CRS NG-20 launches cargo, science to ISS aboard Falcon 9

by Justin Davenport

The NG-20 mission has flown the Cygnus spacecraft S.S. Patricia Hilliard Robertson to a path that will take it to the International Space Station. However, as a first, it has launched atop a SpaceX Falcon 9 instead of an Antares rocket. This will be the first of three Cygnus missions to fly aboard Falcon 9 for Northrop Grumman to fulfill its cargo delivery contract while the new Antares 330 is under development.

NG-20 successfully launched on Tuesday, Jan. 30 at 12:07 PM EST (17:07 UTC) from SLC-40 at the Cape Canaveral Space Force Station in Florida. B1077-10 flew on a trajectory inclined to 51.6 degrees to the equator so that the Cygnus spacecraft will be in the same orbital plane as the Station. After stage separation, the booster successfully conducted a return to launch site (RTLS) landing and touch down at Landing Zone 1.

The RTLS landing was the third of this month while some SpaceX marine assets have been in Charleston, South Carolina for maintenance. This includes the drone ship Just Read the Instructions, meaning SpaceX’s East Coast operations are down to one drone ship at the moment. Because of this, additional RTLS landings may be performed on some Starlink flights over the coming months to relieve pressure on SpaceX’s marine operations and to keep up the high launch cadence.

The weather forecast for Tuesday was 95 percent favorable, as per the 45th Weather Squadron of the US Space Force. The only primary concern was the cumulus cloud rule. The backup days, now not needed, were almost as good. Wednesday’s forecast was 85 percent favorable with the only concern being liftoff winds, and Thursday’s was 90 percent favorable with the same liftoff wind concern.

L-1 weather forecast for the NG-20 launch. (Credit: USSF)

B1077 started its career on Oct. 5, 2022, when it launched the Crew-5 mission to the ISS. This booster has since flown various missions, including GPS III-6, Inmarsat I-6 F2, Starlink 5-10, CRS-28, Galaxy 37, and Starlinks 6-13, 6-25, and 6-33. Every mission this booster has performed has been from either Pad 39A or SLC-40 in Florida, and all missions up until now have landed on a drone ship. This flight featured B1077’s first RTLS landing.

After the Cygnus spacecraft was separated and inserted into orbit, it will take around two days to get to the ISS if all goes as planned. As early as 4:20 AM EST (09:20 UTC) on Thursday, Feb. 1, the S.S. Patricia Hilliard Robertson is to be grabbed by the Station’s Canadarm2. Using the robotic arm, astronaut Jasmin Moghbeli will berth Cygnus to the nadir (Earth-facing) port on the Unity module.

A surgical robot experiment is seen during ground testing. (Credit: Virtual Incision Corporation)

NG-20 will arrive at the Station loaded with around 3,750 kilograms of cargo. The cargo onboard Cygnus includes the first surgical robot to be flown to ISS as well as a metal 3D printer that will test printing small metal parts. In addition, a 3D cartilage cell culture, the MSTIC autonomous semiconductor manufacturing platform, and three reentry capsules that will test out different heat shield materials are also aboard Cygnus, along with supplies for the Station crew.

In addition to the experiments, an iROSA solar array upgrade kit will be sent to the Station aboard NG-20. This is the seventh upgrade kit and the third of four modification kits needed to allow for the installation of the final set of these upgraded arrays. Replacement units for station equipment, such as the hydrogen dome assembly, ARED exercise device, ion exchange bed, catalytic reactor, urine processing assembly, and others are also aboard Cygnus.

Northrop Grumman’s Cygnus space freighter is pictured moments away from being captured with the Canadarm2 robotic arm during a previous mission. (Credit: NASA)

S.S. Patricia Hilliard Robertson is scheduled to remain berthed to the ISS until May and can be called upon to perform orbital re-boost maneuvers during its stay. When the time does come for the unberthing, it will be loaded with trash from the Station before the unberthing.

After departure, Cygnus will be commanded to make a destructive reentry over the South Pacific after releasing the University of Kentucky’s KREPE-2 reentry experiment with three capsules equipped with different NASA-provided heat shield materials.

The Cygnus is named after a member of the 1998 astronaut class who tragically passed away before she could fly into space. Dr. Patricia “Patty” Hilliard Robertson was an accomplished pilot with over 1,500 hours of flight experience, and was a medical doctor with degrees in biology and medicine from Indiana University of Pennsylvania and the Medical College of Pennsylvania, respectively.

Robertson was scheduled to fly to the International Space Station in 2002 and had served as the Crew Support Astronaut for the Expedition 2 crew. She was also the office representative for the Crew Healthcare System. However, she died of her injuries two days after a private plane crash on May 22, 2001, in Manvel, Texas.

Astronaut Patricia Hilliard Robertson’s name is on the next cargo mission to ISS. (Credit: NASA)

The naming of the NG-20 Cygnus spacecraft is consistent with Northrop Grumman’s – inherited from Orbital Sciences who originally developed the Cygnus – tradition of naming these craft for deceased astronauts or other important figures in space exploration. Past Cygnus spacecraft were named after STS-107 crewmembers Rick Husband, Laurel Clark, and Kalpana Chawla, as well as astronauts Alan Bean, Deke Slayton, Gene Cernan, Roger Chaffee, and others.

For this mission, the Falcon 9 has seen some modifications to launch the Cygnus spacecraft. There is a 1.5 by 1.2 meter (five by four foot) door in the fairing that can be opened to allow for late loading of cargo, which has been a key feature of Cygnus operations with the Antares rocket family. Once the fairing door is opened, a platform is erected that allows access to the Cygnus craft’s hatch while the rocket is horizontal.

While the Falcon 9 has been pressed into service for Cygnus launches for the time being, the Antares 330, with a new first stage developed in conjunction with Firefly Aerospace, is currently planned to fly starting no earlier than June 2025. This will restore Northrop Grumman’s ability to fly Cygnus on its own rockets, and will also give the company a more capable launcher to compete for other contracts besides ISS commercial cargo.

Render of the Antares 330 vehicle. The first stage is to be used on the future MLV rocket as well. (Credit: Mack Crawford for NSF)

This is not the first time the Cygnus craft has had to be launched on vehicles other than Antares. Cygnus was designed to be launch-vehicle agnostic, and this capability was first used after the failure of the Orb-3 mission on Oct. 28, 2014. Three launches in the 2015-2017 timeframe — OA-4 S.S. Deke Slayton II, OA-6 S.S. Rick Husband, and OA-7 S.S. John Glenn — was flown aboard ULA’s Atlas V 401 while the Antares was modified to use a different engine.

Besides NG-20, the NG-21 and NG-22 missions are also scheduled to fly on Falcon 9, with NG-23 becoming the first Cygnus mission aboard the Antares 330. Firm launch dates for NG-21 and NG-22 are not yet set. In the meantime, NG-20 was the 10th Falcon 9 launch of this month, and of 2024, as SpaceX continues to try for as many as 148 launches this calendar year.

(Falcon 9 B1077-10 launches the Cygnus spacecraft on mission NG-20. Credit: Sawyer Rosenstein for NSF)

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