- "«The Jedi must not find our designs for the Ultimate Weapon. If they find out what we are planning to build, we're doomed.»"
"I will take the designs with me to Coruscant. They will be much safer there with my master."
- ―Archduke Poggle the Lesser, and Count Dooku
The Death Star was designed by Geonosians led by Archduke Poggle the Lesser, a member of the Confederacy of Independent Systems. During the First Battle of Geonosis, he gave the plans to Count Dooku, who decided to ferry them to his master Darth Sidious, who would keep them safe. Dooku was intercepted by Obi-Wan Kenobi and Anakin Skywalker in his solar sailer's hangar, but defeated them and fled from Yoda by dropping a pillar on the two unconscious Jedi. Dooku met Sidious in The Works on Coruscant. Sometime after the Second Battle of Geonosis, Supreme Chancellor Palpatine presented the plans to the Republic Strategic Advisory Cell, which started to build the station.
Galactic Civil War
Stolen during the Battle of Scarif by the Rogue One squad at the cost of heavy Rebel losses, the remaining copy of these blueprints was transmitted to Princess Leia Organa's starship and into the hands of members of the Rebel Alliance, stationed aboard the Tantive IV. However, as the ship arrived at Tatooine to ferry Kenobi to Alderaan, it was intercepted by the Devastator, and Organa, in a desperate gamble, entrusted the blueprints to the memory systems of the astromech droid R2-D2. He and the protocol droid C-3PO were then sent in an escape pod to Tatooine, where they eventually ended up being purchased by Owen Lars from Jawas, who gave them to Luke Skywalker to look after. R2-D2, however, determined to fulfill the mission given to him by Organa, tricked Skywalker into removing his restraining bolt so that he could seek out Kenobi.
Luke, worried about his uncle's reaction, sought out R2 in the Jundland Wastes, where he was rescued by the very Kenobi that the R2 series astromech droid was seeking. The group returned to Kenobi's home, where Kenobi discovered that R2-D2 was carrying a message for him from Organa explaining that R2 was carrying information vital to the survival of the Rebellion that needed to be delivered to Alderaan, but that the Tantive IV had been captured by the Empire.
The group secured passage to Alderaan aboard the Millennium Falcon, piloted by Han Solo and Chewbacca. Upon the ship's exit from hyperspace at the planet's coordinates, however, they discovered that it been completely obliterated by the very vessel whose stolen plans R2-D2 was carrying. The group managed to hide from the Empire and, in sneaking aboard the vessel to disable its tractor beam, found that Organa was being held prisoner there. The group, sans Kenobi, hatched a plan to rescue her, while Kenobi disabled the tractor beam. Though Kenobi was killed in a lightsaber duel with Darth Vader, the remainder of the group escaped and made their way to Yavin 4. There, the stolen plans were brought to the leaders of the Rebellion as the Empire pursued the tracked Millennium Falcon to the location.
Upon examination, the Rebels discovered the work of Galen Erso, a scientist forced to participate in the Death Star's design and construction: a subtle sabotage of the Death Star's design to include a flaw in the superlaser reactor by which a pressurized explosion would cause a chain reaction that would destroy the entire station. The Rebels determined the best way to reach the reactor was for a starfighter to fire proton torpedoes into a two-meter-wide thermal exhaust port that led directly to the station's power core, and thus planned an attack with that objective, having observed the Death Star's defenses were built to withstand assaults from larger vessels.
Although the target was considered a highly difficult one, and the resulting Battle of Yavin resulted in heavy casualties with Darth Vader coming within a hairsbreadth of defeating the attack, Skywalker, with the aid of the Force, was ultimately able to fire two proton torpedoes perfectly into the port to destroy the Death Star.
Behind the scenes
The Death Star plans were central to the plot of the original Star Wars film, ultimately enabling the Rebellion to find a key weakness in the Death Star, allowing Luke Skywalker to destroy it. The plans were also seen in the prequel film Star Wars: Episode II Attack of the Clones, showcasing the early development of the Death Star, known at the time as the "Ultimate Weapon." The means by which the Death Star plans were captured by the Rebellion was the subject of numerous, mutually exclusive stories in the Expanded Universe of Star Wars, later rebranded as Star Wars Legends, leading Pablo Hidalgo to comment that "...if you had to throw a dinner party and invite everyone who had ever stolen the Death Star plans, you'd be surprised at how many place settings you'd have to worry about." The canonical theft is depicted in Rogue One: A Star Wars Story.
The grid plan animations shown during the Rebel briefing for the attack on the Death Star late in A New Hope were an actual computer graphics simulation from the Jet Propulsion Labs (JPL) made by Larry Cuba and Gary Imhoff as part of a project for school at CalArts, and had been included during filming for Star Wars: Episode IV A New Hope (then known as just Star Wars). Originally, the writers and staff planned to thank JPL for assisting in the graphics, but it was changed to the specific programmers' names after one of the programmers, Mike Plesset, pointed out that JPL didn't even know their computers had been used. Interestingly, the images in Episode IV (and consequently Rogue One) contained in the plans feature the Death Star with its superlaser in the equatorial zone, instead of the upper hemisphere. This is because in the early drafts for A New Hope, the superlaser was intended to be situated on the center of the equatorial trench, but was then repositioned to the station's "northern hemisphere." However, the film crew forgot to notify Cuba and Imhoff to make the same change to their own designs, thus creating an on-screen blooper.