Northrop Grumman Corp.’s NG-15 Cygnus cargo ship is zeroing-in on a berth at the International Space Station (ISS), as it passes the midpoint between its spectacular Saturday lunchtime launch from Wallops Island, Va., and its expected Monday morning arrival at the sprawling orbital outpost.
Current plans call for Expedition 64 astronauts Soichi Noguchi and Mike Hopkins—both based inside the station’s multi-windowed cupola—to grapple Cygnus with the 57.7-foot-long (17.6-meter) Canadarm2 robotic arm at about 4:40 a.m. EST tomorrow. Shortly thereafter, the cargo ship and its 8,200 pounds (3,900 kg) of equipment, payloads and supplies will be berthed at the Earth-facing (or “nadir”) port of the Unity node, its place of residence until early May.
With a 75-percent probability of acceptable weather conditions at T-0, tempered only by a slight risk posed by ground winds and cumulus clouds, pre-launch preparations for the mission ran like clockwork.
The 133-foot-tall (40.5-meter) Antares 230+ booster—a two-stage behemoth, fueled by liquid oxygen and a highly-refined form of rocket-grade kerosene, known as “RP-1”—was trundled horizonally out to Pad 0A at the Mid-Atlantic Regional Spaceport (MARS) on Wallops Island, Va., last Thursday, where a mobile payload processing facility was sealed over its nose fairing to afford clean-room conditions and permit the insertion of time-critical cargoes into Cygnus.
The specialized fairing (nicknamed the “pop-top”), was then removed to provide access to the expansive interior of the spacecraft’s Pressurized Cargo Module (PCM).
Yesterday’s liftoff at 12:36:49 p.m. EST was spectacular, as Antares’ pair of Russian-built RD-181 engines powered the rocket smoothly away from the Virginia coastline. They burned for 3.5 minutes, before shutting down on time, after which the first stage was discarded and the solid-fueled Castor-30XL upper stage motor ignited for another 2.5 minutes to position NG-15 into low-Earth orbit.
Seventy minutes after leaving MARS, Cygnus’ fan-like UltraFlex solar arrays were satisfactorily deployed and the spacecraft settled down for an approximately 40-hour chase of the space station.
Early tomorrow morning, with Noguchi at the controls of Canadarm2 and Hopkins backing him up, Cygnus will approach to its first “Hold Point” at a distance of 820 feet (250 meters) from the ISS. Following approval for it to proceed, it will move inside the so-called “Keep Out Sphere” (KOS), a virtual exclusion zone which extends some 660 feet (200 meters) around the space station to avert any risk of collision.
Passing through a second Hold Point at 100 feet (30 meters), Cygnus will then move to its final Capture Point at 30 feet (10 meters), whereupon Noguchi and Hopkins will be given a “Go for Capture”.
Grapple of the cargo ship is due to occur at about 4:40 a.m. EST and it will be berthed at the Earth-facing (or “nadir”) port of the Unity node a couple of hours later. Berthing will occur in a two-step fashion.
First Stage Capture will see hooks from Unity’s nadir-mounted Common Berthing Mechanism (CBM) extend and engage with Cygnus, after which Second Stage Capture will encompass a series of 16 bolts—four gangs of four bolts each—being driven to rigidize the two vehicles into a tight mechanized embrace.
With tomorrow’s arrival of NG-15, a total of four visiting vehicles will reside at the ISS. Longest-lasting is Russia’s Soyuz MS-17, which has been docked at the nadir-facing Rassvet module since the middle of October. A month later, at the extreme opposite end of the station, SpaceX’s Dragon Resilience moored at International Docking Adapter (IDA)-2 on the forward port of the Harmony node.
And just last week, Russia’s Progress MS-16 cargo ship arrived safely and docked at the nadir-facing Pirs module. Whilst NG-15 is in residence, that figure is expected to climb to five ships, with Boeing’s CST-100 Starliner also slated to arrive in early April on the second Orbital Flight Test (OFT-2).
And both Noguchi and Hopkins are primed and ready for an early wake-up call tomorrow morning. Only a handful of minutes before NG-15’s Saturday launch, as the ISS flew directly over the Virginia coastline, Noguchi snapped a photograph, complete with the ever-ready Latching End Effector (LEE) of Canadarm2.
“Hey, Virginia,” the Japanese astronaut tweeted. “#ISS just flew over you.” For his part, Hopkins shared a photograph of himself and Noguchi training with the robotic arm for their critical task. “Practice with the robotic arm the other day,” Hopkins told his terrestrial audience, “in preparation for the arrival of NG-15 on Monday.”
When it reaches the space station tomorrow morning, the NG-15 spacecraft—named in honor of mathematical genius and former NASA “Hidden Figure” Katherine Johnson—will deliver about 8,200 pounds (3,700 kg) of payloads, equipment and supplies to the seven-strong Expedition 64 crew.
Notably, this haul includes the second flight of the Hewlett Packard Enterprise (HPE) Spaceborne Computer, which will demonstrate the usefulness of high-performance, commercial off-the-shelf hardware for long durations aboard the ISS. The first Spaceborne Computer rode to orbit aboard SpaceX’s CRS-12 Dragon in August 2017 and operated without incident for 615 days, before it was returned to Earth aboard the CRS-17 Dragon in June 2019.
In its first incarnation, the Spaceborne Computer functioned near-flawlessly in the peculiar microgravity environment of low-Earth orbit, despite unpredictable levels of high radiation and unique power and cooling conditions. It also achieved the significant milestone of running one teraflop, which equates to more than a trillion calculations in a single second; for comparison, this is over 30 times faster than an average laptop and closely approximates the performance of a ground-based supercomputer.
Elsewhere aboard NG-15 is a second experiment from retinal implant manufacturer LambdaVision, Inc., of Farmington, Conn., in collaboration with Space Tango, Inc., of Lexington, Ken. Led by Principal Investigators Nicole Wagner and Jordan Greco, the experiment seeks to evaluate a manufacturing system to create artificial retinas in space.
Using a light-activated protein known as “bacteriorhodopsin”, the experiment aims to develop a high-resolution, protein-based artificial retina to restore vision to millions of patients suffering from retinal degenerative diseases, including Age-Related Macular Degeneration (AMD). It is hoped that bacteriorhodopsin will help to replace the functionality of damaged photoreceptor cells and flexible subretinal implants offer a potential for far greater resolution than competing electrode-based technologies.
Additionally, research teams from as far afield as Texas Tech University in Lubbock, Texas, and the UK’s University of Nottingham in Derby are providing an experiment which looks at roundworms to understand whether decreased genetic expression of muscle proteins is associated with decreased strength.
The roundworm selected for this study is Caenorhabditis elegans and it is hoped that it will provide a better understanding of how spaceflight-dependent changes in genetic expression are linked to muscle function and how this might support the development of countermeasures to main astronaut health on long-duration missions into deep space.
In addition to its pressurized payloads, NG-15 includes a number of CubeSats, released from the spacecraft via Slingshot and NanoRacks deployment mechanisms. These include DhabiSat, developed by Khalifa University in Abu Dhabi in the United Arab Emirates, and 42 ThinSats as part of a Science, Technology, Engineering and Mathematics (STEM) outreach program for students from the fourth through 12th grades.