Orbital poised to launch cargo ship to space station
The liftoff is scheduled for 12:52 pm (1652 GMT) aboard an Antares rocket from Wallops Island, Virginia.
The mission, named Orb-2, is the second official trip for Orbital's cargo carrier, and is one of eight journeys the company has contracted with NASA.
Orb-2 was initially supposed to launch in May, but a Russian-built rocket engine in the Antares rocket failed during a prelaunch test, delaying the mission.
Cygnus will carry some 3,300 pounds (1,500 kilos) of cargo to the station, including food and supplies for the crew, scientific experiments, and a pump for the Japanese module to replace one that failed.
If launch goes as planned, the Cygnus should arrive at the orbiting outpost on Wednesday, July 16.
The weather forecast was 90 percent favorable for takeoff.
Coverage of the launch begins on NASA television at noon (1600 GMT).
Orbital Sciences and SpaceX are the two private US companies that have won billion-dollar contracts with NASA for multiple missions to carry supplies to the International Space Station.
NASA lost its capacity to reach the space station after the 30-year space shuttle program ended in 2011.
SpaceX and Orbital now make regular resupply journeys with their unmanned cargo ships. Europe and Russia also have their own spaceships that can tote equipment and provisions to the research outpost.
In order for astronauts to get there, nations must buy seats aboard Russia's Soyuz spacecraft, at a cost of $70.7 million each. The spaceship carries three people at a time.
Several American companies are competing to be the first to complete a crew vehicle that will restore US access to the station in the next few years.
Orbital's cargo ships burn up on reentry into Earth's atmosphere, unlike SpaceX's Dragon spacecraft, which makes an intact splash landing in the ocean.
Orb-3 is scheduled to launch in November, and three more Cygnus missions are planned for 2015.
© 2014 AFP