Elon Musk’s plan for SpaceX to “become a major mobile carrier in the U.S.” sent shares of the nation’s big three wireless carriers sliding by double digits Friday, wiping out more than $50 billion in market value before lunch.“Once we receive final FCC approval, Starlink Mobile will deploy a flexible architecture combining our satellite-to-mobile constellation in space with an advanced terrestrial deployment that can seamlessly connect devices everywhere,” the company said late Thursday. It also announced that the Federal Communications Commission had approved the launch of 15,000 new satellites, also under Starlink Mobile, which is a subsidiary of SpaceX.Shares of…