June 28, 2016

— NASA's past and future came together in Utah on Tuesday (June 28) for the test fire of the world's largest human-rated solid rocket motor.

The space agency and its contractor, Orbital ATK, ignited the booster — which was assembled in part out of casings that had previously launched on 40 space shuttle missions — in a ground test supporting the development of NASA's next heavy-lift rocket, the Space Launch System (SLS).

The test, which fired the horizontally-mounted rocket for a full two minutes at the Orbital ATK facilities in Promontory, Utah, was the second and last demonstration before two of the solid rocket motors are used to launch the SLS's first uncrewed test flight in late 2018.

"What an absolutely amazing day!" said Bill Gerstenmaier, NASA's associate administrator for human exploration and operations. "It's not just a test fire, it is really a qualification for a sequence that essentially says this design is ready to go fly and go do the mission for which it is designed to do."

Click to enlarge and view video in a new pop-up window. (NASA)

Before the 11:05 a.m. EDT (1505 GMT) ignition, the rocket booster was chilled to 40 degrees Fahrenheit (4.4 degrees Celsius), to the colder end of propellant's accepted range. When ignited, the temperature inside the 154-foot-long (47 meter) motor reached nearly 6,000 degrees F (3,315° C).

During the firing, the booster produced 3.6 million pounds of thrust, which is more than 14 Boeing 747-400 jumbo jets generate at full takeoff power. The flame exited the booster at three times the speed of sound, or Mach 3, and instantly converted the desert sand in its path to glass.

The Qualification Motor-2 (QM-2) test provided NASA with data on 82 design objectives that will support certification of the booster for flight. Engineers will evaluate the results, as captured by more than 530 instrumentation channels on the vehicle.

"The immense roar from the booster was really a delight," said Charlie Precourt, general manager and vice president of Orbital ATK's propulsion systems division. "They asked me what would signal that [the QM-2 test] was a complete success and I said, 'So long as you see flames for the two minutes and six seconds... we've done the vast majority of the work,' because that is what we need when we power crew on out beyond low Earth orbit."

The flight and use history for Orbital ATK's QM-2 rocket booster.

Prior to going to work for Orbital ATK, Precourt personally experienced the power of the company's boosters, riding atop four four-segment pairs as a NASA astronaut. His first launch, on the space shuttle Columbia's STS-55 mission in 1993, included the same capture feature cylinder as was in place as part of the middle segment used on Tuesday.

The same cylinder also flew on Precourt's fourth and final shuttle mission, STS-91, lifting off with orbiter Discovery in 1998. The flight marked the last time that a NASA shuttle visited Russia's Mir space station, setting the stage for the International Space Station.

The full heritage of the QM-2 motor includes components that launched all five orbiters in NASA's now-retired shuttle fleet, on missions as early as STS-51F in July 1985 and as late as STS-134, the penultimate flight of the space shuttle program, in May 2011.

Not that NASA and Orbital ATK simply reused the shuttle-era hardware without modifications.

"In simple terms, the outside of the car looks the same, but when you lift up the hood of the vehicle, almost everything else has changed," said Alex Priskos, manager of NASA's SLS Boosters Office at the Marshall Space Flight Center in Huntsville, Alabama.

In addition to using a fifth segment to produce the needed extra energy to launch the larger SLS, the rocket boosters also feature a different grain configuration, a new state-of-the-art digital avionics system and a strengthened forward skirt.

"For performance and cost reasons, and how we are going to evolve this program, we don't have a recovery system on these boosters," added Priskos, referring to the drogue and main parachutes that enabled the shuttle-era boosters to be recovered and reused. "We have plenty of assets to do what we need to do."

During a Space Launch System (SLS) flight, two boosters like QM-2 seen here, will provide more than 75 percent of the thrust needed to escape the gravitational pull of the Earth. (NASA/Bill Ingalls)

Orbital ATK's inventory of space shuttle-era hardware will support eight SLS launches. By the time those 16 motors fly, NASA expects to replace the five segment solid rockets with upgraded boosters.

The QM-2 booster also tested a new joint sealant on its nozzle. The carbon fiber rope used to hold the two parts of the nozzle together for Tuesday's test will be compared to the previous performance of an o-ring tested as part of the first qualification motor (QM-1) in March 2015. The carbon fiber rope and o-ring are potential alternatives to the RTV caulk used during the shuttle program.

To date, Orbital ATK has casted three of the rocket booster segments that will launch the first SLS flight, Exploration Mission-1 (EM-1), in the fall of 2018. The flight will loft an uncrewed Orion spacecraft on a trajectory out beyond the moon and back.

The two solid rocket boosters will operate in parallel with four RS-25 main engines — also shuttle legacy hardware — for the first two minutes of the SLS's ascent, providing more than 75 percent of the thrust needed for the rocket to escape the Earth's gravity. The boosters and main engines will produce 15 percent more thrust than the Apollo Saturn V, enabling SLS to fly more than three times the payload of the space shuttle.