WALLOPS FLIGHT FACILITY, VA. - An Orbital Science Corp. Antares launch vehicle lifted off from the state-owned commercial pad here Sunday carrying a Cygnus cargo carrier loaded with almost 3,300 lb. of supplies for the International Space Station (ISS).

Launch from the seaside pad the Commonwealth of Virginia built for Antares missions came at 12:52 p.m. EDT, setting up a rendezvous, grapple and berthing with the ISS early Wednesday. The flight was the third for the Antares/Cygnus stack, including a demonstration flight, and the second operational mission under the company’s $1.9 billion Commercial Resupply Services (CRS) contract with NASA.

The mission went as planned, with main engine cutoff 235 sec. after ignition, fairing separation 331 sec. into the flight, followed 5 sec. later by interstage separation, and ignition of the solid-fuel second stage 4 sec. after that. The second stage burned out 477 sec. into the ascent, and the Cygnus separated 597 sec. after main-stage ignition. The spacecraft was placed in an initial orbit of 284 x 190 km (176 x 118 mi.). The spacecraft's arrays deployed on schedule and all systems are reported as nominal.

The main stage, built by Ukraine’s Yushmash organization, was powered by two surplus Soviet-era NK-33 kerosene-fueled engines, redesignated AJ-26 after refurbishment by Aerojet Rocketdyne. A similar engine failed during an acceptance test at Stennis Space Center on May 22, forcing a delay in the launch while engineers inspected the two flight engines. Orbital officials offered few details about the test stand failure, which apparently destroyed the test engine, but said visual inspections cleared the flight hardware.

Loaded into the pressurized Cygnus vehicle were 1,684 lb. of crew supplies, 783 lb. of hardware for the ISS,  18 lb. of photo, video and other equipment listed as computer resources, 87 lb. of gear for future spacewalks, and 721 lb. of hardware for the scientific research that is the station’s main function now that it is essentially complete. Grappling with the space station's robotic arm is scheduled for 6:39 a.m. EDT Wednesday.

Included in the scientific payload were 32 cubesats that will be deployed from the exposed “porch” on the Japanese Kibo module, which has an airlock and a robotic arm. Crew members will use the arm to grasp spring-loaded deployers and position them to jettison the cubesats down and away from the ISS to avoid future recontact.

Among the cubesats launched were a “flock” of 28 more Dove cubesats from Planet Labs, a commercial startup that is developing a constellation of tiny, low-orbit Earth-observation satellites designed to image the entire surface of the Earth daily. To date the company has launched 71 cubesats, including those on the Sunday flight.

Under the CRS contract Orbital will receive $1.9 billion to deliver as much as 44,000 lb. (20,000 kg) of cargo to the ISS through late 2016. The agency, which is shifting to commercial transport to the ISS for cargo and crew, has issued a call for post-2016 commercial resupply services.