An Overview of the Cygnus Mission to ISS

OSC's Taurus II and Cygnus system is almost as global as the International Space Station itself.
OSC’s Antares launch vehicle and Cygnus freighter are almost as global as the International Space Station itself.

Antares/Cygnus Mission Summary

Company: Orbital Sciences Corporation
Launch Vehicle: Antares
Payload: Cygnus cargo freighter
Destination: International Space Station
Launch Date: Sept. 17, 2013
Launch Site: Mid-Atlantic Regional Spaceport (MARS), Wallops Island, Virginia
Orbit: LEO
Program: NASA Commercial Orbital Transportation Systems (COTS)
Mission Description:  Inaugural test flight of the first Cygnus cargo freighter to the International Space Station under NASA’s COTS program. Cygnus will carry a token cargo to astronauts aboard the orbiting laboratory. This is the second flight of the Antares launch vehicle. A successful maiden flight was flown in April.

Cygnus Freighter

The Cygnus spacecraft is composed of two elements with spaceflight heritage. The Service Module incorporates avionics systems from Orbital’s LEOStar and GEOStar satellite product lines as well as propulsion and power systems from the company’s GEOStar communications satellites.

Cygnus_overview_slideCygnus module. (Credit: Orbital Sciences Corporation)

The Pressurized Cargo Module (PCM) is being produced by Thales Alenia Space in Torino, Italy. The PCM is based upon Thale’s Multi-Purpose Logistics Modules, which space shuttles carried to the International Space Station (ISS) filled with supplies. One of the MPLMs was refitted and permanently docked to ISS.

Other non-U.S. suppliers include Mitsubishi Electric Corporation (MELCO) of Tokyo for the Proximity Location System and Dutch Space of the Netherlands for its solar arrays. Partners also include:

  • Draper Laboratory, guidance, navigation and fault tolerant computer support;
  • Odyssey Space Research, visiting vehicle requirements support;
  • JAMSS America, operations support; and,
  • Vivace, systems engineering support.

The Cygnus demonstration mission will carry token cargo that to ISS. The flight is being done under the NASA-funded Commercial Orbital Transportation Services (COTS) program.

If the flight is successful, Orbital will begin a series of eight cargo runs to the station under the space agency’s Commercial Resupply Services (CRS) program. NASA will pay about $1.9 billion for the flights.

cygnus_standard_enhanced
Cygnus Standard and Enhanced Pressurized Cargo Modules. (Credit: Orbital Sciences Corporation)

The initial deliveries will feature a standard cargo module with an interior volume of 18.9 cubic meters that will be capable of delivering 2,000 kg of cargo to ISS. Missions four through eight will feature an enhanced cargo module with a volume of 27 cubic meters and improved solar panels that will deliver up to 2,700 kg to the orbiting facility. In all, Orbital is contracted to deliver 20,000 kg to the station.

Cygnus Specifications

Service Module Heritage: GEOStar, LEOStar
Power Generation: 2 fixed wing solar arrays, ZTJ Gallium Arsenide cells
Power Output: 3.5 kW (sun-pointed)
Propellant: Dual-mode N2H4/MON-3 or N2H4
Pressurized Cargo Module Heritage: Multi-Purpose Logistics Module
Total Cargo Mass: 2,000 kg Standard/2,700 kg Enhanced
Pressurized Volume: 18.9 m3Standard/27 m3 Enhanced
Berthing at ISS: Node 2 Common Berthing Mechanism (CBM)

Antares Launch Vehicle

The medium-lift Antares flew its maiden flight from Wallops Island with a Cygnus mass simulator in April. Orbital Sciences officials said that it was a perfect flight with no anomalies.

The launch vehicle is also an international collaboration. Orbital is the prime integrator and has overall responsibility for systems engineering, avionics, primary structure, testing and software. It also has responsibility for the first stage development and integration.

Antares rocket. (Credit: Orbital Sciences Corporation)
Antares rocket. (Credit: Orbital Sciences Corporation)

KB Yuzhnoye and PO Yuzhmash of Ukraine are providing the first stage propellant tanks and associated pressurization system. The technology is based on Zenit launch vehicle. The first stage includes two Aerojet AJ-26 engines, which are updated NK-33 motors manufactured by the Kuznetsov Design Bureau for the Soviet Union’s manned lunar program.

The second stage incorporates Castor solid stage motors produced by ATK in the United States. Ruag of Sweden is providing the payload separation system.

The rocket is designed to lift more than 5,000 kg. into low Earth orbit. The first Antares launches will be from Wallops Island in Virginia, but the rocket is also compatible with launch facilities at Cape Canaveral in Florida, Vandenberg Air Force Base in California, and Kodiak Launch Complex in Alaska.