# Cygnus (spacecraft)

Cygnus is an expendable American automated cargo spacecraft designed for International Space Station (ISS) resupply missions. It was initially developed by Orbital Sciences Corporation with financial support from NASA under the Commercial Orbital Transportation Services (COTS) program. To create Cygnus, Orbital paired a pressurized cargo module, largely based on the Multi-Purpose Logistics Module, built by Thales Alenia Space and previously used by the Space Shuttle for ISS resupply, with a service module based on Orbital's GEOStar, a satellite bus. After a successful demonstration flight in 2013, Orbital was chosen to receive a Commercial Resupply Services (CRS) contract. A larger Enhanced Cygnus was introduced in 2015. Orbital Sciences merged into Orbital ATK in 2015; Northrop Grumman purchased Orbital ATK in 2018 and has continued to operate Cygnus missions. A further enlarged Mission B Cygnus is expected to be introduced in 2025.
Cygnus is typically launched using its parent company's Antares rocket from the Wallops Flight Facility in Virginia, however it is able to fly on other launch vehicles. After the failure of an Antares rocket destroyed Cygnus CRS Flight 3 and damaged the Wallops facility, two Cygnus missions were launched with Atlas V rockets in 2015 and 2016. Additionally, two Cygnus missions have launched on the Falcon 9 rocket in 2024 with one more scheduled to launch in 2025, operated by CRS competitor SpaceX.
In addition to Cygnus, ISS resupply missions have been flown by the Russian Progress spacecraft, the European Automated Transfer Vehicle, the Japanese H-II Transfer Vehicle and the American SpaceX Dragon.
Cygnus is the Greek word for swan and the name of a constellation.

## Development

After the retirement of the Space Shuttle was announced, NASA began to look for commercial space launch companies who could fly cargo to the ISS. In early 2006, the agency started its Commercial Orbital Transportation Services (COTS) program, where it would help fund the development of cargo spacecraft after a competitive process. SpaceX and Rocketplane Kistler won contracts in the COTS program, however Rocketplane Kistler failed to meet several financial milestones and on 18 October 2007, NASA announced it would terminate its contract and re-award it after a second competition.
Orbital Sciences Corporation participated in this second round, proposing a largely "off-the-shelf" design. The spacecraft, named Cygnus, would be built around a service module based on Orbital's Star Bus, a satellite bus in use since 1997, which would be attached to a pressurized cargo module built by Thales Alenia Space, which had also built the MPLM cargo module used by the Space Shuttle, the cargo module for the European ATV spacecraft and several permanent modules on the ISS.
Cygnus was awarded a COTS contract worth $170 million in February 2008, which was later increased to $288 million. On 23 December 2008, NASA awarded Orbital Sciences a $1.9 billion contract under the Commercial Resupply Services (CRS) program. Under this contract, Orbital Sciences agreed to deliver up to 20 tons of cargo to the ISS through 2016 in eight Cygnus spacecraft flights.
To propel Cygnus into space, Orbital developed the Antares rocket, which also leveraged lower-cost, off-the-shelf parts and designs. Construction and design of the first stage was subcontracted to Ukrainian companies and used refurbished NK-33 engines, remnants of the Soviet N1 moon rocket. The second stage was the Castor 30, which Orbital had previously used on another rocket project (the Minotaur-C) and was based on a Peacekeeper ICBM first stage.
The first Cygnus flight was originally planned to occur in December 2010, but was repeatedly delayed. The Antares made its maiden flight lifting a payload mass simulator to low Earth orbit on April 21, 2013. On September 18, 2013, Antares successfully launched a Cygnus spacecraft on a flight test to rendezvous with the International Space Station. On 12 January 2014, the first scheduled Cygnus resupply mission arrived at the space station; the capsule carried Christmas presents and fresh fruit for the astronauts. Its arrival was delayed, first by the need to repair the station, and then by frigid weather at the launch site and solar flares that forced postponements.
With the December 2015 launch of Orb CRS-4 on Atlas V, the enhanced version of Cygnus made its debut. While it was planned from the beginning to fly on the fifth mission, the Orb CRS-3 failure and subsequent move to Atlas V meant a delay. However, lessons learned on packing and the extra capabilities of the Atlas allowed payload to be increased to 3,500 kg (7,700 lb).

## Design

The Cygnus spacecraft consists of two basic components: the Service Module (SM) and the Pressurized Cargo Module (PCM).
The SM was based on prior products developed by Orbital including the GEOStar and LEOStar (collectively known as Star Bus) satellite buses and the Dawn spacecraft. It has a gross mass of 1,800 kg (4,000 lb), 32 thrusters for attitude control and one BT-4 main engine fuelled with 800 kg (1,800 lb) of hypergolic propellants, hydrazine and nitrogen tetroxide. The SM is capable of producing up to 4 kW of electrical power via two solar arrays. During a typical CRS missions, Cygnus maneuvers close to the International Space Station, where the Canadarm2 robotic arm grapples the spacecraft and berths it to a Common Berthing Mechanism, typically the nadir (Earth facing) port of the Unity module.
The PCM is manufactured by Thales Alenia Space in Turin, Italy. The first "Standard" PCMs had a length of 5.14 meters (16.9 ft), a payload capacity of 2,000 kilograms (4,400 lb), and a pressurized cargo volume of 18.9 cubic metres (670 cu ft).
The fourth and all subsequent Cygnus spacecraft are the "Enhanced" variant. These have a stretched PCM with a length of 6.39 meters (21.0 ft), a payload capacity of 3,500 kilograms (7,700 lb), an increase of 32%, and a pressurized cargo volume of 27 cubic metres (950 cu ft), an increase of 19.5%. To launch the added weight, Orbital used the more powerful Castor 30XL solid-fuel rocket as a second-stage.
A further enlarged "Mission B" Cygnus was announced by Northrop Grumman in August 2023. It will have a length of 7.89 meters (25.9 ft), a payload capacity of 5,000 kilograms (11,000 lb), an increase of 19.5%, and a pressurized cargo volume of 36 cubic metres (1,300 cu ft), an increase of 15.5%. This version is expected to enter service with the NG-23 mission in the fourth quarter of 2025 (the first to use the new Antares 330 launch vehicle).
An earlier proposed version of Cygnus would have replaced the PCM with the Unpressurized Cargo Module (UCM), based on NASA's ExPRESS Logistics Carrier, and would have been used to transport unpressurized cargo, such as ISS Orbital Replacement Units. Another proposed variant would have replaced the PCM with the Return Cargo Module (RCM), which would have allowed Cygnus to return cargo to Earth.
Cygnus does not provide cargo return capability. However, it can be loaded with obsolete equipment and trash which will burn up as the Cygnus makes a destructive reentry.

### Lunar Gateway module variant

In August 2019, NASA decided to sole source its design for the Minimal Habitation Module (Habitation and Logistics Outpost, or HALO) of the Lunar Gateway to Northrop Grumman Innovation Systems, which offered a minimalist 6.1 m (20 ft) by 3 m (9.8 ft) design based directly on the Enhanced Cygnus, as well as a larger 7 m (23 ft) by 4.4 m (14 ft) design having radial docking ports, body-mounted radiators (BMRs), batteries and communications antennas added on the outside. Northrop Grumman Innovation Systems opted to build the minimalist design, which offered the advantage of component compatibility and expedited testing of life support systems on existing Cygnus spacecraft. On 5 June 2020, NASA awarded Northrop Grumman Innovation Systems a $187 million contract to complete the preliminary design of HALO. NASA will sign a separate contract with Northrop for the fabrication of the HALO, and for integration with the Power and Propulsion Element (PPE), being built by Maxar.

## Missions

The following list includes only missions that have flown and six planned missions. As of August 2024 one more mission is planned to be launched on the Falcon 9 rocket from Cape Canaveral Space Launch Complex 40, and three from Wallops on an Antares 330. Cygnus is the only cargo freighter to launch on four different launch vehicles: the Antares 100 series, Atlas V, Antares 200 series and Falcon 9 Block 5. Each mission is named for a notable member of the Human spaceflight community.
| # | Mission | Patch | Payload | Variant | Launch date (UTC) | Rocket | Payload mass | Outcome |
| 1 | Orb-D1 G. David Low | (patch) | Orbital Sciences COTS Demo Flight | Standard | 18 September 2013, 14:58:00 | Antares 110 | 1,299 lb (589 kg) | Success |
| First Cygnus mission, first mission to rendezvous with ISS, first mission to berth with ISS, second launch of Antares. Docking to ISS delayed due to a computer data link problem, which was later was resolved. |||||||
| 2 | Orb-1 C. Gordon Fullerton | | Orbital Sciences CRS Flight 1 | Standard | 9 January 2014, 18:07:05 | Antares 120 | 2,780 lb (1,260 kg) | Success |
| First Commercial Resupply Service (CRS) mission for Cygnus, first Antares launch using the Castor 30B upper stage. |||||||
| 3 | Orb-2 Janice E. Voss | | Orbital Sciences CRS Flight 2 | Standard | 13 July 2014, 16:52:14 | Antares 120 | 3,293 lb (1,494 kg) | Success |
| 4 | Orb-3 Deke Slayton | | Orbital Sciences CRS Flight 3 | Standard | 28 October 2014, 22:22:38 | Antares 130 | 4,883 lb (2,215 kg) | Failure |
| First Antares launch to use Castor 30XL upperstage. Suffered a catastrophic anomaly resulting in an explosion shortly after launch, damaging launch pad. Contents of the cargo included food and packages for the crew, parts, experiments, and the Arkyd-3 flight test system from Planetary Resources. |||||||
| 5 | OA-4 Deke Slayton II | | Orbital ATK CRS Flight 4 | Enhanced | 6 December 2015, 21:44:57 | Atlas V 401 | 7,746 lb (3,514 kg) | Success |
| First flight of Enhanced Cygnus spacecraft. Due to damage at launch pad after the explosion of the Antares rocket carrying Orb-3, Orbital contracted with United Launch Alliance to launch this Cygnus on an Atlas V rocket from Cape Canaveral Air Force Station. First of three missions to fly on an Atlas V rocket. |||||||
| 6 | OA-6 Rick Husband | | Orbital ATK CRS Flight 6 | Enhanced | 23 March 2016, 03:05:52 | Atlas V 401 | 7,758 lb (3,519 kg) | Success |
| Second of three missions to fly on an Atlas V rocket. |||||||
| 7 | OA-5 Alan Poindexter | | Orbital ATK CRS Flight 5 | Enhanced | 17 October 2016, 23:45:36 | Antares 230 | 5,163 lb (2,342 kg) | Success |
| First flight of an Antares 200 series rocket. |||||||
| 8 | OA-7 John Glenn | | Orbital ATK CRS Flight 7 | Enhanced | 18 April 2017, 15:11:26 | Atlas V 401 | 7,443 lb (3,376 kg) | Success |
| Third of three missions to fly on an Atlas V rocket. |||||||
| 9 | OA-8E Gene Cernan | | Orbital ATK CRS Flight 8 | Enhanced | 12 November 2017, 12:19:51 | Antares 230 | 7,359 lb (3,338 kg) | Success |
| 11 November 2017, launch was scrubbed just before launch when a general aviation aircraft entered the hazard zone and did not respond to calls. |||||||
| 10 | OA-9E J.R. Thompson | | Orbital ATK CRS Flight 9 | Enhanced | 21 May 2018, 08:44:06 | Antares 230 | 7,385 lb (3,350 kg) | Success |
| First a commercial vehicle to perform ISS reboosting when, at 20:25 UTC on July 10, 2018, Cygnus's main engine was fired for about 50 seconds. Raised ISS altitude by about 295 ft (90 m). |||||||
| 11 | NG-10 John Young | | Northrop Grumman CRS Flight 10 | Enhanced | 17 November 2018, 09:01:31 | Antares 230 | 7,386 lb (3,350 kg) | Success |
| 12 | NG-11 Roger Chaffee | | Northrop Grumman CRS Flight 11 | Enhanced | 17 April 2019, 20:46:07 | Antares 230 | 7,575 lb (3,436 kg) | Success |
| 13 | NG-12 Alan Bean | | Northrop Grumman CRS Flight 12 | Enhanced | 2 November 2019, 13:59:47 | Antares 230+ | 8,221 lb (3,729 kg) | Success |
| 14 | NG-13 Robert H. Lawrence | | Northrop Grumman CRS Flight 13 | Enhanced | 15 February 2020, 20:21:01 | Antares 230+ | 8,009 lb (3,633 kg) | Success |
| 9 February 2020 launch attempt scrubbed due to a ground support issue. |||||||
| 15 | NG-14 Kalpana Chawla | | Northrop Grumman CRS Flight 14 | Enhanced | 3 October 2020, 01:16:14 | Antares 230+ | 7,624 lb (3,458 kg) | Success |
| 1 October 2020 launch attempt delayed due to boat in range, later scrubbed due to a ground support issue. |||||||
| 16 | NG-15 Katherine Johnson | | Northrop Grumman CRS Flight 15 | Enhanced | 20 February 2021, 17:36:50 | Antares 230+ | 8,400 lb (3,800 kg) | Success |
| 17 | NG-16 Ellison Onizuka | | Northrop Grumman CRS Flight 16 | Enhanced | 10 August 2021, 22:01:05 | Antares 230+ | 8,208 lb (3,723 kg) | Success |
| 18 | NG-17 Piers Sellers | | Northrop Grumman CRS Flight 17 | Enhanced | 19 February 2022, 17:40:03 | Antares 230+ | 8,049 lb (3,651 kg) | Success |
| Performed the first operational reboost of ISS by a commercial vehicle on 25 June 2022 after it was aborted after few seconds on 20 June 2022. |||||||
| 19 | NG-18 Sally Ride | | Northrop Grumman CRS Flight 18 | Enhanced | 7 November 2022, 10:32:42 | Antares 230+ | 8,173 lb (3,707 kg) | Success |
| 6 November 2022 launch attempt scrubbed due to fire alarm in mission control. |||||||
| 20 | NG-19 Laurel Clark | | Northrop Grumman CRS Flight 19 | Enhanced | 2 August 2023, 00:31:14 | Antares 230+ | 8,345 lb (3,785 kg) | Success |
| Final flight on an Antares 200 series rocket. |||||||
| 21 | NG-20 Patricia "Patty" Hilliard Robertson | | Northrop Grumman CRS Flight 20 | Enhanced | 30 January 2024, 17:07:15 | Falcon 9 Block 5 (B1077.10) | 8,345 lb (3,785 kg) | Success |
| Northrop Grumman contracted with SpaceX to launch this Cygnus on a Falcon 9 Block 5 rocket from Cape Canaveral Space Force Station. First of three missions to fly on a Falcon 9 Block 5 rocket. |||||||
| 22 | NG-21 Francis R. "Dick" Scobee | | Northrop Grumman CRS Flight 21 | Enhanced | 4 August 2024, 15:02:23 | Falcon 9 Block 5 (B1080.10) | 8,503 lb (3,857 kg) | In orbit |
| Second of three missions to fly on a Falcon 9 Block 5 rocket. |||||||
| 23 | NG-22 TBA | | Northrop Grumman CRS Flight 22 | Enhanced | June 2025 | Falcon 9 Block 5 | TBA | Planned |
| Third of three missions to fly on a Falcon 9 Block 5 rocket. Originally scheduled to fly in January 2025, but delayed until June due to avionics issue. Container carrying pressurized cargo module was damaged during shipment to Cape Canaveral which may further delay launch. |||||||
| 24 | NG-23 TBA | | Northrop Grumman CRS Flight 23 | Mission B | Q4 2025 | Antares 330 | TBA | Planned |
| Scheduled to be the first flight of an Antares 300 series rocket and first flight of a Mission B Cygnus spacecraft. |||||||
| 25 | NG-24 TBA | | Northrop Grumman CRS Flight 24 | Mission B | 2026 | Antares 330 | TBA | Planned |
| 26 | NG-25 TBA | | Northrop Grumman CRS Flight 25 | Mission B | 2026 | Antares 330 | TBA | Planned |