Spaceflight Insider

Fourth and long – ULA launches Atlas V 401 with OA-4 Cygnus to ISS

A ULA Atlas V 401 rocket lifts off at 4:44 p.m. EST (21:44 GMT) with the OA-4 mission for Orbital ATK and NASA. Photo Credit: Jared Haworth / SpaceFlight Insider

A ULA Atlas V 401 rocket lifts off at 4:44 p.m. EST (21:44 GMT) with the OA-4 mission for Orbital ATK and NASA. Photo Credit: Jared Haworth / SpaceFlight Insider

CAPE CANAVERAL, Fla. — After four long days of waiting on the weather to cooperate, Colorado-based United Launch Alliance (ULA) got the fourth of Orbital ATK’s Cygnus spacecraft (OA-4) on its way to the International Space Station at 4:44 p.m. EST (21:44 GMT) via the launch of an Atlas V 401 rocket. Liftoff occurred at the very beginning of the roughly 30-minute launch window from Cape Canaveral Air Force Station’s Space Launch Complex 41 (SLC-41) in Florida.

The mission was one of the most unique to take flight in 2015 from the historic launch site as it marked the first time that ULA’s venerable Atlas booster had been brought into service under NASA’s Commercial Resupply Services program.

Orbital ATK's Frank Culbertson gives a "thumbs up" during the pre launch press conference at Kennedy Space Center in Florida. Photo Credit: Michael Seeley / SpaceFlight Insider

Orbital ATK’s Frank Culbertson gives a “thumbs up” during the pre-launch press conference at Kennedy Space Center in Florida. Photo Credit: Michael Seeley / SpaceFlight Insider

The mission had originally been slated to get underway on Dec. 3; however, rough weather including rain saw the 60 percent chance of favorable conditions for launch drop to 10 percent before a scrub was eventually called. The launch team at the Atlas Spaceflight Operations Center (ASOC) then began working on a 24-hour turnaround which ended in another scrub on Dec. 4 due to high ground level winds. On Dec. 5, the launch director scrubbed that launch at 1:51 p.m. EST (18:51 GMT) – three hours before the window even opened.

Meanwhile, guests at the Kennedy Space Center Visitor Complex were instructed to leave the center after a water main break. This evacuation was caused by the requirement of the facility to have an operational fire suppression system (according to a representative with the tourist destination).

For their part, ULA was taking no chances and went from an automated redline monitoring system to a manual one for this launch.

Orbital ATK selected the Atlas V due to its proven track record as well as the fact that the Russian-made RD-180 engine lends the launch vehicle with increased up-mass capabilities. This fact was highlighted when a journalist at NASA’s press site asked why this Cygnus would be able to hoist 7,745 lbs (3,513 kg) of cargo to the orbiting laboratory and why the mission had such a long launch window (many cargo runs only have 1 second windows in which to get off the pad and on their way to orbit). The response was as simple as it was telling.

“It’s because of Atlas’ performance. It’s a good luxury to have a 30-minute launch window which allows us to handle a lot of contingency cases, such as boats in the range zone, weather issues, what have you,” Orbital ATK’s Cargo Resupply Services Program Director Frank DeMauro told SpaceFlight Insider.

ULA Atlas V 401 lifts off from Cape Canaveral Air Force Station's SLC 41 with Orbital ATK Cygnus spacecraft on OA-4 mission to International Space Station. Photo Credit: Bill Jelen / SpaceFlight Insider

Liftoff! Photo Credit: Bill Jelen / SpaceFlight Insider

That performance became evident as the moment approached T–0 with the RD-180 rocket engine roaring loudly, announcing its intentions to the surrounding marshlands.

As is always the case with the Atlas booster, the mission got underway slowly, almost languidly with the rocket pushing its way upwards through the skies above Florida’s Space Coast. The steady drone of insects was momentarily drowned out by the dull roar of the 860,200 lbf (3,826.4 kN) of thrust being unleashed by the Russian-made (NPO Energomash) rocket engine.

The single RD-180 engine, with its two nozzles, actually activated almost three seconds prior to liftoff. After all had been deemed ready for launch, the booster thundered off of SLC-41 about 1 second after T–0.

Eighteen seconds into the mission and Atlas began a pitch/yaw maneuver to place it on the proper orbital trajectory. For those in the surrounding area, the rocket was only visible for about two more seconds before it disappeared into the clouds. However, due to the increased moisture (clouds) in the air, the rocket was audible for some time after that.

At about a minute and 22 seconds, the rocket was traveling at Mach 1. This was followed some 10 seconds later by Atlas passing through the region known as maximum dynamic pressure – or “max-Q”.

Booster engine cutoff took place approximately four minutes and 16 seconds after the launch vehicle and its precious cargo had left the pad with stage separation occurring six seconds after that.

United Launch Alliance Atlas V 401 rocket Orbital ATK Cygnus OA-4 Cape Canaveral Air Force Station Space Launch Complex 41 photo credit Michael Howard SpaceFlight Insider

Poor weather and wind conditions caused the launch attempts on Dec. 3, 4, and 5 to be scrubbed. Photo Credit: Michael Howard / SpaceFlight Insider

Ten seconds later and the RL-10C rocket engine in the Centaur upper stage activating. This was followed shortly thereafter by the jettisoning of the payload fairing.

After about 21 minutes, Cygnus separated from the Centaur upper stage and was free to begin its journey to the space station.

“In the 12 months since this launch was ordered, the ULA and Orbital ATK teams worked very closely together to integrate the Cygnus with the Atlas launch system, including development of a new structural adapter and also a mission design that includes a 30-minute launch window for this ISS rendezvous mission, ” said ULA’s Vice President, Atlas and Delta Programs Jim Sponnick.

The Vehicle Assembly Building at NASA's Kennedy Space Center in Florida. Photo Credit: Jared Haworth / SpaceFlight Insider

Weather conditions at the Cape began to deteriorate on Tuesday, Dec. 2. Photo Credit: Jared Haworth / SpaceFlight Insider

Orbital ATK is scheduled to deliver 63,052 lbs (28,600 kg) of cargo over the course of the $1.9 billion CRS-1 contract.

“This launch marks the completion of the critical first step of our go-forward plan for the CRS-1 contract to meet our commitments to NASA,” said Orbital ATK’s President of  the company;’s Space System Group Frank Culbertson. “Everything looks great in this early stage of the mission. I congratulate the combined NASA, ULA and Orbital ATK team for its hard work to get us to this point, and I look forward to completing another safe and successful flight to the ISS in several days.”

As is the case with any of NASA’s CRS missions, this mission is a flight with many names. NASA referred to it as CRS-4 and Orbital ATK as OA-4. However, on the Atlas V’s payload fairing another name was posted – Orb-4. In the end, however, only one name was of any real consequence – Deke. The Cygnus spacecraft that conducted this evening’s mission was named in honor of the famed Mercury and Apollo astronaut Donald K. “Deke” Slayton.

This was the second time that a Cygnus carried that name (hence the spacecraft’s full name: SS Deke Slayton II). The first time was on Oct. 28, 2014, when the Orb-3 Cygnus was sent aloft atop an Antares rocket from Wallops Flight Facility’s Pad-0A in Virginia. That ill-fated mission ended after 12 seconds with the rocket exploding due to an issue with a turbopump in one of the two Aerojet Rocketdyne AJ26 rocket engines.

Even before that accident, Orbital ATK had been moving away from the AJ26 to the RD-181 rocket engines in the Antares booster. At present, the Dulles, Virginia-based company is working to get this new “enhanced” Antares into service as soon as late spring of next year (2016).

ULA Atlas V 401 rocket lifts off from CCAFS SLC-41 with Orbital ATK OA-4 mission. Photo Credit: Jared Haworth / SpaceFlight Insider

Lifting off into hazy skies, tonight’s launch marked the 60th flight of an Atlas V and the 30th of the 401 configuration of the rocket. Photo Credit: Jared Haworth / SpaceFlight Insider

Orbital ATK has already tapped Atlas for another mission to the ISS, OA-6, with that flight currently scheduled to take place on March 10, 2016 (according to SpaceFlight Now). Officials with Orbital ATK noted some of the changes that had been made to the “enhanced” version of Cygnus prior to tonight’s launch.

“We’ve taken some weight out of Cygnus’ service module, which includes lighter solar arrays from our facility in Goleta, California, a more streamlined propulsion system with tanks from our facility in Commerce, California, a lighter structure, and a different spacecraft layout that allows us to save some of the wire harness mass,” DeMauro said.

According to DeMauro, this new version of Cygnus has an increased cargo carrying capability of some 50 percent compared to the prior version of the spacecraft.

This evening’s launch was the final flight that United Launch Alliance conducted under its 2015 manifest. It also was the 60th flight of an Atlas V booster and the 30th time that the 401 configuration of the rocket has been tapped to carry out a mission.

Tonight’s mission also served as a kind of high-tech “Santa’s Sleigh” delivering some much-anticipated “surprises” for the Expedition 45 crew currently serving on the International Space Station. For DeMauro, this portion of the soda can-shaped cargo freighter’s payload should serve as extra-added motivation for the station’s inhabitants.

“The crew will be happy to find in there as it will essentially be ‘Santa’s Sleigh’ delivering holiday gifts to the crew and I know that they are looking forward to that and it might be one of the reasons that they will empty the module pretty quickly so that they can get their presents out,” Demauro said.

The station was roughly over Cuba at an altitude of some 252 miles when the launch took place. If the mission continues the successful path that it is currently on, it should arrive at the outpost on Wednesday, Dec. 9. For Dulles, Virginia-based Orbital ATK, it marked a welcome return to cargo resupply runs to the space station.

“This launch begins a high tempo of cargo resupply missions supporting the International Space Station,” said Culbertson. “With our enhanced Cygnus spacecraft and upgraded Antares rocket, we are prepared to continue delivering vital cargo to the ISS for the foreseeable future.”

This marked the first time ULA had contributed to NASA's CRS efforts. Photo Credit: Jared Haword / SpaceFlight Insider

This marked the first time ULA had contributed to NASA’s CRS efforts. Photo Credit: Jared Howard / SpaceFlight Insider


Jason Rhian spent several years honing his skills with internships at NASA, the National Space Society and other organizations. He has provided content for outlets such as: Aviation Week & Space Technology,, The Mars Society and Universe Today.

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