First Cygnus flight to ISS set for September

The target launch date for Orbital Sciences Corporation’s Cygnus spacetruck is no earlier than September. This decision was made by Orbital Sciences over the need to replace one of the booster engines.
Previously, the flight was planned for early summer.

The launch of the vehicle to the ISS is not possible in August due to a "scheduling conflict" with the Japanese spacecraft HTV, which will go into orbit in the same month.

If HTV launch is delayed, Cygnus may be able to fly to the ISS earlier; otherwise, the launch will be in September.
In 2008 Orbital Sciences along with SpaceX company received NASA contracts to deliver cargos to the ISS.