Spaceflight Insider

OA-4 Cygnus encapsulated in PLF in preparation for flight

Orbital ATK United Launch Alliance Atlas V 401 OA-4 Deke Slayton II Cygnus spacecraft International Space Station photo credit Michael Howard SpaceFlight Insider

The OA-4 Cygnus spacecraft has been encapsulated into its Cygnus spacecraft in preparation for a Dec. 3, 2015, launch date. Photo Credit: Michael Howard / SpaceFlight Insider

Orbital ATK’s Cygnus advanced maneuvering spacecraft has been encapsulated into its Payload Fairing (PLF) and is scheduled to launch Dec. 3 on an International Space Station (ISS) resupply run. The mission, called OA-4, will launch from Cape Canaveral’s SLC-41 and will be boosted into orbit aboard a United Launch Alliance (ULA) Atlas V 401 rocket. The cargo freighter is scheduled to rendezvous with the space station two days later.

Cygnus spacecraft have already successfully delivered cargo to the ISS on three prior missions. The vehicle for the OA-4 mission consists of an upgraded Service Module (SM) and an enhanced Pressurized Cargo Module (PCM). The cargo capability has increased to more than 7,700 lbs (3,500 kg) on this mission.  The spacecraft’s previous maximum capacity was 5,070 lbs (2,300 kg). This mission will carry a full cargo of supplies and science experiment equipment to the space station.

The scheduled December flight should last approximately 21 minutes from ignition of the Atlas V’s RD-180 rocket engine to the spacecraft’s separation from the launch vehicle. About one hour after separation, Cygnus will unfurl the spacecraft’s circular “Ultraflex” solar arrays. Over the following two days, it will raise its orbit to bring it into position to rendezvous with the orbiting laboratory.

Once there, ISS astronauts will operate the station’s robotic arm to grab the “Deke Slayton II” and guide it to a locked berth on the station’s Unity node. It will remain berthed to the ISS for approximately two months, during which time the station’s crew will periodically unload different portions of the cargo, and later stow other material aboard the craft for disposal. Cygnus will then depart the station and reenter over the Pacific Ocean where it will burn up in Earth’s atmosphere.

The Cygnus spacecraft has heritage systems from Orbital ATK’s flight-proven LEOStar and GEOStar spacecrafts. The SM incorporates avionics from LEOStar, and power and propulsion systems from the GEOStar communications satellites. The PCM is based on the Multi-Purpose Logistics Module (MPLM) developed for NASA by Italy’s Thales Alenia Space, who are also providing the thermomechanical systems for the Orion spacecraft’s Service Module.

Orbital ATK developed Cygnus for ISS resupply missions under the NASA Commercial Orbital Transportation Services (COTS) Space Act Agreement. The company is under currently contract to complete eight missions to the ISS and deliver approximately 63,000 lbs (28,700 kg) of cargo under the $1.9 billion Commercial Resupply Services contract.  The first of these missions was completed in early 2014.

The Cygnus spacecraft for the OA-4 mission has been named the S.S. Deke Slayton II, after the Mercury and Apollo-Soyuz astronaut, and long-time leader of the astronaut program.


Michael Cole is a life-long space flight enthusiast and author of some 36 educational books on space flight and astronomy for Enslow Publishers. He lives in Findlay, Ohio, not far from Neil Armstrong’s birthplace of Wapakoneta. His interest in space, and his background in journalism and public relations suit him for his focus on research and development activities at NASA Glenn Research Center, and its Plum Brook Station testing facility, both in northeastern Ohio. Cole reached out to SpaceFlight Insider and asked to join SFI as the first member of the organization’s “Team Glenn.”

Reader Comments

Good luck to the entire Orbital ATK team!

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