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Doubts About Future GPS Reliability
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.'"
They fail to mention that there are a number of backup satellites sitting up there, waiting to go into the consellation if any fail.
Indeed, I'm sure I remember reading something somewhere about the US government recently launching newer, more accurate GPS satellites. Of course, what we need these days is more alarmist rhetoric, so I suppose this is apropos.
It sounds like they are already in the midst of replacing it - check out SpaceFlightNow. The new series is going up with the next generation in the works. Maybe it's just a matter of keeping at or above the crucial 24 limit...?
Slashdot: all your pointless conjecture are belong to us!
You're joking right?
For those few that don't get it, the satellites aren't geostationary, so a failed satellite (once the minimum # is reached) will probably create a dead spot that moves around the planet, in which GPS service is degraded.
Several US firms - and the US governement are active in the development of Galileo as even the most basic search will turn up. However, the big difference comes down to the desire by several of the EU backers to piggyback their encrypted signal in the same space as the GPS encrypted signal. You can imagine anyone getting upset when a newcomer decides to ride on the same signal area (i.e. BPL and hamms).
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
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.
He said new and useful, key word being NEW.
Your examples are all at least 50 years behind us. In addition, none of those inventions were world-wide systems that America made power grabs for... the current situation with the UN/EU wanting power over the internet is completely different than the American use and application of those English inventions. And, for the record, the US developed a jet engine independently and simultaneously.
The U.S. Navy made very substantial contributions to the GPS program. They were the pioneers in satellite-based navigation.
Mea navis aericumbens anguillis abundat
Hmmm, lessee. Seem to recall that the first steam engine was built by a Greek named Hero, although the first useful one was built by Newcomen. The first self propelled vehicle was built by Cugnot of France, another Frenchman built the first steamboat (and that was acknowledged by Fulton). The first high pressure steam engines were built by Trevithick of England and Oliver Evans of the US. Trevithick also built the first steam locomotive. While the first locomotives in the US were imported from England, the US became a net exporter of steam locomotives by the mid-1830's. The first elecric locomotive (albeit model sized) was built by Thomas Davenport of Vermont in 1834.
the telephone
Huh? I would believe "The telegraph" (Wheatstone).
internal combustion
Funny, the names for the two most common ICE cycles are Otto and Diesel - sounds suspiciously German to me.
the jet engine
Which was devloped from turbocharger technology - ISTR was a Swiss development. The Swiss had a working gas turbine in 1940.
One thing you did leave out, the steam turbine was developed by an Englishman by the name of Parsons.
GPS is funded by the military, so they are launched by the Air Force, not NASA. I know nothing about the budget of either, but I would be surprised if the Air Force was unable to afford 2 launches a year - or even 6 or 7 if the failure rate kicks up.
Leaving off the Swiss turbocharger thing (Americans made them practical).
Jets just flat out don't come from turbochargers.
Jets use fan blades, turbochargers do not. Turbochargers use impellers and are only compressors. Jets have different compression sections, burners (flame fronts) and actually make thrust.
It's like saying cars came from trains because both have round wheels. It just doesn't work.
I don't see how England invented TV. Nipkow (German) invented mechanical TV, and Farnsworth (American) invented electronic TV (far more important to getting us to where we are now).
The grandparent did miss that England invented RADAR. A great invention.
Note to other posters, Alexander Graham Bell was not Canadian. He resided there fora while, but never changed nationality, he was a Scot up intil he became American. He was a Scot (living in Boston?) when he invented the telephone.
http://lkml.org/lkml/2005/8/20/95