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June 12, 2012

Orbital Sciences Corp. Awaits its Turn for Space Station Supply Trip

By Doug Mohney, Contributing Editor


With SpaceX's successful completion of a supply run demonstration to the International Space Station (ISS), industry watchers now turn to see if Orbital Sciences (News - Alert) Corporation can duplicate the feat later this year, with a successful launch of its Antares (Formerly Taurus II) rocket, followed by a full-up separate rendezvous and ISS berthing mission with its Cygnus cargo freighter by the end of the year. 

Orbital's entry into ISS supply efforts is a mishmash of old and new. The Antares rocket uses liquid oxygen and RP-1 fueled first stage with a pair of Aerojet AJ26 engines, originally built as the Soviet Union's NK-33. Antares's first stage was designed and built in the Ukraine by Yuzhnoye SDO, while its second stage is the American-built ATK (News - Alert) Castor 30 solid rocket.

Antares will launch from Wallops Island, Virginia from a newly built "wet" pad at the Virginia MARS spaceport.  Orbital previously launched rockets from the MARS spaceport, but they were all-solid rockets. Delays in Orbital's first flight of Antares have been attributed to difficulties in building, testing and certifying the new infrastructure for the RP-1 and liquid oxygen fuels for the first stage.

First flight of Antares is penciled in for August 2012. If successful, Orbital will conduct its COTS space station supply demo in the last quarter of 2012. The Antares will carry a Cygnus spacecraft into Low Earth Orbit (LEO) for a rendezvous and berthing with ISS to demonstrate that Orbital can conduct commercial supply operations for the space station.

Cygnus is another mix of old and new. Orbital built the service module for Cygnus here in the U.S. using technologies from its LEOStar and GEOStar satellite product lines, while the pressurized cargo module is based on the Multi-Purpose Logistics Module (MPLM) created by Thales (News - Alert) Alenia Space for NASA.

Initial versions of Cygnus will deliver 2,000 kilograms of cargo to the station, while the enhanced version will deliver up to 2,700 kilograms.

If both demonstration flights are successful, Orbital will get a green light to start regular cargo runs to ISS under NASA's CRS (Commercial Resupply Services) contract. Orbital is slated to provide eight cargo missions to ISS through 2015 with a contract value of $1.9 billion for all successful deliveries. 

Obviously, there are differences in the SpaceX (News - Alert) and Orbital approaches. SpaceX's Dragon delivers less cargo ("upmass") to the space station, but also has the capability to move cargo ("downmass") back to Earth via re-entry and splashdown of the Dragon capsule. Orbital's Cygnus will deliver more cargo per flight, but the craft is designed to simply burn up upon re-entry.

The biggest visual difference between SpaceX and Orbital is where the two are launched from. SpaceX launches from Cape Canaveral Air Force base in Florida while Orbital conducts its flights about four hours drive time from Washington DC.

Orbital boasts that on a clear day, an observer in the Nation's Capital will be able to see the Antares climb to orbit.




Edited by Braden Becker



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