Orbital’s Antares launches Cygnus on debut mission to ISS
Orbital Sciences Corporation have launched the first Cygnus spacecraft Wednesday, beginning a demonstration mission to the International Space Station which will verify that the vehicle is ready to support NASA’s resupply needs. Liftoff from the Mid-Atlantic Regional Spaceport on Wallops Island, Virginia, atop an Antares rocket occurred at 10:58 EDT.
The Cygnus Orb-D1 mission is the maiden flight of Orbital Sciences’ Cygnus spacecraft and the final stage of the Commercial Orbital Transportation Services (COTS) program, which has led to the development of the Cygnus and Dragon spacecraft to provide US resupply services to the International Space Station.
Orbital Sciences were awarded a COTS contract to develop Cygnus in 2008, in the second round of the program. Rocketplane Kistler had originally been awarded a contract to develop their K-1 vehicle, however they were unable to keep up with NASA’s targets and their contract was terminated in 2007.
Cygnus Orb-D1 is the third and final COTS demonstration mission, and the only one to be conducted by Cygnus. SpaceX’s Dragon made two demonstration flights in 2010 and 2012 before beginning operational flights under a Commercial Resupply Services contract awarded in December 2008 for twelve missions to the ISS.
Orbital has a similar contract for eight Cygnus missions, which will begin once the spacecraft has passed its final COTS milestone – a demonstration mission to the ISS, which will be conducted by Orb-D1.
A standard Cygnus spacecraft has a pressurized volume of 18.9 cubic meters (667 cubic feet) and can carry 2,000 kilograms (4,400 lb) of cargo – increasing to 2,700 kg (6,000 lb) from the fourth operational mission onwards. For the Orb-D1 mission, however, the payload mass is only 700.09 kilograms (1,543.04 lb).
This cargo, which is stowed in two M-01 and eight M-02 bags consists mostly of items for the crew. Three M-02 bags, with a total mass of 194.5 kilograms (428.8 lb) are loaded with Bulk Overwrap Bags (BOBs), containing food for the astronauts. Thirty seven BOBs are contained within these three bags, with an unspecified amount included in a fourth, 90.3 kg (199 lb) bag along with items for the crew’s flight kit.
Another bag contains electrical hardware; a replacement printer for the station’s computers and hardware for the PS-120 electrical junction. Three contain unspecified “Crew Provisions”, along with hardware for the commercial crew program and a Camera Light Pan-Tilt Assembly (CLPA).
The remaining bags contain hygiene equipment and gloves, and miscellaneous equipment. All of the Cygnus spacecraft’s cargo is intended for the US Orbital Segment of the space station.
Once the cargo has been removed from the Cygnus, the spacecraft will be loaded with approximately 1,100 kilograms (2,400 lb) of unwanted goods and hardware for disposal. Once it departs the space station Cygnus will be deorbited, disintegrating in the upper atmosphere over a remote part of the southern Pacific.
Cygnus was designed to use as much existing hardware as possible. It consists of two affixed modules – a service module which contains spacecraft systems such as avionics, propulsion, attitude control and power generation, and a Pressurized Cargo Module (PCM) containing the vehicle’s payload. Unlike the Dragon and HTV spacecraft which have space for unpressurized cargo, Cygnus only carries pressurized cargo.
The Pressurized Cargo Module was built by Thales Alenia Space in Italy, and is based on the Multi-Purpose Logistics Modules flown aboard several Shuttle missions to the ISS. It also draws upon hardware and technologies developed for the two European-built ISS nodes, Harmony and Tranquility, and ESA’s Automated Transfer Vehicle.
The Service Module is based on commercial satellites developed by Orbital Sciences Corporation. It has a propulsion system derived from the GEOStar-2 satellite bus used for geostationary communications satellites.
The vehicle’s avionics come from the LEOStar platform used by many small NASA and US military research satellites. The Japanese Space Exploration Agency’s PROX communications system will provide communications between Cygnus and the International Space Station, while Cygnus will use an s-band antenna to connect to NASA’s Tracking and Data Relay Satellite System (TDRSS) for downlink.
Cygnus generates power by means of six gallium arsenide panels mounted on twin solar arrays deployed from the sides of the Service Module. These can produce up to 3,500 watts of power for the spacecraft’s systems.
Deployment of the solar arrays will be one of the first milestones for the mission following launch – and was successfully completed. A Canadian-built Power Video Grapple Fixture (PVGF) will allow the ISS to provide additional power to the spacecraft following capture with the Canadarm2 arm.
The propulsion system uses a Japanese-built IHI BT-4 engine, configurable to either a monopropellant mode using hydrazine, or a bipropellant mode which oxidizes the hydrazine with mixed nitrogen oxides (MON-3).
The engine can develop 445 newtons (100 pounds) of thrust. In addition, thirty-two Rocket Engine Assembly (REA) reaction control thrusters are mounted around the spacecraft. Each REA produces 27 newtons (6 pounds) of thrust; the engines will be used for maneuvering and attitude control.
The launch of Cygnus Orb-D1 marked the second flight of the Antares rocket, which will be flying in the Antares 110 configuration. It is expected to be the last Antares launch to use this configuration, with future missions using the 120 and 130 variants. Each of these configurations uses a different variant of the Castor 30 solid rocket motor as its second stage.
Each of the three digits in the Antares’ numerical designation represents a stage – while Cygnus launches only use two stages, several three-stage configurations are offered for future flights with other payloads.
The first digit, which denotes the first stage, is 1 for all configurations since only one type of first stage is currently planned. This stage, which was built in Ukraine by KB Yuzhnoye and PO Yuzhmash – the same companies responsible for the Zenit rocket – is powered by a pair of Aerojet AJ26-2 engines.
The AJ26 was developed from the NK-33 engines built in the 1960s by Nikolai Kuznetsov’s OKB-276 design bureau in the Soviet Union. The NK-33 was intended to power the first stage of the N1F rocket, the Soviet Union’s answer to America’s Saturn V.
Following four consecutive failures of the N1, a prototype using less powerful NK-15 engines, the program was abandoned and most of the hardware destroyed.
A stockpile of NK-33 engines was placed into storage, with some later being sold to Aerojet for conversion to AJ26s.
The NK-33 will also power the first stage of the Soyuz-2-1v rocket, which is scheduled to make its first launch in the closing stages of the year. NK-33 and AJ26 engines burn RP-1 propellant, which is oxidized by liquid oxygen.
The Antares has a solid-fuelled second stage, of the Castor 30 family, which was developed by Alliant Techsystems. The Castor 30 is based upon the larger Castor 120, used as the first stage of Taurus and Athena rockets. The solid fuel mixture in the Castor 30 consists of aluminum and TP-H8299, the latter a hydroxyl-terminated polybutadiene (HTPB) based compound.
The Castor 30A variant will be used for Wednesday’s launch, as denoted by the second digit of the vehicle’s configuration being a 1. Antares 12x and 13x launches will use the more capable Castor 30B and Castor 30XL stages respectively. The Castor 30XL will be required to carry the Cygnus flights with the Enhanced Pressurized Cargo Module.
For two-stage configurations, the third stage of the rocket’s designation is a zero, indicating that no third stage is present. On three-stage flights the digit will denote the type of third stage in use. Two such stages are currently offered – a 1 denotes a Bipropellant Third Stage (BTS), based on hardware developed for the GeoStar-2 communications satellite bus, while a 2 denotes the presence of a Star-48BV solid rocket motor. No three-stage launches are currently manifested.
Wednesday’s launch began at T-0 with the ignition of the two first stage engines. After a short hold-down to allow the engines to reach full thrust and verify that they are burning correctly, liftoff occurred at T+2.1 seconds.
The first stage burned for three minutes and 53 seconds, separating five seconds later at an altitude of 113 kilometers. Following stage separation, the combined assembly of the interstage, second stage and payload fairing coasted for 82 seconds before the next separation event.
The second stage was encapsulated inside the payload fairing. This separated, along with the interstage, three minutes and 20 seconds after liftoff. The second stage ignited nine seconds later to perform orbital insertion.
Its 99-second burn placed Cygnus into an orbit with a perigee of 243 kilometers, an apogee of 299 kilometers, and an inclination of 51.64 degrees.
Spacecraft separation occurred two minutes after second stage burnout; ten minutes and two seconds after liftoff.
Following separation from the Antares’ second stage, Cygnus Orb-D1 began on-orbit operations by deploying its twin solar arrays.
Following tests of its attitude control and propulsion systems on flight day 1, the spacecraft will begin a series of maneuvers on flight day 2 which will set it up for its rendezvous with the ISS. Rendezvous itself is scheduled for flight day 6, with the intervening time being used for testing and calibration.
Ten demonstration objectives must be completed before docking; the first is a test of the spacecraft’s use of Global Positioning System satellites to determine its position, which will be accomplished shortly after Cygnus has made its first engine burn. Following this, demonstration 2 is a test of the spacecraft’s free-drift and abort capability. The remaining objectives will be tested during joint operations and rendezvous with the space station.
The next three demonstrations will occur with Cygnus holding at four kilometers below the ISS, and will verify that the spacecraft can maneuver autonomously, relying on GPS and onboard data to determine its position relative to the station. With this complete, the spacecraft will close to 1.4 kilometers from the station, where it will conduct a holding test using the Hold Control Panel (HCP) aboard the space station.
Cygnus is equipped with the Space Integrated GPS/INS (SIGI) navigation system, using Global Positioning System (GPS) and Inertial Navigation System (INS) data to work out is position relative to the ISS. A LIDAR (laser radar) system will then be used for final approach and docking.
Once the HCP test has been completed Cygnus will align itself for an R-bar approach to the space station, conducting a LIDAR test, a further holding test, and a test of its ability to retreat from the station en route. Once this is complete, it will be cleared for final rendezvous maneuvering to a point 12 meters below the station.
The Expedition 37 crew will use the ISS’ Remote Manipulator System, Canadarm2, to grapple Cygnus and berth it with the nadir Common Berthing Mechanism of the Harmony module – the same port used for Dragon and Kounotori (HTV) missions to the outpost.
Harmony’s Nadir CBM was previously occupied by Japan’s fourth H-II Transfer Vehicle (HTV), Kounotori 4, which was unberthed on 4 September and deorbited three days later. Launched in early August, the HTV had spent a little under a month at the ISS. JAXA’s Proximity Communications System (PROX), used to relay commands to HTVs during rendezvous operations, will support the Cygnus rendezvous.
Cygnus Orb-D1 is expected to spend a month berthed to the station before it too is unberthed and released using Canadarm2. Following undocking the Cygnus will be deorbited over the South Pacific, burning up in the Earth’s atmosphere on reentry.
Wednesday’s launch was the second flight of the Antares rocket, following its maiden flight in April with the Cygnus Mass Simulator and a group of CubeSats. It was the fourth mission of the year for Orbital Sciences, who were also responsible for the June launch of IRIS on a Pegasus-XL, and for the launch of NASA’s LADEE mission to the moon earlier this month atop a Minotaur V.
The Minotaur launch occurred from Launch Pad 0B at the Mid-Atlantic Regional Spaceport, adjacent to Launch Pad 0A which will be used for the Antares launch.
The Mid-Atlantic Regional Spaceport (MARS) is a commercial spaceport on Wallops Island, Virginia, close to NASA’s Wallops Flight Facility which supports sounding rocket missions from nearby complexes. MARS consists of two launch pads – Pad 0A is used by Antares while Pad 0B is used for smaller solid-fuelled rockets; mostly Minotaurs.
Pad 0A was built in the 1990s for Space Services Incorporated’s Conestoga rocket. One launch was attempted in 1995, however when it failed the program was abandoned and the launch pad remained derelict for years. The original complex was demolished in 2008 to make way for the Antares pad.
Orbital launches from Wallops Island in the past have also used old Scout pads at Launch Area 3 and 3A of NASA’s Wallops Flight Center as it was then named, while Pegasus rockets have been air-launched from the Stargazer L1011 aircraft flying from the Wallops Flight Facility Research Airport.
The launch of Cygnus Orb-D1 was the fifty third or fifty fourth orbital launch attempt of 2013 – a rumored Safir launch failure in February has still not been fully confirmed. Antares flew just a few hours after an Atlas V launched from Cape Canaveral carrying an AEHF communications satellite for the US Air Force.
Given Atlas flew as planned, Cygnus was the fourteenth US launch of the year.
America’s next orbital launch is currently scheduled for the end of the month, when SpaceX will launch the first Falcon 9 v1.1 from Vandenberg Air Force Base with the Canadian Space Agency’s CASSIOPE satellite and several secondary payloads.
The next launch for Orbital Sciences and the Mid-Atlantic Regional Spaceport will occur on 4 November with a Minotaur I on the ORS-3 mission – deploying a large number of small satellites.
The next Antares launch is planned for December with the first operational Cygnus joined by 28 Flock-1 CubeSats and according to some reports, Lithuania’s first satellite – LituanicaSAT-1.
That Cygnus mission is the next scheduled US flight to the ISS, although Russia will conduct three missions to the outpost in the meantime.
Two of these are manned Soyuz launches to replace the station’s crew – Soyuz TMA-10 is scheduled for launch on 25 September, with TMA-11 following it on 7 November.
An unmanned resupply mission, Progress M-21M, is slated to fly on 20 November.
(Images: via Orbital and L2′s Antares and Cygnus Section – containing presentations, videos, images, interactive high level updates and more, with additional images via Orbital and Philip Sloss, NASASpaceFlight.com).
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