Orbital Sciences' Taurus II motors near testing

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One of the most logistically complex projects being undertaken in spaceflight is gaining momentum. Orbital Sciences is starting hardware testing for the Taurus II rocket it is developing as part of NASA's bid to draft private companies into its effort to replace the launch capacity that will be lost when the Space Shuttle fleet is retired in a year's time.

Orbital has a long history of developing systems based on existing technologies. Its Minotaur I launcher is a four-stage solid fuel rocket whose first and second stages are motors from decommissioned Minuteman intercontinental ballistic missiles, available owing to US-Soviet arms reduction treaties. Similarly, Minotaur IV - capable of launching payloads beyond Earth orbit - uses three US government-furnished solid rocket motors from decommissioned Peacekeeper ICBMs and a commercial solid rocket upper stage.

INTERNATIONAL SUPPLIERS

But Taurus II and Cygnus rely on key components brought in from a United Nations of suppliers. Taurus II's first-stage engines are provided by US company Aerojet. Now called AJ26-58/59, they were designed by Samara, Russia-based Kuznetsov and designated NK-33. Taurus II's first-stage fuel tanks are being built in Ukraine.

To build the Cygnus cargo capsule, Orbital has placed its largest-ever order with Thales Alenia Space, for the nine pressurised modules it will use for a March 2011 Taurus II-Cygnus demonstration mission to the International Space Station for NASA's Commercial Orbital Transportation Services (COTS) programme and also for work it is undertaking to meet a NASA Commercial Resupply Services contract.

Other international elements in the Cygnus design are its Dutch Space solar arrays and proximity operations hardware as used by Japan Aerospace Exploration Agency's H-II transfer vehicle, which has already flown.

Cygnus could also be developed as a crew transport capsule, with the addition of a life-support system, heat shield and parachutes. Such a capsule would also need a launch abort system, but Orbital is working on one for the Orion crew exploration vehicle that features in NASA's Moon return planning.

Orbital's COTS mission to the International Space Station was set for December 2010, to carry unpressurised cargo. But a change to pressurised cargo "significantly increased the complexity and cost", and put the mission back to March 2011, says Orbital's advanced programmes group general manager Antonio Elias.

Taurus II first-stage engine testing will begin imminently, in Russia, and be followed by work at NASA's Stennis Space Center. Testing of the second-stage solid rocket motor could begin shortly or in November in the USA.

Elias adds: "We did not intend to do testing in Russia, [but] they offered a good price." He says, however, that US technology export control laws are not the biggest problem Orbital faces in its test programme - the key issue is "time zone difference".

LAUNCH PAD

Taurus II will be built at Virginia's Mid-Atlantic regional spaceport, where it will be launched. Factory construction is under way and pylons are being driven up to 40m (130ft) into the ground to support the launch pad, which is being built on sandy soil at sea level.

Orbital's proposal for NASA's Commercial Crew Development programme crew launch competition, calls for a modified Cygnus capsule to be launched from Mid-Atlantic by Taurus II.

Whether NASA fully develops crew transport or not, Orbital will have a new rocket for its family and the ISS will likely need Cygnus cargo delivery until 2020.