The first flight of Orbital ATK’s Enhanced Cygnus resupply craft for the International Space Station is set to launch in December atop an Atlas V rocket. Helping Orbital ATK return to flight operations, the Enhanced Cygnus spacecraft will allow the company to meet their initial CRS cargo up-mass contract with NASA in just four more missions.

Enhanced Cygnus:

December’s upcoming OA-4 mission of Cygnus to the International Space Station (ISS) will be the first flight of Cygnus under the newly merged company Orbital ATK and the first flight of the company’s resupply vehicle on a non-Antares rocket.

The OA-4 mission will be lofted to orbit on a United Launch Alliance Atlas V rocket launching from the Cape Canaveral Air Force Station, FL.

Cygnus’ ingrained adaptability to launch on rockets other than Antares has allowed Orbital ATK to purchase an Atlas V rocket for the OA-4 mission and, in turn, gain significant up-mass capability on the OA-4 mission than would have been possible launching on Antares.

This additional up-mass capability supported by the powerful Atlas V rocket’s core stage and its Centaur upper stage will allow Orbital ATK to reach a major milestone in the company’s Commercial Resupply Contract (CRS) with NASA sooner than expected.

In an exclusive interview with NASASpaceflight.com, Frank DeMauro, CRS Program Director for Orbital ATK stated that “with the upgraded Antares 230 and then with the couple of Atlas V [missions], we’re actually going to meet our initial cargo delivery requirement through the OA7 mission.”

While Enhanced Cygnus on an Atlas V is part of what will allow Orbital ATK to meet their cargo delivery up-mass requirement on the OA-7 mission instead of the OA-8 mission, the enhanced version of Cygnus was planned from the inception of the program and is not a change stemming from the Orb-3 launch failure in October 2014.

According to Mr. DeMauro, “we had planned from the beginning of the program that there would actually be two versions of Cygnus.”

The first variant, the Standard Cygnus, flew on all three previous Orbital CRS ISS missions (including October’s failed Orb-3 CRS mission) in 2014 as well as the predecessor COTS Demo flight of Cygnus to ISS in Sept. 2013.

The Standard Cygnus, flying on Orbital’s Antares 110, 120, and 130 series rockets, could carry a maximum payload of approximately 2,000 kg (4,400 lbs) to ISS.

Enhanced Cygnus, on Atlas V, will be capable of lifting a maximum payload of 3,500 kg (7,700 lbs) to the ISS and 3,200 kg (7,100 lbs) of payload to ISS on the Antares 230 series rocket — set to debut early next year as part of Orbital ATK’s return to flight path.

According to Mr. DeMauro, “we had planned a long time ago that we would start flying, on the fourth mission, a longer cargo module — with essentially more volume to carry more cargo.”

In fact, Enhanced Cygnus will have a stretched Pressurized Cargo Module (PCM) that will increase the total interior PCM volume to 27 cubic meters — an increase from the 18 cubic meter PCM volume of the Standard Cygnus.

Moreover, the stretched PCM is not the only aspect of the Enhanced Cygnus that will debut on December’s OA-4 flight. Orbital ATK ultraflex solar arrays will also grace the Enhanced Cygnus later this year.

“One of the more visible changes was the change-out from the flat panel solar array to an Orbital ATK ultraflex solar array — which deploys sort of like a fan,” stated Mr. DeMauro.

“The biggest difference between [the Orbital ATK ultraflex array] and a more traditional array is the structure behind the cells. It’s essentially a lightweight material to which the cells are mounted, as opposed to a more heavy structure.

“The key is to develop the array in such a way that you have a small stowed package with a highly reliable deployment system, but that when it’s open, the amount of surface area you get is about the same as you would get from a regular flat panel area.”

This approach to the Enhanced Cygnus design will allow Orbital ATK to have a lower mass solar array that produces the same amount of power as the previous generation Cygnus solar arrays.

Importantly, though, the visual changes of the Enhanced Cygnus aren’t the only improvements Orbital ATK has made to its ISS resupply craft.

Lessons learned in terms of loading cargo into Cygnus have led to a significant increase in the amount of cargo that can be arranged within Cygnus.

According to Mr. DeMauro, “As we learned other things we could do in the cargo module, we’ve actually significantly increased the amount of cargo we can load in the same volume on the Enhanced Cygnus.

“So that’s why you’re seeing, for a relatively low percentage of size increase of the PCM, a significant increase in cargo carrying capability.”

With its introduction on the OA-4 mission in December, Enhanced Cygnus will become the only variant of Cygnus used for ISS resupply missions through the completion of Orbital ATK’s CRS contract with NASA — a contract that was recently extended by three missions.

Following the OA-7 mission in 2016, the OA-8E, OA-9E, and OA-10E missions will launch between 2017 and the first part of 2018.

Those added missions will continue to focus solely on Cygnus’ pressurized up-mass capability to ISS.

When asked about possible Cygnus variants to allow for external cargo deliveries to ISS, Mr. DeMauro stated that Orbital ATK’s “focus right now and moving forward is on pressurized up-mass and pressurized disposal.

“What we do, what NASA is counting on us to do, is to deliver as much pressurized up-mass as possible. And then also, very importantly, the removal of disposal cargo from inside the Station.”

Mr. DeMauro specifically noted that this service from Cygnus compliments the other contracted services NASA has for Station resupply efforts, and that there are no plans to redesign Cygnus for external supply delivery ops at Station.

If the current schedule holds, the first Enhanced Cygnus will launch to the ISS atop an Atlas V rocket – flying in the 401 configuration (with a 4-meter fairing, zero solid rocket boosters, and a single-engine Centaur upper stage) – on 3 December 2015 during a launch window that opens at 17:55 EST and closes at 18:25 EST (22:55 – 23:25 GMT).

(Images: via L2’s Antares/Cygnus Section – Containing presentations, videos, a vast set of unreleased hi-res images, interactive high level updates and more, with additional images – including the new Atlas V with ORB-4 Cygnus via L2 artist Nathan Koga. Other images via Orbital and NASA).

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