At 4:39am EDT tomorrow, Orbital ATK will launch their Antares rocket carrying the Cygnus spacecraft to the International Space Station from the Wallops Flight Facility in Virginia. The launch was previously targeted for today, but was moved for "further pre-launch inspections and more favorable launch conditions" according to Orbital ATK.
Orbital ATK launches Cygnus under NASA's CRS (Commerical Resupply Services) contract to send supplies and experiments to the International Space Station. Cygnus is loaded with 7,385lbs (3,350 Kilograms) of Science Experiments, Food, Clothes, and other various supplies. Cygnus will also deliver an experiment from the Cold Atom Laboratory (CAL), which will create the coldest man-made area in the universe.
A live broadcast of this launch will be streamed by NASA over at NASA TV.