Having seen no evidence of orbital defenses on Earth, I think we are forced to assume either lunar-based (torpedo-launchers or interceptors), or system-based (Sabre fleet?). If there had been orbital weapons, we would have seen them taking out some of the aforementioned hostile vessels.

Also, one of the best forms of defense is early information. I'd assume that the Solar system's sensor net is fairly tight (except for cloaked ships). An interceptor task force could be vectored onto any threat fairly efficiently. And it would make more sense to station the interceptors as close to the target as possible (lunar orbit?).

As for the Cardassian/Romulan and Breen attacks, I think they could be downplayed a bit if necessary. The former could have destroyed 30% of its designated target area, not of the entire surface (the dialogue and visuals certainly allow for this, and such rate of destruction would also better fit the initial estimates of how long it would take to melt the planet to slag). The latter attack could have lasted for two seconds, or two hours, and involved a rapid delivery of a superior weapon, or a long and bloody battle where a few shots got through. I tend towards the latter, considering that the destruction seemed so sporadic and minor (pillars of smoke from various spots in the city, a damaged HQ building instead of a smoking crater, a severed instead of vaporized Golden Gate bridge).

The Dominion has used ground-based beam weapons as well - 'Once More Unto The Breach' - they seemed pretty effective to me.

I think we would have heard about/seen Earth's orbital weapons by now, if they existed at all.

FOrce:
The Chin'Toka assault fleet was an invasion force, not one committed to nuking the planet. They had to take out all forms of the planet's defensive system before they could start landing troops on it.

If they wanted the planet wiped out, a simple missile launch from a planetary site or an attack � la 'For The Uniform' would be much easier.

David:
It took a heap of Starships, fixed in position, to maintain the tachyon grid in 'Redemption' - I'd balk at the logisitcal necessities for one required to cover the Solar System from all angles!

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At that point, McDonald fired his gun three times in the air to emphasize his point. The crowd, estimated at 350,000, loudly cheered the new candidate.

"Let me make this clear: I am the law! I am your ruler! And you will have fries with that, motherf*cker!"

but it also must be costly to set up such a system
even though they were unmanned.

of course people argue the cardassains were idiots to have them all use the same power source that was incredibly not hard to find.
why didn't each platform have their own generator? people asked....

i think giving each generator would weaken the platforms. each will have weaker shields due to their small generator...whereas the main generator could have supplied alot of power to a single platforms under attack and not waste power to ones that weren't.

plus giving a platform each their own generator would have been a waste of resources.

Just where were the shields on that ship?

BTW, we do know a little about Earth's global defense from that map in "Paradise Lost" showing most of the major cities connected through routes. On the other hand, the fact there are no reliable back-ups for the power grids employed by Earth seem a little to sloppy for a major homeworld.

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Ace

"Objects in mirror are closer than they appear."

About the Defiant penetrating Earth's surveillance nets: I don't think she ever did that. In "Paradise Lost", she was heading towards Earth at high speed, uncloaked, when she was intercepted by the Lakota in what looked like deep space. Worf decided it was too late to cloak since the Lakota was already firing. A battle ensued, the Lakota capitulated, and both ships then sailed to Earth openly and without cloaking.

In "The Die is Cast", the Romulans estimated they'd destroy the planet's crust in an hour, and the mantle in five after that. What they ended up with was 30% of the crust destroyed with initial volley. But the wording (which I have to check once again) did NOT explicitly claim it was 30% of the WHOLE planet (although this may have been the writers' intention). The word "planet" was not used in the sentence.

But having the orbit of Earth be empty is easy enough to explain. It's simply that all the stuff in orbit is so far away from all the other stuff that it cannot be seen. Only when two pieces of hardware are functionally connected (like the "orbital office" and its apparently associated dock facilities in TMP, with all those workbees shuttling in between) will they be close enough to each other to be seen with naked eye.

If Earth has orbital weapon platforms, they are probably higher up than the orbits we have visited, and more distributed than the corresponding systems of Chin'toka or Cardassia Prime, owing to greater range, better targeting systems, and higher reliance on the power of diplomacy and starship deterrence... We'd then not see the platforms, unless we saw an actual attack and the platforms started firing.

And you don't destroy a spotted owl's habitat when the thing goes BOOM.

I'm 75%+ sure that TOS references getting shields up as = to becoming invisible to primitive cultures. I'd think this sort of capability would be crucial for sneaking in to look at pre-warp civilizations and such - same idea would absorb and defeat radar/laser based detection systems.

The big bonus for Earth would be that if all the various orbital "suburbs" aren't visible then you can still have your nice night sky.

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TK