WASHINGTON, Sept. 14, 2013 /PRNewswire-USNewswire/ -- Orbital Sciences Corp. of Dulles, Va., will postpone by at least 24 hours the launch of its Antares rocket and Cygnus spacecraft on a demonstration mission to the International Space Station. The new launch window is targeted for Wednesday, Sept. 18 between 10:50 to 11:05 a.m. EDT from the Mid-Atlantic Regional Spaceport Pad-0A at NASA's Wallops Flight Facility in eastern Virginia. (Logo: http://photos.prnewswire.com/prnh/20081007/38461LOGO ) Cygnus' rendezvous with the space station remains scheduled for Sunday, Sept. 22. NASA Television will air pre- and post-launch news conferences and provide live launch and rendezvous coverage of the mission. The postponement is due to a combination of Friday's poor weather, which delayed rollout of Antares to the launch pad, and a technical issue identified during a combined systems test held Friday night involving communications between ground equipment and the rocket's flight computer. The problem has been identified and corrected. The teams are working to understand why the problem occurred. NASA will preview the launch and mission in a news conference at 2 p.m. Tuesday, Sept. 17, at the Wallops Visitors Center. NASA TV and the agency's website will air the briefing live with question and answer capability available from participating NASA centers or on the telephone. To participate using the phone bridge, which is operated out of NASA's Johnson Space Center in Houston, journalists must call the Johnson newsroom at 281-483-5111 by 1:45 p.m. Questions also can be asked during all briefings via Twitter by using the hashtag #askNASA. The prelaunch briefing participants are: -- Alan Lindenmoyer, program manager, NASA's Commercial Crew and Cargo Program-- Frank Culbertson, executive vice president, Orbital Sciences Corp.-- Mike Pinkston, Antares program manager, Orbital Sciences Corp.-- Sarah Daugherty, test director, NASA's Wallops Flight Facility NASA TV launch commentary coverage will begin at 10:15 a.m. Wednesday, Sept. 18. Video b-roll of launch preparations will air at 10 a.m. A post-launch news briefing will begin at approximately 12:30 p.m. at the Wallops Visitors Center. Johnson Space Center will operate a phone bridge for the post-launch briefings. To participate in the briefing by phone, reporters must call the Johnson newsroom at 281-483-5111 at least 15 minutes before the start of the briefing. The deadline to apply for accreditation to attend the launch has passed.