If successful, this will be Orbital ATK's eighth implementation of the ISS Replenishment mission, which will also be the company's second mission this year. The company's first mission was not launched through the Antares rocket in April, but with the joint Atlas V rocket launch. Last year, NASA demanded that the Orbital ATK use the Atlas V rocket to replace the mission, as the rocket could carry more supplies into orbit. At that time, NASA has been worried that SpaceX may not be able to complete the supply task after the failure.
Now, however, the supply task is running smoothly again and the ISS is well stocked. Orbital ATK will use Antares rockets Saturday to provide more supplies and scientific experiments for cosmonauts on the ISS. Some of these projects include testing of antibiotic resistance in microgravity and testing of experimental hybrid solar panels that serve as communication antennas.
Launch time is scheduled for the United States Eastern time at 7:37 on the 11th. Orbital ATK said the Antares rockets could not be started at temperatures below 20 degrees Fahrenheit, and on the day of launch temperatures should be between 25 and 30 degrees Fahrenheit. If the weather is fine, then residents of the East Coast may be able to see the rocket. NASA's maps show exactly when the rocket is visible.