WASHINGTON — Following a weeklong delay, Orbital Sciences Corp.’s first Cygnus cargo module successfully berthed with the international space station (ISS), marking a critical milestone in the company’s efforts to field a commercial logistics system for the orbital outpost.

In its first demonstration flight, Cygnus was launched Sept. 18 atop Orbital’s Antares rocket, which was making only its second flight, from the Mid Atlantic Regional Spaceport on NASA’s Wallops Flight Facility, Va. The capsule arrived at the station following a series of orbit-raising maneuvers and tests and was grappled by the outpost’s crew-operated robotic arm.

Cygnus was originally supposed to arrive at the station Sept. 22 but was delayed, initially by a communications issue and then to make room for the arrival of an ISS crew aboard a Russian-built Soyuz capsule. The Soyuz capsule docked with the space station Sept. 25.

Antares/Cygnus is one of two ISS logistics systems developed with NASA funding aid under the agency’s Commercial Orbital Transportation Services, or COTS, program. The other, developed by Space Exploration Technologies Corp., has already made two successful cargo deliveries to the station under a follow-on Commercial Resupply Services contract valued at $1.6 billion.

With two successful COTS demos under its belt, Orbital appears in position to begin executing on its $1.9 billion Commercial Resupply Services Contract. “We look forward to moving ahead with regularly scheduled ISS cargo delivery missions for NASA as early as the end of the year,” Orbital President and Chief Executive David W. Thompson said in a prepared statement Sept. 29.

Cygnus carried 589 kilograms of supplies including food, clothing and experimental equipment to the station, Orbital said in a press release. After those supplies are unloaded, the ISS crew will begin filling the freighter with 800 kilograms of ISS refuse, which along with Cygnus will burn up on atmospheric re-entry after the vehicle separates from the station in late October.

Cygnus’ cargo-carrying capacity currently is 2,000 kilograms, but later versions will be capable of carrying 2,700 kilograms of cargo to the station, Orbital said. The company is under contract to deliver a total of 20,000 kilograms to the ISS through 2016.

Warren Ferster is the Editor-in-Chief of SpaceNews and is responsible for all the news and editorial coverage in the weekly newspaper, the spacenews.com Web site and variety of specialty publications such as show dailies. He manages a staff of seven reporters...