How much would it cost to build the Death Star?

Cafe Society
1

The Death Star is 120km across, according to 2000 Meters per Pixel

Using the 4/3 pi r-cubed formula for the volume of a sphere, we find a volume of about 7.2 million cubic kilometers. This is 7,200,000,000,000,000 cubic meters.

Now, we want to get a rough idea of how much steel that implies, so let’s look at the mass per volume of, say, one of the Twin Towers.
According to http://www.physforum.com/What-was-the-weight-of-a-WTC-Tower_4299.html, one of the Twin Towers used about 96,000,000 kg of structural steel.
(By the way, searching for “world trade center facts” sure comes up with a lot of garbage)

According to World Trade Center - Wikipedia, the trade center was 413 meters high. It has 800,000 square meters of floor, so divide that by the number of stories (110) to get a cross-sectional area of about 7200 square meters. Multiplying height by cross-sectional area gives a volume of 3,000,000 cubic meters. Thus, we get a ratio that 3,000,000 cubic meters of a building implies 96,000,000 kg of steel.

Take the volume of the death star and divide it by this ratio to get 230,000,000,000,000,000 kg of steel are in the death star.

So, what’s the current cost of steel per kilogram? According to http://web.ead.anl.gov/uranium/pdf/ducretecosteffec.pdf, it’s about $1.10 per pound.
So, the cost of the steel would be about $230,000,000,000,000,000 ($230 quadrillion).

That’s JUST the cost of the steel, ignoring labor costs. I also ignored the impact of the purchase of that much steel on the cost of steel, and a bunch of other stuff.

For comparison, the world’s GDP is $65.95 trillion (2006 est.) (just google for “world gdp”).

That’s a hell of a sports bar that Darth Vader told the bank he was building.

2

I already see some mistakes (including mixing up radius and diameter). No matter.

3

Much of the labor costs can be mitigated by using a droid and slave workforce. I’d assume that they have high end fabrication technology that allows them to do the work much easier, faster and cheaper than it would be done by Earthly standards.

The supply of materials would be eased by dragging some solid iron asteroids in for processing on the spot.

Also they have a galactic empire of a million worlds so assuming that the average world has the GDP of Earth that’s a galactic GDP of 65,000,000,000,000,000,000. Couple that number with oppressive taxation, high levels of automation and workplace safety standards that would make OSHA scream it seems as if it’s in the realm of possible.

But it’s science fiction so you can just assume that they possessed whatever technology it would take to build it in the time frame and resources they had.

I don’t see us building one any time soon until we get at least a 100,000 world empire.

4

I wouldn’t be surprised if the relative cost per kilo of metal was significantly lower than in real life. If you can build generators more powerful than stars, energy costs for mining, transporting and processing steel are probably going to be a lot lower.

5

If you accept the drek known as the prequel trilogy, then they spent about 20 years building the first one. This could mean that the Emperor had to keep things under wraps and build it covertly, which would add to the cost significantly. Or, you could take the attitude that Lucas died in 1982, and thus the prequels or RotJ (with its double sized DS that only began construction after the first one got blowed up real good) never happened.

6

That’s okay, the Emperor hired independent contractors.

7

Probably one could do a rough guess of the cost by taking the cost for making the first atom bomb per the time it took, and then expanding the time period to 20 years.

The value of things change, but in general the cost of equivalent projects will be equivalent in price per the value of things at that time and place.

8

How many innocent contractors where on that death star when it exploded? The rebels killed tens of thousands of innocent workers just trying to feed their familes. Not to mention taking out the Empires two most senior officers and the power struggle in the huge leader vacuum that must have made the Empire have a civil war with itself. Costing hundreds if not thousands of planets

9

Reminds me of this funny scene from the original Clerks movie about contractors who were killed when the under-construction death star was blown up: http://www.youtube.com/watch?v=n6lzEhoXads

10

Don’t forget, they saved some money by skimping on guardrails and other safety features.

11

Well, how much Illudium Pu-36 do you need and what is it’s cost/gram?

Kaboom.

12

Well, to be fair, if they had installed guardrails, the guys would have just spent their shift leaning against it.

13

You also keep labor costs down by employing illegal aliens.

14

One of the things that bothered me was that when they see the Death Star for the first time Han thinks it’s a moon that’s not on the charts and Obi Wan classically says “That’s no moon, that’s a space station”. So it figures that ships that can make the jump to hyperspeed depend on navigation computers that know where known obsticles are in a particular star system, to help you avoid smashing into them at just below hyperspeed. Designing a moon sized space station in secret then lends itself to the idea that you’d better use it quick before someone decides to pop over to Alderaan for a few space beers and plows into your giant unmarked space station making a huge damned mess.

Also, didn’t anyone on Alderaan notice, you know, a new planet that could be seen in the night sky or by passing ships coming too and from?

15

You know, a lot of the mass of a skyscraper goes into holding up its own weight. A big sphere floating in space wouldn’t have to worry about that so much, what with the lack of gravity. I’d imagine that cuts down on the density to a large degree.

To answer Cluricaun: The Death Star wasn’t built near Alderaan. It flew there, albeit slowly. Remember how it then flies to Yavin IV to take out the Rebels? I’m sure the Alderaanians saw it, but they were a peace people with no weapons, and how quickly can you really evacuate a planet?

16

Something that huge produces it’s own gravity, if less than an Earth sized planet. And then there’s it’s own artificial gravity; who knows exactly what effect that has on structural strain ?

17

You’re overestimating material costs by several orders of magnitude. If the Empire was smart (you in the back, stop giggling), they’d just locate an iron/nickel asteroid of sufficient size and convert it on the spot to the Death Star. Or perhaps strip mine a moon.

I’d be concerned about tidal forces. The stresses on it when it orbits a planet have to be incredible.

18

Dragging asteroids doesn’t sound a heck of a lot easier than rocketing steel up from a planet. And now BEFORE you start working on the Death Star, you’ve got to build the most gigantic steel mill ever conceived in space.

“Its,” dude.

But you make an interesting point - but how much gravity is it?

If we assume to OP’s guess of 230 quadrillion kilograms is accurate, and then add more weight to account for the fact that you need more than steel - you’ll need furniture, wiring, details, engines, piping, troops, supplies, monsters for your garbage disposal - and push it up to 300 quadrillion kilograms, that’s… uhhhh… 300 trillion tonnes.

Now, that may SOUND like a lot, but by gravitational standards it’s miniscule. The Earth weighs about six sextillion tonnes, making our Death Star twenty million times lighter, and hence possessing 20,000,000 times less gravity at a like distance. The structural strain would be insignificant… indeed, if you think about it, a building constructed on Earth, which is effectively part of the Earth, therefore suffers from 20000000 times more gravitational stress.

Which is why the weight of our proposed battle station is way off. Structural steel choices are made based on the fact that the building being put together must live under the strain of the Earth’s gravity. Heck, that’s why we started building things with steel. But the Death Star would be weightless in space, and its own gravitational force would be very, very small. So you just wouldn’t need that much steel - comparing its steel volume to that of the WTC is way, way off. You’d need a fraction of the structural strength of an Earth-bound building, and so you could use much smaller, weaker beams and angles, or could even use other metals.

It’s still pretty expensive, though. Today I examined a plan for the steel construction portion of a small college campus addition. Just designing and making the steel parts - not even putting them together onsite - was going to cost ten million dollars. It ain’t cheap.

19

No that I think you’re wrong in your overall thinking, Rick, but unless it’s a stationary battle station, I would think it’s entirely possible that whatever sublight engines you stick on that big ol’ thang is going to put some kind of stress/strain on it, even if they’re so weak that you need to pull up a lawnchair, pop some popcorn, and wait a while to tell that it’s actually moving.

Of couse, we can handwave that away with “Structural Integrity Fields,” or “Inertial Dampeners,” with Unubtainium reinforcements at key structural junctions.

20

Transporting all the raw materials to a planet and then lifting billions of tons to orbit versus a significantly simpler bit of space construction than what we’ve seen them capable of. The space steel mill makes more sense.

You’re right that for space construction that different materials would be an option but I think they would have had to use something heavy in iron (presumably steel but there’s always strange space materials as well) since there’s a lot of it available. A not insignificant chunk of asteroids are made of it. Admittedly large asteroids are going to be carbonaceous but they could quickly survey for one or haul three or four together to fuse together. And there’s the strip mine a moon option which would give them the spherical core. It would be by far the cheapest option.

They would also have to use a lot of it because of massive forces put upon it. Just rotating the station could rip it apart. Having it orbit a planet would be an easier way to destroy one than sticking a potato in its tailpipe. The superstructure must be incredibly strong and that means heavy. (There are other interesting engineering options but we see no sign of them in the movies.)

If the Death Star was smaller then it would simplify things greatly.