After more than three months as part of the International Space Station (ISS), Northrop Grumman Corp.’s NG-16 Cygnus cargo ship—named in honor of shuttle Challenger hero Ellison Onizuka—has entered the homestretch of its long mission. At 8 a.m. EST Saturday, flight controllers on the ground commanded the station’s 57.7-foot-long (17.6-meter) Canadarm2 robotic arm to detach Cygnus from its Earth-facing (or “nadir”) berth on the Unity node and it was released into free flight at 11:01 a.m. EST. The cargo ship is carrying an estimated 7,500 pounds (3,400 kilograms) of trash and unneeded equipment for disposal in the Earth’s upper atmosphere.
European Space Agency (ESA) astronaut Matthias Maurer of Germany, newly arrived at the ISS aboard Dragon Endurance, monitored Cygnus’ systems as the spacecraft drifted away into the inky darkness, primed for a destructive re-entry in mid-December. At the point of separation, the ISS and Cygnus were orbiting some 268 miles (430 kilometers) above the South Pacific Ocean.
Shortly after departure, Cygnus executed its first separation burn to position it outside the limits of the Keep Out Sphere (KOS), a collision avoidance zone which extends to a radius of about 660 feet (200 meters) around the station. Passing outside the KOS at 11:10 a.m. EST, as the ISS orbited high over Chile, the cargo ship’s next point of departure was the Approach Ellipsoid.
Nicknamed “the pizza box”, this region extends 1.2 miles (2 kilometres) x 1.2 miles (2 kilometres) x 2.4 miles (4 kilometers) around the station. After passing the limits of the Approach Ellipsoid at 11:24 a.m. EST, joint control between NASA and Northrop Grumman ended. From now until the mission’s end, Cygnus will be commanded exclusively from Northrop Grumman’s control room in Dulles, Va.
“The Cygnus system has evolved from being just a cargo delivery service to a high performing science platform,” said Steve Krein, vice president of civil and commercial space, tactical space systems and Northrop Grumman. “We continue to develop these capabilities to include the installation of environmental control systems and other upgrades to support the lunar-orbiting Habitation and Logistics Outpost (HALO).”
Cygnus rose into space last 10 August, atop Northrop Grumman’s home-grown Antares 230+ booster from Pad 0A at the Mid-Atlantic Regional Spaceport (MARS) on Wallops Island, Va. The launch came at 6:01 p.m. EDT, right at the end of the five-minute “window”, due to a Ground Support Equipment (GSE) issue with a helium pressurization valve.
After 36 hours in free flight, Cygnus reached the station and at 6:07 a.m. EDT on 12 August was grappled by Canadarm2, under the deft control of Expedition 65’s Megan McArthur.
Monitoring the approach was ESA astronaut Thomas Pesquet of France. At the time of arrival, Cygnus and the ISS were flying some 260 miles (420 kilometres) over the Atlantic Ocean, to the southwest of Portugal’s capital, Lisbon.
Over the course of the next several hours, the Mission Control Center (MCC) at the Johnson Space Center (JSC) in Houston, Texas, assumed command, guiding Canadarm2 to rotate and install Cygnus onto the Earth-facing port of the Unity node. This effort was completed at 9:42 a.m. EDT, with an expectation that NG-16 would remain part of the ISS until November.
Aboard the cargo ship were some 3,000 pounds (1,400 kilograms) of crew supplies, over 2,300 pounds (1,000 kilograms) of scientific experiments, more than 30 pound (15 kilograms) of Extravehicular Activity (EVA) equipment and almost 2,300 pounds (1,000 kilograms) of vehicle hardware. The grand total of cargo lifted uphill was over 8,200 pounds (3,700 kilograms).
And those crew supplies included “care packages” from friends and family. “Busy day with Cygnus capture and first ingress,” tweeted McArthur on 13 August. “Tomorrow, we hunt down our care package.”
Heading up the roster of payloads was a second ISS Roll-Out Solar Array (iROSA) modification kit, set to be affixed to the station’s P-4 truss in readiness for next year’s planned installation of a new set of power-producing solar arrays.
But the science aboard Cygnus, as it always does, took center stage. The Redwire Regolith Print (RRP) investigation, jointly developed by Made in Space, Inc., of Jacksonville, Fla., and NASA’s Marshall Space Flight Center (MSFC) of Huntsville, Ala., was destined to utilize the station’s 3D printer to produce “regolith simulant materials”.
Part of an ongoing campaign to demonstrate the feasibility of using in-situ resources on other celestial bodies to provide raw materials to build habitats, landing pads and other hardware, RRP’s produced samples would furnish an analog of the loose rocks and dust found on the lunar surface. These samples would then be tested to assess their compressive, tensile and flexural strength.
MSFC’s 4-Bed Carbon Dioxide Scrubber was also aboard Cygnus to demonstrate advanced life-support capabilities for deep-space missions. It will remain aboard the ISS for about a year, helping to recycle and regenerate most of the air and water needed to sustain the crew.
It forms one of two next-generation Environmental Control and Life Support System (ECLSS) technologies—alongside the Thermal Amine Scrubber, launched aboard the NG-11 Cygnus back in April 2019—to undergo testing on the station.
The new scrubber is an upgrade to the existing Carbon Dioxide Removal Assembly (CDRA), with benefits including reduced power consumption rates, improved thermal stability and longer lifespan of the absorbent materials.
After its year-long demonstration phase is done, it will be fully integrated into the station’s closed-loop recycling system for at least three additional years to evaluate its viability for longer missions.
Other experiments aboard NG-16 included Cardinal Muscle to examine engineered human muscle cells affixed to a collagen “scaffold” to investigate the accelerated loss of muscle mass in microgravity.
Results may lead to greater insights into the causal factors behind “sarcopenia”, a condition whereby muscle mass diminishes with age on Earth, with a 30-percent progressive degeneration noted between the ages of 20 and 80.
By observing this phenomenon in the microgravity environment, Cardinal Muscle investigators hope to develop new tissue-engineering approaches to create better models for sarcopenia and test new therapeutic drugs.
The Flow Boiling and Condensation Experiment (FBCE) seeks to develop an integrated two-phase flow boiling and condensation facility aboard the ISS, to support the development of improved boilers and heat exchangers for use in microgravity and low-gravity conditions.
And a European Space Agency (ESA) investigation, named “Blob”, will explore the effects of microgravity on the unicellular organism Physarum polycephalum. This slime-mold is part of an experiment to inspire students in the biological sciences.
Although it is just one cell and lacks a brain, Blob can move, feed, organize itself and even transmit knowledge to other slime molds. Students aged 10-18 replicated experiments conducted by Pesquet to evaluate how the Blob’s behavior was affected by microgravity. Using time lapse video from space, students can compare the speed, shape, and growth of the slime molds in space and on the ground.
Also aboard, of course, was a haul of fresh food and treats for the Expedition 65 crew, including apples, tomatoes and kiwis, plus kits to craft their own homemade pizzas.
“Thanks to you,” tweeted Vande Hei, addressing Cygnus as if it were a living thing, “we not only have lots more science we can do up here, but we also had a pizza night on Saturday.” It appeared that McArthur was first to find the NG-16 food stores. “@Astro_Megan wins the Cygnus treasure hunt,” tweeted Vande Hei, sharing a picture of a happy McArthur holding a cargo bag marked “Fresh Food”.
Shortly after Cygnus was securely bolted into place, these scientific experiments came alive in earnest. By 13 August, the Expedition 65 crew had opened the hatches into the cargo ship, to be greeted by a large image of Ellison Onizuka himself, the shuttle astronaut who became the first Asian-American spacefarer when he flew Discovery on STS-51C in January 1985.
Of Japanese parentage, Onizuka was a lieutenant-colonel in the Air Force and later lost his life as a member of Challenger’s ill-fated STS-51L crew in January 1986.
McArthur and Pesquet set to work removing frozen science specimens from Cygnus into the ISS for observation, later joined by crewmate Shane Kimbrough in the effort. Over the following days, the astronauts took turns offloading cargo and supplies and on 17 August work got underway on Cardinal Muscle inside Japan’s expansive Kibo lab.
McArthur set up the initial hardware and engineered muscle cells inside the Life Sciences Glovebox (LSG) and Pesquet continued the work later that day.
“Microgravity speeds up bone and muscle loss, allowing us to study such conditions faster in space than on Earth,” McArthur tweeted on 20 August. “I’m working on the Cardinal Muscle experiment, which could pave the way for quicker testing of muscle loss treatments.”
With the iROSA modification kit having been successfully ferried uphill by Cygnus, hopes were high that a 6.5-hour session of Extravehicular Activity (EVA) on 24 August by Expedition 65 Commander Aki Hoshide of Japan and NASA astronaut Mark Vande Hei would take place to install it onto the P-4 truss. It would thus furnish a mounting location for the solar array itself, which is due to be delivered to the ISS next year.
The excitement for the EVA was palpable. On 17 August, Vande Hei tweeted a photograph of Hoshide as he manhandled the cargo bags holding the pieces of the modification kit out of Cygnus and into the station.
However, Vande Hei suffered a pinched nerve in his neck and the EVA was postponed by a couple of weeks. As circumstances transpired, Vande Hei was substituted for Pesquet. When the spacewalk finally took place on 12 September, lasting six hours and 54 minutes, it became the first EVA using U.S.-built suits to feature no U.S. crew member.
The disappointment of “losing” his EVA did not impair Vande Hei’s efforts with other Cygnus-related work, however, and on 20 August he took microscopic photographs of the first engineered tissue samples from Cardinal Muscle.
The NG-16 research continued unabated over the next few weeks and in mid-September, Kimbrough finalized connections of the 4-Bed Carbon Dioxide Scrubber inside the U.S. Destiny lab. And on 26 October, Vande Hei configured the Light Microscopy Module (LMM) to begin work on the FBCE experiment, which continued over the next several days.
Beginning in earnest in October, Cygnus became a hive of activity yet again, when the astronauts set to work loading trash and unneeded hardware into the cargo ship, preparatory for its return to Earth in the latter half of November.
That work intensified last week, following the arrival of Crew-3, and new Expedition 66 arrivals Raja Chari, Tom Marshburn and Kayla Barron joined Vande Hei in packing Cygnus for departure. In the meantime, Germany’s Matthias Maurer prepared for his role overseeing the cargo ship as it departs the space station after 102 days in orbit, a hundred of which were spent berthed at the ISS.
One large component returning to Earth for disposal in the upper atmosphere is the Space Test Program (STP)-H6, which arrived at the station as an External Payload aboard SpaceX’s CRS-17 cargo mission back in May 2019.
It featured a group of payloads, including a communications demonstration for generating beams of modulated X-rays, an electrostatic analyzer for observations of the ionosphere, a pair of Earth-imaging cameras and a plasma impedance probe. Last week, an end-of-life survey was completed on STP-H6, after which the payload and its Flight Releasable Attachment Mechanism (FRAM) were loaded aboard Cygnus for departure.
But NG-16’s mission of discovery is not yet over and several more weeks will elapse before the cargo ship takes a destructive dive into Earth’s atmosphere in mid-December. During that re-entry, a joint investigation between NASA and the University of Kentucky will assume center-stage.
The Kentucky Re-Entry Probe Experiment (KREPE) will deploy a set of three instrumented “capsules” to evaluate an affordable Thermal Protection System (TPS). The KREPE payload activation was completed yesterday (Friday), just ahead of unberthing.
The capsules are instrumented with thermocouples at various depths within their heat shield framework, the data from which will be “packaged” and transmitted to the ground via the Iridium satellite network. KREPE will demonstrate these new TPS materials through actual hypersonic re-entry conditions, following an earlier series of high-altitude stratospheric balloon trials.Missions » ISS » COTS » CYGNUS »