Orbital Sciences Preps for ISS Launch

The next ship in line to deliver cargo to the International Space Station is undergoing final checkouts on a launchpad at Wallops Island in Virginia. If all goes well, the Orbital Sciences Cygnus, an unmanned, pressurized cargo ship, will lift off on its first demonstration flight to orbit in late February or early March, reach the station in early April with a payload of about 1800 pounds of cargo, and begin regular cargo service to the ISS some time after that.

The Cygnus will compliment the SpaceX Dragon that is already in service delivering cargo to the station. It will be the first time in history that two American ships capable of flights to the space station will be in service at the same time, trying to start filling the gap left by the retirement of the space shuttle.

Orbital Sciences, based in Dulles, Va., has built a new rocket called Antares around a pair of Russian NK-33 engines. Those engines were built in the early 1970s as part of a design intended to power the Soviet Union's N1 manned moon rocket. The Russians never sent astronauts to the moon, but the engines are remnants of the moon race.

Aerojet acquired the engines in the 1990s, and Kurt Eberly, deputy manager at Orbital for the Antares, figures Aerojet got 38 of the original 80 to 100 engines. Refurbished by Aerojet and renamed AJ-26, a pair of the Russian-made engines will now power the first stage of Orbital Science's Antares rocket. It will be the first time the engines will be used in flight, and they will be discarded after a single mission, along with the rest of the rocket and the Cygnus itself.

"It's never easy," Eberly, a 21-year veteran of Orbital Sciences, says of developing a new rocket. "You just have to have the determination to see it through to the end." After more than five years in the making, he says, "it's just really exciting to finally get to the point of having some operations in front of us. I'm really anxious to get to the point of starting to fly these things."

An Antares first stage is sitting on the pad at Wallops Island, slated for a hot-fire test in February. The twin AJ-26 engines will light up just as they would for a launch, but the stage will remain bolted in place and the engines will shut down after 30 seconds?long enough for engineers to check whether they will perform as expected. Before the demonstration flight happens in February or March, the Antares first stage will be topped with a solid-fuel second-stage called a Castor 30B. That stage is built around a motor provided by Alliant Techsystems, or ATK, the same company that made the space shuttle solid-rocket boosters.

"We take their rocket motors," Eberly says, "and we integrate them as the prime contractor." That means installing Orbital-built avionics and building a fairing around them and doing other work to turn the motors into functional booster rockets.

The Cygnus spacecraft will ride to orbit atop the Castor. Orbital Sciences builds the service module of Cygnus, containing the guidance, navigation and control systems, propulsion system, sensors, and other gear needed to get it to the space station. The pressurized cargo section, enclosing about 60 cubic feet of cargo space and able to carry about 4400 pounds in its first iteration, is made by Thales Alenia in Italy. "It's like the bed of the pickup truck," says Carl Walz, a former NASA astronaut and space station resident and current vice president of human spaceflight operations at Orbital. After its demonstrations and its first three real cargo missions are in the books, Orbital plans to upgrade to an Enhanced Cygnus enclosing about 85 cubic feet and capable of carrying close to 6000 pounds.

"Cygnus is fully assembled, fully checked out," Walz says. "The last thing we have to do is load modified software [to match software upgrades on ISS], and we're ready to go."

Orbital has no immediate plans to build more of the AJ-26 engines, even though Aerojet has a license to do so from the original manufacturer, the Kuznetsov Design Bureau. Nor does it plan to fly astronauts on Cygnus. The company is under contract for eight cargo missions to the space station following the two demo flights. That will have the company flying about two missions a year. Whether Antares/Cygnus flights will continue after that is up for grabs.

That means the sole-purpose Cygnus is a different animal from the SpaceX Dragon, which was designed from the start with eventual crew-carrying capability in mind and is part of SpaceX founder Elon Musk's vision of one day colonizing Mars. Nevertheless, Walz argues the Cygnus fills an important niche.

"As a former NASA astronaut, this is something I've always hoped that the United States would do?develop this autonomous cargo capability," Walz tells PM.

Source: http://www.popularmechanics.com/science/space/rockets/orbital-sciences-preps-for-iss-launch-14991680?src=rss

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