May 20 : As Elon Musk's SpaceX races toward what could be the largest IPO in history, its filing delivers a rare mix of hard financial data and bold ambitions of exploring the frontiers of space. The filing's references to lunar missions and Mars settlement echo the popular space-age futuristic themes of "The Martian" and "Interstellar," while grounding those ambitions in the more familiar language of commercial space development. The company identified asteroid mining, in-orbit manufacturing