SpaceX's rocket Starship stands on the launchpad at Starbase in Boca Chica, Texas ahead of a re-launch after an attempt in April ended in a spectacular explosion. Originally scheduled for Friday, the second launch has been postponed until Saturday. "We need to replace a grid fin actuator, so launch is postponed to Saturday," Musk posted on his social media site X, formerly Twitter. Grid fins are aerodynamic controls used by SpaceX to adjust and stabilize its rockets during their descent phase so they can land upright. Actuators refer to the machine parts used to impart motion. IMAGES