Countdown clocks were ticking down on Sunday for the launch of a SpaceX Falcon 9 rocket from a historic launchpad leased from NASA at the Kennedy Space Center in Florida, Reuters reported. Blastoff of Space Exploration Technology Corp's Falcon 9 rocket is targeted for 9:38 a.m. local time/1438 GMT on a mission to fly supplies and science experiments to the International Space Station. SpaceX scrubbed its first launch attempt on Saturday seconds before liftoff due to concerns about the steering system in the rocket's upper stage, the company said. SpaceX founder and Chief Executive Elon Musk wrote on Twitter after the delay, "99% likely to be fine ... but that 1% chance isn't worth rolling the dice. Better to wait a day." The National Aeronautics and Space Administration, which hired SpaceX to fly cargo to the station after the shuttle program ended, will closely monitor Sunday's launch to learn more about SpaceX's operations before it clears the company to fly NASA astronauts on SpaceX rockets. "We're going in and listening to their launches and getting smart so we can have intelligent discussions with them and offer feedback about how things might be different if you're launching people," Stephen Payne, NASA's launch integration manager for the commercial space taxi program, said in an interview.