#journeytomars – Rocketology: NASA’s Space Launch System

All Roads Lead to the Pad

NASA is preparing for the first of many flights of the agency’s Space Launch System rocket and Orion spacecraft. Every day we’re making progress toward their first integrated test flight. Today, that work is taking place at numerous sites around the country, but the work of that nationwide team is firmly focused on one place – the launch pad.

Hundreds of companies across every state have been a part of SLS and the Orion crew spacecraft, many of them small businesses providing specialized components or services. That work comes together at NASA and prime contractor facilities where the “big pieces” are assembled before it all comes together on the launch pad at NASA’s Kennedy Space Center in Florida.

A crane lifts the ICPS test article out of a shipping container. — A test article of the Interim Cryogenic Propulsion Stage was delivered to Marshall Space Flight Center from United Launch Alliance in June.

1) Second Stage, From Alabama to Florida by Barge

Some of the pieces have a relatively direct route to the launch pad. At Marshall Space Flight Center in Huntsville, Alabama, where the SLS program is managed, for example, the flight unit for the Orion Stage Adapter (OSA) that will connect the SLS second stage to the crew spacecraft is being welded, and welding will begin next month on the Launch Vehicle Stage Adapter (LVSA) that will connect the core and second stages. When completed, the LVSA will travel by barge to the gigantic Vehicle Assembly Building (VAB) at Kennedy Space Center (KSC) in Florida, where final stacking of SLS and Orion will take place. The smaller OSA has the option of barge or truck, and after arriving in Florida, will make a stop at a facility where 13 CubeSats will be installed before continuing on to the VAB.

Half an hour away, the second stage of the rocket, the Interim Cryogenic Propulsion Stage (ICPS), is being completed at the United Launch Alliance facility in Decatur, Alabama. The process for the ICPS will be one step longer – after being barged from Decatur to Florida, the stage will be prepared for flight at a payload processing facility before being moved to the VAB for stacking.

Booster segments being delivered by train to Kennedy Space Center during the space shuttle era.

2) Boosters, From Utah to Florida by Train

Propellant is already being cast into booster segments for the first flight of SLS. The boosters will be transported by train from an Orbital ATK facility in Utah to Florida. Since the 17-story-tall boosters are far too long to be transported in one piece, the boosters will be transported in segments. They’ll arrive at a processing facility at Kennedy before being moved to the VAB where they’ll be stacked vertically and joined by the rest of the rocket.

Cutaway view of the core stage inside the Pegasus barge — NASA’s large Pegasus barge will be able to transport the SLS core stage, which will be more than 200 feet long.

3) Engines and Core Stage, From Mississippi to Louisiana to Mississippi to Florida By Barge

This one’s a little more complicated. RS-25 core stage engines are currently in inventory at Stennis Space Center in Mississippi, where engine testing is taking place. The core stage hardware for the first launch of SLS is currently being welded at Michoud Assembly Facility in New Orleans. The engines for the first flight will be transported from Stennis to Michoud, and integrated into the first core stage when it’s completed. The core stage with engines will then be transported back to Stennis, where the 212-foot-tall stage-and-engine assembly will be placed into a test stand and all four engines will be fired together in the largest liquid-engine ground test since Apollo. After the test, plans call for the stage to be shipped to Kennedy by barge, where it will be brought to the VAB for assembly with the rest of the rocket.

Artist concept of SLS and mobile launcher on the crawler transporter. — The crawler-transporter is capable of transporting 18 million pounds from the VAB to the launch complex.

4) Rocket, From VAB to Launch Pad via Crawler

Once all of the elements have arrived at the VAB, they’ll be stacked vertically and prepared for launch. The large crawler transporter will bring the mobile launcher with tower to the rocket, and will then carry rocket and launcher together to the launch pad. Which leaves only one last step:

5) Orion, From Launch Pad to Deep Space, via Rocket

NASA is on track for the first mission to launch no later than November 2018 from Florida. The first test flight of SLS and Orion will be incredible, and it will pave the way for our second exploration mission – our first with crew aboard the spacecraft. As these missions continue to come together, we’re closer to sending astronauts to Red Planet than at other point in our history. All the work we’re doing together today will continue to enable that journey in the future.

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The 83rd Thing Learned from QM-2

View from the forward end of the QM-2 booster during the test firing — During the two-minute booster test, 537 instrumentation channels provided data to meet 82 different test objectives.

They came for an awesome display of pure propulsive power.

They got a lesson in the realities of spaceflight. …Followed by an awesome display of pure propulsive power.

While engineers in Utah prepared for the second Qualification Motor (QM-2) test of a Space Launch System (SLS) solid rocket booster, another team of NASA engineers from Marshall Space Flight Center visited the U.S. Space & Rocket Center in Huntsville, Alabama to give a presentation to Space Camp trainees and museum guests explaining what would be happening during the test, how the boosters work, what the next steps are to get the boosters ready for the first launch, and how Space Launch System will play a key role in NASA’s Journey to Mars.

The museum, which is home to Space Camp, is practically in the backyard of NASA’s Marshall Space Flight Center, where SLS is managed. On the morning of the test, museum attendees and Space Camp trainees filled a theater at the museum to watch the two-minute-long firing of the 17-story solid rocket booster, the most powerful ever built for human spaceflight. The firing would provide information to answer 82 questions about how the booster performs, including how it would respond in cold-weather conditions.

What they ended up seeing that day was a huge milestone for the Space Launch System and a major step toward human exploration of deep space. The motor performed as anticipated for the burn. The inside of the motor, where the propellant had been cooled to 40 degrees Fahrenheit to simulate a cold day at the launch site, reached nearly 6,000 degrees, and the flames leaving the booster melted sand into glass. The test clears the way for qualification of the solid rocket boosters as ready to fly on the first launch of SLS in 2018.

Marshall engineer Karen Bishop gives a presentation — While the test was delayed, attendees of the viewing heard a NASA engineer explain information about the test and boosters, and their path from QM-2 to the launch pad.

In addition to the test and presentation, they also got a real-life lesson on the challenges in developing and flying space systems. As hundreds of children took their seats, the live NASA TV feed appeared on the giant theater screen, showing the booster mounted in the test stand – and the word “hold” underneath it.

A technical issue had delayed the test – a problem with a sequencing computer. When one listens to the audio feed of a rocket or shuttle launch, you can hear announcements of the steps being taken as the countdown clock nears zero – “vehicle is on internal power,” “main engines start,” etc. For a rocket to launch, numerous things have to all happen properly, and all in the correct order, one event paving the way for the next. The booster test required that same sort of preparation and precision – many things had to happen properly, and in the proper order, both before and after ignition of the booster. When the computer responsible for managing that sequence failed to function correctly, the test had to be delayed.

From a big picture view, the delay was relatively minor – after a discussion on how best to proceed, the software was changed out, the clock was reset, and the test took place just one hour after it was originally scheduled.

During the delay, the audience heard the NASA team’s presentation and got a big-screen viewing of last year’s first qualification motor test (QM-1) test. But they also got a real-world demonstration of what they’d been learning in Space Camp – the best word you can hear in the space business is “nominal,” meaning everything is proceeding as expected, but there are sometimes you don’t hear that word. You work as hard as you can to make sure that you do, and you work as hard as you can to be prepared for when you don’t. When an “off-nominal” challenge arose, the NASA and Orbital ATK team in Utah rapidly assessed the problem, identified options for moving forward, evaluated the risks and benefits, and implemented a solution that allowed the test to proceed quickly and successfully.

Museum visitors and Space Camp trainees watching the QM-2 test at the U.S. Space & Rocket Center in Huntsville, Alabama.

While some of the original attendees had to leave in favor of hands-on activities like microgravity water-tank training, when the test took place, the remaining audience counted down to the firing, and cheered when the booster ignited and extinguished, the giant screen showing the close-up shots at almost life size and the sound system doing its best to do justice to the roar of the motor as it turned desert sand into glass. There was excitement over the observation that the next time a booster like this is lit, it will be powering SLS off the launch pad for its first flight.

The one QM-2 solid rocket motor, by itself, produced more thrust than it takes to lift most rockets off the ground and send them into space, and required millions of pounds of concrete in the test facility to make sure it didn’t move.

Next time, there will be nothing holding it back.

Next Time: All Roads Lead to Florida

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Happy (Earth-) Independence Day!

On Monday, the United States celebrated the Fourth of July. Fireworks and backyard grills were ignited across the country.

A couple hundred miles above us, the International Space Station orbited Earth with two spacecraft attached to it.

What do these two things have in common? A quest for independence.

The Fourth of July, of course, is the United States’ Independence Day, celebrating the anniversary of the 1776 signing of the Declaration of Independence, announcing that the former colonies were becoming a sovereign nation.

The International Space Station is an early, but prominent step in NASA’s effort to achieve “Earth independence” in human deep-space exploration, a key part of our Journey to Mars. On the station, we are learning how to live off the Earth by conducting investigations to learn how the human body adapts to space and testing new technologies needed for longer missions. However, the two spacecraft docked to the space station demonstrate that our human spaceflight operations today are “Earth dependent.” While astronauts float freely in the microgravity aboard the station, they remain tethered to our planet by a supply chain of provisions needed to survive. Deliveries of food, science experiments, spare parts and gifts from home arrive and depart by spacecraft on a regularly scheduled basis. Earlier this year, the number of docked spacecraft reached six: American Dragon and Cygnus cargo ships, and Russian Progress cargo ships and Soyuz crew vehicles. Should something go wrong, the return to Earth is only a short distance away.

A Dragon capsule is being berthed to the International Space Station — American Dragon and Cygnus spacecraft can be seen here at the International Space Station, joining Russian Soyuz and Progress vehicles.

In order to travel to Mars, astronauts will have to survive without that tether. When they depart Earth, they will sail into the void of space without the comfort of frequent visits from resupply ships. They will have no quick return; should something break or go wrong, Earth is potentially more than a year away. These pioneers will rely on themselves and what they have with them, or what has been sent ahead. They will be the first to be independent of our home planet, with both the freedom and responsibility that carries with it.

Significant challenges await us as we move from Earth dependence into Earth independence, learning to operate in space in a way we never have before. To accomplish this, we will carry out “proving ground” missions – missions where we will, innovate, test, and validate new systems and capabilities that will help us learn to live longer and farther away from home. The first launch of the Space Launch System (SLS) rocket with the Orion crew vehicle will mark our entry into this proving ground era, relying on new systems farther from Earth than any human spaceflight mission has ever ventured. SLS and Orion will allow us to launch habitats and other equipment that will support the first astronauts to not only visit, but to live in deep space around and beyond our moon.

A spacecraft approaches Mars and its moons — Astronauts in deep space will need to be able to survive without frequent resupply missions from Earth or being able to return quickly to Earth.

When we have demonstrated the ability to live and thrive in deep space, the time will come for the first mission to leave the neighborhood of the Earth and moon and extend human existence into the solar system, a mission that will not only be a major step toward human landings on Mars but will be our declaration of Earth-independence.

In that moment, the word “Independence” will designate the time when humankind became an interplanetary species.

Get the grills and fireworks ready, because that will be an occasion to celebrate.

Next Time: A Real-World Space Lesson

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SLS Avionics: The Brain Without a Body

By Martin Burkey

If you compared NASA’s powerful Space Launch System (SLS) rocket to a human body, the avionics and software would be the nervous system and brain that monitor the body’s condition and makes and sends decisions. Just a few of the hundreds of operations that they make include: liquid propellant flow, engine throttling, engine and booster exhaust nozzle steering, trajectory updates, receiving and sending data to the crew and ground control, and responding to off-nominal issues such as wind gusts or an engine failure.

The avionics are required to work in environments of temperature, pressure, sound, etc. that no human body – and actually few machines – could tolerate. So everything from the boxes, to the boards, to the individual processors are “ruggedized” and tested at every step in development to survive launch.

Ultimately the avionics boxes and software have to work perfectly. But how can you be sure without putting it on the world’s largest rocket and seeing how it works? That’s the focus of the Integrated Avionics Test Facility – or IATF – at NASA’s Marshall Space Flight Center, where the computer, routers, processors, power, and other black boxes and software collectively known as “avionics” are being tested in preparation for the planned 2018 first flight of SLS.

Possibly the coolest thing about the test facility is that it can create an artificial vehicle operating in an artificial world and virtually “fly” SLS hundreds of times – from pre-launch activation and checkout to liftoff to core stage separation at about 17,500 miles per hour and 100 miles in space – to test the entire avionics package.

Expanded view of SLS showing various avionics locations. — Location of avionics aboard SLS Block 1.

Avionics can be found all over SLS: in the booster aft skirt and forward skirt, the core stage engine controllers mounted on the engines themselves, in the core stage engine section, intertank, and forward skirt, in the launch vehicle stage adapter, and in the Interim Cryogenic Propulsion Stage. Of course, avionics for the Orion crew vehicle are also linked in to the performance of the whole vehicle. So basically top to bottom.

Inside the test facility, the vehicle avionics boxes are mounted on a semi-circular, 18-foot-tall frame in the same relative position they will be inside SLS – right down to the length of the connecting cables. Outside the frame, several large towers house the equipment for simulating the SLS “world” and running test after test.

The virtual world of SLS is created by a pair of software tools, ARTEMIS and MAESTRO. They stand for A Real-Time Environment for Modeling, Integration and Simulation (ARTEMIS) and Managed Automation Environment for Simulation, Test, and Real-Time Operations (MAESTRO). (How do engineers come up with this stuff?) ARTEMIS is a suite of computer models, simulations and hardware interfaces that simulates the SLS and its virtual “world.” For instance, it simulates the Earth’s rotation, gravity, propellant tank sloshing, vehicle bending in flight, engine and booster pressure, temperature and thrust, and weather, from hot sunny days to cold stormy nights, and inputs from the Orion crew vehicle and launch facilities. In fact, ARTEMIS has far more lines of software code than SLS itself. MAESTRO serves as the test conductor for the virtual missions. This software configures and controls test operations, sets up the external conditions, monitors the tests, and archives all test data for analysis. That’s where engineers and software writers find out if their code needs fixing or supplementing.

The actual flight avionics for SLS will never be tested in this facility – only their flight-like equivalents. The actual flight avionics will be installed directly into the core stage at the Michoud Assembly Facility in Louisiana and tested there prior to flight. The test team at Marshall can already say that they’ve flown SLS “virtually” thousands of time to help ensure that SLS flies safely on its first real mission in a couple of years.

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

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

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.

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

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.

“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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Small Hitchhikers Ride through the Galaxy

By Beverly Perry

On the first launch of the Space Launch System (SLS), America’s next-generation heavy-lift rocket, the Orion Stage Adapter (OSA) will carry 13 CubeSats, or boot box-sized science and technology investigations, that will help pave the way for future human exploration in deep space. Engineers and technicians at NASA’s Marshall Space Flight Center have built the main structure of this hardware that will be part of the rocket when it lifts off from Launch Complex 39B at NASA’s modernized spaceport at Kennedy Space Center in Florida.

The Orion Stage Adapter being designed and manufactured at NASA’S Marshall Space Flight Center in Huntsville, Ala. nears completion. — Jennifer Takeshita, the lead for friction stir welding at Teledyne Brown Engineering, compares a model of the Orion Stage Adapter (OSA), including brackets to secure CubeSats during their spaceflight, to the flight hardware nearing completion at Marshall Space Flight Center.

The Orion Stage Adapter does exactly what its name indicates: it connects the Orion spacecraft to the second stage of the launch vehicle. Using enormous friction-stir welding machines, engineers just finished welding three large panels into a ring that is 18 feet in diameter and 5 feet high. With this welding complete, it’s time for analysis. The main structural ring is currently undergoing nondestructive analysis using 3-D structured light scanning and photogrammetry, which creates a computer model using photography, to ensure hardware was built to design specification.

Three-dimensional structured light scanning, photogrammetry, and solid modeling software are helping engineers visualize the minute differences between the OSA that was designed and the hardware that was built. — Engineers use 3-D structured light scanning and photogrammetry to analyze the main structure of the Orion Stage Adapter (OSA) at Marshall Space Flight Center. Targets for the optical scanner and SLR camera can be seen on the aluminum structure. Solid modeling software will combine the images into a single computer model so engineers can compare finished hardware to the design.

Next, engineers will trim it, weld upper and lower rings onto the large ring, machine it to final dimensions, apply paint, and install the diaphragm, a barrier that separates SLS from Orion. After that, installation of cables and the brackets that will secure the secondary payloads during their spaceflight will complete this critical piece of flight hardware.

The 13 CubeSat secondary payloads will be some of the first small satellites to explore deep space and answer critical questions relevant to NASA’s future exploration plans. These small but mighty scientific investigations include ten satellites from U.S. industry, government, and commercial partners as well as the three CubeSats being built by international partners.

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Next Generation Wants Its Mars Shot

By Beverly Perry

We don’t know who will take those first steps on Martian soil, ushering in the age of humans as a multi-planetary species. But we do already know a couple things about those first intrepid explorers: They’re taking steps on Earth right now; and they belong to a generation that is tech-savvy, and raised on the internet and social media. But do today’s students think about exploring beyond this world and into deep space?

University of Illinois Urbana-Champaign student rocketry team — Members of the University of Illinois Urbana-Champaign’s rocketry team said at NASA’s Student Launch competition that they look forward to NASA’s Journey to Mars and aspire to be a part of it.

“Every day – we can’t get enough of that stuff!” said Ben Collins from the University of Illinois Urbana-Champaign on a recent windy morning that was spent launching rockets in a field north of Huntsville. Collins and his teammates were among 51 student rocketry teams that competed in various challenges and sent their amateur rockets soaring during the 16^th annual Student Launch rocketry challenge April 13-16.

Tuskegee University’s rocketry team at NASA’s Student Launch competition — Members of Tuskegee University’s rocketry team enjoy their day at NASA Marshall’s Student Launch.

At this year’s Student Launch, middle and high school students and university computer scientists, physicists and engineers of all stripes (aerospace and mechanical were particularly well-represented) got to tour NASA’s Marshall Space Flight Center, the center responsible for developing the Space Launch System (SLS), the country’s next-generation heavy-lift launch vehicle.

While there, the students heard from a member of their generation actively involved in designing and engineering SLS: Marshall engineer Kathryn Crowe, who is part of a generations-spanning workforce blending fresh thinking with years of experience. (See Time Flies: Next-Generation Rocket is the Work of Generations for more about Kathryn’s work.)

For some, the competition – and the visit – were a taste of things to come.

“My biggest career goal is to work on the Journey to Mars – to somehow be a part of it,” said Brandon Murchinson, also of the University of Illinois Urbana-Champaign. “I think SLS is incredible. As someone who’s always been interested in space exploration and travel, it’s why I chose this career path.”

NASA’s call for new astronauts earlier this year also made an impact on the future engineers and scientists at the Student Launch. Paul Grutzmacher, a 17-year-old senior at St. Vincent-St. Mary High School in Akron, Ohio, said that his career goal is to become a pilot for the Orion crew vehicle that will launch on SLS. “SLS excites me because it’s supposed to take us farther than we’ve gone before and it’s also our next heavy lifter,” he added.

St. Vincent-St. Mary High School rover at 2016 Student Launch. — St. Vincent-St. Mary High School’s Project Manager Raykwon Wookdruff describes the team’s rover, which autonomously located the team’s downed rocket, providing a proof of concept that an autonomous rover on Mars could locate and retrieve a supply rocket without astronauts having to leave the vicinity of their habitat.

Grutzmacher thinks he’s got the right stuff to fly on SLS, but so does Vanderbilt University’s Rebecca Riley, a senior computer science major who plans to continue her education in particle physics. “I think we’re all pretty excited that we might be the right age to be going to Mars. I’m like, Man, that’s going to be me going to Mars!”

These students recognize the value in missions that build expertise in long-duration spaceflight – and the technological spinoffs that arise from the process. To hear them tell it, long timelines just don’t scare them.

Auburn University’s student rocketry team tracks progress on America’s next great rocket by following social media and events like solid rocket booster static test firings and RS-25 main engine tests. “Social media makes it a lot more tangible,” said Auburn’s Burak Adanur. “And I think it gives people something to look forward to,” he said.

Vanderbilt University’s Andrew Voss has participated in the Student Launch over the past four years. “I have seen a lot of work go down,” he said. “And I like seeing the test stands because the work that goes into testing is a feat of engineering.” Check out our recent blog post on Engine 2059 for more about how an engine helped test a test stand.

Tech-obsessed students have no trouble spouting off advancements that have arisen from America’s space program: cell phone cameras, scratch-resistant sunglasses, memory foam, and the list goes on. Vanderbilt’s Voss said, “That’s part of what NASA’s always done, and what could come out of SLS is not just spaceflight, but technology that drives the world forward.”

Vanderbilt University rocketry team launches rocket — Members of Vanderbilt University’s student rocketry team spoke about the future of deep space exploration after successfully launching their rocket.

“I think that’s one of the most important aspects to space exploration,” said Auburn’s Adanur. “We have to go space because it’s a mechanism – it’s a crucible – that will change us as a society and give us new technologies. I think it has more of a ripple effect than most people think.”

Chris Lorenz of the University of Illinois at Urbana-Champaign said he sees the value of NASA’s proving ground missions to build up for human Mars landings. “I’m a big fan of what NASA does in robotic exploration. It’s smart to go unmanned and build up infrastructure first before attempting manned missions,” he said.

Vanderbilt’s Mitch Masia said that while proving ground missions are necessary, deep space exploration really gets people going. “The space station is awesome and a huge feat and deep space missions will get people even more excited.” Case in point: Worldwide amazement and wonder at the photos of Pluto NASA’s New Horizons spacecraft has been sending back to Earth.

Sylvania Northview High School rocketry team at NASA’s Student Launch competition — Members of Sylvania Northview High School’s rocketry team explain their project to other students during the Rocket Fair at NASA’s Marshall Space Flight Center the day before launch.

Participants at the Student Launch emphasized that their generation wants its chance to make history. They want their Mars shot. “I think SLS will bring our generation together,” said Michael D’Onofrio, a 17-year-old senior at Sylvania Northview High School in Sylvania, Ohio. “Something that’s greater than where we are – going beyond Earth – will bring us together.”

Vanderbilt’s Riley said, “I’m excited about SLS in a very patriotic way. SLS and going to Mars is that big goal that we can all get behind and be excited about as an American people.”

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We’ve Got (Rocket) Chemistry, Part 2

Editor’s note: This is the second in a two-part series on the chemical reactions at the heart of rocket propulsion. Last week, we talked about the liquid engines of the SLS core stage , this week we’ll talk about the boosters.

By Beverly Perry

To give SLS extra power to get it off the ground, twin five-segment rocket boosters, built by Orbital ATK, tower more than 17 stories tall, burn six tons of solid propellant each second and help SLS break free from the clutches of Earth’s gravity.

Solid rocket fuel is the original rocket fuel, dating back to the early fireworks developed by the Chinese centuries ago. For the SLS boosters, aluminum powder serves as the fuel and a mineral salt, ammonium perchlorate, is the oxidizer.

Artist rendition of boosters and engines of during launch — The powerful aluminum-ammonium perchlorate reaction fuels the twin SLS solid rocket boosters.

Aluminum is the most abundant metal on Earth. It’s also highly reactive. Aluminum is so reactive, in fact, that it’s not found naturally in its pure form but only in combination with other minerals. It’s this ability to readily combine with other metals that makes aluminum so useful. Every day, we use products made of aluminum alloys, or mixes with other metals, for things like beverage containers, covering leftovers, or iPhones. Amazingly, it’s this same stuff that fuels solid rocket boosters.

Ammonium perchlorate, the salt of perchloric acid and ammonia, is a powerful oxidizer (read: majorly explosive). In the boosters, the aluminum powder and ammonium perchlorate are held together by a binder, polybutadiene acrylonitrile, or PBAN. The mixture, with the consistency of a rubber eraser, is then packed into a steel case.

: Interior of booster case after firing — This is what the inside of the empty booster case looked like after the first qualification motor test in March 2015. Preparations are already well underway for the second qualification test this summer.

When it burns, oxygen from the ammonium perchlorate combines with aluminum to produce aluminum oxide, aluminum chloride, water vapor and nitrogen gas – and lots of energy.

This reaction heats the inside of the solid rocket boosters to more than 5,000 degrees Fahrenheit, causing the water vapor and nitrogen to rapidly expand. Just like in the liquid engines, the nozzle funnels the expanding gases outward, creating thrust and lifting the rocket from the launch pad.

Compared to liquid engines, solid motors have a lower specific impulse – the measure rocket fuel efficiency that describes thrust per amount of fuel burned. However, the propellant is dense and burns quite quickly, generating a whole lot of thrust in a short time. And once they’ve burned their propellant and helped propel SLS into space, the boosters are discarded, lightening the load for the rest of the spaceflight.

So that’s it really. Make water and shoot off an enormous firecracker and you’ve got: Rocket Chemistry. On this scale though, you can’t try this at home. Watch the real show when SLS launches in 2018.

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