In the early days of space exploration, the frequent term of the week was “A-OK,” but for Orbital Sciences Corp. this week everything will center on “A-ONE,” the maiden voyage of the company’s long-awaited Antares launch vehicle. Liftoff of the 133-foot-tall rocket is scheduled to occur from Pad 0A at the Mid-Atlantic Regional Spaceport (MARS) on Wallops Island, Va., at 5 p.m. EDT, Wednesday, 17 April. Final preparations are ongoing and have been highlighted by a 29-second hot-fire test of Antares’ twin AJ-26 engines on 22 February and, most recently, the one-mile rollout of the vehicle from its assembly building to the pad on 6 April.
Although A-ONE is a bare-bones test mission for the new rocket, it carries enormous importance for Orbital, which was selected (alongside SpaceX) as one of two partners for NASA’s Commercial Resupply Services (CRS) contract in December 2008. Orbital’s share of the CRS contract totals $1.9 billion and requires the company to launch eight flights of its Cygnus cargo craft to the International Space Station by 2016, transporting upwards of 44,000 pounds of equipment, payloads, and supplies to the sprawling outpost. Assuming a successful launch Wednesday, Orbital is quietly optimistic that an inaugural demo mission of Cygnus will be achievable “around mid-year,” with current estimates placing it in the June timeframe. However, the company, which celebrated its 30th anniversary last year, has much to prove, for SpaceX has already tested its own Falcon 9 rocket, has already completed its own demo flight, and has conducted two operational flights of its Dragon cargo craft in October 2012 and, most recently, last month.
Wednesday’s liftoff of Antares will enable Orbital to validate its first cryogenically-powered rocket, as well as its largest launch vehicle to date. It is propelled by a pair of Aerojet-built AJ-26 engines, developed from a batch of Soviet-era NK-33 powerplants, whose own heritage extends back to the ill-fated N-1 lunar booster of the 1960s. Fueled by rocket-grade kerosene (RP-1) and liquid oxygen, these old engines have never been used. Aerojet purchased 36 of them from Russia in the mid-1990s, at a cost of $1.1 million per engine, and added modern electronics and made other performance enhancements. Early plans called for a single AJ-26 on Antares’ first stage, supplemented by strap-on boosters, but it was eventually decided to add a second engine and eliminate the boosters. Each engine produces a sea-level thrust of about 338,000 pounds, and they have generally performed well in a series of lengthy test-firings, dating back to March 2010. A notable anomaly occurred in June 2011, when an engine caught fire after a kerosene leak, apparently due to stress-corrosion cracks in its 40-year-old metal.
For A-ONE, the twin AJ-26s will be complemented by a second stage, equipped with an Alliant TechSystems Castor-30A solid-fueled motor, although subsequent missions are expected to benefit from a final stage, powered by hypergolic propellants. When fully operational, it is expected that Antares will be capable of injecting up to 15,000 pounds of payload into low-Earth orbit, although Orbital has contracted with Teledyne Brown to build a fully-U.S. version of the AJ-26, reportedly capable of 500,000 pounds of thrust. This makes it a possible contender for inclusion in NASA’s Space Launch System (SLS) effort.
Clearly, NASA has great confidence in Antares. Last year, it added the vehicle to its NASA Launch Services Contract (NLS-II), which will enable Orbital to bid for future missions to carry medium-class scientific payloads into space. It also hopes to deliver scientific, civilian government, military intelligence, and commercial satellites aloft. However, the vehicle’s history has been mired with delay and difficulty, partly due to problems with its launch facility and the certification of propellant-handling operations at the MARS site. As the rocket evolved, so too did its name. Until December 2011, Antares was known by its developmental name of “Taurus II,” but this was changed in accordance with Orbital’s tradition of using ancient Greek celestial names—Pegasus, Taurus, Minotaur, for instance—for its projects. “A launch vehicle of this scale and significance,” explained Orbital Sciences President and CEO David Thompson at the time, “deserves its own name.” As a result, “Taurus II” was dropped in favor of “Antares.” In addition to being one of the brightest stars in the sky, the red-hued supergiant Antares also lent its name to the lunar module which ferried Apollo 14 astronauts Al Shepard and Ed Mitchell to the Moon in early 1971.
And that scale is certainly extensive. Standing 133 feet tall and 12.8 feet in diameter, the rocket in its present form has the capacity to boost up to 11,000 pounds of payload into low-Earth orbit. After receiving its initial push to the edge of space by the AJ-26s, Alliant TechSystems’ Castor-30A will ignite to complete the climb into orbit. With a maximum thrust of 89,000 pounds, this engine was originally part of the first stage for Orbital’s Athena and Taurus I rockets and can trace its heritage back to the Peacekeeper missile. The first two Antares launches—including the Cygnus demo flight, which Orbital expects to stage in June of this year—will utilize the Castor-30A, after which an upgraded Castor-30B will be introduced for two subsequent launches and, eventually, a “stretched” Castor-XL to boost payload capacity from 4,400 pounds to almost 6,000 pounds for the final five dedicated Cygnus cargo missions.
On Wednesday’s A-ONE mission, Antares will loft a “mass simulator” for the Cygnus craft into an orbit of 155-186 miles, inclined 51.6 degrees to the equator, providing a close parallel for its upcoming ISS launch schedule. Ignition of the twin AJ-26 engines will occur two seconds ahead of liftoff, and the liquid-fueled powerplants will burn for almost four minutes, shutting down at T+230 seconds, at an altitude of 66 miles. Five seconds will elapse before the separation of the first stage, after which the rocket will coast for almost two minutes, ahead of the jettisoning of the payload fairing and ignition of the Castor 30A-powered second stage at T+328 seconds. By this point, Antares will have reached an altitude of 117 miles. The Castor-30A will burn for more than two and a half minutes, providing the final impulse to achieve low-Earth orbit, and at T+601 seconds the Cygnus Mass Simulator will separate from the vehicle.
The simulator is heavily instrumented to gather data on the launch environment, although Antares will also deploy four tiny “picosatellites” from a pair of dispensers. All this will offer a taste for the first Cygnus demo mission to the International Space Station, which will follow an approach profile similar to the one pursued by Dragon. The spacecraft will perform an intricate two-day rendezvous and numerous systems and functionality tests, eventually closing within range of the station’s Canadarm2 robotic arm for grappling and berthing onto the Earth-facing port of the Harmony node. Like Dragon, each Cygnus mission is expected to spend about a month at the ISS, but unlike the SpaceX-built craft it is not intended to survive re-entry and will instead execute a destructive dive into the atmosphere.
“NASA’s commercial space program is helping to ensure American companies launch our astronauts and their supplies from U.S. soil,” said Associate Administrator for Communications David Weaver, speaking last year. That soil, however, has been part of the problem for Antares’ lengthy wait for its maiden voyage. Launch pad modifications at the MARS site included the construction of a horizontal integration facility and a wheeled transporter, capable of rolling the entire vehicle to the pad a mere 24 hours ahead of liftoff. The program also required the complete demolition of Pad 0A itself and the construction of an entirely new facility with kerosene and liquid oxygen tankage. Certainly, Orbital is proud of its accomplishment, which represents—in the words of President and CEO David Thompson—“the first all-new, large-scale liquid-fuel launch site to be built in the U.S. in decades.”
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