WALLOPS ISLAND, Va. — Orbital Sciences Corp. rescheduled the maiden launch of its Antares rocket for no earlier than April 19 after an ethernet cable linking the ground control center here with the computer on the second stage of the launcher came loose at the launch pad.

The cable became disconnected about 10 minutes before the rocket’s planned liftoff at 5 p.m. EDT. The cause is not yet known, Frank Culbertson, executive vice president and general manager of Orbital’s advanced programs group, told reporters here in a post-scrub briefing.

Although windy weather and clouds were headed toward the Wallops Island Flight Facility in the late stages of the countdown, Culberston said wind speeds at the pad when the cord came loose were “about six knots. They were really light.”

“There are going to be people working all night” to figure out why the second-stage umbilical cord — which carried only data — popped out in the first place, Culbertson said at the briefing.

While Orbital is working toward a 5 p.m. launch on April 19, the weather forecast for Wallops Island and the surrounding area that day calls for wind, rain and possibly thunderstorms.

Orbital personnel planned to meet at 8 a.m. on April 18 to evaluate the next launch opportunity. A weather briefing from Wallops range officials is to follow at 4 p.m.

Antares is the cargo rocket Orbital is developing for eight cargo delivery missions to the international space station under a $1.9 billion NASA contract. Cargo hauling duties will be handled by Cygnus, Antares’ companion space tug.

Antares will not be carrying Cygnus during the upcoming launch. Instead, the rocket will haul to orbit a sensor-equipped dummy payload with roughly the same mass as Cygnus.

Dan Leone is the NASA reporter for SpaceNews, where he also covers other civilian-run U.S. government space programs and a growing number of entrepreneurial space companies. He joined SpaceNews in 2011.Dan earned a bachelor's degree in public communications...