SpaceX has fired at least five employees who were involved with circulating a letter around the company that was critical of CEO Elon Musk, according to two people familiar with the company who declined to be named and an internal email from President and COO Gwynne Shotwell. Shotwell, in a companywide email Thursday, said SpaceX “terminated a number of employees involved” and called “blanketing thousands of people across the company with repeated unsolicited emails” unacceptable, according t...