By MARCIA DUNN (AP Aerospace Writer) SOUTH PADRE ISLAND, Texas (AP) — SpaceX called off its first launch attempt of its giant rocket Monday after a problem cropped up during fueling, Elon Musk’s company had planned to fly the nearly 400-foot Starship rocket from the southern tip of Texas, near the Mexican border. The countdown was halted at the 40-second mark because of a stuck valve in the first-stage booster.