For the second day in a row, a SpaceX Falcon 9 rocket carrying an Intelsat communications satellite was grounded by a last-second glitch Monday, delaying the flight at least 24 hours and raising the prospect of a Fourth of July twilight spectacular if the problem can be resolved in time.

After pushing the launch time back to the end of the window because of threatening weather, countdown clocks were ticking down to blastoff at 8:35 p.m. EDT when telemetry indicated a problem. The countdown stopped at the T-minus 10-second mark and, with no time left for another try, the flight was scrubbed for the day.

A software issue with the rocket's guidance and navigation system triggered a launch abort Sunday at the same spot in the countdown. That problem was quickly resolved, SpaceX officials said, and it was not immediately known what caused Monday's abort.

The launch slip spoiled a holiday weekend doubleheader of sorts. Earlier in the day, a SpaceX Dragon cargo ship departed the International Space Station and wrapped up a month-long flight with an on-target splashdown in the Pacific Ocean southwest of Long Beach, Calif., bringing 4,100 pounds of experiment samples and other material back to Earth.

A SpaceX spokesman said engineers would sift through telemetry from the Falcon 9 to determine what went wrong and what might be required to fix it. The forecast for Tuesday calls for a 70 percent chance of good weather. Assuming the problem can be fixed in time, the launch window will open at 7:37 p.m.

The goal of the 38th Falcon 9 flight is to put the Boeing-built Intelsat 35e communications satellite into orbit, the fourth in a series of high-power all-digital relay stations. This one is bound for an orbital slot 22,300 miles above the Atlantic Ocean to provide service primarily to wireless customers across Latin America, the Caribbean and western Africa.