Northrop Grumman Corp.’s NG-14 Cygnus cargo ship has entered the homestretch of its multi-month mission to the International Space Station (ISS), following a picture-perfect unberthing and departure on Wednesday morning. Physical separation of the spacecraft—which is named in honor of the first woman of Indian ancestry to travel into space, STS-107 astronaut and shuttle Columbia’s final flight engineer, Kalpana “K.C.” Chawla—from the Earth-facing (or “nadir”) port of the Unity node occurred at 10:11 a.m. EST. Cygnus will now spend almost three weeks in autonomous free flight, ahead of a destructive dive into the atmosphere and a harmless disintegration over the Pacific Ocean at 1 p.m. EST on 26 January.
Launched last 3 October atop an Antares 230+ booster from Pad 0A at the Mid-Atlantic Regional Spaceport (MARS) on Wallops Island, Va., NG-14 arrived in the vicinity of the ISS two days later and was duly captured by Expedition 63 Commander Chris Cassidy, using the station’s 57.7-foot-long (17.6-meter) Canadarm2 robotic assets. Cygnus was berthed onto the nadir interface of the Unity node, bringing 7,758 pounds (3,519 kg) of equipment, payloads and supplies to the sprawling orbital outpost.
Almost a third of this total mass was dedicated to science hardware. In advance of this morning’s departure, robotics officers in the Mission Control Center (MCC) at the Johnson Space Center (JSC) in Houston, Texas, successfully detached Cygnus from the Unity nadir port at 8:25 a.m. EST Wednesday and maneuvered the spacecraft to the “release” position. The cargo ship was loaded with over 4,000 pounds (1,800 kg) of trash for disposal.
With a Mission Control team led by Flight Director Pooja Jesrani, and with Japan Aerospace Exploration Agency (JAXA) astronaut Norishige Kanai at the Capcom’s console, Expedition 64 astronaut Kate Rubins—located inside the station’s multi-windowed cupola—was responsible for overseeing today’s departure of Cygnus.
“Release commanded” radioed Kanai at 10:10 a.m. EST, confirming that the release latches were in motion. Cygnus and the ISS officially parted company shortly thereafter, as the two vehicles circled Earth about 260 miles (420 km) above the eastern Pacific Ocean, just off the coast of Ecuador.
Following release, Cygnus conducted a three-minute-long “burn” of its maneuvering engines to position itself beyond the 650-foot (200-meter) Keep Out Sphere (KOS), an imaginary collision-avoidance zone around the ISS, at 10:22 a.m. EST. And as it drifted further away into the inky blackness, heading outside the Approach Ellipsoid (AE)—a region 0.6 miles (1 km) x 0.6 miles (1 km) x 1.2 miles (2 km) in dimension—joint operations ended and Northrop Grumman’s control center in Dulles, Va., formally took command of their spacecraft for the rest of its mission.
Scheduled events over the next couple of weeks, NG-14’s secondary objectives will get underway, including the fifth round of the Spacecraft Fire Experiment (SAFFIRE-V) to safely investigate the processes of combustion, smoke behavior and flame-spreading in the peculiar microgravity environment.
Understanding how fire behaves in space and how different materials propagate flames in the near-total absence of terrestrial gravity is acutely necessary to inform the development of future spacecraft. Additionally, SAFFIRE’s findings will prove invaluable in creating operational protocols for dealing with fire emergencies, particularly when crew members do not have the ability to exit their spacecraft or return quickly to Earth.
Nowhere is that reality more applicable than in NASA’s plans to return a human presence to lunar distance and achieve boots on the surface of the Moon in the next few years. Each SAFFIRE experiment was conducted within a self-contained module, measuring 3 feet (0.9 meters) x 5 feet (1.5 meters), divided into an avionics bay filled with sensors, high-definition video cameras and signal-processing hardware, together with a combustion chamber in which the samples are burned.
Managed by NASA’s Advanced Exploration Systems Division, SAFFIRE-I took place in July 2016 and saw a piece of Solid Inflammatory Boundary at Low Speed (SIBAL) cloth—a cotton blend on a fiberglass substrate—ignited by a hot wire. At the time, SAFFIRE-I marked the largest in-space fire of its type ever conducted.
Over the next few years, further SAFFIRE runs of gradually expanded complexity took place. In November 2016, SAFFIRE-II pushed the envelope further by burning nine samples, including SIBAL and specimens of Plexiglas and Nomex. The latter are typically used aboard spacecraft for windows and as fire-retardant materials.
In June 2017, SAFFIRE-III conducted burn tests at much higher fuel-flow velocities and in May 2019 SAFFIRE-IV began the first of three final missions in the series to run at lower atmospheric pressures of around 8.2 psia and a 34-percent oxygen level. This represents a significantly higher atmospheric concentration than found here on Earth and is being pursued to better understand the energetic vigor of the fires produced.
Original plans for SAFFIRE-V called for about eight days of burn tests, but the experiment may be continued as long as Cygnus remains operational. “The tests are similar to those conducted on SAFFIRE-IV, but with either different materials or different ambient conditions,” NASA’s SAFFIRE Project Manager Gary Ruff explained in comments provided to AmericaSpace. “We were not able to run conditions at reduced pressure and elevated oxygen concentrations on SAFFIRE-IV, but plan to on SAFFIRE-V. We want to conduct tests at 8.2 psia and 34 percent oxygen by volume, which are the ambient conditions being considered for lunar landing systems.”
Another key payload aboard NG-14 is Northrop Grumman’s SharkSat, affixed to one of Cygnus’ panels, which is tasked with gathering telemetry data in support of demonstrating the feasibility of new sensor and processing technologies in low-Earth orbit. It is designed to drive rapid innovation in technology development processes. “Development timelines and lifecycles for space electronics are shrinking as missions are more rapidly evolving,” Northrop Grumman previously told AmericaSpace. “This was an opportunity to bring in some innovation to our traditional processes and “experiment” with how we can quickly leverage robust commercial technology base to meet these new mission timelines.”
With a mass of around 65 pounds (30 kg), and measuring roughly the same size as your average desktop computer, SharkSat will remain affixed to Cygnus throughout its journey in space. “It will not be powered-on until Cygnus departs the ISS,” Northrop Grumman told us, “and will operate for about two weeks. We expect to collect telemetry data and performance information hopefully confirming performance on-orbit.” Several of the SharkSat technology demonstrations have been created and brought to flight readiness within 18 months, in what Northrop Grumman described as “a pathfinder for us on agile space development”.
“For more than six years, Northrop Grumman has supported human spaceflight by delivering critical cargo to astronauts aboard the International Space Station and acting as a host to a number of science experiments and technology demonstrations,” said Frank DeMauro, vice president and general manager, tactical space systems, Northrop Grumman. “Our Cygnus spacecraft will once again demonstrate the capabilities and flexibility we offer our customers by conducting critical experiments during our secondary mission phase.”
With this morning’s unberthing and departure, NG-14 spent a total of 93 days attached to the space station and a destructive re-entry on 26 January will bring the mission to an end after 115 days in space. Northrop Grumman’s next Cygnus mission—NG-15—is set to launch at 12:36 p.m. EST on 20 February to kick off a two-month visit to the ISS. Fueling of the Cygnus is due to commence later this month, preparatory to the onset of cargo loading on 3 February and integration with the Antares 230+ booster on the 10th. After the installation of the payload fairing on Valentine’s Day and rollout to Pad 0A on 16 February, “late” cargo loading will take place, ahead of launch on the 20th.