Monday, October 24, 2016

Orbital ATK’s OA-5 Cygnus Spacecraft Arrives at the ISS

The S.S. Alan Poindexter holds position at the 30-meter mark on its approach to the ISS. Credit: NASA

Nearly a week after its launch, Orbital ATK’s Cygnus spacecraft berthed with the International Space Station (ISS) on Sunday, October 23, 2016, at 10:53 a.m. EDT (14:53 GMT), 250 miles (402 kilometers) above the Indian Ocean. The capsule is now attached to the nadir (Earth-facing) port on the station’s Unity module.

The S.S. Alan Poindexter, designated OA-5 under NASA’s Commercial Resupply Services 1 (CRS-1) contract, delivered 5,300 pounds (2,400 kilograms) of cargo to the orbiting outpost and marks the third flight of the enhanced iteration of the uncrewed cargo vessel, and the first on the redesigned Antares medium-class launch vehicle.

Following the loss of the then-Orbital Sciences Cygnus spacecraft, after the failure of the Antares rocket shortly after liftoff on the Orb-3 mission on October 28, 2014, the newly merged Orbital ATK had to accelerate plans to upgrade their launch vehicle while still honoring their cargo contract with NASA.

Amid the two-year grounding of the Antares vehicle, during which time the rocket was undergoing redesigning, testing, and manufacturing, Orbital ATK partnered with United Launch Alliance (ULA) to launch the OA-4 (December 6, 2015) and OA-6 (March 23, 2016) missions – both of which were the enhanced version of the Cygnus spacecraft – on Atlas V 401 rockets.

However, the goal was always to return to launching CRS missions from Orbital ATK’s “home” launch site at the Mid-Atlantic Regional Spaceport on Wallops Island in Virginia. With the berthing of OA-5, it would appear that Orbital ATK has yet another milestone in a mission replete with such events.

“While all of our missions are important to us, the OA-5 mission is distinct and special to the entire Orbital ATK team,” stated Frank Culbertson, President of Orbital ATK’s Space Systems Group, in a press release issued by the company. “It marked the return to our home base of operations at the Mid-Atlantic Regional Spaceport, where we launched our Cygnus spacecraft atop our upgraded Antares vehicle to deliver critical cargo to the International Space Station. Following our departure from the station, we will again use Cygnus as a platform to conduct scientific experiments for key customers.”

Indeed, though the delivery of cargo to the ISS is the primary objective of this flight, Cygnus still has more work to do when its stay at the ISS comes to an end.

Tapped to ultimately disintegrate over the Pacific Ocean, along with nearly 4,000 pounds (1,800 kilograms) of disposable cargo, the S.S. Alan Poindexter will first play host to two secondary missions prior to its fiery demise.

Building on the Spacecraft Fire Experiment-I (Saffire-I) experiment carried aloft on the OA-6 mission, OA-5 has the Saffire-II experiment on board. Designed to investigate how materials burn, along with the nature of flame propagation, in a microgravity environment, the Saffire series of experiments are critical to the understanding of how fires may spread in a spacecraft.

With Cygnus being uncrewed and non-reusable, it provides the perfect platform from which to conduct these experiments.

Additionally, the S.S. Alan Poindexter will release several CubeSats from a NanoRacks deployer sometime after departure from the ISS. These diminutive satellites will be used for weather forecasting.

Cygnus will remain on-station for approximately one month.

Written by: Curt Godwin
Original source: spaceflightinsider.com

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