the Crucible is a vessel operated by the Jedi Order. The ship, which had been in service from the time of the Old Republic through the Clone Wars, was used to ferry Padawans from Coruscant to Ilum. Once on Ilum, the Padawans would undergo a ritual called The Gathering, in which they would find the kyber crystals for their first lightsabers. After retrieving the crystal, the Padawans would learn from Huyang, an ancient droid who would assist in the creation of their lightsabers. see more information@ http://starwars.wikia.com/wiki/Crucible.