NASA says the launch will take place no earlier than 5 p.m. Saturday, with a backup opportunity Sunday.
A Friday attempt was called off due to wind and thunderstorms in the area of Wallops Island on Virginia's Eastern Shore, where the launch of the Antares rocket is slated to take place.
Dulles, Va.-based Orbital Sciences Corp. had originally planned to launch the rocket Wednesday, but was delayed by weather then too. The launch will test whether a practice payload can reach orbit and safely separate from the rocket.
Orbital is one of two private companies NASA contracted to restock the space station. NASA ended its shuttle program in 2011.