The Death Star is a fictional mobile space station and galactic superweapon featured in the Star Wars space-opera franchise. The first version, which appears in the original 1977 film Star Wars, is stated to be more than 160 kilometers (99 mi) in diameter, and is crewed by an estimated 1.7 million military personnel and 400,000 droids. The second Death Star appears in Return of the Jedi, and is significantly larger at 200 kilometres (120 mi) in diameter and while unfinished, is technologically more advanced than its predecessor. Both Death Stars were built by the Galactic Empire to strengthen its control over the galaxy, and are armed with kyber crystal-powered superlasers, which can destroy entire planets. The first Death Star requires significant time to fully recharge its superlaser, and is easily destroyed by the Rebel Alliance taking advantage of its one weakness: an exhaust port which, when hit with a precise shot, triggers a chain reaction throughout the station's entire infrastructure. The second Death Star is destroyed by a direct attack on its main reactor, as its incomplete state allows ships to fly through its infrastructure.