How to Build a Death Star

The moon-size, weaponized space station, Death Star, is seen in "Rogue One: A Star Wars Story."

(Image credit: copyright 2016 Lucasfilm Ltd. All Rights Reserved.)

This article was originally published at The Conversation. The publication contributed the article to Live Science's Expert Voices: Op-Ed & Insights.

I'm very excited about seeing Rogue One: A Star Wars Story, which tells the tale summarized in the original Star Wars' opening crawl. This is the story of how the rebels stole the plans to the original "Death Star" – a space station the size of a small moon with a weapon powerful enough to destroy a planet.

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So would it possible in the real world? Let's not worry about the vast quantities of raw materials required. For example, at current production rates of steel it would take 182 times the current age of the universe to accrue enough. I'm more concerned conceptually with how to power such a colossal battle station and how to generate gravity for everyone on board. It turns out our conventional technologies might not cut it.

The International Space Station requires about 0.75 W of power for every m³ of the space station. These are provided by eight solar arrays, 112 feet (34m) long by 39 feet (12m) wide. Even if we had 100% efficient solar panels covering the much larger Death Star, we'd still be a factor of 45 times short of the ISS's power requirements per unit volume. Not to mention that power would severely diminish if we took the space station further away from the sun.

Perhaps the clue was in the name the whole time. What if at the heart of the Death Star is an artificial star? Surely that would solve the gravity problem? This makes the station something of a Dyson sphere, the sort of technological megastructure physicist Freeman Dyson imagined advanced civilisations might be able to build to harness all the energy from their stars. However, Dyson spheres of the rigid shell variety usually run into problems from being under immense stresses due to the gravitational forces. Even if the sphere isn't ripped apart by this, just a small push certainly would be enough to send the structure crashing into its star.

But Dyson spheres are usually imagined to be the size of the Earth's orbit around the sun. For a much smaller Death Star, most of the problems with the Dyson sphere go away. The 13.2 km diameter reactor core would only require a mass 370 times less than our moon's. It turns out while steel and titanium would just about fail under these conditions, the wonder material graphene, for example, could easily withstand the gravitational forces involved.

And we wouldn't actually need a real star at the centre of the station – the future technology of nuclear fusion could easily provide enough power. While at the moment we tend to put more energy in than we get out in our fusion experiments, many plasma physicists think the key is going bigger and hope that the ITER experiment, which will be one-third of the volume of an Olympic swimming pool, will turn the tide in this regard. If successful, we could expect power from our Death Star up to two million times that consumed by the entire human race.

But there are still problems. The pressures involved inside our Death Star reactor would be immense. The artificial star's own gravity would not be enough to contain the fusion plasma, so we would need something extra. As we've learned from thinking about lightsabers, magnetic fields could provide the solution. The only snag is that we'd need some of the strongest magnetic fields in the universe – a million times greater than we've ever created on Earth and comparable to those of magnetars – a type of neutron star with an extremely powerful magnetic field.