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Marry Christmas!
Has anyone calculated the minimal distance required for a mon cal cruiser (Liberty type) to survive the explosion of the DS2? (If there is not other info, based on the generator output of an ISD directed fully into the shields.) Is it possible to calculate it at all?

vakundok wrote:Marry Christmas!
Has anyone calculated the minimal distance required for a mon cal cruiser (Liberty type) to survive the explosion of the DS2? (If there is not other info, based on the generator output of an ISD directed fully into the shields.) Is it possible to calculate it at all?

Probably, since we never actually saw a Mon Cal killed by an ISD in the battle of Endor that I'm aware of, its safe to say they have shielding at least comporable to that of an ISD, if not superior as the EU suggests.

According to the site, the ISD should have about 100x the power generation ability of the Acclamator so probably 100x the shielding as well. After that point its left to others to define just what the Acclamator's shielding is, the figure given in ICS if taken literally says that the Acclamator can take around 17 terratons, rounded up and if I didn't misplace a decimel point. So 1.7 petatons for the ISD.

After that its not basic arithmetic so I'll leave it to the competent.

SCVN 2812 wrote:Probably, since we never actually saw a Mon Cal killed by an ISD in the battle of Endor that I'm aware of, its safe to say they have shielding at least comporable to that of an ISD, if not superior as the EU suggests.

According to the site, the ISD should have about 100x the power generation ability of the Acclamator so probably 100x the shielding as well. After that point its left to others to define just what the Acclamator's shielding is, the figure given in ICS if taken literally says that the Acclamator can take around 17 terratons, rounded up and if I didn't misplace a decimel point. So 1.7 petatons for the ISD.

After that its not basic arithmetic so I'll leave it to the competent.

IIRC, one of the higher estimates of DSII's explosive force is about in the 1E30J range, total. It was based off a reasonable mass for the DSII and the 80km/s class fragmentation velocity, but I don't remember any other details other than "It was proposed by Connor."

Even if that's so, that's only an intensity of about 8E21J per square kilometer at the surface (of the DSII). Figuring an ISD and Mon Cals to have an exposed area within that order of magnitude, it should be survivable, at least in energy terms.

For momentum terms, 8E21J worth of KE, with the 80km/s figure, implies 2.6E12kg of rock (1/2mvv=KE). Since momentum = mv, 2.6E12*80000 = 2.1E17kg*m/s. So, that much momentum is imparted every square kilometer, at the surface of the DS.

In any case, as far as we know, they survived. So they obviously must have been able to take the energy and momentum.

vakundok wrote:Marry Christmas!
Has anyone calculated the minimal distance required for a mon cal cruiser (Liberty type) to survive the explosion of the DS2? (If there is not other info, based on the generator output of an ISD directed fully into the shields.) Is it possible to calculate it at all?

Probably. It really depends on a.) How far away the Rebels were (arguably, though, the farther away they are the better off they are: inverse square law in the case of EM radiation and a longer travel time for the case of debris, which allows them more time to shoot down/slow down the debris.) as well as what form the "energy" is delivered in (EM radiation, Ke via debris/vapor/whatnot, etc.)

And without getting into the whole "Endor holocaust" debate, the moon itself puts indirect limits on how much energy the rebel ships absorbed (esp since they were involved on screening the party on Endor) - e10-11 megatons for example would be more than enough to guarantee rapid extinction even IF the Rebels screened the planet (in fact, if the energgy level gets very much greater, its likely the atmosphere of the planet would be dissipated - ie accelerated to escape velocity) Since the moon can only absorb so much enerrgy, this allows an estimate of the relative intensity, which can then provide an idea of how much energy each ship might have absorbed.) Indeed, the fact that the Rebels could survive for hours on the planet tends to suggest the energy the planet absorbed was much less.

Another not so minor factor to consider is the fact the Rebels were able to overwhelm the Executor's shielding (at least the dissipation capacity, if not at least some of the heat sink capacity), which suggests that they must have been capable of delivering a sustained, combined firepower of e27 watts (and output should be *roughly* compable to shielding capacity to within an order of magnitude or so.) which might give us another idea on what they can achieve.

It should be noted that the most probable "situation" the Rebel ships faced was kinetic energy from the DS2's debris, with little to no radiation. If most of the "enerrgy" released when the DS2 exploded was radiation, it would have bathed the planet with billions of megatons (or more) worth of radiation - fatal no matter how you look at it. Furthermore, its likely that if that much radiation had been released we would be seeing a blinding flash many times more brilliant than the sun (superheated vapor, atmospheric interactions, etc.) Given the "explosion" of the DS2 looked to be no brighter than, say, the asteroid vaporizations in TESB, we can safely conclude that most of the "energy" was absorbed by the station's own mass (parrticularily since the DS2 was rotating to fire on Endor, which means that the "completed' half would have been facing the moon.)

A final problem with "pure energy" striking the moon is the starfighters, particularily the Falcon (which escaped mere seconds before the DS2 explodes) - its questionable whether any of them would be able to endure that much energy unscathed (I estimate the relative intenstiy at 2000 km of a 1e30 joule detonation to be roughly 2e16 joules per square meter - more than enough to overwhelm most fighter shields. At 1000 km, assuming the Falcon made it that far away - a rather generous assumption - the intensity jacks up to some 8e16 joules per square meter, making survival of the Falcon seem unlikely)


As for the mass itself, based on visuals we can infer that a substantial portion of the station's mass was probably vaporized in the detonation, but there was obviously some fairly sizable solid debris in evidence, and we can probably infer there was some molten debris in there as well as much smaller "particles" (dust, whatnot.) Some of the energy would thus be in a thermal form (the molten/vaporized debris, etc.) but most would *probably* be in the form of kinetic energy. Velocity is probably quite variable - the debris is not ALL going to travel uniformly at 80 km/s, but its probably not much lower than 15-20 km/s, so we're not facing a *substantial* difference either. The difference in the velocity of the debris will help in that it helps "stretch out" the time the Rebels have to deal with it (though probably not affecting the calcs by more than an order of magnitude.)

Debris also allows weapons and tractor beams/repulsorlifts to be utilized in diverting/deflecting it, instead of just shields. Moreover, you don't need to totally "stop" debris either, you just need to redirect its path enough so that it will pass "by" the moon.

And if all else fails, one *could* try arguing the distance of the DS2 over the Sanctuary Moon was somewhat greater than the 2000 km Curtis estimates - which is IIRC based on the "Hologram" in the Rebel Briefing and could be expected to not be 100% "precise" for various reasons - however, the "difference" one could reasonably expect could onyl differ from that figure by a couple of times (2-3 times maybe) given that other visuals of the battle around the 2nd Death Star tend to suggest distances much less than 10-15k km.). Anyhow, by itself it wouldn't really "solve" any problems, it would just fudge the calcs up a bit more to make survivability for the Rebels more reasonable.

Why was the DSII rotating towards Endor? Wasn't the Emperor's first priority destroying the Rebel fleet, ship by ship with the super laser and his second deep fried Ewok? Or was it a means of trying to force the Rebel fleet out of the Imperial fleet out where Palpy could shoot them without hitting his own forces?

Unless I'm mistaken the positioning of the DSII and the Rebel Fleet was such that the fleet was approaching the moon or did they end up between the DS2 and the moon when they moved to point blank range with the Imperial fleet?

Wasn't the reason the DSII was at the end facing the moon was the plan had changed to destroy the moon to wipe out the Rebel Commandoes?

Darth Bowser wrote:Wasn't the reason the DSII was at the end facing the moon was the plan had changed to destroy the moon to wipe out the Rebel Commandoes?

Actually, Jerjerrod was doing it just out of spite. If he was gonna die, he was gonna take that Endor bastard with him.

Darth Garden Gnome wrote:

Darth Bowser wrote:Wasn't the reason the DSII was at the end facing the moon was the plan had changed to destroy the moon to wipe out the Rebel Commandoes?

Actually, Jerjerrod was doing it just out of spite. If he was gonna die, he was gonna take that Endor bastard with him.

Ah, at what point does he make this decision? Once the Executor crashes into the Death Star or Rebel fighters penetrate the structure? Just curious.

Darth Garden Gnome wrote:Actually, Jerjerrod was doing it just out of spite. If he was gonna die, he was gonna take that Endor bastard with him.

In the novelization at least, the Emperor gave the order to vape Endor should they somehow breach the shield. The charitable thing that could be said about it (whoever ordered it) is that it would probably have wiped out the Rebel Fleet, if we assume they inserted a 1E38J blast into the planet. The Earth's surface area is about 5E14m^2, and Endor is smaller, so that would have been an energy intensity of 2E23J/m^2 or more at the surface. That would probably be enough to put the Rebel fleet (only about 2000km from the surface) in deep shit. The bad news is that the Imperial Fleet is also screwed. Oh well, considering it was supposed to have been the whole Rebel fleet at Endor, trading the Rebel fleet for a Imperial Fleet makes strategic sense, I guess.

I did some thinking.
Well, the DS 2 was preparing (actually positioning) to fire at the moon. Since Jerjerrod accelerated the rotation, the energy to fire was most likely ready. Whether what happens (with the stored energy) when an SW energy storage explodes, I do not know, but most likely it does not simply disappear. So, likely the station stored E32-E38J energy for the shot plus what came from the exploding reactor itself minus the vaporisation. Am I correct?

Connor, thanks for the Falcon. I forgot about it completely. I thought that smaller ships/fighters could hide behind the cruisers. I think the shape of the DS cannot really help Endor. Even if the finished parts had been able to completely shield their surroundings, half the side that faced toward Endor was unfinished.

If we assume the explosion produced E30J energy outside the DS, the shields has no chance to recharge/cool (which was not necesserely the case with KE), the Liberty type has 30,000 m^2 frontal face (0.03 square kilometer) and can deal with 1.7 petatons (7.1128 E24J) (plus many other things, the most important is that neither the gravity of Endor, nor the unfinished shape affected the things significantly); we can estimate that it could have survived from 18.32 km, so, they could have survived even on the surface of the DS 2.

vakundok wrote:I did some thinking.
Well, the DS 2 was preparing (actually positioning) to fire at the moon. Since Jerjerrod accelerated the rotation, the energy to fire was most likely ready. Whether what happens (with the stored energy) when an SW energy storage explodes, I do not know, but most likely it does not simply disappear. So, likely the station stored E32-E38J energy for the shot plus what came from the exploding reactor itself minus the vaporisation. Am I correct?

Probably towards the lower end, if that. Remember that there is only so much energy the DS could have contained if the moon is not to be immediately incinerated to a crisp (Since we don't see Han and Leia dying in global firestorms before kissing..)

In general, we don't really know precisely how much energy was released by the explosion as my previous estimate was simply a lower-limit guesstimate. However, to crunch a few numbers:

- the ITW:OT book implies that the Superlaser blast was hundreds of times greater in output than a supergiant star, which implies a total energy release around e31-32 joules. Depending on the type of "Supergiant" and how one defines "hundreds", the output could be as high as e35 joules or so, by my estimates.)

- Knowing the sustained output of the DS1 and that the DS2 should be at least 4x as great, one might infer a 4e33 watt output as possible)

- the AOTC: ICS entry for the Acclamator specifies that a ship's fuel supply is "many orders of magnitude denser than the bulk of the ship itself" - in other words (due to their prodigious power supplies), a starship or battlestation would carry hundreds of times its own mass in fuel (this is generally borne out by known estimated power outputs and "endurances" - ie "thousand gee" accelerations for hours, etc.) This means that using my prior DS2 mass figure, we could expect the DS2 to carry around the equivalent in e36-3e37 joules worth of fuel at least.

However, as I have already explained, the larger this figure becomes, the more problematical becomes the fact that the Rebel commandos were not incinerated along with the rest of Endor by the DS2's explosion - EVEN accounting for any protecting/shielding efforts by the Rebel Fleet - and disregarding the fact they were already battle-weary from fighting off an opponent with both a qualitative and numerical advantage.

Connor, thanks for the Falcon. I forgot about it completely. I thought that smaller ships/fighters could hide behind the cruisers.

Most could, but Lando's survival is iffier (since he's still racing away when the DS2 explodes..) Wedge is kinda iffy as well.

I think the shape of the DS cannot really help Endor. Even if the finished parts had been able to completely shield their surroundings, half the side that faced toward Endor was unfinished.

I don't quite follow.

Anyhow, there's problems with this as I already noted - any UNFINISHED side facing endor runs the risk of bathign the planet in massive doses of radiation, which is MUCH MUCH harder to reconcile with canon than debris impacts is (since the debris takes much longer to reach the planet compared to radiation.)

If we assume the explosion produced E30J energy outside the DS, the shields has no chance to recharge/cool (which was not necesserely the case with KE), the Liberty type has 30,000 m^2 frontal face (0.03 square kilometer) and can deal with 1.7 petatons (7.1128 E24J) (plus many other things, the most important is that neither the gravity of Endor, nor the unfinished shape affected the things significantly); we can estimate that it could have survived from 18.32 km, so, they could have survived even on the surface of the DS 2.

Energy output maybe, but shield dynamics aren't quite that simple. (intensity plays a matter, as does momentum.) It is entirely conceivable for them to "survive" the energy output, only to fail because their momentum-handling capabilities are exceeded. And lets not forget that these would be Rebel ships concerned with protecting the commandos at least, as well as the fact they've already sustained fairly substntail damage from at least half an hour of combat. (Which is where intensity would come in - some sections of the shield could/would be weaker than others, if not down already.. and thus be prone to failure more readily.)