* * * * *

                I did forget to factor in union labor though …

> Yes, Septillion, that is a 1, followed by 24 zeros.
>
> A very, VERY large number, especially when it concerns money. And why is it
> a deal? Because that figure ignores a lot of very important costs. Costs
> for what? Why to build a Death Star of course!
>

Via my good friend Hoade, “One Death Star for $15 Septillion? What a deal!
[1]”

Not quite. Ryszard Gold there seriously overcalculated the price of the Death
Star, by several orders of magnitude.

First off, his figure of 17,157,284,678,805,056 cubic meters is too high, and
I think I know his mistake. The volume of a sphere is (roughly) the radius
cubed. Ryszard used a figure of 160km (or 160,000m) for the diameter, and
cubed that (160,000m) instead of the actual radius (80,000m), so his Death
Star is 8 times too large. It's actually 2,144,660,584,850,632 cubic meters.

So his cost of the raw steel, $1.3×10^19, is too high—it's closer to
$1.6×10^18—an order of magnitude cheaper. But that's the cost of steel made
on earth (excluding shipping, which is $1.2×10^25, or $12 septillion
dollars). But if you're shipping that much steel up to Earth orbit, you're
doing it wrong. It'd be way cheaper to ship steel in from the Asteroid Belt
than to lift it to Earth orbit. Or heck, cheaper still to find some asteroid
and build the Death Star right there. It'll only take a medium sized
asteroid.

Taking Ryszard's figure of 1/10 the mass as structural, and assuming that
asteroids are 80% pure ore (which isn't all that unreasonable) then all you
need is an asteroid 80km in diameter. Plenty of candidates to choose from
[2]. And it wouldn't surprise me if there aren't a few, or a score, of
asteroids made out of CHON (Carbon, Hydrogen, Oxygen, Nitrogen) [3], so no
need ship air or water up from Earth either.

So yes, the price tag of the Death Star is up there, but nowhere near the
$1.5×10^25.

[1] http://rickgold.info/ds/Site/Welcome.html
[2] http://en.wikipedia.org/wiki/Asteroid_belt#Characteristics
[3] http://en.wikipedia.org/wiki/CHON

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