Less than two days before his scheduled return to Earth, NASA astronaut Kjell Lindgren has completed his last major activity as a member of the Expedition 45 crew aboard the International Space Station (ISS). Earlier today (Wednesday), Lindgren was at the controls of the station’s 57.7-foot-long (17.6-meter) Canadarm2 robotic arm and successfully grappled Orbital ATK’s OA-4 Cygnus cargo ship at 6:19 a.m. EST. A little over three hours later, under the command of the Robotics Officer (ROBO) in the Mission Control Center (MCC) at the Johnson Space Center (JSC) in Houston, Texas, the cylindrical spacecraft—whose design is based upon the Italian-built Multi-Purpose Logistics Module (MPLM)—was securely berthed at the Earth-facing (or “nadir”) port of the Unity node. The arrival of OA-4 brings 7,383 pounds (3,349 kg) of payloads and supplies to the incumbent Expedition 45 crew and Cygnus is expected to remain berthed at the station until late January.
As outlined in a recent AmericaSpace article, the OA-4 launch took place aboard a United Launch Alliance (ULA) Atlas V booster at 4:44 p.m. EST on Sunday, 6 December. Flying from the storied Space Launch Complex (SLC)-41 at Cape Canaveral Air Force Station, Fla., it represents the first of two Cygnuses contracted to ride the Atlas V in its “barebones” 401 configuration—equipped with a 14-foot-diameter (4-meter) payload fairing, no strap-on rocket boosters and a single-engine Centaur upper stage—following the loss of the ORB-3 mission, shortly after lifting off atop an Antares booster from Pad 0A at the Mid-Atlantic Regional Spaceport (MARS) on Wallops Island, Va., in October 2014. Although the OA-4 mission was delayed on three successive days, due to the highly dynamic Florida weather, the Atlas V perfectly delivered Cygnus into space on Sunday afternoon.
Shortly after insertion into an initial orbit of 124.1 nautical miles (229.8 km), inclined 51.6 degrees to the equator, the cargo ship’s two lightweight UltraFlex solar arrays were successfully unfurled in a fan-like manner; their circular configuration offering a distinct visual difference from the four previous Cygnuses—the ORB-D (“Demonstration”) mission in September 2013, followed by ORB-1 in January 2014 and ORB-2 in July 2014, before the ill-fated ORB-3 in October 2014—whose electricity-generating “wings” were rectangular in shape. Described by Orbital ATK as “significantly lighter” and capable of stowing “more compactly than traditional, rigid-panel arrays, due to their circular shape and fan-like deployment”, the UltraFlex hardware provides 3.5 kilowatts of power to Cygnus. Each array measured 12.1 feet (3.7 meters) in diameter when fully deployed.
Over the next two days, Orbital ATK controllers guided their ship through a series of intricate maneuvers to draw closer to the ISS, where U.S. Orbital Segment (USOS) crew members Lindgren, Kelly and Japan’s Kimiya Yui prepared to oversee its rendezvous, grapple and berthing early Wednesday. With Lindgren identified as “Prime Arm Operator”, he has spent the past few days undertaking Canadarm2 practice. “I knew those hours playing video games would come in handy,” he joked in a 7 December tweet, whilst participating in Cygnus “track and capture” rehearsal activities. Assisting Lindgren in the space station’s multi-windowed cupola, Expedition 45 Commander Scott Kelly—who has now passed the 75-percent-complete mark of his one-year mission with Russia’s Mikhail Kornienko and on Sunday excitedly tweeted a stunning view of the Cygnus separating from the Atlas V in the rarefied high atmosphere—opened the shutters at about 3:30 a.m. EST.
Ninety minutes later, the spacecraft had approached to its first “Hold Point” at a distance of 820 feet (250 meters). The Mission Control Center (MCC) at the Johnson Space Center (JSC) in Houston, Texas—with Canadian Space Agency (CSA) astronaut David Saint-Jacques at the ISS Capcom console—and Orbital ATK’s Cygnus Flight Control Room in Dulles, Va., both granted unanimous approval at 5:18 a.m. for OA-4 to proceed within the so-called “Keep-Out Sphere” (KOS), which it achieved a few minutes later. This virtual exclusion zone extends 660 feet (200 meters) around the space station to prevent the risk of a collision. By 5:45 a.m., Cygnus had attained its next Hold Point at 98.4 feet (30 meters) and after further “Go/No-Go” polls were smoothly passed, it headed towards its quarry. The Expedition 45 crew was given a “Go for Capture” at 6:14 a.m.
At this stage, the OA-4 Cygnus entered “free drift”, with all thrusters disabled to ensure that no disturbances were imparted between the two vehicles, and the station itself entered a strict period of “attitude hold”, reliant upon its suite of Control Moment Gyroscopes (CMGs). “Vehicle capture is where ISS motion control really shines,” AmericaSpace was told by ISS Flight Controller Ben Honey. “It’s not so much a vehicle as a stable stationary platform, from which to joystick the arm in.”
Lindgren and Kelly edged Canadarm2’s Latching End Effector (LEE) closer to the grapple pin on Cygnus. At 6:19 a.m., shortly after passing high above Cape Town, and with pinpoint precision, Lindgren captured the OA-4 spacecraft. The grapple marked the 16th overall capture of a cargo ship by Canadarm2, which was installed aboard the space station by the STS-100 shuttle crew, way back in April 2001. Since September 2009, the “Big Arm”, as it is called, has supported the capture and berthing of five H-II Transfer Vehicles (HTVs) on behalf of the Japan Aerospace Exploration Agency (JAXA), seven SpaceX Dragons and three Cygnuses.
“Happy to accept #Cygnus with an open arm this morning,” Kelly tweeted, making reference to the Big Arm’s critical role in today’s capture. “Look forward to bringing on-board new #ISSCargo! #YearInSpace.” As outlined by AmericaSpace’s Talia Landman in a recent article, the OA-4 spacecraft is laden with 7,383 pounds (3,349 kg) of payloads and supplies for the Expedition 45 and upcoming Expedition 46 crews. This represents a haul about 40 percent greater than any previous Cygnus and has been achieved through the first flight of its “Enhanced” configuration, which boasts a larger Pressurized Cargo Module (PCM) and is loaded with EVA equipment, scientific investigations, crew supplies, vehicle hardware and computer resources.
Over the course of the next 2.5 hours, flight controllers and Expedition 45’s USOS crew worked to maneuver the OA-4 spacecraft toward its eventual location at the Earth-facing (or “nadir”) Common Berthing Mechanism (CBM) of the Unity node. The physical berthing of the cargo ship occurred in two parts, with the astronauts overseeing “First Stage Capture”, in which hooks from Unity’s nadir CBM extended and grabbed the Cygnus to pull their respective CBMs into contact. This was followed by “Second Stage Capture”, in which a series of 16 bolts—four gangs of four bolts apiece—were driven to rigidize the two spacecraft in a tight, mechanized embrace at 9:26 a.m. EST. “Capture went flawlessly,” tweeted a proud ISS Capcom David Saint-Jacques. “Congrats @astro_kjell @StationCDRKelly @Astro_Kimiya!”
For the first time in history, an unpiloted Visiting Vehicle (VV) had been attached to Unity nadir. Although the node was one of the earliest ISS components to reach orbit—launched aboard shuttle Endeavour on STS-88 in December 1998—it has been occupied at various stages during its 17 years aloft. It provided an early home for Pressurized Mating Adapter (PMA)-3, enabling the shuttle dockings of STS-97 and STS-98 in the winter of 2000-2001, and routinely supported Italian-built Multi-Purpose Logistics Modules (MPLMs) during several flights prior to and after the Columbia disaster, before being occupied by the Leonardo Permanent Multipurpose Module (PMM) in February 2011.
This “permanence” ended in May 2015, when the Leonardo PMM was robotically relocated to a new home on the Tranquility node, allowing the Unity nadir interface to once again become available for visiting cargo craft. As a result, the ISS now has two berthing locations—one at Unity nadir, the other at the nadir port of the neighboring Harmony node—for unpiloted Cygnuses, Dragons and HTVs. This will allow for the simultaneous presence of two VVs and, with SpaceX expected to launch its Commercial Resupply Services (CRS)-8 Dragon mission towards the ISS in early January 2016, the New Year should see both of NASA’s COTS partners on-station at the same time, for the very first time.
Although the actual ingress of the crew into the Cygnus—which, like its ill-fated predecessor, has been named in honor of Mercury astronaut Deke Slayton—was originally timetabled for Thursday, it appeared that the astronauts were keen to get started as quickly as possible. “#Cygnus, AKA #SSDekeSlayton has arrived just in time for #Christmas!” Kelly tweeted with unmistakable excitement, late Wednesday morning. It is expected that after the initial effort of outfitting the pressurized “vestibule” between the Unity and Cygnus CBMs, hatches will be opened and the astronauts will ingress the new cargo ship on Thursday.
However, it remains a pity that Lindgren and his Soyuz TMA-17M crewmates—Russian cosmonaut Oleg Kononenko and Japan’s Kimiya Yui—will not be aboard the ISS for much longer and likely will miss most of the Cygnus unloading. As we will outline in an AmericaSpace article tomorrow (Thursday), Kononenko, Lindgren and Yui are slated to return to Earth on Friday, after 4.5 months in orbit. They will leave Scott Kelly in command of Expedition 46, joined by cosmonauts Mikhail Kornienko and Sergei Volkov, although Soyuz TMA-19M is scheduled to fly from the Baikonur Cosmodrome in Kazakhstan next week, ferrying a new crew of Russia’s Yuri Malenchenko, U.S. astronaut Tim Kopra and Britain’s Tim Peake to the station for a half-year occupancy. In the minutes after today’s capture, Peake, who is currently in Baikonur with his crewmates, tweeted: “Congratulations @astro_kjell @StationCDRKelly & @Astro_Kimiya on a great capture…looking forward to unpacking it!”
Current plans call for OA-4 to remain “on-station” for almost seven weeks, with unberthing and departure scheduled for 25 January 2016, after which the spacecraft will execute a destructive re-entry into the atmosphere. However, with Orbital ATK’s Antares 230 booster—featuring Russian-built RD-181 first-stage engines, replacing the Aerojet Rocketdyne-furnished AJ-26 of the earlier Antares 130—expected to launch its next Cygnus cargo in May 2016, there is one more ISS-bound flight on the books for United Launch Alliance. Another Atlas V 401 rocket will deliver the OA-6 Cygnus towards the space station in March. In the minutes after today’s successful capture and berthing, Orbital ATK tweeted: “Thanks for the ride, @ulalaunch” and added “Let’s do it again in March?”
The response from ULA CEO Tory Bruno came swiftly: “We’ll be there!”
With thanks to ISS Flight Controller Mr. Ben Honey, for his assistance in the rendezvous aspects of this article.
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