VANDENBERG SPACE FORCE BASE, Calif.—A SpaceX Falcon 9 rocket blasted off from California on Friday and carried 50 more satellites into orbit for the Starlink internet constellation. A SpaceX webcast showed the rocket’s upper stage deploying the satellites a little over an hour after the 9:12 a.m. liftoff from Vandenberg Space Force Base. The satellites will use their own thrusters to move into their operational orbits over a period of weeks. The first stage successfully landed on a “droneship” in the Pacific Ocean. It was the fourth successful launch and landing of the reusable booster. Starlink is a space-based system that SpaceX has been building for years to bring internet access to underserved areas of the world. Hawthorne, California-based SpaceX has close to 2,000 Starlink satellites orbiting Earth at an altitude of 340 miles (550 kilometers).