The launch of NASA's US$1.5 billion Parker Solar Probe was scrubbed at the last minute on Saturday because of a technical glitch that could not be resolved before the launch window closed.
NASA and rocket-builder United Launch Alliance plan to make another attempt to get the long-awaited mission off the ground Sunday at 7:31pm (NZ time), the opening of a 65-minute window.
Forecasters are predicting a 60 percent chance of acceptable weather.
The Parker Solar Probe is the most ambitious sun-study spacecraft ever built, designed to repeatedly fly through the sun's outer atmosphere, or corona, to learn more about the mechanism that heats it to millions of degrees and accelerates charged particles in the solar wind to supersonic velocities.
The Delta 4 Heavy's countdown ran into problems before fuelling late Saturday, prompting ULA to delay the launch by 20 minutes. Then, inside of 10 minutes to launch, a hold was ordered due to problems with a data stream from the rocket.
The countdown finally came out of a built-in hold at the T-minus four-minute mark, ticking toward a launch when an engineer called out "hold, hold, hold" at the T-minus 1m, 55s mark.
The problem with a helium pressurization system could not be resolved in the 10 minutes left in the launch window, forcing ULA to order a 24-hour delay.
CBS / Newshub.