Elon Musk is poised to have “virtually unchecked executive authority” when SpaceX goes public this year, Reuters reported. Documents show SpaceX is looking to limit investors’ ability to challenge company management, as the rocket maker sets its sights on massive projects. SpaceX, set to be the largest IPO in history, has previewed huge expenditures, including launchpads and a new solar-cell factory, The Wall Street Journal reported. Activists a…