The Rocket Comes to the Rocket City

By David Hitt

Over the next year, the rocket comes to the Rocket City in a big way.

Huntsville, Alabama, a.k.a. “Rocket City,” is home to NASA’s Marshall Space Flight Center, where today the Space Launch System (SLS), the powerful rocket NASA will use for human exploration of deep space, is being developed.

More than six decades ago – before NASA even existed – Huntsville laid claim to the nickname thanks to its work on missiles and rockets like the Juno that launched the first American satellite or the Redstone used for the first Mercury launches.

In the years since, Huntsville, and Marshall, have built on that legacy with work on the Saturn V rockets that sent astronauts to the moon, the space shuttle’s propulsion systems, and now with SLS.

New test stand at Marshall Space Flight Center
A steel beam is “flown” by crane into position on the 221-foot-tall (67.4 meters) twin towers of Test Stand 4693 during “topping out” ceremonies April 12 at NASA’s Marshall Space Flight Center in Huntsville, Alabama.

While the program is managed at Marshall Space Flight Center, contractors around the country are building the rocket. Engines are being tested in Mississippi. The core stage is being built in Louisiana. Booster work and testing is taking place in Utah. Aerospace industry leaders and more than 800 small businesses in 43 states around the country are providing components.

The Marshall team has also been involved with the hardware, largely through testing of small-scale models or smaller components. The center also produced the first new piece of SLS hardware to fly into space – a stage adapter that connected the Orion crew vehicle to its Delta rocket for Exploration Flight Test-1 in 2014 (See Orion’s First Flight for more.) The same adapter will connect Orion to SLS for their first flight in 2018.

The top half of a test version of the SLS Launch Vehicle Stage Adapter on a weld tool at Marshall
Workers prepare the top half of a test version of the SLS Launch Vehicle Stage Adapter. The completed adapter will undergo structural testing at Marshall later this year.

Now, however, big things are happening in the Rocket City. The new Orion stage adapter for the upcoming launch is being built. The larger Launch Vehicle Stage Adapter, which will connect the core and second stages of the rocket, is being built at Marshall by contractor Teledyne Brown Engineering. This year, test versions of those adapters and the Interim Cryogenic Propulsion Stage (ICPS) will be assembled into a 56-foot-tall stack, which will be placed in a test stand to see how they handle the stresses of launch.

Those test articles built locally will be joined by larger ones produced at the Michoud Assembly Facility outside New Orleans. Test versions of the rocket’s engine section, oxygen tank and hydrogen tank will be shipped by barge from Michoud to Marshall. Two new test stands – one topped out last month at 221 feet tall – have been built at Marshall, joining historic test stands used to test the Saturn moon rockets.

The Payload Operations Center at Marshall Space Flight Center
In addition to rocket development, Marshall is involved in numerous other efforts, including supporting all U.S. scientific research conducted aboard the International Space Station.

Fifty-five years ago this month, Alan Shepard became the first American in space riding on a Redstone rocket, named for the Huntsville army base where his rocket had been designed – Redstone Arsenal. Today, Marshall, located on the same red clay that gave the arsenal and rocket their name, is undertaking perhaps its largest challenge yet – building a rocket to carry humans to the red stone of Mars.

Huntsville grew substantially from its small Southern town roots during its early days of rocket work in the 1950s and ‘60s, and Marshall has gone on to be involved in projects such as Skylab, Spacelab, the Hubble Space Telescope and the International Space Station, to name a few. But despite branching out its work both in space and other technology areas, Huntsville remains the Rocket City.

…After all, we built this city on a rocket role.

Join in the conversation: Visit our Facebook page to comment on the post about this blog. We’d love to hear your feedback!

Making a Lot of Fire in Two “Easy” Steps

On one end of the technology spectrum, you have rocket science, mastering the laws of physics to allow human beings to break the chains of gravity and sail through the void of space.

On the other end, you have the earliest humans, first learning to use the world around them in innovative ways to do things they previously couldn’t.

What do these two extremes have in common? Making fire. Just like the secret to learning to cook food was mastering the creation of flames, creating fire is also the secret to leaving the planet.

We just use a much bigger fire.

Close-up of aft end of SLS during launch
Solid rocket motors and liquid-fuel engines will work together to propel the first SLS into space.

If you’ve watched the first video in our No Small Steps series you’ve learned why going to Mars is a very big challenge, and why meeting that challenge requires a very big rocket. In the second installment we talked about how NASA’s Space Launch System (SLS) builds on the foundation of the Saturn V and the space shuttle, and then uses that foundation to create a rocket that will accomplish things neither of them could.

Now, the third No Small Steps video takes a step further by looking at the basics of the monumental energy that makes the rocket go up. If you’ve been following this Rocketology blog and the No Small Steps videos, you’re aware that the initial configuration of SLS uses two different means of powering itself during launch – solid rocket boosters and liquid-fuel engines.

But why? What’s the difference between the two, and what role does each play during launch? Well, we’re glad you asked, because those are exactly the questions we answer in our latest video.

With more SLS engine and booster tests coming in the next few months, this video is a great way to get “fired up” about our next steps toward launch.[/embedyt]
If you do not see the video above, please make sure the URL at the top of the page reads http, not https.

Join in the conversation: Visit our Facebook page to comment on the post about this blog. We’d love to hear your feedback!

Think You’re Stressed? Try Being A Rocket

You know how big the SLS vehicle will be. We described the tremendous power and thrust of just one of the RS-25 engines after last year’s test firings. You may have witnessed live as we fired one of the massive five-segment solid rocket boosters last March. Through all that, perhaps you can imagine how incredible it will be at launch when all four engines and both boosters ignite together to lift this 322 feet tall, 5.75 million pound rocket up through the atmosphere and toward deep space. Imagine the thunderous vibration in your chest even as you stand several miles away.

Artist’s concept of an SLS launch
Note: Actually watching an SLS launch from this close is strongly not advised (or permitted). Orion hardware is being tested to withstand sound levels that would turn a person to liquid.

We’ve talked about how it will feel to be there when the rocket launches. Now, let’s talk about how it would feel to BE the rocket, launching.

Envision the power generated at launch as the engines and boosters throttle up to 8.8 million pounds of thrust. The heat is incredible! The vehicle starts to shake. The engine nozzles, as big and solid as they seem, will warp under the pressure of heat when the engines ignite seconds ahead of the boosters. While still on the pad, the boosters are bearing the weight of the entire vehicle even as they fire up for launch – the weight of almost 13 Statues of Liberty resting on an area smaller than an average living room.

Then, you – the rocket – are released to fly, and up you go. More than 5 million pounds of the weight of the rocket pushing down are now counteracted by more than 8 million pounds of thrust pushing from the opposite direction. Remember those 13 Statues of Liberty? Now the bottom of the rocket is feeling the pressure of 29 of them instead!

And now things are heating up on the front end of the rocket as well. Approaching Mach 1, shock waves move over the entire vehicle. Friction from just moving through the air causes the nose of the vehicle to heat. The shock waves coming off the booster nose cones strike the core stage intertank and can raise the temperature to 700 degrees. The foam insulation not only keeps the cryogenic tanks cold, it keeps the heat of ascent from getting into the intertank structure between the hydrogen and oxygen tanks.

Computer model of a shock wave at the front of the SLS vehicle at the time of booster separation during launch.
Computer model of a shock wave at the front of the SLS vehicle at the time of booster separation during launch.

Are you feeling it yet? That’s a lot to handle. These impacts from weight (mass), pressure, temperature and vibration are called “loads.” It’s a key part of the “rocket science” involved in the development of the SLS vehicle.

A load is a pressure acting on an area. Sounds simple, right? There are all kinds of loads acting on SLS, some even before it leaves the launch pad. Tension and compression (pulling and pushing), torque (twisting), thermal (hot and cold), acoustic (vibration), to name a few. There are static (stationary) loads acting on the big pieces of the rocket due to gravity and their own weight. There are loads that have to be considered when hardware is tipped, tilted, rolled, and lifted at the factory. There are “sea loads” that act on the hardware when they ride on the barge up and down the rivers to various test sites and eventually across the Gulf of Mexico and up the Florida coast to Kennedy Space Center for launch. Engineers have to consider every single load, understanding how they will affect the structural integrity of the rocket and how they will couple and act together.

The Pegasus barge that will transport SLS
You’ve probably never thought of “riding on a boat” as rocket science, but SLS has to be designed to handle sea loads as well as space loads.

When SLS is stacked on the mobile launcher at KSC, there are loads acting through the four struts securing the core stage to the boosters and down into the booster aft skirts that have to carry the entire weight of the launch vehicle on the mobile launcher. Then there are roll-out loads when the mobile launcher and crawler take SLS more than 4 miles from the Vehicle Assembly Building to the launch pad. There are many more loads as the vehicle is readied for launch.

How do engineers know the rocket’s ready to handle the loads it has to face to send astronauts into deep space? Step One is good design – developing a rocket robust enough to withstand the strains of launch. However this is difficult as the vehicle needs to be as lightweight as possible. Step Two is digital modeling – before you start building, you run many, many simulations in the computer to a level of detail that would make any Kerbal Space Program fan jealous. Step Three is to do the real thing, but smaller – wind-tunnel models and even scale-model rockets with working propulsion systems provide real-life data. And then comes Step Four – build real hardware, and stress it out. Test articles for the core stage and upper stage elements of the vehicle will be placed in test stands beginning this year and subjected to loads that will mimic the launch experience. Engines and boosters are test-fired to make sure they’re ready to go.

Still want to be the rocket? Stay tuned for more on loads as we do everything possible to shake, rattle, and yes, even roll, the pieces of the rocket, ensuring it’s ready to launch in 2018.

Next Time: No Small Steps Episode 3

Join in the conversation: Visit our Facebook page to comment on the post about this blog. We’d love to hear your feedback!

What’s A Spacecraft Factory Like? Think Big!

“I’ve been to the Smithsonian,” said one awed observer. “I’ve seen crew capsules before. They’re not that big!”

Last month, welding concluded on the pressure vessel, the basic structure of the Orion deep-space crew vehicle. Workers from around the country who had prepared components and materials for the spacecraft were invited to NASA’s Michoud Assembly Facility outside New Orleans to see the culmination of their labor before it was transported to Kennedy Space Center in Florida for completion.

The Orion team at the Michoud Assembly Facility poses with the Exploration Mission 1 crew module pressure vessel
The Orion team at the Michoud Assembly Facility poses with the Exploration Mission 1 crew module pressure vessel prior to its transfer to the Kennedy Space Center ,where it will undergo final assembly in preparation for flight in 2018.

Even to those who helped build it, and even in that unfinished state, Orion was an impressive sight. Workers found themselves standing feet away from the core of a spacecraft that will travel around the moon, farther into space than Apollo ever went, and then return to Earth; hardware that they had helped create. And even though they had seen components of it, some expressed surprise at the size of what they’d helped build.

From a big crew vehicle to a big rocket to “the world’s largest dishwasher” (What’s that? Keep reading) “big” was the word of the day when the team at Michoud marked the completion of welding of the pressure vessel for the first Orion capsule to fly on a Space Launch System (SLS) rocket.

It was … well, a big deal.

Which is appropriate, because Michoud Assembly Facility is a big place. Originally built in 1940 to produce plywood airplanes for World War II, Michoud is one of the largest manufacturing plants in the world, with the main facility covering 43 acres under one roof. Michoud became a NASA facility in 1961. Among its contributions, Michoud produced stages for Saturn V rockets, and the external tanks that fueled every space shuttle flight.

The Orion pressure vessel at Kennedy Space Center
The Orion pressure vessel has now arrived at Kennedy Space Center, where it will be outfitted for its next mission, going beyond the moon.

Today Michoud is a multi-user facility, with government and commercial tenants. Walk through Michoud, and as you begin to understand just how big 43 acres is. As you come in, you see state-of-the-art tooling being used for Orion and SLS. Venture even farther, and you find private companies making use of the factory’s diverse array of equipment including some of the same tools that sent men to the moon. (The factory is also home to some big movies – just recently, filming has taken place there for “Jurassic World” and “Dawn of the Planet of the Apes,” among others.)

How big is Michoud? The factory is so large that if you don’t know what you’re looking for, you could walk through and totally miss the largest spacecraft welding tool in the world – not because it’s easily missed, but because it’s set apart from the main floor in its own separate chamber, behind one of many bay doors and a couple of mundane-looking doorways. Enter the chamber, however, and there is nothing mundane about the 170-foot-tall Vertical Assembly Center, a new tool built custom for SLS. Into the VAC are placed 27.6-foot diameter barrels, domes and rings, and it welds them together into giant fuel tanks for the SLS core stage. Then they go in the “largest dishwasher,” as SLS core stage manager Steve Doering referred to it at the event, a piece of equipment on the other side of the chamber that washes them post-welding.

Overhead view of the Vertical Assembly Center and a welded barrel stack
Core stage barrel sections are now being welded together to form fuel tank test articles in the Vertical Assembly Center at Michoud.

On the day of the event, visitors to the chamber of the Vertical Assembly Center were greeted by its first product – a stack of two barrels, about 40 feet high, which filled the entrance to the VAC chamber. By itself, the stack looms over visitors as they approach it, but it invites a quick mental calculation: The core stage of SLS will be five times taller still than that. And that’s still less than two-thirds the height of the entire rocket. It’s big.

Orion then traveled to Kennedy Space Center to be outfitted as a cutting-edge spacecraft. At the same time, the SLS fuel tanks are in production at MAF and will undergo testing before a complete SLS core stage is test fired and shipped to Kennedy as well. There, the core stage and the SLS boosters and upper stage will join Orion for stacking and then launch.

And that will be one really big day.

Next Time: Think You’re Stressed? Try Being A Rocket

Join in the conversation: Visit our Facebook page to comment on the post about this blog. We’d love to hear your feedback!

The Next Steps Are Here

Back in November, we debuted the first in a set of new videos, “No Small Steps.” Now, the next “Steps” is here!

The first video in the series explained why going to Mars is a very big challenge, and why meeting that challenge requires a very big rocket. (Hint: You need a whole lot of fuel.)

The second installment goes a step further, by discussing how NASA’s Space Launch System (SLS) builds on the foundation of the Saturn V and the Space Shuttle, but then uses that foundation to create a rocket that will accomplish something neither of them could – sending humans to the Red Planet.

Illustration showing a Saturn V and SLS launch, with the text The physics of sending a rocket into space haven’t changed, but our engineering has.SLS takes advantage of some of the best concepts and systems from its predecessors. Like the Saturn V, SLS is a massive, staged rocket. Like the space shuttle, it uses solid rocket boosters and RS-25 engines. But unlike either of those vehicles, SLS will be able to support human missions to Mars. How do you combine elements of two different vehicles and produce a new one with a capability neither of the others had? You take the best of yesterday and INNOVATE.

Today’s teams have the added advantage of a few decades of technology development. The teams that built the Saturn and Shuttle were pioneers of rocket science, but today we’ve not only built on their foundation but also improved on things like welding science.

And while they may not be as glamorous as making smoke and fire, advances in things like modeling and analysis, welding techniques and software development add up to be a very big deal.

Why? Because on the journey to Mars, there are No Small Steps.[/embedyt]

Next Time: Visiting the Rocket Factory

Join in the conversation: Visit our Facebook page to comment on the post about this blog. We’d love to hear your feedback!

A Model Employee

This week, I’d like to introduce guest blogger Jared Austin, a fellow writer on the SLS Strategic Communications team, for a peek into a part of the SLS team that is rarely seen, but creates some of our most-seen tools. — David

Parts of SLS models during assembly
Ever wonder what the sides of the new SLS booster design look like? Now you know!

Few people know Barry Howell and what he’s done for the space program for decades. Neither astronaut nor engineer, through his work as a master model maker Barry has helped NASA visualize spacecraft before they existed.

For more than 40 years, Barry’s “office” has been a space model workshop filled with the past, present and futures of NASA. Barry has created models of many of NASA’s greatest endeavors – from the mighty Saturn 1B and Saturn V, to the iconic Space Shuttle, to early concepts of the International Space Station, to the Hubble Space Telescope, and many other vehicles. Those models aren’t the mass produced, off-the-shelf toys that little Timmy or Sarah receives for their eighth birthdays. Barry’s models are works of both artistic and technical mastery that are painstakingly crafted to scale in a variety of sizes from models that will fit on your desk to a giant that is over 12 feet tall.

Barry Howell with a freshly updated 1-to-50 scale model of SLS
Barry Howell with a freshly updated 1-to-50 scale model of SLS.

You don’t last forty years at a job unless you’re extremely passionate about what you do. Barry’s craft is a rare calling – there are only a small handful of modellers at Marshall Space Flight Center, and only a few NASA centers have model shops. Model makers who get a job like this tend to keep it for a long time, so turnover is low and opportunities are infrequent. Barry came to the job from a background in machining, which he started working while in high school. But when there is an opening in the model shop, there really is only one job qualification – be the best at what you do. There’s no particular education or experience requirement, unmatched skill is the determining factor.

Over the course of his career, Barry’s work has helped solve the agency’s most challenging problems, letting engineers visualize the hardware they are designing and building, and to prove concepts such as the shade on Skylab. After Skylab’s launch, NASA had only 10 days to design and build a sunshade for the space station. Barry helped build a model to demonstrate that the umbrella-like shade that Marshall engineers were designing would properly shield Skylab from the sun’s heat. And his work is rather unique within NASA.

Now Barry is taking his decades of experience in modeling all types of NASA systems and using it to produce models of America’s next great rocket, the Space Launch System.

A row of Saturn-era models in the model shop archive
In decades past, Barry created his models directly from vehicle engineering blueprints.

During his tenure in the model shop, Barry has seen changes in technology and process, along with classic methods that have stood the test of time. In the old days of Saturn and early Shuttle, each and every model would be carefully machined according to actual blueprints that allowed Barry to ensure they were precise representations of the real rockets. Working with aluminum or plexiglass blocks, Barry would carefully drill into blocks with a mill or strip away pieces with a lathe, using nothing more than his focused eye, steady hands, and well-honed judgment to carve the individual parts of the rocket from those blocks.

Today, for SLS, model production is a combination of old and new techniques. There’s no longer a need to individually handcraft each model that’s produced; resin casting allows for mass production of models, allowing the model shop to churn out the models at a faster rate and lower cost. But in order to produce the mold for that casting, the old ways are still best. To this day, Barry produces his initial master for each model line with the meticulous same mill and lathe machining process that he used during Saturn.

Close-up of parts for SLS models
In order to capture the fine detail of an official Marshall model, Barry machines the prototype for each model series the shop produces.

Recently, though, even more modern techniques have entered the model shop in the form of 3D printing, creating small astronaut figures, handheld models of the rocket, or small versions of the SLS engines. It’s a new area that the modelers have just begun to explore and holds many possibilities for improving the way they make SLS models going forward.

“I truly love every part of the model-making process, as well as the variety of different models that I’ve gotten the chance to make at NASA,” Barry said. “And the young guys I get to work with, they come up with a lot of great ideas on how to make things even better.

Barry has also been very gracious in passing on his knowledge to others. Modelers who create their own models at home will often request Barry’s inputs to help them make custom-made parts that look more realistic.

Now, as Barry rides off into the sunset of retirement in a couple of months, he’ll be leaving behind a legacy of models showing NASA’s greatest technological achievements. Barry has helped tell the exploration story and by capturing NASA history in 3D for decades.

Close-up of parts for SLS models
In addition to providing a way to share the vehicles NASA is building, Barry’s models have allowed engineers to visualize concepts that have been proposed.

Next Time: A Model Worker

Join in the conversation: Visit our Facebook page to comment on the post about this blog. We’d love to hear your feedback!

Next Giant Leap, No Small Steps

Our focus today at the Space Launch System (SLS) program is on building a new rocket – the most powerful in the world. On its first test flight, Exploration Mission-1, SLS will carry atop it an uncrewed Orion spacecraft, which will someday carry astronauts on a journey to deep space.

A similar scene was unfolding at NASA 48 years ago. On Nov. 9, 1967, the Saturn V rocket launched for the first time, carrying an Apollo spacecraft.

Less than two years later, a Saturn V rocket and Apollo spacecraft sent three astronauts sailing through the void between two worlds, culminating in two members of the crew becoming the first to set foot on another celestial body. The words spoken as the first boot dug into the powdery gray lunar regolith took their place among the most famous ever said.

“That’s one small step for [a] man; one giant leap for mankind.”*

Launch of Apollo 4
The launch of Apollo 4 was the first from NASA’s Kennedy Space Center in Florida.

With SLS, Orion, and a revitalized space launch complex, we are developing capabilities for our next pioneering endeavor – a journey to Mars.

We continue to make progress toward that journey. Testing has begun on the boosters and engines for the Space Launch System rocket. The One-Year Crew is currently aboard the International Space Station, learning more about living in space for long durations. Our robotic explorers on Mars discovered flowing water and the history of the Martian atmosphere. The Orion vehicle made its first spaceflight, traveling 15 times higher than the orbit of the space station before successfully returning to Earth. These accomplishments, and many more over the last year, bring us closer to the “next giant leap” to Mars, but are all important in their own right. The journey to Mars is hard and the “small steps” along the way aren’t really that small.

And that’s the general idea behind a set of new videos we’re launching today – “No Small Steps.” The challenge of going to Mars is monumental, and it’s going to take a monumental rocket to make it possible. In an entertaining and informative format, “No Small Steps” gets into the “how” of making that happen – taking rocket science and making it relatable to answer questions like how you power a rocket designed for Mars, how you build a rocket the same size as the Saturn V but make it more powerful, how SLS combines the best of NASA’s greatest launch vehicles and makes it even better. We’ll release the next two installments about a month apart, so stay tuned.

Because when it comes to our journey to Mars and beyond, there are no small steps.[/embedyt]

Next Time: A Model Employee

Join in the conversation: Visit our Facebook page to comment on the post about this blog. We’d love to hear your feedback!

*My take on the “for man”/”for a man” discussion: Neil was pretty awesome either way.

CDR, Orange Rockets And A Sense of “Since”

Artist’s version of SLS during launch
NASA’s Space Launch System: New look, same great ability to enable human exploration of deep space!

Who knew signing some paperwork could be so exciting?

Already in 2015, the Space Launch System team has done things like successfully fired an incredibly powerful qualification test version of the solid rocket boosters, completed an entire series of full-duration tests of a RS-25 core stage engine, built a structural test article of the first flight’s upper stage and filled a factory floor with 50 barrels, rings and domes, all 27.6 feet around, all waiting to be stacked into sections of the core stage.

And, amidst all the smoke and fire and bending giant pieces of metal, there was the Critical Design Review. While it may not have generated the exciting pictures and video those other milestones did, the Space Launch System CDR is a huge step forward and one for the history books – the first CDR of a NASA crew launch vehicle since the space shuttle almost 40 years ago.

The design documents for a rocket are incredibly complicated, and the CDR process is an incredibly complicated review of an incredibly complicated design. Two teams – one chartered by the SLS program and the other an independent review board consisting of aerospace experts – go through the documents looking for any issues – from big-picture concerns about the function of the vehicle to “minor” discrepancies between two pieces of documentation. They go through the design with a fine-tooth comb, and then go through the results of that with an even finer-tooth comb.

The CDR process officially determines that the design for the vehicle is mostly complete – a requirement that SLS exceeded – and is ready to move into manufacture and assembly. In the case of SLS, where the major elements of the vehicle had previously completed individual CDRs and are already under construction, this milestone paves the way for assembly and testing as those elements become the complete vehicle.

Along with the completion of CDR, we were excited to make one other announcement – the official new look of SLS.

Expanded view of the elements of Space Launch System
All the ingredients needed for building an exploration-class rocket.

When we first announced Space Launch System four years ago, the rocket was still in the very early phases of design, and the artist’s concepts we revealed then didn’t have nearly as much technical detail to go on. Now, the designs and processing plans for the vehicle matured to the point that we were ready to make updated decisions about the appearance of the vehicle.

With CDR, we’re proud to reveal a look of the rocket based on the results of four years of work maturing the design – integrating the engineering reality of the vehicle and a lot more color.

On the surface, the new look may appear to be a cosmetic change, but those changes speak to the depth of complexity involved in maturing the design for a rocket – the trade-offs between extra thermal protection versus extra payload capability, the balancing act of making sure some parts of the rocket don’t get too hot while other parts don’t get too cold.

You may recognize the orange color of the core stage; it’s the natural color of the spray-on foam insulation that covered the external tank of the space shuttle. Under the white-and-black exterior we’ve been showing the foam has always been there, and for essentially the same reason as on the shuttle’s external tank. Inside the structure are tanks holding super-cold liquid oxygen and liquid hydrogen, and the insulation helps prevent the cryogenic liquids from evaporating as well as mitigating the formation of ice on the outside of the stage.

By not adding paint to the core stage, we’re reducing the weight of the rocket, which increases payload capability, and saving cost of both paint and the equipment needed to apply it. During the first year of the space shuttle program, the external tank was painted white to provide additional protection. After the first two flights, the decision was made that the benefit of the increased payload capability without paint outweighed the protective benefits the paint provided. While today it would be possible to paint the larger SLS core stage with less paint than was used on the external tanks, it was discovered during those missions that paint could actually cause the foam to absorb so much water that, in the case of SLS, the combined impact of paint and water could reduce payload capability by a thousand pounds.

Launch of the STS-135 space shuttle mission in July 2011
If the orange color looks familiar, it’s because you have seen it somewhere before. (Also, one of the engines in this picture of the final launch of the shuttle will be flying again on the first flight of SLS. Cool, no?)

While most of the core stage consists of the large hydrogen and oxygen tanks, the orange foam will cover two other sections as well – the intertank structure between the two tanks and the forward skirt at the top of the core stage above the liquid oxygen tank. The foam in these two areas will also contribute to maintaining propellant temperatures and to ice mitigation, but serves another purpose as well. During launch and ascent, the foam protects sensitive equipment inside those areas from the high temperatures on the vehicle’s exterior.

Also insulated with the orange foam is the Launch Vehicle Stage Adapter, the conical section that connects the core stage with the upper stage. Because this section widens so much from top to bottom, it will experience extreme aerodynamic heating during launch, and the foam will protect the metal underneath from the high temperatures.

We made one other change to the look of the vehicle, a design on the solid rocket boosters that reflects the upward momentum of the rocket. Unlike the core stage tank, the booster design has negligible impact on payload, and gives SLS a unique look entirely its own, fitting for a 21st century launch vehicle.

And while the new look may make the rocket seem a little more real, the Critical Design Review marks a huge step forward toward a completed rocket. There can be motivation in a sense of “since.” We test-fire an RS-25 engine, and it’s a first since we retired the shuttle. We complete the CDR, and it’s the first of its kind since the shuttle was in development. You look at what happened the last time NASA did these things, and you realize the significance of what we’re doing.

And they’re just going to get bigger. CDR was a first since shuttle development, and it paves the way for the test firing of core stage in a couple of years. And the combined thrust of four RS-25 engines in a test stand at Stennis Space Center will be the most not just since shuttle, but since the Apollo program. And that paves the way for the first launch of SLS, which will send Orion farther into space than Apollo ever ventured. At some point, “since” stops, and is replaced with “never before.”

And that “never before” will be just the beginning.


Next Time: A Model Worker

Join in the conversation: Visit our Facebook page to comment on the post about this blog. We’d love to hear your feedback!

Meet the New Boss

Guest blogger Martin Burkey, the SLS strategic communications team’s resident expert on all things engines and stages, returns this week to introduce a man he’s worked with closely, new SLS Program Manager John Honeycutt. — David

New SLS Program Manager John Honeycutt
New Program Manager John Honeycutt speaks to the SLS workforce at his first team meeting.

Three golf putters lean against one wall in John Honeycutt’s office. They haven’t seen much action lately, and it may be a long time before they do again. Honeycutt, who takes his golf game seriously or not at all, was recently named to lead NASA’s Space Launch System Program, which is fast becoming crowded (pleasantly) with spaceship parts for testing and even flight.

He succeeds the program’s first manager, Todd May, who was recently named deputy director of Marshall Space Flight Center, where SLS is based.

Within NASA, he’s a known quantity with 25 years of experience on both the development and operation side and the challenges that came with both. As imposing a figure as he may be in person, he’s also surprisingly soft-spoken. He tends to do a lot of listening, asking questions designed to cut through knotty issues and reveal trends or issues lurking in the dense, detailed, “eye charts” typical of NASA presentations.

He’s collaborative, essential for working with other programs. He’s customer-focused, which makes him responsive to strategic direction from above. And he enjoys cutting up with his team on special occasions. Better judgment prevents me from posting the pictures.

Honeycutt grew up in Huntsville, a city that evolved from agriculture to manufacturing and to high tech thanks to military projects and NASA space programs. When he was growing up, it was just assumed that, if you lived here, you were going to work with the Army or NASA. His father is a mechanical engineer who was a metals expert first for the Army in the 1960s and then for a space shuttle contractor in the 1980s, and he continues to work in metals analysis today at Marshall.

The younger Honeycutt worked his way through college, managing a small grocery store, a gas station, and working in a hardware store. He attended college part time until he was about 24 and turned full-time student until he graduated with a mechanical engineering degree from the University of Alabama in Huntsville. Through the wife of one of his part-time employers, he soon got a job interview with Rockwell, the shuttle program integrator. And the rest, trite as it sounds, is history.

Honeycutt, 55, is no stranger to space hardware. If you could ‘letter’ in human space flight, he’d have the jacket. He worked in industry for nine years on environmental and structural testing as part of developing the International Space Station, as well as the main propulsion system, external tank, and launch support for the Space Shuttle Program before joining NASA.

Since joining NASA, he’s managed the shuttle external tank program, and he’s served as deputy manager of the SLS Stages office, SLS deputy chief engineer, and most recently as the SLS deputy program manager.

That’s all standard press release stuff, but his experience is worth mentioning just because he doesn’t consider it the most important aspect of his new job.

As program manager, Honeycutt knows that he can’t be just a hardware guy. He sees his main job as asking questions, seeing where people need help, especially when they don’t realize it, and challenging teams to push through barriers.

He also sees himself as program integrator. He places a high priority on getting the SLS team more closely integrated. It’s particularly important when things don’t go as expected… as they can understandably with the largest rocket in the world.

New SLS Program Manager John Honeycutt
New SLS Program Manager John Honeycutt

When he was named SLS deputy chief engineer, the program was not yet to its preliminary design review – PDR – one of the early design stages. The various hardware elements – boosters, engines, core stage, etc., were loosely coupled through various interface and performance requirements.

SLS has most recently completed its Critical Design Review – CDR – and the pieces that were once separate will start coming together in every sense of the word at every level for assembly and testing. Big rocket. Big integration job.

“In the earlier design stages, integration is not as strict relative to how communications takes place,” Honeycutt observed. “As you roll out of CDR and are pressing toward certification and on to launch, that transition requires you coordinate much closer. It will come to a point soon where I have to stand up and say this vehicle is certified for flight and can show how the pieces interconnect. We’re becoming more tightly integrated as a team, not just the SLS team, but its sister programs – Orion and Ground Systems (at Kennedy Space Center) – all under the Exploration Systems Directorate enterprise.”

Having worked on the hardware development side and the hardware operations side, he understands there’s a difference in how you approach challenges. That cross-cultural experience should help Honeycutt now as SLS moves from design into the “pencils-down”, design-complete, manufacturing and assembly that is gearing up.

The design is at least 90 percent complete by definition, and the vehicle is literally taking shape in factories around the country. Having been through challenges ranging from the Columbia shuttle accident to the destruction of Hurricane Katrina, and the ongoing lessons that every shuttle mission taught, Honeycutt knows SLS has more challenges ahead.

“I’m not going into this thinking we’re going to sail smoothly all the way up through Design Certification Review,” he says. “It’s up to me to look through things and see what’s coming.”

His decisions will be aimed at flying the first SLS mission on schedule and then having the second rocket ready as close behind the first as possible. Of course, that’s his job.

But Honeycutt has one more, longer-range personal goal that looks beyond delivering hardware to what that hardware will mean for the nation, and for the people who built it – a goal “for everybody working on this program to look back and say it’s the best thing they’ve ever done.”

To make that happen, it looks like a serious commitment to his golf game will have to wait.

Next Time: Passing A “Critical” Milestone
Join in the conversation: Visit our Facebook page to comment on the post about this blog. We’d love to hear your feedback!

RS-25 Engines: Meeting the Need for Speed

Guest blogger Martin Burkey, the SLS strategic communications team’s resident expert on all things engines, returns this week as we prepare for this afternoon’s RS-25 engine testing event at Stennis Space Center – if you’re not already, follow @NASA_SLS on Twitter and our Facebook link below for more info. — David

Rocket engines are among the most amazing machines ever invented. That’s mainly because they have to do one of the most extreme jobs ever conceived – spaceflight – starting with escaping Earth’s deep gravity well. Orbital velocity, just for starters, is over 17,000 mph, and that only gets you a couple hundred miles off the surface. Going farther requires going faster. Much faster.

The RS-25 makes a modern race car or jet engine look like a wind-up toy.

It has to handle temperatures as low as minus 400 degrees where the propellants enter the engine and as high as 6,000 degrees as the exhaust exits the combustion chamber where the propellants are burned.

It has to move a lot of propellants to generate a lot of energy. At the rate the four SLS core stage engines consume propellants, they could drain a family swimming pool in 1 minute.

Graphic showing top speeds for an Indy car and SLS of 230 mph and 22,653, respectively
To be fair, the Indy car probably handles better in the turns.

The most complex part of the engine is its four turbopumps which are responsible for accelerating fuel and oxidizer to those insanely high flow rates. The high pressure fuel turbopump main shaft rotates at 37,000 rpms compared to about 3,000 rpm for a car engine at 60 mph.

The bottom line is that the RS-25 produces 512,000 pounds of thrust. That’s more than 12 million horsepower. That’s enough to push 10 giant aircraft carriers around the ocean at nearly 25 mph.

If the performance requirement to turn massive amounts of fuel into massive amounts of fire wasn’t enough, an engine can’t take up a lot of mass or area in a rocket. A car engine generates about half a single horsepower to each pound of engine weight. The RS-25 high pressure fuel turbopump generates 100 horsepower for each pound of its weight.

But forget mere car engines. The RS-25 is about the same weight and size as two F-15 jet fighter engines, yet it produces 8 times more thrust. A single turbine blade the size of a quarter – and the exact number and configuration inside the pump is now considered sensitive – produces more equivalent horsepower than a Corvette ZR1 engine.

Expanded view of an RS-25 engine
And this is still only the major components of an RS-25 engine.

On the other hand, when you chug fluids that fast, a hiccup is a bad thing. In the case of a rocket engine, that hiccup is called cavitation. At the least, it robs the engine of power. At worst, it can cause catastrophic overheating and overspeeding. So rocket engineers spend a lot of time making sure fluids flow straight and smooth.

That’s also why they test rocket engines on the ground under highly instrumented and controlled conditions. It’s a lot less costly to fail on the ground than in flight with a full rocket carrying people on board and/or a one-of-a-kind multi-million- or multi-billion-dollar payload.

As rocket engines go, the RS-25 may be the most advanced, operating at higher temperatures, pressures, and speeds than most any other engine. The advantage comes down to being able to launch more useful payload into space with less devoted to the rocket structure and its propellants.

In addition to its power, another key consideration for SLS was the availability of 16 flight engines and two ground test engines from the shuttle program. It’s much harder and more expensive to develop a new engine from scratch. Using a high-performance engine that already existed gave NASA a considerable boost in developing its next rocket for space exploration.

Top of an RS-25 engine during a test firing
The RS-25 handles a wide range of temperatures – super-cold on top, super-hot at the bottom.

The remaining shuttle engine inventory will be enough for the first four SLS flights. As for the maturity part, the RS-25 design dates to the 1970s and the start of the Space Shuttle Program. But it’s undergone five major upgrades since then to improve performance, reliability, and safety. If only we could all upgrade 5 times as we age. Further, much of the knowledge and infrastructure needed to use the available engines and restart production already existed. Another hidden savings in time and money.

In its next evolution, the RS-25 design will be changed to make it a more affordable engine designed for just one flight and certify it to even higher thrust – which it is very capable of – to make SLS an even more impressive launch vehicle.


Next Time: The Engine Experience

Join in the conversation: Visit our Facebook page to comment on the post about this blog. We’d love to hear your feedback!