Planetary repulsors were engineering tools beneath a planet used to propel it to a different location.
The repulsors were buried deep underground. The central cavern was half a kilometer high and shaped like a cone. In the middle of the cavern was a platform about 5 meters long that extended from a door on the side. This platform had a console in the middle that was able to control the repulsor, move the viewing platform around, and seal shut the door leading to it. On the base of the cavern were seven conical shapes; six smaller cones surrounding a larger central one. Surrounding the repulsor was a giant underground complex that contained many other pieces of machinery. The door leading from the viewing platform followed a long hallway, at the end of which had a secret door connecting to the rest of the complex.
When activated, the repulsor could bore a hole through the top of its chamber, that was big enough for the viewing platform to pass through. Any rocks that fell into the chamber from the boring would be repelled back out. The repulsors had the ability to move the planet it was on, along with destroy any ship orbiting it.
The Corellian system was highly theorized to have been built by the Celestials using these devices and Centerpoint Station, as all five of its planets (Corellia, Selonia, Drall, Talus, and Tralus) had a repulsor beneath their surfaces. At some point, these repulsors and the surrounding complexes were eventually abandoned. The tunnels surrounding Corellia's repulsor became covered in a layer of dust, while the ones around Drall's flooded multiple times and were filled with mud.
In 18 ABY, the Sacorrian Triad, the rulers of the planet Sacorria in the Corellian sector wanted to break away from the New Republic and form an independent state. They backed various extremist groups in the Corellian sector to cause division and instability; each wanting an uprising to overthrow their planet's respective governments. They ordered each group they backed; the Human League on Corellia, the Absolutists on Selonia, and the Drallist Front on Drall; to search for the planetary repulsors on their respective planets to use as weapons in their uprisings.
The Selonians were able to find theirs first and quickly made it operational, but a near-civil war occurred over what to do with it. The opposing faction to the Absolutists, the Republicanists, wanted to turn the repulsor over to the New Republic in return for Selonia's sovereignty inside it and the Corellian Sector government. The Absolutists, however, wanted to use it as a weapon to establish absolute independence.
On Corellia, the search for the planetary repulsor was done by members of one of the Human League's Heritage Squads under the command of General Brimon Yarar, disguising their goal by claiming to be digging up the structures underground for historical purposes. The group allowed New Republic Chief of State Leia Organa Solo and her family to tour the dig site while they were on Corellia to attend a trade summit. On the tour, Organa Solo's kids, Jacen, Jaina, and Anakin Solo separated themselves from the group and, using Anakin's Force sensitivity, discovered the planetary repulsor. They were found by Q9-X2, the astromech droid belonging to their tutor, Ebrihim, who lead them back to the group.
Not long after, when the various groups launched their uprisings; Jacen, Jaina, Anakin, and their father's friend, Chewbacca managed to escape Corellia with Ebrihim and Q9; and fled to Drall. They met with Ebrihim's aunt, the Duchess of the Mastigophorous clan, Marcha, who took interest in the underground repulsor that the Solo children had seen. Having heard of a similar dig site on Drall, she decided to travel to it to study the repulsor herself. Upon arriving, Chewbacca used a Sounder to find a tunnel close to the surface and a Borer to dig it open. The group entered the tunnel and, using a diagram of the Corellian repulsor that Q9 had taken, along with Anakin's Force ability, were able to find the repulsor chamber. They moved the ship they used to fly to Drall, the Millennium Falcon, into the repulsor while they studied it.
Concurrently, upon request of Jedi Master Luke Skywalker, the Bakuran Defense Fleet managed to reach the Corellian system to help the New Republic. Immediately, the various groups started launching Starfighters. Admiral Hortel Ossilege, knowing that the groups were likely leading them into a trap, opted to sacrifice one of his ships, the Watchkeeper. Ossilege was correct, as a loose plan had been made that consisted of various groups starfighters luring any large ships that made it into the system to a specific point, where the repulsor on Selonia would destroy it. The Watchkeeper, having been evacuated and being piloted by Slave circuit took the bait and continued towards the point the starfighters were drawing it to. When the ship reached it, the repulsor fired, destroying it.
- Cracken's Threat Dossier
- The Official Star Wars Fact File7
- Coruscant and the Core Worlds
- Star Wars Galaxies: An Empire Divided Quick Reference Guide
- The New Essential Chronology