OA-6 launch
An Atlas 5 carrying a Cygnus cargo spacecraft lifts off from Cape Canaveral, Florida, March 22. Credit: NASA TV

WASHINGTON — A United Launch Alliance Atlas 5 successfully launched a Cygnus cargo spacecraft on a mission to the International Space Station March 22, the second such mission in less than four months.

The Atlas 5 lifted off on schedule at 11:05 p.m. Eastern time, placing the Orbital ATK-built Cygnus into orbit a little more than 20 minutes later. The Cygnus, named the SS Rick Husband after the late commander of the shuttle Columbia’s final mission, is scheduled to arrive at the ISS on March 26.

The Cygnus is carrying more than three tons of cargo for the International Space Station, including crew supplies, vehicle hardware and experiments. That payload includes experiments ranging from an advanced 3-D printer to a flammability test that will be performed in the Cygnus after it leaves the station.

The launch is the second time a Cygnus has flown on an Atlas 5, after the launch of the previous Cygnus mission in December. There were few changes in the processing of this Cygnus compared to the previous one, said Frank DeMauro, vice president of human space systems at Orbital ATK, in a March 22 interview. “It’s very, very, similar,” he said.

The biggest change in operations will be at the end of the mission, after Cygnus is unberthed from the station. On previous Cygnus flights, the spacecraft has reentered the Earth’s atmosphere within a couple days of departure. This time, it will carry out the Saffire-1 flammability experiment and deploy several cubesats before reentering up to a week after departure.

“Flying the Saffire experiment is exciting for us,” DeMauro said. “We’re using Cygnus now not only as a logistics vehicle for cargo delivery and removal but also really as a testbed for NASA research.”

The Cygnus launches on the Atlas 5 were meant as a temporary measure until Orbital ATK resumes launches of a updated version of its Antares vehicle, grounded since an October 2014 launch failure. The new version of the Antares, powered by RD-181 engines from NPO Energomash, should be ready for launch by June, according to Kurt Eberly, Antares deputy program manager at Orbital ATK.

“We’ll be ready to go in the June timeframe,” he said in a March 22 interview. A specific date will depend on NASA’s schedule of missions to the station and overall cargo requirements. “They’ll take stock of where they are and what their needs are and then find a good slot for us.”

Prior to that launch, Orbital ATK plans to carry out a static fire test of another Anatres first stage on the pad at the Mid-Atlantic Regional Spaceport in Virginia, likely in early May, he said. “That’s going to hit all the operating points we’re going to fly in flight,” he said of that pad test.

If that launch goes as planned, another Antares launch of a Cygnus spacecraft would take place in the fall, Eberly said.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...