East Coast test rocket launch scrubbed (Update 2)

A private company contracted by the U.S. space agency to make supply runs to the International Space Station scrubbed a Wednesday test launch of an unmanned rocket, saying cables linked to the rocket's second stage apparently detached too early in blustery winds.

The Antares rocket had been scheduled to blast off Wednesday from Virginia when the countdown clock was halted 12 minutes before a 5 p.m. launch window was to open.

Barron Beneski, a spokesman for Orbital Sciences Corp., said it wasn't immediately clear when officials would attempt a launch again. He said officials initially suspected winds had caused a premature separation of a cord linked to the second stage of the rocket. But he said experts would release more details later.

Officials said the most likely prospect would be to try again Friday, though no date was immediately announced.

The planned launch was designed to test whether a practice payload could reach orbit and safely separate from the rocket.

Orbital is one of two private companies contracted to restock the space station by NASA, which ended its shuttle program in 2011. SpaceX completed its third supply run to the station last month.

SpaceX was awarded a $1.6 billion contract by NASA in 2006 to make a dozen missions to restock the space station. Orbital jumped into the mix in 2008 when it was awarded a $1.9 billion contract for eight deliveries.

SpaceX has connected with the space station three times, though only two of those deliveries occurred under its resupply contract. Its Dragon capsule is the only supply ship capable of two-way delivery

"We've been playing catch up, but we're about caught up," said Frank Culbertson, executive vice president and general manager of Orbital's Advanced Programs Group, had said recently as plans of this week's test launch loomed. "By the end of next year we should have an additional four or five cargo missions under our belt, so we're going to be moving fast."

If ultimately successful in testing Antares, Orbital executives have said they hoped to launch a rocket this summer carrying its Cygnus cargo ship aloft to see whether it can safely dock with the space station.

Orbital is under contract to deliver about 44,000 pounds (19,950 kilograms) of supplies to the space station and plans to make about two deliveries per year.

Unlike the SpaceX's Dragon capsule, the Orbital cargo ship is not designed to return with experiments or other items from the space station. Instead, plans call for filling its Cygnus ship with garbage that would be incinerated with the vessel upon re-entering Earth's atmosphere. That's also what Russian, European and Japanese cargo ships do.

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