By Irene Klotz
WALLOPS ISLAND, Virginia (Reuters) - An unmanned Antares rocket blasted off from a seaside launch pad in Virginia on Wednesday, sending a cargo capsule to the International Space Station.
The 13-story rocket, developed by Orbital Sciences Corp., lifted off at 10:58 a.m. EDT from the state-owned Mid-Atlantic Regional Spaceport on Wallops Island.
The two-stage booster, making its second flight, soared southeast over the Atlantic Ocean, leaving behind a pillar of smoke and flame visible from New York City to South Carolina as it headed into orbit.
Perched on top of the rocket was Orbital Sciences' new Cygnus freighter, one of two robotic spaceships developed in partnership with NASA to fly cargo to the space station following the space shuttles' retirement.
On Sunday, the capsule was expected to reach the space station, a $100 billion research complex that flies about 250 miles above Earth.
"This is a very exciting day for us," Orbital Sciences executive vice president Frank Culbertson told reporters after launch.
"It's difficult to get a rocket off of a launch pad, no matter how many times you do it," he said.
Privately owned Space Exploration Technologies, which began work about 18 months before Orbital Sciences, has made three trips to the station.
NASA invested $686 million in Orbital Sciences and SpaceX and awarded the firms contracts totaling $3.5 billion to fly cargo to the station.
This mission is intended to show Orbital Sciences' ability to transport cargo to the space station. A successful flight may boost its chances for additional NASA work, and could attract commercial and scientific customers for the Antares rocket and Cygnus capsule.
"We have a lot interest from people who are waiting to make sure we do, in fact, succeed with this before they place a firm order," Culbertson said.
Cygnus capsules are not designed to return to Earth. Since they can stay in orbit for extended periods of time, Orbital Sciences envisions secondary missions after the capsules depart the station, as well as dedicated flights for customers besides NASA.
On Wednesday, the rocket placed the Cygnus capsule, loaded with about 1,543 pounds (700 kg) of food, clothing and other supplies, into orbit about 170 miles above Earth.
The spacecraft then unfurled its solar panel wings. Data relayed from the Cygnus showed its computers and positioning system were operating as expected.
Over the next four days, the capsule will demonstrate its ability to maneuver in space and communicate with the station.
If all goes as planned, NASA would clear Orbital Sciences to maneuver Cygnus as close as about 30 feet from the station on Sunday.
Astronauts aboard the space station would use a robotic crane to pluck the capsule from orbit and attach it to a berthing port.
Cygnus is expected to remain docked at the station until October 22. About two days later, it is expected to fire braking rockets to leave orbit and fall back into Earth's atmosphere, burning up in the process.
(Editing by Doina Chiacu and Stacey Joyce)