Cygnus performing well at the ISS ahead of unberthing

by Chris Bergin

Orbital’s ORB-D Cygnus is into the final leg of its debut mission to the International Space Station (ISS), ready to pave the way the ORB-1 Cygnus – set to launch on December 15. The new kid on the block has enjoyed a trouble-free stay on the ISS, with the only issue relating to a cabin fan problem.

Cygnus at the ISS:

Cygnus arrived at the orbital outpost on September 28, a week later than planned, due to a discrepancy in the GPS data between the ISS and Orbital’s spacecraft.

However, the flawless rendezvous and berthing more than made up for the delay, as Cygnus was put through a challenging set of manuevers aimed at proving its ability to safely arrive within the Keep Out Sphere (KOS) and then be in a stance to abort from the $100 billion Station in the event of a system failure.

Z3With ISS crewmembers Luca Parmitano and Karen Nyberg inside the Cupola, Cygnus eased its way towards the Station.

“The spacecraft’s performance (was) impeccable (230 meters away). Karen runs a test that the spacecraft needs to complete for its maiden flight: she commands a retreat and the Cygnus slows down, stops, and backs up to a distance of 250 meters,” recalled Parmitano.

“When Houston tells us that Cygnus has resumed its approach, Karen prepares a second test, again at 230 meters. She sends the command to hold. The spacecraft obediently stops and waits for new commands.”

Z4The “Tally Ho” of Cygnus had extra meaning to the Italian native, not least because the Orbital vehicle’s Pressurized Cargo Module (PCM) was manufactured by Thales Alenia Space in Turin and is a relative of the Leonardo Permanent Multipurpose Module (PMM).

“Its navigation lights are clearly visible, two white strobes in the centre with a red and green light on either side, the colours of the Italian flag floating in space. Cygnus’ pressurised module is built in Italy and I smile at the thought of this unintentional tribute to my country,” Parmitano added.

“In a few minutes everything is ready for the approach that will bring Cygnus to thirty metres and then to ten meters. At that point the spacecraft’s interface will be only five metres away from the robotic Canadarm2. My job is to bridge that distance and then catch Cygnus.”

Z5With the Space Station Remote Manipulator System (SSRMS) touching Cygnus, Parmitano sends the command to activate the Latching End Effector on the end of the arm to close the snares to confirm the capture of the vehicle.

“I press the trigger that starts capture. We were less than a minute into the procedure. But our smiles form a memory that will last a lifetime,” the ESA astronaut continued.

“In a few hours, Karen and I perform robotics to position Cygnus and attach it to Node 2. We then move the spacecraft and integrate it with the station.”

Z6With the hatch opening occurring the following day, the crew began to unload the 1,100 kgs of cargo contained within the vehicle’s PCM. Although ORB-D is a demo mission, Cygnus’ successful arrival provided the Station with some much needed supplies.

With the payloads removed, the crew began to fill Cygnus back up with trash items – an important operation to ensure the Station does not become overloaded with unwanted items in what is limited space on the outpost.

Cygnus has behaved well during these operations, with only one minor listed on the ISS Status Reports in L2.

“Cygnus Cabin Fan Status: The Cygnus Cabin fan was unpowered by MCC-Dulles due to erratic delta pressure readings. In an effort to gather additional trend data, the fan is being activated daily during crew wake periods then deactivated prior to crew sleep. Results from this trending data will help ground teams decide whether to activate the fan permanently or not.”

The Expedition 37 crew are expected to load the third and final layer of trash by next week, followed by PCM close out. Unberthing from the station is expected on October 22, with re-entry into Earth’s atmosphere on October 24.

Z7Pending a review by Orbital and NASA teams, Cygnus will change call signs from being a spacecraft under the NASA Commercial Orbital Transportation Services (COTS) program into the Commercial Resupply Services (CRS) contract.

The next Cygnus – along with its Antares launch vehicle – is already being processed at Orbital’s Wallops facility, with a target launch date of December 15, with an available launch window through to December 21 – per L2 information.

This mission will involve a standard three day flight profile to berthing with the ISS, with its launch aided by the Castor 30B second stage upper stage engine – ATK’s upgraded variant of the Castor 30A that rode with the ORB-D Cygnus.

For the ORB-1 mission, approximately 1,350 kilograms of cargo are currently manifested to be taken up to the Station, including the first powered payload in Cygnus.

(Images: via L2’s Antares/Cygnus Section – Containing presentations, videos, images – including 100s of mbs of unreleased ORB-D hi-res photos – interactive high level updates and more, with additional images via Orbital and Neptec).

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