Can Star Wars ships destroy Star Wars ships?

[Connor MacLeod]

yeah Lando used that in Flamewind of Oseon to crack apart some asteroid or something it was hiding on by expanding the shields. I also vaguely recall that in normal operations shields extended only a hsort distance from the hull, but actually extended at least a few millimeters under it as well (anchored perhaps.) The Essential Guide to weapons and technology notes the same thing, and that energy weapons striking the shield could leave some sort of scorch or scar across the surface of the material but little else (indicating some bleedthrough is possible, but not neccesarily anything seriously threatening in most cases.) Slave-1 was also noted as having 'contact' ray shields in/under its hull in addition to regular deflector shields. We know that particle shields exhibit some osrt of structurally augmenting/reinforcing properties as wlel (from the essential guide to W&T again)

Brian young also once suggested that hull armor acts as a sort of back up "heat sink" to shields, which is certainly possible and may justify the shield/armor interactions mentioned in a number of sources.

Edit: oh yeah and on the "filtering" aspect of shields, we can probably throw in the "ability for slow moving objects to pass inside shields" as one such factor - the mass/momentum/velocity/whatever threshold dictating that probably is variable.

[Ahriman238]

yeah Lando used that in Flamewind of Oseon to crack apart some asteroid or something it was hiding on by expanding the shields. I also vaguely recall that in normal operations shields extended only a hsort distance from the hull, but actually extended at least a few millimeters under it as well (anchored perhaps.)

Close. He used it as sort of an improvised anchor to hide in the asteroid. Flying into a crevice barely wider than the Falcon, than cranking up the shields to wedge the ship firmly into place. Suggests interesting things regarding the shield's interaction with ordinary matter.

[Eternal_Freedom]

@Connor, on the matter of localised shield breakthroughs, we see such a thing happen in "The Bacta War," where the torpedo volley fired at the Interdictor Aggregator (?) makes the shield fail, but it does so with holes opening inplaces, allowing the last four missiles to smack into the hull while the shields were still up elsewhere.

Also, localised shield breakthroughs are exactly what Torpedoe Spheres are designed for are they not? Overwhelm a section, then nail the generator through the gap.

[Connor MacLeod]

@Connor, on the matter of localised shield breakthroughs, we see such a thing happen in "The Bacta War," where the torpedo volley fired at the Interdictor Aggregator (?) makes the shield fail, but it does so with holes opening inplaces, allowing the last four missiles to smack into the hull while the shields were still up elsewhere.

Also, localised shield breakthroughs are exactly what Torpedoe Spheres are designed for are they not? Overwhelm a section, then nail the generator through the gap.

It happens a number of times in the X-wing novels.. they share firing data and then fire simultaneously or near-simultaneously - I remember it happening in the first novel, the third, a number of times in the fourth (against the Lusankya, the Interdictor, the VSD they took out..), and at least once in Isard's revenge against a Golan platform. What seems to be involved is coordinating a large (how large varies - of course we dont know yields involved so that complicates things somewhat) numbers of torpedoes striking more or less the same point at as close to the same time as possible, which yes does seem quite similar to Torpedo Spheres. The Spheres are actually more involved: They have to spend lots of time with specialized/dedicated scanning arrays to locate a weak point in planetary shielding, which they then target with a concentrated bombardment of some 500 proton torpedoes, all specially configured to be effective against shields. If successful, it opens a brief (sources state from micro/milliseconds to several seconds IIRC) hole in the shields which turbolasers are designed to fire through. If any part of that process fails, it all has to begin over again.

How much of that applies to the more generalized stuff we see Rogue Squadron do, we don't know, but it implies that while its possible to locally overwhelm the shields without battering them down (some sort of bleedthrough?) possibly involving lower yields than the shield as a whole needs, it does not seem to be a common or easily exploitable tactic - at least in Star Wars. We've only seen Rogue Squadron pulling it off to my memory, suggesting that only highly skilled human pilots (or a computer) could probably pull it off.

This doesn't rule out other factors - how does range play into this? Typically SW ships (especially fighters) get ludicrously close as far as interstellar ranges go - to pull this off - kilometers for the strafing runs. Torpedo spheres are also stationary platforms firing on a stationary target - it can't be easy for targets that can move to neccesarily be hit. Likewise, if we believe the Black Fleet crisis novels, shield gaps/weak points/interference zones may not be easily exploited (they had to use weapons fire to "light it up" so to speak, which may in part explain why the sophisticated shield system is needed for ) and they may not even be predictable.

As an aside, another potential quality I remembered being discussed by Curtis - et all WRT SW shielding is shield geometry and how it may matter (again the angling) as far as it's protective properties go. I believe its something akin to the use of sloped or angled armor in military vehicles nowadays.

Also another thing I didnt' comment more on was the double blind effect. Basically SW shields seem to be impervious to both incoming and outgoing things. That means to fire shields either have to be weakened or lowered or otherwise filtered to let the gunfire through, but this can also apply to sensors, deploying fighters, missiles, probes or any other physical object, and so on. lightspeed comms seem only partly effected, but FTL comms (both subspace and hyperwave) appear to be totally blocked by shields and they need to be lowered. Engine exhaust probably requires shields be lowered as well. Or at least configured so nozzels (or weapons barrels, or sensor antaennae) extend beyond the shield perimeter. However you do it, that leaves exploitable weaknesses, however temporary, which is something that even fighters can exploit in combat (as we saw in ANH, novels like the Bacta War, etc.)

[Connor MacLeod]

Also I decided to throw out a few novel quotes that might be useful, highlighting some of the stuff I mentioned already. I'm gonna try to dig up the torpedo sphere stuff, but I dont remember where all my books with that are.

Anyhow, regarding the superconducting armor from Shatterpoint: possibly less useful than I thought.

And the metal itself. well, that's an interesting story of its own. It seems to be an alloy that the fungi don't attack. It is extremely hard, and never loses its edge. Nor does it rust, or even tarnish.

It also seems to be a superconductor.

This is why my blade could not cut it: the entire shield is always the same temperature throughout. Even the energy of a lightsaber is instantly conducted away. Hold a blade against it long enough and the whole thing will melt, but it cannot be cut. Not by an energy blade.
...

The source of this metal is a mystery; though Kar never speaks of it to anyone, I believe I know what it
is.

Starship armor.

Thousands of years ago-before the Sith War-when shield generators were so massive that only the largest capital ships could carry them, smaller starships were armored with a mirrorlike superconducting alloy, which was sufficient to resist the low-fire-rate laser cannons of the day.

So its not necesarily "modern" armor, although from what I remember in the EGW&T and other sources, the "ancient" technology (at least of thousands of years back and that era) is generally antiquated, inefficeint, and overall much less powerful than modern stuff, so I don't think we can treat this as unusual/supertech that may be lost. It may or may not be widespread use - but given this is the "peaceful" Republic era that isn't saying much either.

Maybe at some later point I can pull out data on molecularly bonded armor, which is also "high end" SW armor and is technobabbled into super-strong materials.

Next one of the "coordinated torpedo salvo" instances mentioned in ISard's Revenge, describing in a bit of detail what supposedly is happening.

A battle station like the Golan sported very powerful shields and individually fired proton torpedoes would have been 'unable to pierce it. Eight torpedoes coming in at the same time, aiming for the same point, would overstress the shields, draining them of energy. This would create a critical time window in which the shields would be weakened, or would totally fail, and have to be regenerated.

Last quote is one I remembered today, from Shield of Lies, featuring the bomber mounted T-33 plasma torpedoes (which is one example of "shield disrupting/penetrating" torpedo type weaponry.

Each of the six bombers was carrying two fat T-33 plasma torpedoes, known among the crews as shield-busters or rotten eggs. Designed to
detonate at the shield perimeter rather than to penetrate it, the plasma warheads of the T-33s created the most intense radiation burst of any New Republic weapon, several times the output of a capital ship's ion cannon batteries.

The focused cone of radiation was designed to overload rayshielding generators, either burning them up with the feedback or pushing
them overlimit with the bounceback. Once even one generator was down, the towers for the particle shields would be vulnerable to the turbolaser turrets on the gun frigates. If everything went according to plan, the carriers, already falling back behind the cruiser screen, would never come close to engaging the enemy directly.

[Eternal_Freedom]

In later works, the NR does indeed focus on it's starfighter forces. Heavy vessels and force flagships are carriers not battleships, such as the fleet carriers Intrepid and Endurance (the latter of which proved why carriers do not fight dreadnoughts directly - it got obliterated by the SSD Reaper).

By the time of the Second Galactic Civil War, there are Mon Calamari "heavy carriers" like Blue Diver.

IMHO the NR's love of fighters comes from the fact that in their early days they did not, or could not count on, having ships that could counter ISD's one to one, but with much cheaper fighter squadrons they cu=ould inflict disproportionate damage.

Also, fighter squadrons alone can't really cause serious damage to capships. They can drop the shields, take out the bridge, damage weapons and so on, but not actually kill the thing. What they CAN do is drive off said capship, which from a Rebel point of view is almost a better option. That ship is now out of actio for repairs, and everyone can see what the Rebels have done.
Spoiler

(Heck, in the example from "The Bacta War" where the VSD Corrupter is destroyed, the X-Wings drop the shields but it is turbolaser fire from the War Frigate Valiant that really kills it. Antilles blows the bridge to pieces, and the crew abandons ship. The VSD drifts down into the Alderaan Graveyard and gets chewed up.

The problem with the fighter attacks on capships, or "Trench Run Diesease" as the Alliance pilots know it, is tht the careful timing leaves the fighters vulnerable to Imperial fighters. Agian in the case from "The Bacta War" Antilles and Co. can only do it because they have another squadron of fighters holding off the TIE's.

[Eternal_Freedom]

Generally, focus fire seems to be the way to go in sci fi. Each time you take out another guy's ship, that's a little less power he can do to you while you do the same to the others, so if you start with a small advantage, you can grow it quickly this way.

The important thing about this particular swarming attack was that whilst the corvette's and frigates could hurt the VSD, they did not cause enough damage to put it out of the fight. And later, one of the frigates and two corvettes are dead in space, another frigate and three corvettes are criplled/heavily damaged and the other ships are suffering.

I think that aptly shows that small ships, even en masse, can't be expected to slug it out with larger ships.

[Eternal_Freedom]

I think that aptly shows that small ships, even en masse, can't be expected to slug it out with larger ships.

Yes. It looks like the redundancy of big ships really helps here - take out one section, and its ok because the other sections can still fight as a single, slightly less effective, but still very deadly ship.

Indeed.

Let us suppose we have one large ship with twenty heavy turbolasers mounted on it. It is engaged in battle by twenty single ships, each of which can mount a single heavy gun and nothing else.

Now, clearly the two sides are evenly matched in firepower. But, if we also suppose that the small ships can be destroyed in five hits, and the bigger ship can be destroyed in two hundred because it has more power for shields or armour, the bigger ship is going to win.

Also, in this battle, taking a single hit for the smaller ships is a BIG deal. As in, "oh bollocks, we can't take another hit like that" kind of thing. On the big ship, it's "This could be a problem soon."

If anything, this makes sense if the SW combat is "age of sail" in space. In the age of sail, two frigates could carry the same number of guns as a capital ship, but had no place fighting line-of-battle ships. They could not withstand the heavier rounds, and their guns could not penetrate the sail-of-the-line's hull. Add the longer range of the capships guns and you get a recipe for a can of whoop-ass for the frigates.

[avatarxprime]

I just wanted to address a few points. I actually think your conclusion that the DS1 was considered invincible based on a combination of its offensive and defensive abilities is quite interesting.

f) The DS2 had a shield to stop ships from getting close, but it depended on a ground station. The DS1, even though complete, had nothing of the sort. Interestingly, in ESB, the Falcon was able to land on a star destroyer, despite it's shields probably being up. (it's been a while since I've seen the film, but the captain thought Han was actually going to attack, so surely he would have raised his shields)

From (f) it seems that they don't have the tech to stop objects from coming inside a mobile shield. Perhaps they can stop inert things, but something with it's own power at least can push through. (it might be like a repulsor beam - an inertial object hits it then slows down or bounces off. A thing with engines though slow down, then push themselves the rest of the way through anyway.)

I don't think you should use the DS2 shield situation for this, the DS2 was clearly unfinished and the remarks about it being "fully operational" seemed to revolve entirely around the fact that the Superlaser was in full working order. It's likely that once the station was complete it would be as self-sufficient in its defense as the DS1. It should also be noted that the DS2 was constructed to account for the weaknesses found in the DS1. As to the issue of physical shields, here the Executor took 3 ISDs slamming into it (by accident) and the shield held long enough to protect the ship. Obviously the shield is therefore capable of blocking physical impactors that have engines and the Executor shield should certainly count as mobile.


Also in regards to the Falcon, I'd wager the magnetic clamp could work through shields. It's likely similar to a tractor beam, which we know can work on a shielded object, we also know that ion beams can penetrate shields, so charged, magnetic particles can get past shields. Now obviously an ion cannon is far more powerful than the Falcon's magnetic clamp, but between tractor beams and ion cannons the possibility exists that the clamp can work through shields.

[Connor MacLeod]

Stuff I don't disagree with, have nothing to add to, or would just be repeating myself with I will skip over, just so we're clear I'm not trying to "ignore" something.

Here's something that I've been wondering for the last day:

Was the Death Star invincible due to it's shields or due to it's guns?

Why is it neccesarily either/or?

Let's list some facts:

a) It had some kind of shield that the X-wings passed through

The ANH novel says that they were outer shields they passed, and the "shields" apparnetly had gaps or weak points that could be slipped through - something I've mentioned before (hence the "tighter defense" IIRC the novel correctly.)

However, the radio drama, which is at least of same status as the novelization for ANH, mentions that the X-wings were specificalyl outfitted with countermeasures to enable them to bypass the so called "shields", which complicates any assumptions we make about shield permeability.

b) Once inside, they were able to shoot the surface to take out guns, cause internal explosions, etc.

We dont know what they were shooting at though, and how inert/volatile it was. I believe you in fact made this sort of objection to Mike's X-wing laser calcs based on vaporizing the Death STar hull at one point, did you not?

e) The Imperial guy was confident that the Rebels weren't a threat to the DS, though they could hurt the starfleet.

I'm not quite sure what you mean by this, context wise. "Starfleet" has variable connotations depending on your source, from meaning "the Imperial Navy as a whole" to "a small fleet/squadron/flotilla of warships." For example Vader's Death Squadron has been referred to as a "star fleet" in the TESB radio drama.

f) The DS2 had a shield to stop ships from getting close, but it depended on a ground station. The DS1, even though complete, had nothing of the sort. Interestingly, in ESB, the Falcon was able to land on a star destroyer, despite it's shields probably being up. (it's been a while since I've seen the film, but the captain thought Han was actually going to attack, so surely he would have raised his shields)

There's lots of problems I can think with this (Jedi not TK throwing shit through Droidekda shields in TPM if matter-stopping shields were rare, dropping rocks on the REbel base in TESB, etc.) I already pointed out the problems WRT x-wings bypassing the shields, nevermind that in TPM we know that slow moving objects CAN bypass shields without harm - how fast/slow were X-wings moving in ANH again?

And yes, Needa (IIRC it was him) ordered shields raised when he thought the Falcon was going to ram, but we dont know if the shields got up or not in time, and even if they did, it's probable they were only raising either forward shields, or they had shields angled forward to maximize protection against ramming, which might very well leave the rear section unprotected (This actually happened with the Executor in one of the SW comics - the same series avatarxprime mentions. Shields are directed forwards, and the Falcon hits something on the Executor which cripples its ability to manuver.)

There's also ROTJ when the Executor's bridge shields failed, and Piett ordered guns to intensify fire so nothing could "get through" - SW has never shown B5 interceptor technology to my knowledge, so that means physical objects.

From (f) it seems that they don't have the tech to stop objects from coming inside a mobile shield. Perhaps they can stop inert things, but something with it's own power at least can push through. (it might be like a repulsor beam - an inertial object hits it then slows down or bounces off. A thing with engines though slow down, then push themselves the rest of the way through anyway.)

This would be problematic WRT Piett and ROTJ as I outlined above. Besides which, how are we defining "mobile" anyhow? Its not like we see SW ships moving at high speeds all the time.

The TL;DR approach to your theory is to point out that the EU will certainly invalidate this, but that's too easy.

Next up, once inside the shield, they apparently don't help much - small fighter weapons were doing (localized) damage to the station. Only one special place couldn't be hit by the lasers.

We dont know enough to make this supposition. For all we know, ray and particle shields can be modified independently - that certainly seems to be the case based on ROTS on the invisible hand - the DS1 may have just had its particle shielding extended a significant distance away for whatever reason (better defleciton angles, more time to act on matter, or whatever.) and kept its ray shielding close to the hull.

Alternately those are separate, dedicated shield generators, which is not inconsistent with anything we know either (again IH example in ROTS would support that idea, as would the WEG idea thta Slave-1, Boba Fetts ship, had its own dedicated, surface-contact ray shield projectors augmenting the hull.)

I think the answer is getting such a large ship inside the shield is much easier said than done, especially if it's taking fire from 1000 turbolasers at once.

By this logic, it should be relatively easy to destroy the Star Destroyer with any sort of minefield (or at least, deny it the ability to get within range of the target) or any sort of deployable, stand off attack munition (if fighters can get close, a robot missile could eaisly get within range as well.)

[Connor MacLeod]

I stand by my belief that turbolasers and blasters have a physical component to them, and angling would definitely help bounce them off.

Blasters, lasers and turbolasers have been alternately described in or argued as projectiles or beam weapons of myriad types. I'm probably happier with projectile weapons ymself, but beam weapons would have their value too.

Extending stuff reminds me of a book I haven't actually read yet (heresay alert!): The Mote in God's Eye. The Langston fields blocked it all, so they actually used some kind of periscope! Me like.

I havent read Mote either, and that has occured to me, but I suspect Curtis was going more for an Asimov-type feel with his view on SW. I've noticeda lot of parallels between the two.

This is why I figure it's a little of both: enough wattage means you damage the inside a little, but they can also be battered down with just enough time.

Whether the battering is a heat sink filling up, or bleed through causing damage that eventually hits too much important, or plain wear and tear on the shield mechanism is unknown though.

What's interesting about bleedthrough though is it is non-deterministic; it's essentially random when your shields will fall. Each shot has a x% chance of hitting something important, and once y important things are hit, they are down.

Thus it's possible for a one hit kill on them, and it's possible to last for days... you'd model this as "odds of surviving for time T", that can even out to something on the large scale, so fleet engagements are probably the same ballpark of time (like how radioactive decay works).

Could be. We dont really even know what the heat sinks are for. They may not actually absorb/store the energy of gunfire, but simply keep the shield generators from overheating during operation - some sources as I've noted indicate that generating defensive shields is an energy-intensive process.

Aye. One thing I like here is firing might mean pausing shield regeneration, or better yet, aborting it.

I'm still thinking in terms of a video game where press that key and you defend yourself, but the timer starts over!

Most of the numbers given in the ICS material assume "maximum operation" - EG 200 GT turbolasers assumes the Turbolasers are fired at their peak capacity, reactor outputs are given as the maximum possible energy the reactor can put out, accelerations are given as the maximum the engines can push the ship at, etc. it seems likely that the shields are operating at their maximum capability as well, but operate at much lower levels (for whatever reason).

Maybe there is a 'cooldown time' which is what you are talking about, but I dont know. That sounds more like 40K void shields (they function to absrob a certain amount of punishment, go down, tehn have a brief cooloff period where they vent energy then go back up.) 40K ships though get around this by having multiple, redundant generators active forming layers/sections on the hull.

IThis is what I'm getting at with my listing of stats. Sure, you could think of shields as being a kind of "black box" that just work. But if you think of them as being made of individual parts, each of which with their own capabilities and drawbacks and each of them can fail - like a real machine - all kinds of fun come out of it.

Fun in discussing tactics, fun in engineeing discussions, fun for story ideas. (this btw is why I put hard/soft sf on a different axis than realistic/unrealistic. Soft sci-fi takes the black box approach. The tech just does it's job for the story and you leave it at that. Hard sci-fi gets into those details and lets them shape the story. The way I see it, whether the tech is realistic or not is a separate issue; you can have the spirit of hardness with pure fantasy tech!)

I understand and yeah, it can be fun. I got into vs debating mainly because I liked to do that kind of thing, but nto many people like to discuss or speculate about fictional technologies. Curtis I know likes to speculate about how SW tech works more than the vs debate angle, although he's got his own ideas *shrugs*

Sensors are one I often forget about, but yes big indeed. Especially with how active sensors scale - you've gotta power it to not just get to the object you're scanning, but the signal needs to get back to you too!

But, compared to SW weapons, I find it hard to see how these signals need to be that strong; I'd expect them to be moe like 1% than 20% of the total budget.

normal realspace sensors and comms probably only make up a marginal portion of the energy budget (I somehow doubt that the comms array would double as point defnese on a starship for exmaple) but the FTL sensors (and they have at least 2-3 diff types) and comms may be another story entirely.



well time to get back to work. I'll hopefully be back sooner than a week to continue next time![/quote]

[Darth Nostril]

Extending stuff reminds me of a book I haven't actually read yet (heresay alert!): The Mote in God's Eye. The Langston fields blocked it all, so they actually used some kind of periscope! Me like.

I havent read Mote either, and that has occured to me, but I suspect Curtis was going more for an Asimov-type feel with his view on SW. I've noticeda lot of parallels between the two.

It reads like Horatio Hornblower in space, I was expecting them to have a midshipman crawl out on the bow and lower a knotted rope to find out how many fathoms above the planet they were. The sequel, The Moat Around Murchesons Eye (published in the US as The Gripping Hand), is a lot more up to date.

[Scottish Ninja]

Here's something that I've been wondering for the last day:

Was the Death Star invincible due to it's shields or due to it's guns?

Let's list some facts:

a) It had some kind of shield that the X-wings passed through

b) Once inside, they were able to shoot the surface to take out guns, cause internal explosions, etc.

c) It did have ray shields on the exhaust port

d) The general said the DS' defenses were centered around large scale assaults

e) The Imperial guy was confident that the Rebels weren't a threat to the DS, though they could hurt the starfleet

f) The DS2 had a shield to stop ships from getting close, but it depended on a ground station. The DS1, even though complete, had nothing of the sort. Interestingly, in ESB, the Falcon was able to land on a star destroyer, despite it's shields probably being up. (it's been a while since I've seen the film, but the captain thought Han was actually going to attack, so surely he would have raised his shields)


I think that's everything relevant that we know.



Let's see about drawing some conclusions.

From (f) it seems that they don't have the tech to stop objects from coming inside a mobile shield. Perhaps they can stop inert things, but something with it's own power at least can push through. (it might be like a repulsor beam - an inertial object hits it then slows down or bounces off. A thing with engines though slow down, then push themselves the rest of the way through anyway.)

Though, regardless of if they can or not, the Death Star certainly didn't.



Next up, once inside the shield, they apparently don't help much - small fighter weapons were doing (localized) damage to the station. Only one special place couldn't be hit by the lasers.



So, what if a big ship like a Star Destroyer parked it's nose right inside the shield and opened up with 200 gigatons? It seems likely that the station would be destroyed in very short order.



This raises the question: why were they so confident it could fight off such an attack?



I think the answer is getting such a large ship inside the shield is much easier said than done, especially if it's taking fire from 1000 turbolasers at once.


Essentially, the armor doesn't help much. The shield protects it from long-range attacks, and it's the guns that ultimately give the real protection, by forcing the battles to stay at those long ranges.

It's a factor of both, really - I don't think it's fair to say that "the armor doesn't help much".

I think a useful comparison here is tank warfare, since I'd been explaining this to a friend recently.

The biggest advantage of having a tank with thicker armor is range: it gives a tank a larger window in which it can act without fear of enemy fire. In the case of a Tiger against an M4 Sherman, the Tiger, with its powerful gun, can reliably penetrate the Sherman's comparatively thinner armor at very long ranges. In return, the Sherman has to get relatively close to penetrate the Tiger's thicker armor with its weaker gun (especially in the case of the 75mm). So a Tiger can essentially knock out Shermans with impunity at ranges over roughly 500 meters. (Of course, there can be better ways to knock out Tigers besides rushing them on open ground from the front. Fighters with rockets, for example. Wait a minute...)

Without that armor - say, if the Tiger were replaced by a Nashorn tank destroyer - the Sherman suddenly has much better odds; though the Nashorn's gun can still penetrate the Sherman at long range, so too can the Sherman penetrate the thin armor of the Nashorn. The Sherman's effective range has just been lengthened, though its gun is still the same. Or if the swap went the other way - say the Tiger's gun is replaced with a 37mm gun, drastically reducing its effective range against the Sherman and allowing the Sherman to safely close to a range where it can penetrate the Tiger's armor.

I think you've recognized at least most, if not all of this, already, but it's clear to me that it's in the combination of firepower and armor that makes the Death Star so dangerous against fleets - in the time it takes for an attacking fleet to either hammer down the shields or close the range to get inside them, the Death Star's defensive armament will have inflicted significant losses on the attackers. Without either it would be massively more vulnerable.