MOJAVE — Virgin Orbit is preparing for its fourth orbital satellite launch mission, which could take place as early as 10 p.m., tonight, from the Mojave Air and Space Port. “It is great to be back up in Mojave with a 747 at the end of the runway, with a rocket hanging under its wing and a few pieces of ground equipment poised to finish loading fuel and get under way,” CEO Dan Hart said, Tuesday, during a virtual press conference.