Hawthorne-based SpaceX, the commercial space launch venture of Elon Musk, has signed a $492M contract with satellite firm Iridium Communications. The firms said this week that the contract is the largest commercial launch deal ever signed. SpaceX's Falcon 9 rocket will provide launch services for Iridium NEXT, Iridium's next generation satellites. The firms said the satellites are expected to launch from Vandenberg Air Force Base between 2015 and 2017. The contract comes on the heels of the successful June 4th inaugural launch of the Falcon 9.