Monday, May 21, 2018

Orbital ATK’s Antares Rocket Launches OA-9 Cygnus to Resupply ISS

Antares sends the OA-9 Cygnus spacecraft toward space. Photo Credit: Michael Deep / SpaceFlight Insider

Another load of supplies, science experiments and CubeSats is on its way to the International Space Station. In the early-morning hours of May 21, 2018, Orbital ATK launched its OA-9 Cygnus spacecraft atop an Antares 230 rocket.

Following a 24-hour launch slip to allow more time for pre-launch inspections and for the launch forecast to improve, the OA-9 Cygnus spacecraft atop the Antares rocket lifted off at 4:44 a.m. EDT (08:44 GMT) from Pad-0A at the Mid-Atlantic Regional Spaceport at NASA’s Wallops Flight Facility.

About 45 minutes before the original launch time of 4:39 a.m. EDT (08:39 GMT), the decision was made to move the launch time to the end of the five-minute launch window due to a violation of the cumulus cloud rule. However, conditions improved and about 15 minutes before the new liftoff time the weather was deemed acceptable.

“Watching an Antares launch cargo to the International Space Station is always impressive,” Scott Lehr, president of Orbital ATK’s Flight Systems Group, said in a news release. “The team works very hard to ensure each NASA commercial resupply mission is successful.”

The OA-9 Cygnus, christened the S.S. J.R. Thompson, was packed with 7,400 pounds (3,400 kilograms) of supplies and experiments in its 953-cubic-foot (27-cubic-meter) Pressurized Cargo Module.

Orbital ATK’s Cygnus spacecraft is 20.9 feet (6.4 meters) long and 10.1 feet (3.1 meters) wide. With its two circular “UltraFlex” solar arrays, the vehicle has a wingspan of about 35 feet (10.5 meters).

When the countdown reached zero, the Antares rocket’s two NPO Energomash RD-181 first stage engines roared to life, sending birds flying away from the launch pad and lighting up the pre-dawn sky for the thousands of spectators gathered around the coastline to watch the launch. The two engines, producing about 864,000 pounds (3,800 kilonewtons) of thrust, lifted the rocket off the pad just 3.7 seconds later.

The rocket rose from the pad and, about 11 seconds after launch, vanished into the clouds briefly—save for a dull glow. But then the clear, bright flame of the Antares appeared through the overcast skies and was sharp and visible for more than five minutes as the rocket thundered away and downrange. 

“Earth’s newest spacecraft launched this morning in a column of fire and roar,” said Kirk Shireman, International Space Station Program Manager, said in the post-launch briefing at Wallops Flight Facility. “Launching a rocket and launching a spacecraft into orbit is a big team sport…and we are very excited about how the mission started and how it is progressing.”

Climbing away from the coastline, the vehicle headed southeast from the pad to begin its three-day pursuit of the ISS orbiting above. 

Having expended its load of liquid oxygen and rocket grade kerosene, the first stage main engines cut off about three minutes and 35 seconds into the flight at an altitude of around 61.5 miles (99 kilometers). With the vehicle still gaining altitude, the first stage separated six seconds later and about 3.7 miles (6 kilometers) higher.

The second stage and Cygnus spacecraft, still protected by the payload fairing continued climbing for another 30 seconds before the fairing was jettisoned. This was followed five seconds later by the interstage jettisoning.

Having now climbed to approximately 83.2 miles (134 kilometers) in altitude, the Castrol 30XL second stage ignited. It burned through its load of solid rocket fuel in just two minutes, 42 seconds to push Cygnus to around 122 miles (196 kilometers) above the Earth. Spacecraft separation occurred about two minutes later, releasing the Cygnus cargo freighter to chase down the ISS.

About 90 minutes after launch the Cygnus spacecraft deployed its two “UltraFlex” circular solar arrays to provide it with power during its stay on orbit.

“Orbital ATK is proud to once again support the crew on the International Space Station by delivering valuable supplies, equipment and science,” Frank Culbertson, president of Orbital ATK’s Space Systems Group, said in a news release. “The upgraded avionics and communication system on the spacecraft demonstrate our commitment to increasing the flexibility and versatility of Cygnus to carry a wide range of payloads. We are also honored to name this mission after J.R. Thompson, a pioneer in the space industry and someone who many of us here at Orbital ATK and in the NASA community were honored to call a colleague and friend.”

In the post-launch media briefing, Orbital ATK said the rocket placed Cygnus in an orbit slightly higher than nominal at 123 by 197 miles (198 by 319 kilometers). The company was targeting 117 by 185 miles (189 by 296 kilometers) in the 51.6 degree orbital plane of the ISS.

Regardless, Cygnus is in a lower orbit than the 250-mile (402-kilometer) altitude of the ISS. Over the next three days, the spacecraft will slowly increase its altitude and close the distance to the orbiting outpost using the cargo freighter’s onboard thrusters.

Once the spacecraft rendezvous with the ISS, the outpost’s Expedition 55 crew will then use the station’s robotic Canadarm2 to capture and then berth the spacecraft with the Earth-facing port of the Unity module.

Cygnus is expected to stay attached to the ISS until mid-July. During that time, the station’s crew will unload the cargo and, just as importantly, is re-load it with some 6,000 pounds (2,700 kilograms) of trash and unneeded equipment that will be disposed of when the spacecraft performs a destructive reentry and burns up in the Earth’s atmosphere at the end of its mission.

Written by: Lloyd Campbell
Michael Cole contributed to this story
Original source:


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