Monthly Archives: June 2016

Behind the Scenes at QM-2: Getting Ready to Test the World’s Largest Solid Rocket Motor

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By Beverly Perry

For two monumental minutes on June 28, the Space Launch System (SLS) solid rocket boosters — the largest ever built for flight — will fire up in an amazing display of power as engineers verify their designs in the last full-scale test before SLS’s first flight in late 2018. Each piece of hardware that’s qualified and each major test — like this one, dubbed QM-2 — puts NASA one step closer on its Journey to Mars.

The smoke and fire may last only two minutes, but engineers at NASA’s Marshall Space Flight Center in Huntsville, Alabama and Orbital ATK in Promontory, Utah have been preparing weeks — even months — in advance for the static test of Qualification Motor 2 (QM-2). Here’s a behind-the-scenes look at what goes into getting ready to fire up the largest and most powerful solid rocket motor ever built for flight.

T (for test) minus weeks and months. In the months prior to the test, propellant-filled segments began arriving at Orbital ATK’s Test Bay T-97 after being cast in nearby facilities. Many of these segments are veterans of space shuttle flights. In fact, the various metal case segments that comprise the five-segment QM-2 motor flew on 48 shuttle flights!

T minus 14 days. In the two weeks leading up to the test, Orbital ATK engineers begin dry runs that simulate the final test as closely as possible (without the smoke and fire). They put the motor and associated systems through their paces no fewer than 11 times before the big day to ensure not only that all systems are functioning as expected, but also that the test will be executed properly. “We only get one shot at firing the rocket motor,” says Dr. Janica Cheney, Orbital ATK’s director of Test Operations. “All the dry runs and other preparations that take place ahead of time are critical to ensuring we get the data we need from this test firing.”

NASA and Orbital ATK test SLS Qualification Motor-2 (QM-2) before first flight.

Are you ready? It’s time for the final full-scale test before the first flight test of the SLS solid rocket motor June 28 at 10:05 a.m. EDT (8:05 a.m. MDT). Many cameras record data during the test, such as this one which captures nozzle plug performance during the test.

T minus 24 hours. For this final full-scale static test, engineers have 82 goals, or test objectives, they need to measure and evaluate. One day before the test, it’s crunch time; caffeine’s flowing as engineers work around the clock the day before the test to ensure all systems function properly and all necessary data can be collected.

T minus 8 hours. Game day. There’s focus — and excitement. There are two more dry runs leading up to the test. Engineers, technicians and operators are “on station,” — present and accounted for at key locations such as the test bay, the instrument rooms and the control bunker. When you hear “control bunker,” think mission control — a command and control center that directs every aspect of the test, similar to what you see at mission control during a launch. Time flies during the final eight hours before the test.

Orbital ATK’s Test Bay housing rolls back to reveal Qualification Motor-2 (QM-2).

At T minus 6 hours with a “go” decision for testing QM-2, engineers at Orbital ATK will roll back the booster test bay housing so the massive motor can be fired.

T minus 6 hours. At 4:05 a.m. EDT (2:05 a.m. MDT), engineers and managers at Orbital ATK and NASA will make a “go” or “no go” decision on testing that day. Assuming the test’s a go, technicians “roll back” Orbital ATK’s specially designed moveable test bay housing and begin running final checks to make sure everything is ready. “We check the status of all the data and control systems, the test bay, the motor preparation and weather conditions,” Cheney says.

Weather is one variable that can halt the QM-2 test. “We make sure there’s no lightning in the area; no high winds; no storms,” explains Orbital ATK Fire Chief Blair Westergard. “We also establish fire breaks. Along with the Box Elder County Fire District, we’re prepared to extinguish any secondary wildfires too.”

Engineers also make sure cameras are ready to film and all data recording systems are online and functioning properly. Orbital ATK Security ensures the area around the test is clear.

T minus 3 hours. Crowds begin to gather as the public viewing area near Promontory off State Route 83 opens at 7:30 a.m. EDT (5:30 a.m. MDT). Orbital ATK Security directs traffic with the help of the Utah Highway Patrol and provides crowd control support to ensure everything remains orderly — vital when 10,000 people are in attendance.

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T minus 1 hour. The formal countdown commences; the public address system broadcast begins. The crew in the test bay begins final procedures to prepare the booster for testing.

T minus 9 minutes. Final system and timing checks are underway.

T minus 4 minutes. A “go for test” announcement sounds from the public address system.

T minus 1 minute. A siren begins; it will blare through T minus 20 seconds.

T minus 45 seconds. The “Safe and Arm” system sequence begins, which arms the motor. The Safe and Arm device is remotely activated from the “safe” position into the “armed” position, allowing the motor to ignite when the “fire” command is given.

T minus zero. At 10:05 a.m. EDT (8:05 MDT), two minutes of pure awesome commence as the gigantic motor burns through about five and a half tons of propellant each second during the approximately two-minute test. Inside the control bunker, there will be jubilation — and relief. “This is serious business — this is rocket science,” Cheney emphasizes. “But there’s nothing better than the smoke and fire and the data that comes with it when you’ve had a successful day. Our success is NASA’s success — we don’t do it alone.”


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Three Cool Facts About QM-2

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By Beverly Perry

The countdown to the last full-scale test firing of the massive Space Launch System (SLS) solid rocket boosters has begun. Mark your calendars: June 28, 8:05 a.m. MDT.

Expect two minutes of shock and awesome as the flight-like motor burns through about six tons of propellant each second during the test. With expanding gases and flames exiting the nozzle at speeds in excess of Mach 3 and temperatures reaching 3,700 degrees Fahrenheit, say goodbye to some of the sand at Orbital ATK’s test facility in the Utah desert because after the test, the sand at the aft, or rear, end of the booster motor will be glass.

NASA and Orbital ATK are rolling back the house and rocking the Utah desert for QM-2 June 28.

NASA and Orbital ATK are rolling back the house and rocking the Utah desert for QM-2 June 28.

The 154-foot long Qualification Motor 2 (QM-2) consists of the five propellant-filled segments in the middle of the booster; the aft skirt is also part of the test, but the forward assembly (nose cap, forward skirt) won’t be. (See our Boosters 101* infographic if you need a refresher on booster parts and assemblies). The test will broadcast live on NASA TV and our Facebook page. We will also live tweet from @NASA_SLS on Twitter.

For those watching at home (or work), here are three cool things that might not be so obvious on the screen, in countdown order.

3. This motor’s chill. QM-2’s been chilling — literally, down to 40 degrees — since the first week in May in Orbital ATK’s “test bay housing,” a special building on rails that moves to enclose the booster and rolls back so the motor can be test-fired. Even though SLS will launch from the normally balmy Kennedy Space Center in Florida, temperatures can vary there and engineers need to be sure the booster will perform as expected whether the propellant inside the motor is 40 degrees or 90 degrees (the temperature of the propellant during the first full-scale test, Qualification Motor 1 or QM-1).

2. This booster’s on lockdown. If you happen to be near Promontory, Utah on June 28, you can view the test for yourself in the public viewing area off State Route 83. And don’t worry, this booster’s not going anywhere — engineers have it locked down. The motor is held securely in place by Orbital ATK’s T-97 test stand.

During the test, the motor will push against a forward thrust block with more than three million pounds of force. Holding down the rocket motor is more than 13 million pounds of concrete — most of which is underground. The test stand contains a system of load cells that enable engineers to measure the thrust the motor produces and verify their predictions.

Solid rocket booster test burns so hot it turns sand to glass.

The solid rocket motor test firing will burn so hot the sand at the aft end of the motor will turn to glass.

Putting out the fire at the end of the test is the job of the quench system, which fills the motor with carbon dioxide from both ends of the test stand. A deluge system sprays water on the motor to keep the metal case from getting too hot so the hardware can be re-used. Both the quench and deluge systems had to be upgraded to handle the heat and size of the big five-segment boosters.

1. Next time, it’s for real. These solid rocket boosters are the largest and most powerful ever built for flight. They’ve been tested and retested in both full-scale and smaller subsystem-level tests. Engineers have upgraded and revamped vital parts like the nozzle, insulation and avionics control systems. They’ve analyzed loads and thrust, run models and simulations, and are nearing the end of verifying their designs will work as expected.

Most of this work was necessary because, plainly put, SLS needs bigger boosters. Bigger boosters mean bolder missions – like around the moon during the first integrated mission of SLS and Orion. So the next time we see these solid rocket motors fire, they will be propelling SLS off the launch pad at Kennedy Space Center and on its first flight with Orion. For real.

Next time: Behind the Scenes at QM-2: Getting Ready to Test the World’s Largest Solid Rocket Motor.


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A (much) Closer Look at How We Build SLS

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By Martin Burkey

How do you put the world’s largest rocket under a microscope?

One piece at a time, of course.

NASA’s Space Launch System – SLS – will be the world’s most powerful, capable rocket. It will send intrepid explorers, their spacecraft, their landers, their habitats, and all their other equipment to survive and thrive in deep space.

But, first, it has to survive launch. SLS is an extreme machine for operating in extreme environments – 6 million pounds going from zero to around 17,500 miles per hour in just 8 minutes or so after liftoff. Some parts are minus 400 degrees F. Some parts are 5,000 degrees. Extreme.

So NASA works hard to make sure everything works as planned, including the largest part, the core stage – 212 feet long, 27 feet in diameter, and weighing more than 2 million pounds all gassed up and ready to go.

NASA and core stage prime contractor Boeing are building hardware at Michoud Assembly Facility in New Orleans, Louisiana for the first flight in 2018. Engineers have put the design through numerous computerized structural analyses and simulations, but that’s not the same as actually cutting, welding, and assembling giant metal panels, domes, rings, etc. on new manufacturing tools with new processes for the first time. Each time, the team starts to weld new flight hardware, they methodically go through a series of steps to make sure that first flight hardware is perfect.

SLS liquid oxygen tank weld confidence article comes off the Vertical Assembly Center at Michoud Assembly Facility.

A liquid oxygen tank confidence article for NASA’s new rocket, the Space Launch System, completes final welding on the Vertical Assembly Center at Michoud Assembly Facility in New Orleans.

“Perfect” is a relative term. Some technically-minded people consider welding itself as a defect in a metal structure because the weld is never as strong as the rest of the metal, according to Carolyn Russell, chief of the metal joining and processes branch at Marshall Space Flight Center in Huntsville, Alabama, with 32 years of experience in the field. Given the advanced state of welding technology, other people might consider the term “defect” as a bit extreme.

None other than legendary rocket scientist Wernher von Braun declared in the midst of Saturn V moon rocket development in 1966: “A lifetime of rocketry has convinced me that welding is one of the most critical aspects of this whole job.”

The first step to SLS flight hardware was establishing the “weld schedule,” – how the welding will be done. SLS uses “friction stir welding” – a super fast rotating pin whipping solid metal pieces until they are the consistency of butter and meld together to bond the core stage’s rings, domes, and barrel segments. The result is a stronger and more defect-free weld, than traditional methods of joining materials with welding torches.

The completed SLS Launch Vehicle Stage Adapter awaits testing.

The completed SLS Launch Vehicle Stage Adapter (LVSA) structural test article awaits transfer to a test stand at NASA’s Marshall Space Flight Center in Huntsville, Alabama. Measuring 56-feet tall, the LVSA connects the SLS core stage to the upper stage.

Based on the particular aluminum alloy and thickness, engineers establish the required pin rotational speed, travel speed, how hard it pushes on the metal Before committing the welding schedule to full size or flight hardware, the core stage team checks the process on test panels about 2 feet long. Test panels are made at Michoud and sent to Marshall, where they are nondestructively inspected, sectioned and then analyzed microscopically for minute defects.

A false color composite image of the metal grain in an LVSA panel.

A false color composite image produced by an electron beam microscope at NASA’s Marshall Space Flight Center shows the crystal orientation of a portion of the thickness of a metal panel for the Launch Vehicle Stage Adapter.

Marshall materials scientists study the samples under magnification in the search for cracks and voids, and to understand how deeply the weld penetrated the parts. They also undergo non-destructive evaluation, including x-ray, ultrasonic, and dye penetrant testing.

With weld processes tested for every part of the core stage, the manufacturing team can begin building weld confidence articles, or “WCAs.” There are WCAs for the engine section, the liquid oxygen tank, and the liquid hydrogen tank. Likewise, the WCAs are cut into samples that are again put under the microscope at Marshall. In theory, the WCAs should be perfect if the weld schedule was followed. In reality, it doesn’t quite work out.

WCA welding consists of lots of “firsts,” Russell explained. It’s a test of the tooling and factors like parts alignment and tolerances. Heat transfer from the welds to the surrounding metal is different once large parts are clamped together. It short, stuff happens. Adjustments are made. Weld samples are cut and again put under the microscope until the weld schedule is perfected.

All this testing and microscope-gazing has led to a major SLS milestone: the welding of structural test articles – STAs – and flight articles for the hydrogen and oxygen tanks, engine section, and forward skirt, which is underway now. The STAs will be shipped to Marshall next year. Secured into test stands – that are secured firmly to the ground – these test articles will be rigged with hundreds of sensors and then pushed and prodded to see if they can survive the stresses the flight hardware will experience – accelerating bending, twisting, etc.

Then, and only then, can engineers say that the giant core stage is ready for its launch debut. But that’s a story for another day.


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