Building a Death Star - How much would it cost?

The US military is really good at spending huge sums of money on expensive weapons. With annual spending usually fluctuating between 500 and 600 billion dollars and a requested several billion dollar budget increase for 2018, there seems to be nothing too expensive for the US military. But what if they wanted to expand beyond Earth? If we've learned anything about doing things in outer space it's that it's very expensive.

What would it cost to build a space-based super weapon like the Death Star?

Believe it or not a petition on We the People, to build a Death Star actually gathered enough signatures to merit official government response. Unsurprisingly the US government didn't think it was the best idea. Their response was: The administration does not support blowing up planets and why would we spend countless taxpayer dollars on a Death Star with a fundamental flaw that can be exploited by a one man starship?!

As silly as the petition was there actually are estimates on how much it would cost to build a Death Star in real life. The student economics blog at Lehigh University determined that it would cost 852 quadrillion dollars just to produce the steel required for construction, even without taking into account the communications equipment, weapons, personnel and day-to-day operating costs of our hypothetical Death Star. That 850 quadrillion dollar price tag is more than 13,000 times the GDP of the entire world. Once you start considering the full price things get even more ridiculous. A british energy company crunched the numbers and the cost of operating a Death Star is truly absurd after the upfront cost of constructing the base. The daily cost to keep it running would be an unbelievable 7.8 octillion dollars that's more than a hundred trillion times the annual economic activity of the entire planet!

It's hard to fathom that huge of a sum, but when you break down everything that goes into running a space station of that magnitude, it starts to make sense the first Death Star depicted in Star Wars Episode four is said to have been between 100 and 140 kilometers in diameter, crewed by 1.7 million military personnel, four maintenance droids and 250,000 civilians and independent contractors. Assuming you don't have to pay the droids or the civilians and assuming you could get away with paying everyone the same low rate of say $10 an hour, paying your staff alone would set you back over 32 trillion dollars per year. Almost twice the annual GDP of the United States. Lighting the whole space station would cost fifty two billion dollars per day and every single load of laundry would cost two hundred million. Then there's waste disposal feeding your crew, fueling fighters, faster than light travel and of course powering the giant laser which would cost the reasonable sum of eight octillion dollars per use. Assuming you didn't fire the laser very often that brings us to the daily operating cost of 7.8 octillion dollars.

Okay so it's pretty reasonable to assume we won't be building a Death Star any time soon but will it ever be possible in the future? Well probably not while earth does have plenty of iron to produce the steel required to build a Death Star, enough to build two million of them in fact. The problem is that this iron is mostly located in the Earth's core which would be hugely difficult and dangerous to remove. Assuming we ever figure out how to do it, if we did manage to get enough iron on the surface, at today's rate of steel production it would take over 800,000 years to produce the required amount of steel just to build the shell of the Death Star. Then to launch all that steel into orbit at the current cost of $20,000 per kilogram you're looking at over 21 quintillion dollars before you can even begin assembly.
The more cost-effective option would be to mine the required resources from asteroids or moons near the construction site. Of course this would still be prohibitively expensive for a one planet species like us. Even for the empire building a Death Star would have been hugely expensive according to one Star Wars expert, at its peak the Empire controlled one and a half million Core Worlds and 69 million colonies all linked together by a single economy.

So if we want to build a Death Star we have a little bit of work to do and if we ever do build one maybe we'll learn from history and not put a conveniently sized thermal exhaust port anywhere on it :)