NASA will stream the first test flight of the 13-story Antares rocket Wednesday. The launch is scheduled for 5 p.m. EDT from the NASA launch facility called the Mid-Atlantic Regional Spaceport in Wallops Island, Va.

Due to low clouds in the area, weather is the major concern as the launch approaches, with only a 45-percent chance of favorable conditions. However, the launch window is from 5 p.m. to 8 p.m. EDT, giving Orbital Science Corporation several opportunities Wednesday and later in the week.

The primary mission for the Antares A-One rocket test flight will be to demonstrate the ability for the Antares rocket to place a payload into orbit. If the test is successful, Orbital Sciences will join SpaceX as a private company with the ability to provide cargo delivery access to the International Space Station.

In the test flight, Antares will deploy a dummy mass of cargo simulating the Cygnus module. This dummy mass allows Antares to simulate the weight of the Cygnus module and predict its pattern in space. The simulated Cygnus module will separate from the upper stage 10 minutes after liftoff. Also onboard are the Phonesat-1a, -1b, and -1c micro-cube satellites and the Dove 1 satellite.

Orbital Sciences hopes that the Antares rocket and Cygnus module will provide a cargo delivery service similar to the Falcon 9/Dragon system developed by SpaceX Corporation.

The SpaceX system has already docked three times to the ISS during linkups in 2012 and earlier this year.  The latest flight of the Dragon made a parachute-assisted return to Earth on March 26. These missions are pivotal to NASA after the space shuttle program shutdown in 2011.

Orbital has signed a contract to provide eight commercial resupply missions, manifested under a $1.9 billion contract with NASA. The contract states Orbital will deliver approximately 20,000 kilograms of supplies and equipment to the ISS.