it also quite reliably squashes complete and utter idiocy. And guess what, because the EU only moves by compromise the government that yells the loudest hardly ever wins. It is the ones that can moderate compromises the best that end up with the most influence.