A private company is planning a test launch Wednesday of a rocket intended to make eventual supply runs to the International Space Station (ISS), but officials warned weather could delay the launch.Orbital Sciences Corporation is set to launch its unmanned Antares rocket Wednesday from Wallops Island, Virginia, and it could be visible in cities from Washington to New York.But the National Aeronautics and Space Administration (NASA) said Tuesday there is only a 45 percent chance that weather conditions would allow a launch Wednesday. Orbital Sciences would try again Thursday if necessary.If successful in sending a practice payload into orbit, Orbital Sciences aims to send its cargo spacecraft to dock with the ISS this summer on a test mission.Orbital Science and SpaceX are the two private companies that have contracted with NASA to make space-station supply runs. The U.S. space agency ended its space-shuttle program in 2011.