Orbital Sciences Corp. this week successfully test fired the Russian engine that will propel the Taurus 2 rocket from the launch pad next year, but the accomplishment comes as the company says the first operational flight of its space station cargo freighter is delayed until early 2012.

The AJ26 engine fired for 10 seconds Wednesday at NASA's Stennis Space Center. Credit: NASA

The Taurus 2 rocket and Cygnus resupply spacecraft are under development to partially fulfill the International Space Station's logistics needs after the space shuttle's retirement. SpaceX is designing and testing the Dragon capsule and Falcon 9 rocket, and NASA has tapped both companies for commercial cargo services through 2016.

Orbital engineers ignited the Taurus 2's first stage engine Wednesday on a test stand at NASA's Stennis Space Center in Mississippi.

The AJ26 engine fired for 10 seconds to verify start and shutdown sequences, the functionality of the E-1 test stand, and the ground control system, according to statements released by NASA and Orbital.

Two more tests of the engine are planned by the end of 2010. A 50-second firing will serve as an acceptance test for the AJ26, then another test will help engineers tweak engine control valves, the statements said.

The AJ26 is a kerosene-fueled engine modified by Aerojet from the Russian NK-33 powerplant. Each Taurus 2 rocket first stage will be powered by two AJ26 engines.

Kept in storage for four decades, the NK-33 engines were originally designed and built in the 1960s and 1970s for the ill-fated Soviet N1 moon rocket.

Aerojet converts the NK-33 to an AJ26 engine by removing some harnessing, adding U.S. electronics, qualifying it for U.S. propellants, and modifying the system to gimbal for steering, according to company officials.

The NK-33 has been test fired in Russia to ensure the engines remain in good condition after being stockpiled for so long. NASA modified the E-1 test stand at Stennis to support AJ26 acceptance testing, and Orbital plans to route every flight-ready AJ26 engine through Mississippi before shipment to the Taurus 2's launch site at Wallops Island, Va.

"Congratulations to Orbital and Aerojet for successfully completing another major milestone," said Doug Cooke, associate administrator for the exploration systems mission directorate at NASA Headquarters in Washington. "This brings us one step closer to realizing NASA's goals for accessing low Earth orbit via commercial spacecraft."

The first AJ26 production engine is moved into the E-1 test stand at Stennis earlier this year. Credit: NASA

In a conference call with investors last month, Orbital executives said work on the cargo program is slipping behind schedule, pushing the Taurus and Cygnus system's first operational mission until the beginning of 2012. That flight is supposed to haul more than 3,400 pounds of supplies to the space station.

A significant chunk of the delay stems from the Taurus 2's specially-built launch infrastructure at Wallops. Orbital is building a new launch pad, water tower and horizontal integration building on the Virginia coast.

"By the end of the year, the horizontal integration facility, the launch pad and the propellant and gas supply facility will be nearing completing and beginning the test and certification activity," said J.R. Thompson, Orbital's vice chairman and chief operating officer.

Designed and manufactured by Yuzhnoye and Yuzhmash in Ukraine, the first model of the Taurus 2 core stage was shipped to Wallops last month from Dnepropetrovsk, Ukraine.

The Taurus 2's second stage, based on the Castor 30 motor built by ATK, should be ready for delivery within a few months.

Officials expect a static fire of the first stage on the launch pad around May.

Orbital is planning a demonstration flight of the Taurus 2 rocket between July and September of 2011, assuming the company receives augmentation funding outlined in NASA's budget blueprint passed by Congress and signed into law in late September.

Congress has not acted on a final fiscal year 2011 budget yet, so the availability of the extra money is unclear. But Orbital officials say an additional test flight will increase the chances of a successful cargo flight in early 2012.

"If Congress's final fiscal year 2011 budget includes NASA's requested augmentation funds for risk reduction work in the COTS program, as we currently expect it will, then we plan to conduct a Taurus 2 test flight with the first launch-ready Taurus 2 rocket but without the Cygnus spacecraft," said David Thompson, Orbital's chairman and CEO.

Artist's concept of the Cygnus cargo freighter approaching the International Space Station. Credit: Orbital Sciences

"We would then follow it with the full-up COTS demonstration mission about three months later with the second launch-ready Taurus 2 rocket," Thompson told investors Oct. 21. "This will permit us to substantially reduce the risk both to the COTS demonstration mission itself, and to the follow-on operational CRS cargo missions, which are due to begin about 15 to 16 months from now in the early months of 2012."

The Cygnus spacecraft service module, built by Orbital in Dulles, Va., is expected to begin final assembly by early next year. The first pressurized cargo module will be delivered around the same time from Thales Alenia Space in Turin, Italy.

SpaceX has scheduled the first test flight of its Dragon spacecraft for no earlier than Dec. 7, but the mission will be a brief up-and-down voyage that won't visit the space station.

A space station rendezvous demonstration and a berthing mission are planned for no earlier than April and June, but the flights could be combined if the December test meets its objectives.

SpaceX spokesperson Kirstin Brost said the company expects to begin operational resupply missions in 2011.