Spacecraft in Rogue One zoom across the galaxy in a matter of minutes. That’s hugely remarkable, even more so when you think about the hundreds of thousands of pounds these vehicles probably carry. The weight increases exponentially when we talk about fully armed and operational battle stations like the one being built in the latest Star Wars flick. And it’s going to take a ton of energy to make these hunks of metal zip around outer space as quickly as we see on the silver screen and television.

In a time of energy consciousness and environmental awareness, physics blogger Charlie Wood considered an important question: Which spacecraft is the most egregious energy guzzler? He tallied the numbers of the most famous imaginary ships, calculating how much energy each required to perform their functions.

Perhaps unsurprisingly, the worst offender was the Death Star. The “artificial moon” needs to house millions of people, keeping them safe from the vacuum of space while providing them the necessary quarters to eat, sleep, and use the bathroom. Considering that the Death Star is also equipped with a weapon designed to literally blow up worlds, and we’re talking about much bigger energy requirements than is usually necessary, at least in a sci-fi universe.

But there’s a dimension to Wood’s calculations that’s worth digging into. Traveling around in space consumes a ton of energy — unless we’re talking about using the ultimate cheat code uttered in practically every Star Wars battle sequence: hyperspace.

Remember the ships we know and love in science fiction that travel back and forth between star systems are usually fitted with some sort of hyperdrive mechanism. Most people often think this means the ship is traveling at or faster than the speed of light. That’s probably not true at all.

Hyperdrive systems basically allow a ship to access an alternate dimension (or dimensions) of spacetime in which ultra-fast travel is possible. The physics of those dimensions are never quite explained — maybe they create a wormhole that folds up the departure point with the destination point, maybe faster-than-light travel becomes a possibility for any object — who really knows. But the implication of hyperspace travel is that it lightens the load of a big-ass engine and its corresponding large, unwieldy propulsion system. You just have to open yourself up to a new dimension — or six.

If you combine hyperspace travel with minimal resources — say, a single pilot — you end up getting the most bang for your buck. According to Wood’s calculations, the X-Wing is the most energy efficient spacecraft in popular science fiction (at least among the ships he’s looked at). Hyperdrive allows the X-Wing to travel very fast from place to place; interstellar journeys wouldn’t take more than a few hours at the most.

But even with hyperspace in the equation, the various iterations of the Death Star, because of its sheer size, remains the least efficient. And the little flaw of an open vent leading to the core means you don’t want to be on it if a rebel fighter manages to fire off a well-timed proton torpedo.

Photos via Star Wars