Archived posting to the Leica Users Group, 2007/02/25
[Author Prev] [Author Next] [Thread Prev] [Thread Next] [Author Index] [Topic Index] [Home] [Search]The GPS constellation orbits about 12,000 miles above the surface, NOT in low Earth orbit. The satellite the Chinese hit was about 500 miles up. This is useful for hitting spy satellites but getting up to 12,000 miles is a different kettle of fish and MUCH more difficult. There's a reason they are that high. Add in the ESA constellation at 14,000 miles or so and you have a difficult problem. Vehicles built to reach either constellation are NOT aircraft launchable and I think they are sufficiently large as to be not portable-launch either. Since shooting at either constellation would be a serious act of war in and of itself a ballistic response to the launch sites would be possible and likely. I believe no nation on the planet has the launch capability to go after the constellations at one time. The launch facilities would be unlikely to survive a reload. So you might hit a segment of GPS or Galileo's capability but you'd be hard pressed to get a lot of them. Adam On 2/25/07, Marc James Small <marcsmall@comcast.net> wrote: > At 10:50 AM 2/25/2007, Lawrence Zeitlin wrote: > > >As far as knocking out GPS by hostile intent, it can only be done > >over a very limited area, i.e. over a city or a harbor. Usually the > >area is smaller than the accuracy limits of celestial navigation. > >Furthermore, alternative electronic navigation methods (e.g. LORAN) > >are even more useful than GPS in coastal areas. I'm glad the Air > >Force and Navy stopped training navigators in celestial navigation > >methods. Technology has demystified another arcane skill and saved us > >taxpayers a bundle of money. > > Larry > > The Chinese are building rockets to knock out the > GPS satellites. They tested one about a month > ago, successfully. No satellites, no GPS. > > And the Air Force still requires celestial > navigation for aircrew -- and they do have > precision chronometers and updated almanacs on > their aircraft. It would be more than a bit > embarrassing if the Chinese took out the GPS grid > and our bombers on the way to clobber the PRC had > to stop to ask directions. For that matter, it's > only been in the past twenty years that > commercial aircrew in international flights no > longer needed to know celestial navigation: I > had a client at that time who was one of the last > to have had to pass an exam on it to get his ATR > endorsed for international flights. > > Marc > > > msmall@aya.yale.edu > Cha robh b?s fir gun ghr?s fir! > > > > _______________________________________________ > Leica Users Group. > See http://leica-users.org/mailman/listinfo/lug for more information >