A Maginot Line In The Sky by Ralph Peters

[selil]

The reliance on satellites, especially GPS without alternatives is dangerous. I've thought that where possible towers and buoys could be used as a backup to GPS. It could be further extended by using positions of ships, aircraft and some ground units with continually updated positions acting as positioning points on their own. It probably wouldn't hurt to have access to the European and Russian GPS systems as well.

LoranC and the DGPS systems still work (for awhile anyways) there are a few other solutions such an OMNI and other radio direction finding services. The problem is not with ships or aircraft because there area always dead reckoning systems in place and astrogation as methods of location. The issue is with smart munitions and missiles. The European and Russian navigation systems are in place and can be used but much like selective GPS they can be turned off at a moments notice.

I recall reading somewhere about an idea to equip all aircraft (civilian and military) with some sort of responder that would act similar to a satellite. The idea is that with the amount of air traffic (especially commercial), we'd have near total global coverage. I've tried to locate the article again, but no luck.

I don't know the article to which you speak, but there are several commercial systems that work on this type of technology. They are good for stopping accidents from occurring but fairly useless for munitions.

Another aspect to this is China's anti-satellite shot back in January. If memory serves, the shot was from a mobile platform. The stuff I read didn't go much into specifics about the platform, but I wonder if this is something that can be built or bought by terrorists? Is it possible that a terrorist group could shoot down a key satellite that could cause immense damage for a lengthy period of time? Or what about a rogue nation doing the same thing? Or let me go way out on a limb here: is it possible that a critical satellite that controls movement in Iraq be taken out to coincide with a Tet-like offensive? I don't know the tech side here, so maybe I've ventured into the realm of the impossible.

The Chinese system is static if I remember correctly and not likely to be recreated as they developed by terrorists. However earth orbit is achievable by hobbyists (and terrorists) should it be desired. The science is static, the methods are well known, and the tools to create the vehicle exist in most high school shop classes.

What about EMP(ElectroMagnetic Pulse)?

This has some traction.

I am not fully up on this as I am not scientific but, and perhaps someone out there knows the truth here, would not an EMP caused by a nuke be the real concern about a terrorist/ or threat nation attack on our satelite system?

From my cursory knowledge a nuke exploded in orbit could cause major issues for satelites, particularly the EMP. Not something a nation would do as it would adversely effect their own satelites but a terrorist? Maybe.

http://www.defensetech.org/archives/001526.html

Reverse the thought process. Instead of attacking the satellite (and likely ALL satellites) attack the ground stations. Same effect and much less savvy needed. An EMP in space would be fairly catastrophic to a small number of satellites. Use the ping pong ball and softball analogy. The ping pong ball is the earth and the softball the high earth orbit (HEO) satellites (+200 mile orbits). The objective of the analogy is to explain how much "space" there is between satellites and why EMP in space is less of an issue (unless it is a BIG emp).

GPS? Not likely. A 50 MT weapon would generate irradiance on the order 10 W/m^2 at GPS satellite altitudes (I = E/(4*pi*r^2)). The irradiance from the sun incident on satellites in the Earth sphere is roughly 1400 W/m^2, not including particle bombardment outside of the radiation belt; you can imagine the tolerances built into our sats to withstand that kind of punishment. My understanding is EMP launchers are sub-orbital--LEO. Nobody can launch one into GTO without somebody noticing, and if the Chinese have ASAT that can reliably strike up that high we're screwed no matter which way you slice it.

The Chinese system from what I've read is HIGHLY capable.

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I think the concern is countries like Iran getting their hands on powerful enough lasers to dazzle satellites. It should be doable for any country with multi-megawatt power generation. Jamming GPS signals is, of course, far more academic, but susceptible to anti-radiation attacks. Peters' network security objection is a bit stronger, assuming that battlefield networks at some point(s) connect up with DoD VPNs.

As to using lasers. A placid lake surface can blind SBIRS part of the Defense Satellite Program and other SAT systems (widely reported in the 1990's as a cause for a NORAD alert) that are in and around the vision spectrum. That being the case there are new kinds of heat/power generation power plants that use highly tunable mirrors over hundreds (or thousands) of acres and are able to follow the sun (1), (2), (3) (4). Imagine if you missed the top of the power tower and with pin point accuracy hit just the general location in space with them?