DeathStar II: Why so big?

[Lord of the Farce]

Why the first Death Star couldn't (easily) target ships with it's SL? I think one answer is this question: Why would you want to waste the time and resources to make one weapon do the job that is done better with thousands-to-millions of weapons you already have?

On topic, the DS2 was probably designed as a virtually indestructable mobile base of operations, it can probably launch dozens of capital ships from inside it.

[Gandalf]

On topic, the DS2 was probably designed as a virtually indestructable mobile base of operations, it can probably launch dozens of capital ships from inside it.

"... this fully armed and operational battlestation!" - Palpatine

This quote basically helps that argument along.

[vakundok]

Warning! Personal oppinion:
I doubt Saxton's estimate. It was based on two things:
1: One model made for the DS scenes (actually, what the modeller said about it).
2: We know Endor.
I dislike his trench inside trench explanation and that he did not use the hologram of the DS as a reference. So, I think the DS2 is 'only' 350-450 km in diameter.

[Ghost Rider]

What do we know about Endor?

And also it would help to have a much more concise reason then two vague examples to say WHY you disagree with Saxton.

Because saying he's wrong, does require proof...just like everything else

[vakundok]

Personal oppinion:

What do we know about Endor?

And also it would help to have a much more concise reason then two vague examples to say WHY you disagree with Saxton.

Because saying he's wrong, does require proof...just like everything else

The Endor Moon must be of a size which is approximately equal to that of the Earth (which has a radius of 6400km). If it were very much smaller then it would not have enough gravity to hold an atmosphere thick enough for human comfort, let alone thick enough to allow Ewok glider craft to fly.

This is based on that Endor has a very similar composition than Earth. It can or cannot be the case.
(Side note:
The Emperium chose it for some reason. For logistic? With hyperdrives its location does not really matter. For secrecy? It has an intelligent population who had contact with the rest of the galaxy in the past. For energy generation? What makes a planet more capable for energy generation than others? Likely its composition.)

My problems with the trench inside trench theory:
1: Both surfaces above and under the docking trench (the trench containing the docking 'boxes') were lit whereas the lower part of the trench was shadowed when watched from farther.
2: He suggested that the inner trench was approximately one third as high as the outer. That outer trench quite high on the tactical hologram of the VHS edition, but it did not show the inner trench. (Of course it doesn't contradict, only doesn't support the theory.)

And I think a more exact relation (between the diameter and the distance of the hemispheres) could be done using the tactical hologram than using the model or the show where even that part was still under construction (so the height was not constant).

EDIT: However, I am not a physicist, so I cannot say he is wrong or he made a mistake when he threw away the description of the novelisation (about the geostacioner orbit for example).

[nightmare]

This is based on that Endor has a very similar composition than Earth. It can or cannot be the case.

Earth has the highest density of all known planets. You can have a planet with lower density, which means greater radius, which in this case means an even larger DS2. You can not have it the other way around.

[RedImperator]

My Death Star theory:

Let's say a heavily defended world is defying the Emperor, but for whatever reason, you don't want to blow it up? It has a shield, orbital defenses, a system fleet, and probably ground based weapons. A fleet can engage the space defenses and take down the shields, but it will take weeks to do and you'll take heavy casualties before you even get the troops on the ground.

What to do, then? Why, use the Death Star. Its shields and defensive weapons are planetary scale, so it can sweep the system defenders aside. Use a lower powered superlaser shot to crack the planetary shield. Then, you launch an entire army, complete with heavy equipment, along with Star Destroyers to provide cover fire from orbit (as even the Death Star can't see the entire planet at once).

And there you go. Instead of tying up a fleet for weeks and taking thousands of naval casualties, the Death Star can knock out a planet's defenses in hours and probably be done in the system in days. Something the size of DS2 could carry an entire fleet with it, so while it moves towards the planet, its fleet chases down and destroys enemy ships out of the DS's range.

[vakundok]

This is based on that Endor has a very similar composition than Earth. It can or cannot be the case.

Earth has the highest density of all known planets. You can have a planet with lower density, which means greater radius, which in this case means an even larger DS2. You can not have it the other way around.

Do you seriously mean that because Earth has the highest density of all currently known planets there cannot be planets with higher density? Excuse me, but we do not know fully our own solar system, not to mention our galaxy ...

[nightmare]

Do you seriously mean that because Earth has the highest density of all currently known planets there cannot be planets with higher density? Excuse me, but we do not know fully our own solar system, not to mention our galaxy ...

But we do know the relative amount of periodic elements in the universe, and can conclude that there's no reason to believe that a planet consisting of mostly of unstable high density matter would exist naturally - and if it did, it would be a) found only in very specific conditions, and b) certainly not be able to sustain life.

You can of course theoretically have a planet with a little higher density than Earth, but then we are talking about a planet with more iron in it, which would mean ~9% higher density if we assume it has 100% iron in it. Which in turn would mean less than 9% smaller radius to maintain the same gravity as Earth because of the shorter distance to the center of gravity.

We can do a bit additional head-wrenching and assume that there's some very rare planet consisting largely of rare heavy elements, but it still gets nowhere close to what you are suggesting.

Your hypothetical small Earth-like planet with high density can not exist.

[Sea Skimmer]

Your hypothetical small Earth-like planet with high density can not exist.

In addition I recall reading on Saxtons site that the FX personal who did the movie said it was meant to be about 800 kilometers across.

[Publius]

The short story "Betrayal" from Star Wars: Empire reveals that, prior to the ill-fated coup d'état of the late Grand Moff Trachta et al., the Emperor had originally planned to join Grand Moff Tarkin aboard the Death Star. It is possible that the second Death Star was so much larger than the first because it was planned to replace Imperial Centre as the seat of the Imperial Government and the Emperor's court, and therefore required extensive additional facilities.

Publius

[vakundok]

Your hypothetical small Earth-like planet with high density can not exist.

Really? Let's see:
-average density of Earth: 5.052 g/cm^3
-radius of Earth: 6371 km
-radius of Endor: 11.5 times the radius of the DS

Let's assume that the diameter of the DS is 420 km.
-radius of Endor: 2415 km
-it means that the volume of Endor is approximately: (2415/6371)^3 * V(Earth)
-mass of Endor (to have the same gravity): (2415/6371)^2 * M(Earth)

These means that my theoretical Endor must have an average density of 13.327 g/cm^3 to have the same gravity as Earth (or 10.662 to have 80% the gravity).
You are right, it is over the density of iron (7.86), but well under the heavier elements like gold (19.3) or iridium (22.5) for example.
So, stating that it cannot exist is incorrect.

[Connor MacLeod]

Lets not forget this from the canon ROTJ novelization:

At the feathered edge of the galaxy, the Death Star floated in stationary orbit above the green moon Endor -- a moon whose mother planet had long since died of unknown cataclysm and disappeared into unknown realms. The Death Star was the Empire's armoured battle station, nearly twice as big as its predecessor, which Rebel forces had destroyed so many years before -- nearly twice as big, but more than twice as powerful. Yet it was only half complete.

at the absolute, bare-assed mniimum, it was 2x the size of the Death Star, suggesting at least 320 km in diameter. But it also mentions being only "Half complete", suggesting 4x larger, or 640 km in diameter.

Either way, its incredibly frigging massive.

[vakundok]

Lets not forget this from the canon ROTJ novelization:

At the feathered edge of the galaxy, the Death Star floated in stationary orbit above the green moon Endor -- a moon whose mother planet had long since died of unknown cataclysm and disappeared into unknown realms. The Death Star was the Empire's armoured battle station, nearly twice as big as its predecessor, which Rebel forces had destroyed so many years before -- nearly twice as big, but more than twice as powerful. Yet it was only half complete.

at the absolute, bare-assed mniimum, it was 2x the size of the Death Star, suggesting at least 320 km in diameter. But it also mentions being only "Half complete", suggesting 4x larger, or 640 km in diameter.

Either way, its incredibly frigging massive.

EDIT: The 4x diameter of DSI is only true theoretically. If you watch the movie you will see that the diameter was already completed, so the 'half complete' cannot mean that the diameter would be doubled again.

[nightmare]

*snip*

You are right, it is over the density of iron (7.86), but well under the heavier elements like gold (19.3) or iridium (22.5) for example.
So, stating that it cannot exist is incorrect.

Apparently you read my post, but you didn't get my meaning - your theoretical planet is precisely that. Since you claimed it can exist, how about you present the natural conditions which can produce for example, a mostly gold planet?

[vakundok]

Apparently you read my post, but you didn't get my meaning - your theoretical planet is precisely that. Since you claimed it can exist, how about you present the natural conditions which can produce for example, a mostly gold planet?

First of all you wrote that it could not exist because that density would require 'a planet consisting of mostly of unstable high density matter'. It was clearly wrong.

EDIT: DELETED

Any gravitic condition that can prevent even iron from reaching the forming planetoid.

Or what about the conditions those led Endor to loose its mother planet? Since moons don't loose 'their' planets regularly, something abnormal happened or abnormal conditions were present.

Side note: As I know Mercur has (slightly) higher density than Earth.

[greenmm]

Lets not forget this from the canon ROTJ novelization:

At the feathered edge of the galaxy, the Death Star floated in stationary orbit above the green moon Endor -- a moon whose mother planet had long since died of unknown cataclysm and disappeared into unknown realms. The Death Star was the Empire's armoured battle station, nearly twice as big as its predecessor, which Rebel forces had destroyed so many years before -- nearly twice as big, but more than twice as powerful. Yet it was only half complete.

at the absolute, bare-assed mniimum, it was 2x the size of the Death Star, suggesting at least 320 km in diameter. But it also mentions being only "Half complete", suggesting 4x larger, or 640 km in diameter.

Either way, its incredibly frigging massive.

Um... not quite.

2x diameter for DS2 = 8x volume, and (assuming same density) 8x mass of the DS1.

2x volume and mass would require about 1.2599x diameter, putting the DS2 at about 200-202 km diameter.

As for the "half complete"... well, if it's anything like modern shipbuilding, IIRC you normally work on completing the framework and outer shell first, then work on completing all the internal systems. This would, IMHO, be especially critical in outer space, as obviously work in the exposed sections would require remote-controlled work robots or space-suited technicians; OTOH, sections where bulkhead and the outer armor had been installed could have life support turned on, even if artificial gravity wasn't available yet, and work could be done by technicians in standard work uniform (coveralls, or whatever the techs wear when working).

Either way, though, even if the DS2 was only 200 km in diameter, assuming no major changes to the design, that's still:
-- enough outer hull space for 58% more turbolaser turrets (LTL's, MTL's, and HTL's)
-- room for a power plant with twice the power output (same lifespan), twice the lifespan (same power output), or 58% more output and 26% more lifespan [I'd lean toward increased output, given the additional turbolasers and the larger superlaser]
-- room for a superlaser with increased output and a faster recharge rate (depends on if the superlaser's output is dependent on the increased volume [2x] or the increased surface area of the outer focusing array [x1.58])
-- enough internal volume for double the number of TIE fighters, shuttles, AT-AT's, and ground troops (although simultaneous launch ability would only be about 58% higher)

[YT300000]

Even if the novelization supports the 160 km diameter, it is still trumped by movie visuals.

http://www.theforce.net/swtc/ds/#dimensions

[Connor MacLeod]

Um... not quite.

2x diameter for DS2 = 8x volume, and (assuming same density) 8x mass of the DS1.

2x volume and mass would require about 1.2599x diameter, putting the DS2 at about 200-202 km diameter.

Why would it neccesarily be volume rather than dimensional comparison? The context isn't clear. (BTW thats only the dimension ofr the partially complete portion. A half completed Death Star would be more like 400 km in diameter. At the bare-ass minimum, its 2/3 complete, so the complete diameter would be 300 km.) Size can refer to diamater just as well as "volume", and is probably more likely if its a "eyeball" comparison.

As for the "half complete"... well, if it's anything like modern shipbuilding, IIRC you normally work on completing the framework and outer shell first, then work on completing all the internal systems. This would, IMHO, be especially critical in outer space, as obviously work in the exposed sections would require remote-controlled work robots or space-suited technicians; OTOH, sections where bulkhead and the outer armor had been installed could have life support turned on, even if artificial gravity wasn't available yet, and work could be done by technicians in standard work uniform (coveralls, or whatever the techs wear when working).

The Death Star was functional enough that it could fire its superlaser (even potentially destroying Endor) and it could manuver. It also presumably had life support and other associated power systems (control systems, lighting, some of its field technologies.) IT still needed a substantial portion of its interior constructed, however.

Either way, though, even if the DS2 was only 200 km in diameter, assuming no major changes to the design, that's still:
-- enough outer hull space for 58% more turbolaser turrets (LTL's, MTL's, and HTL's)
-- room for a power plant with twice the power output (same lifespan), twice the lifespan (same power output), or 58% more output and 26% more lifespan [I'd lean toward increased output, given the additional turbolasers and the larger superlaser]
-- room for a superlaser with increased output and a faster recharge rate (depends on if the superlaser's output is dependent on the increased volume [2x] or the increased surface area of the outer focusing array [x1.58])
-- enough internal volume for double the number of TIE fighters, shuttles, AT-AT's, and ground troops (although simultaneous launch ability would only be about 58% higher)

This of course assumes that all the OTHER considerations are incorrect, and that your interpretation of the quote is correct.

[Connor MacLeod]

Lets not forget this from the canon ROTJ novelization:

At the feathered edge of the galaxy, the Death Star floated in stationary orbit above the green moon Endor -- a moon whose mother planet had long since died of unknown cataclysm and disappeared into unknown realms. The Death Star was the Empire's armoured battle station, nearly twice as big as its predecessor, which Rebel forces had destroyed so many years before -- nearly twice as big, but more than twice as powerful. Yet it was only half complete.

at the absolute, bare-assed mniimum, it was 2x the size of the Death Star, suggesting at least 320 km in diameter. But it also mentions being only "Half complete", suggesting 4x larger, or 640 km in diameter.

Either way, its incredibly frigging massive.

EDIT: The 4x diameter of DSI is only true theoretically. If you watch the movie you will see that the diameter was already completed, so the 'half complete' cannot mean that the diameter would be doubled again.

Pointless nitpick. Concession accepted.

[nightmare]

First of all you wrote that it could not exist because that density would require 'a planet consisting of mostly of unstable high density matter'. It was clearly wrong.

I also wrote "rare planet consisting largely of rare heavy elements". I.e. gold, if you wish. It all depends on how MUCH you have of the material in question in the planet's composition. I thought I didn't have to point out that.

Any gravitic condition that can prevent even iron from reaching the forming planetoid.

Or what about the conditions those led Endor to loose its mother planet? Since moons don't loose 'their' planets regularly, something abnormal happened or abnormal conditions were present.

You're talking about the "Endor gate", right? Somehow I doubt that a randomly occurring space/time rift could create a planet of gold, but hey, whatever floats your boat, we've moved over to the realm of sci-fi now. I was thinking more in the lines of a double star/black hole system or similar.

Side note: As I know Mercur has (slightly) higher density than Earth.

Okay, I give you that point, though Mercury is only Earth-like in the barest sense, and though I already wrote that you can have a planet with a little higher density than Earth when I explained my statement further. I thought my previous post made it clear that it was a simplification of an invariably complex reality, not a "stone tablet handed over by god".

ADDENDUM:

Maybe I should have wrote it like this instead:

Your theoretical planet would have to have more rare heavy elements in is composition than is realistically possible for an Earth-like planet, except under theoretical, rare, highly specific and localized conditions that has yet to be observed.

Better? Or we can go with, "it doesn't exist.". I would also say that apples always fall to the ground, even though there's a small chance that it wouldn't happen.

[Ender]

The SFX guys said it was 500 miles in diameter. Case closed, concession accepted.

[Howedar]

Which AFAIK really has no sembalance of canon status.

I agree that the DS2 is 500mi/800km wide or thereabouts, but I don't see the SFX guy's comment as much more than an interesting tidbit.

[LMSx]

For one absolutely hilarious moment, I saw the question "DS II: Why so big?" and two posts on the first page mix together to create the question/answer: DS II: Why so big? Palpatine-Compassionate Conservative".

[Connor MacLeod]

the real proof is in the comparison to endor (which we can do from several diff sources in ROTJ) - given Endor's habitability and its observed characteristics (IE Ewok glider) we can in fact scale a distinct upper and lower limit to the DS2, which is perfectly valid (And is the primary evidence for the given scaling - all else is really secondary)