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Antares rocket cleared for cargo launch from Virginia
Posted: July 12, 2014

After a string of delays cause by stormy weather, conflicts with other flights and an engine test failure, Orbital Sciences Corp. is readying an Antares rocket for launch Sunday on a voyage to deliver 1.7 tons of cargo and supplies to the International Space Station, the company's second commercial resupply mission.

Photo of the Antares rocket on launch pad 0A at Wallops Flight Facility. Credit: NASA/Bill Ingalls
With forecasters predicting a 90 percent chance of acceptable weather, the two-stage 133-foot-tall Antares was scheduled for launch from the Mid-Atlantic Regional Spaceport at NASA's Wallops Island Flight Facility on the Virginia coast at 12:52 p.m. EDT (GMT-4) Sunday, the opening of a five-minute launch window.

"We're very proud and pleased to be back here at Wallops again, conducting this operation leading up to the launch of Antares," said Frank Culbertson, a former shuttle commander who serves as Orbital's vice president and general manager of advanced programs. "We're real proud to be part of the team that is keeping the station flying and providing the crew with the cargo and research they need."

Orbital engineers had hoped to launch the rocket and its company-developed Cygnus cargo ship Friday, but the flight was delayed through the weekend by severe weather that interrupted ground processing.

Assuming an on-time launch Sunday, the uncrewed Cygnus capsule will reach the space station early Wednesday, pulling up to within about 30 feet and then standing by while the lab's robot arm locks on to pull it in for berthing at the Earth-facing port of the forward Harmony module.

The spacecraft is loaded with 3,669 pounds of crew supplies, including food for the lab's crew, spare parts and other station hardware, science equipment, spacewalk components and computer hardware.

The science equipment includes a variety of student experiments, supplies for NASA's Human Research Facility, igniters for the station's combustion test facility and a Japanese experiment that will study Marangoni convection, a type of heat transfer between solids and liquids that could lead to improvements in microgravity life support systems.

Also on board: 28 small satellites -- nanosats -- built by Planet Labs of San Francisco, part of a growing fleet of "Dove" spacecraft being tested in a commercial venture to continuously photograph the Earth. Four other nanosats also are on board, including one built by NASA to test techniques for returning small experiment samples to the ground.

The Orb-2 mission patch. Credit: Orbital Sciences Corp.
The Cygnus spacecraft will remain attached to the station for about a month. After it is unloaded and re-packed with trash and no-longer-needed equipment, the cargo ship will be released to burn up in Earth's atmosphere. Before re-entry, Orbital flight controllers plan to test new rendezvous equipment and procedures intended to allow Cygnus capsules to remain aloft for extended periods, enabling research after the spacecraft leave the station.

This will be Orbital's second operational station resupply mission -- Orb-2 -- under a $1.9 billion commercial contract with NASA calling for eight flights through 2016 to deliver some 40,000 pounds of supplies and equipment. SpaceX holds a similar $1.6 billion contract covering 12 resupply flights to deliver 44,000 pounds of cargo.

SpaceX has carried out three resupply missions to date with a fourth on tap in September and a fifth in December. Orbital plans its third resupply flight in October with two more on tap next year.

This week's Antares launching originally was planned for May, but the flight was delayed to early June, at NASA's request, because of conflicts with other station traffic. Then, on May 22, a first-stage engine being test fired for an Antares/Cygnus resupply flight next year suffered a catastrophic failure 30 seconds into a planned 54-second burn. The engine was destroyed, and the planned June flight was put on hold pending an investigation.

The Antares first stage is powered by two AJ26 engines supplied by Aerojet Rocketdyne. The engines originally were developed for the Soviet Union's ill-fated N-1 moon rocket. When that program was cancelled after multiple launch failures, the engines were stockpiled and in the 1990s, Aerojet bought about 40 of the powerplants and modified them for use aboard U.S. rockets.

The May 22 test failure "obviously sparked a very thorough investigation led by Aerojet Rocketdyne, our engine supplier, supported fully by Orbital with a lot of help by NASA," said Mike Pinkston, Orbital's Antares program manager. "That was a lengthy process and the primary source of the delay from the early part of June to where we are today."

The failure investigation is not yet complete and no details have been provided to the media. But the engines scheduled for use Sunday were cleared for flight after internal boroscope inspections and a review of data collected during their own test firings earlier.

"We saw what we needed to see with that and with the fact that these engines successfully passed the same acceptance process, not only here in the United States, but also twice after original manufacture in Russia," Pinkston said. "They've got a lot of test time on them. We've got a lot of confidence that the two engines on Orb-2 are ready to go."