Virgin Galactic’s announcement last month that it was bringing its LauncherOne manufacturing site to Long Beach meant two things: The city’s long vacant real estate around Long Beach Airport would have another tenant, and it would need people to build those rockets that Galactic uses to send satellites to space. To fill that need, the company is hosting a job fair and open house Saturday, March 7 at Galactic’s facility in Douglas Park to start the process of composing its team.