The capsule named Cygnus bearing 1,300 pounds of food, clothing and goodies for the astronauts is due at the orbiting outpost on Sunday, following four days of testing.
The Virginia-based Orbital Sciences is only the second business to attempt a shipment like this. The California-based SpaceX company has been delivering station supplies for more than a year under a NASA contract.
Orbital Sciences' unmanned Antares rocket named for the bright red star blasted into a clear sky from NASA's Wallops Flight Facility. A test launch in April went well. So did this one, with a camera on the rocket providing dramatic views of the coastline. The entire commercial effort dates back five years.
It was Wallops' second high-profile launch this month. On Sept. 6, the company took part in a NASA moonshot that dazzled skywatchers along the East Coast. Wednesday's late-morning liftoff, while at a much more convenient hour, was not nearly as visible because of the daylight.
The three space station residents, circling 260 miles high, watched the launch via a live link provided by Mission Control in Houston.
"Good luck!" space station astronaut Karen Nyberg said in a tweet. She's expecting a fresh stash of chocolate.
Come Sunday, Nyberg and Italian astronaut Luca Parmitano will use the space station's robot arm to grab Cygnus from orbit and attach it to the space station. Also on board is a Russian. The crew will double in size next week when another American and two Russians lift off aboard a Russian rocket from Kazakhstan.
NASA is paying Orbital Sciences and Space Exploration Technologies Corp., or SpaceX, to keep the space station stocked since the retirement of the shuttles. The other countries involved in the station count also make deliveries.
The bigger SpaceX Dragon capsule has the advantage of returning items to Earth. The Cygnus will be filled with station trash and cut loose for a fiery destruction upon re-entry. That's how the Russian, European and Japanese supply ships wind up, too as incinerators.
"We categorize it as disposable cargo," said Orbital Sciences' executive vice president, Frank Culbertson. "Others may call it trash."
If all goes well, Orbital Sciences hopes to launch another Cygnus in December, right before Christmas. That will be the first true operational mission under a $1.9 billion contract.
The SpaceX contract is worth $1.6 billion.
SpaceX is working to modify its Dragon capsule for space station crews, so NASA doesn't have to keep paying tens of millions of dollars to the Russians per ticket. Orbital Sciences envisions strictly non-human payloads for the Cygnus but not necessarily just in Earth's backyard.
"We'd be happy to help a mission go to Mars," said Culbertson, a former astronaut who lived on the space station in 2001.
On Wednesday at least, the focus was low-Earth orbit. "This is a big deal for us," Culbertson said.