an effective death star shield

[Shrykull]

How do the planetary shields in star wars work? The one on Endor's moon was a single station that projected it. If Alderaan knew it was coming could it have added more shield generators?

[Warspite]

How could they knew? The station appeared in orbit. They had time to know that was no moon, and that's it, right after, Tarkin's signing his name on the planet.

[Darth Garden Gnome]

How do the planetary shields in star wars work? The one on Endor's moon was a single station that projected it. If Alderaan knew it was coming could it have added more shield generators?

I don't suppose we have any way of knowing how many shield generators were actually protected Alderaan, but if we assume it was one, it wouldn't have been enough.

Alderaan's shield lasted only a split second against the Death Star's beam. It would have to last a couple of seconds (IIRC on how long it took the Death Star's beam to fully reach Alderaan), and that equate to many, many more shields.

And consider this: in the Black Fleet Crisis, Ackbar says that the Black Fleet alone could knock out Coruscant's shield--presumably of equal power to Alderaan's, if not more, since Coruscant is the galaxy's capital--and the Death Star had firepower of over half the Imperial Starfleet. The Black Fleet is an insignifanct speck when it comes to the size of the entire Imperial Starfleet.

[Ender]

How do the planetary shields in star wars work?

Same as standard shields but on a larger scale: Dissipation threshold, energy storage reserve, join up when the meet together, weaken the furtehr theya re from the emitter, can be punched through or worn down, made of "liquid energ", permeable to slow moving objects, create heat in atmospheres via ionization and particle interaction, have a forcefield like volumetric effect, and a couple of other wonky things we aren't real sure about.

The one on Endor's moon was a single station that projected it.

Yes, and standard planetary generators act more like Gungan shields on a larger scale: They are projected from emitters, and a series of emitters interlink them and make them cover the entire planet.

If Alderaan knew it was coming could it have added more shield generators?

It is unclear if the dissapation rate is created by design of the sheilds, or the number of emitters (power seems to have an odd effect being different from particle and energy shields). However, even then, as hits cause the generators to heat up (leading the the eventual shield "burnout"), the strike frm the DS could possibly have cause a heat spike sufficient to cook the local area, rendering the planet dead even if the shield held up.

[PainRack]

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And consider this: in the Black Fleet Crisis, Ackbar says that the Black Fleet alone could knock out Coruscant's shield--presumably of equal power to Alderaan's, if not more, since Coruscant is the galaxy's capital--and the Death Star had firepower of over half the Imperial Starfleet. The Black Fleet is an insignifanct speck when it comes to the size of the entire Imperial Starfleet.

The Black Fleet could overrun Coruscant defences, not knock out Coruscant shields.

There's a difference. All that means is that the Black Fleet probably has as much firepower as a Torpedo Sphere and the like, to find a weak point in Coruscant shield, blast it, hold the gap open while fighters destroy the shield generators.

[Ender]

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And consider this: in the Black Fleet Crisis, Ackbar says that the Black Fleet alone could knock out Coruscant's shield--presumably of equal power to Alderaan's, if not more, since Coruscant is the galaxy's capital--and the Death Star had firepower of over half the Imperial Starfleet. The Black Fleet is an insignifanct speck when it comes to the size of the entire Imperial Starfleet.

The Black Fleet could overrun Coruscant defences, not knock out Coruscant shields.

There's a difference. All that means is that the Black Fleet probably has as much firepower as a Torpedo Sphere and the like, to find a weak point in Coruscant shield, blast it, hold the gap open while fighters destroy the shield generators.

Given the way Coruscant has it's defenses set up, you can't really use a torpedo sphere type scenario. You have tot totally take them down.

[The Cleric]

Coruscant has double overlapping hexagonal shields. That are almost totally inpregnable.

[Darth Wong]

Alderaan's shield lasted only a split second against the Death Star's beam. It would have to last a couple of seconds (IIRC on how long it took the Death Star's beam to fully reach Alderaan), and that equate to many, many more shields.

Even if it lasted that long, the question then becomes what happens to this energy. Most likely, the shield would collapse and enough of the energy would radiate inwards that the planet would be vapourized.

And consider this: in the Black Fleet Crisis, Ackbar says that the Black Fleet alone could knock out Coruscant's shield--presumably of equal power to Alderaan's, if not more, since Coruscant is the galaxy's capital--and the Death Star had firepower of over half the Imperial Starfleet. The Black Fleet is an insignifanct speck when it comes to the size of the entire Imperial Starfleet.

Yes, I think it is not realistic to imagine that any planetary shield would actually protect the planet against a full DS blast.

[Sea Skimmer]

Coruscant has double overlapping hexagonal shields. That are almost totally inpregnable.

Had actually, under the Empire. By the time of the Black Fleet crisis Coruscant had already suffered very heavy damage from the attacks of the clone Emperor and its shields may have been greatly diminished in strength.