SpaceX’s stalwart Falcon 9 rocket has been grounded while the Federal Aviation Administration investigates why its first-stage booster tipped over and exploded while attempting to land after its latest launch, the agency announced Wednesday. SpaceX’s stalwart Falcon 9 rocket has been grounded while the Federal Aviation Administration investigates why its first-stage booster tipped over and exploded while attempting to land after its latest launch, the agency announced Wednesday. Space Exploration Phys.org – latest science and technology news stories