Engineers prepare to transport Orbital ATK's enhanced Cygnus spacecraft, fitted inside the payload fairing of a United Launch Alliance Atlas 5, from the Payload Hazardous Servicing Facility at NASA's Kennedy Space Center to Space Launch Complex 41. Credit: ULA

WASHINGTON — Preparations for the first launch of a Cygnus cargo spacecraft in more than a year, and the first on an Atlas 5 rocket, have gone smoothly despite some changes in timing of loading cargo on the spacecraft, an Orbital ATK executive said.

An Atlas 5 is scheduled to launch the Cygnus craft from Cape Canaveral, Florida, Dec. 3. The launch will be the first for the Cygnus since the October 2014 failure of Orbital’s Antares rocket shortly after liftoff from Wallops Island, Virginia.

Dulles, Virginia-based Orbital purchased the Atlas 5 launch from United Launch Alliance shortly after the failure, and in August acquired a second Atlas 5 for a Cygnus mission planned for March 2016. While the Cygnus has not previously flown on the Atlas, integrating the cargo spacecraft to the rocket has gone well.

“It’s actually been very rewarding,” Frank Culbertson, president of Orbital ATK’s Space Systems Group, said in a Nov. 18 interview about the company’s relationship with ULA . “We found them very easy to work with in that regard and it’s been a good collaboration. We’re very proud of where we’ve gotten in such a short period of time.”

This mission, designated OA-4 by Orbital ATK, is the first “enhanced” version of the Cygnus spacecraft with a larger cargo module, and will carry more than 3,500 kilograms of supplies. The payload includes a combination of space station hardware, crew supplies and experiments.

One challenge Orbital encountered during planning for this mission is that the Cygnus is encapsulated inside the Atlas payload fairing much earlier in launch preparations than it was for Antares launches. That eliminates the ability to accommodate “late load” cargo — cargo that is added to the spacecraft shortly before launch.

“It’s difficult to load items late in the flow at this point,” Culbertson said. The Cygnus was sealed inside the fairing more than two weeks before launch, timing he said was dictated by ULA’s standard payload processing schedule for Atlas missions. “We had to fit into their current way of doing business.”

The early cutoff for loading payload became an issue after the station suffered a malfunction Nov. 13 that shut off one of eight channels that relay electric power. While the problem does not affect station operations, NASA considered flying replacement hardware on the upcoming Cygnus mission.

“It turned out that could have been done, but it would have delayed the launch,” Culbertson said, because Cygnus was already being installed in the payload fairing. “The pros and cons of all the various factors resulted in NASA deciding not to try to destack and load it late.”

That hardware in question will instead fly on a later cargo mission.

The lack of late-load cargo also means that, unlike many other such missions, this one won’t provide any fresh fruit or other perishable items for the station’s crew. “It wouldn’t be fresh when it got there,” he said.

December’s Cygnus mission will be followed by another Atlas launch of a Cygnus, called OA-6, in March. Orbital ATK plans to resume Cygnus launches on an upgraded version of its Antares rocket in May from Wallops.

“Things are going very well at Wallops,” Culbertson said, praising work by NASA and the state of Virginia to repair the pad damaged in last October’s launch failure. “They modified some of the systems, replaced a few items, and painted everything. It looks great.”

Orbital is planning to conduct a hot-fire test of the Antares, now equipped with two RD-181 engines from the Russian company Energomash, on the pad in March. Culbertson said the integration of the new engines into the Antares first stage has gone well, and that only minor changes to the pad were needed to accommodate the engine.

The long-term future of both Antares and Cygnus, though, hinges in large part on whether Orbital ATK can secure another NASA contract to deliver cargo to the station. The company was one of several that submitted proposals to NASA nearly a year ago for the agency’s Commercial Resupply Services (CRS) 2 competition. NASA has delayed awarding CRS-2 contracts several times, and now plans to announce them as late as the end of January.

Culbertson would not say much about the ongoing competition, other than  that Orbital was responding to a NASA request for updated information about its proposal. “We’ll follow their direction and wait for their selection,” he said.

The long delay on the CRS-2 contracts, he suggested, has affected Orbital’s plans to procure components for future Cygnus missions. “Any delay in a contract like that has impacts on what you’re ordering and what you’re spending,” he 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...