Space Exploration Technologies Corp. (SpaceX) expects to reach “preliminary conclusions” on its Cargo Resupply Services-7 (CRS-7) launch failure by the end of the week, company founder Elon Musk said Sunday on Twitter.Musk said SpaceX will brief key customers and the Federal Aviation Administration (FAA) before posting the conclusions on its website. A SpaceX Falcon 9 rocket exploded after launch June 28 on its way to the International Space Station (ISS) while performing one of NASA’s CRS missions, which deliver food…