The Space Launch System: Part 2
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"Houston We Have a Podcast" is the official podcast of the NASA Johnson Space Center, the home of human spaceflight, stationed in Houston, Texas. We bring space right to you! On this podcast, you’ll learn from some of the brightest minds of America’s space agency as they discuss topics in engineering, science, technology and more. You’ll hear firsthand from astronauts what it’s like to launch atop a rocket, live in space and re-enter the Earth’s atmosphere. And you’ll listen in to the more human side of space as our guests tell stories of behind-the-scenes moments never heard before.
Paul Bookout and David Smith continue their conversation about the most powerful rocket since the Saturn V: The Space Launch System. The experts discuss the construction, testing, evolution and potential of the skyscraper-sized launch vehicle. This episode was recorded on March 20, 2018.
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Gary Jordan (Host): Houston, we have a podcast. Welcome to the official podcast of the NASA Johnson Space Center, Episode 42: The Space Launch System, Part 2. I'm Gary Jordan, and I'll be your host today. So in this podcast, we bring in the experts -- NASA scientists, engineers, and astronauts -- all to let you know the coolest information about what's going on right here at NASA. So today, we're talking about the most powerful rocket since the Saturn V moon rocket, NASA's Space Launch System. We've got two guests from the Marshall Space Flight Center in Huntsville, Alabama here with us today to tell us about the rocket, the payloads it can carry, and where it will go. Spoiler alert: It will bring people, big stuff, and little stuff all farther than we've ever gone before. See, I did it again. You had a second chance for Part 2, and you blew it, Gary. If you're slightly confused, it's because this is Part 2 of our two-part episode on NASA's Space Launch System. There's still some good stuff in here, but if you want the full story, just go back and listen to Part 1. So continuing our conversation with us today are David Smith and Paul Bookout. David is the Vice President for Advanced Programs and Victory Solutions in Huntsville, Alabama.
He has a long career in aerospace engineering and is a subject matter expert on rocket architecture and how payloads will fit into the rocket. He wrote the SLS Mission Planner's Guide, which gives payload developers a general idea of the capabilities of the rocket and some technical specifications so they can determine how their payloads might fit inside. He looks after the big payloads. Our other guest today is Dr. Paul Bookout, EM1 Secondary Payloads Integration Manager, who manages the integration of five CubeSats in the giant rocket as well the avionics that will control the deployment of all 13 small satellite payloads on the first mission of SLS and Orion called Exploration Mission 1, EM1. He spends his time managing the little payloads, not much bigger than a shoebox, on a skyscraper-sized rocket. So we're going to talk about just how powerful this monster rocket is, its unique capabilities, what it'll be used for, where it is in its development, its first mission with the Orion crew vehicle, and then look ahead to the future to the Moon, to Mars, and throughout the solar system.
In this particular episode, we talk a lot about propulsion on this rocket, especially comparing solid and liquid fuel for the rockets. So at a very high level, the key differences are cost and control. Solid rocket fuel systems are generally simpler in design, cost effective, and they produce a large amount of thrust. But once the fuel is ignited, you can't really turn it off. Liquid fuel systems provide more flexibility. You can regulate the thrust through system throttle settings, but liquid fuel systems can be more costly. Very smart engineers have assessed the best way to use these two fuels and, for the SLS, they've come up with a combined design of solid and liquid fuel system. Solid fuel boosters and liquid fuel, the main engines to work in tandem to get you off the ground and moving fat, and then liquid fuel carries, or the liquid fuel engines will carry you where you need to go. So we're go for launch with Mr. David Smith and Dr. Paul Bookout for the Space Launch System program, T minus 5, 4, 3, 2, 1, 0, and liftoff of Episode 42 of Houston We Have a Podcast.
Boom, nailed it.
[ Music ] Okay. Paul and David, thanks for sticking around. This is going to be Part 2. We're sort of continuing our conversation, and we were talking a little bit during this I guess intermission, but one of the main things that we forgot to touch on was it takes eight minutes to do the first part of this launch. That's the solid rocket boosters and the core stage--
David Smith: Ignition to disposal of those stages.
Host: Yes. Yeah, but I guess up to this point, all you need is some sort of injection burn, and you can pretty much go anywhere in the solar system. Is that right?
David Smith: That's right.
Host: So it just depend, you just define what kind of injection burn, and you can go anywhere.
David Smith: Well, it's the injection burn, and then the characteristic energy, which is the acceleration to get to that location. You know, it's a curve, so--
Host: Yeah.
David Smith: If you go farther out, the less mass you can bring with that injection burn. So it is, it's the timing of the injection burn and the trajectory. But also, the farther away you go in the solar system, obviously, the less mass you can carry. So that's all kind of combined together.
Host: That's right. And so for EM1, the injection burn is going to be translunar, right?
David Smith: Correct.
Host: But you can also do Mars injection burn, or Jupiter injection burn, or, like, anything after this eight minutes, it's just, you can just define it?
David Smith: That's right. Yep.
Host: So that's really the main thing about this vehicle is after eight minutes, you're ready to go wherever you want, and the fact that it's human rated, and the fact that you can bring really large payloads, right. I guess that, we'll start off with that. So we're building this rocket to pretty much go anywhere, but what are the sorts of missions we're looking at for the future for SLS?
David Smith: Yeah, the first missions that are being considered are translunar and perhaps making something that has a, kind of a complicated acronym, LOP-G, Lunar Orbiting Platform/Gateway. What it really is is like a service plaza on a toll road. So think of Saturn V as the rocket that went out and surveyed everything and, you know, there were no roads, and it kind of established these, you know, these paths to go to the Moon, okay. Now, SLS is going to take that survey information and hopefully make this Lunar Orbiting Platform into a service plaza where, what do you get there? Well, you get a safe place for the crew. You can refuel landers that can go to the Moon. You can have a navigational way station. You can have a communication way station. You have a place for internationals to come by and make sure they got everything together before they go to the Moon. This gateway, in fact, gives you universal, total access to any spot on the lunar surface. Apollo is just equatorial. This station will give you access to any place on the Moon. So it has a lot of really great attributes, but it's a different kind of thing.
Unlike the Space Station, which is purely science, this Lunar Orbiting Platform is probably going to be a lot more utilitarian and allow a lot more understanding and exploitation of the Moon and the lunar surface, which is, in fact, what we need that experience so that we can actually do the same thing for Mars. So it's three days away versus nine months away with Mars. So that, that's our first stage. It seems in the 2020's, we're going to be putting that together one piece at a time. So the first piece might be an EM2 mission that delivers a solar electric propulsion system that essentially is the way that this station keeps in its place. So it's just a little bit of impulse in this halo orbit around the Moon. You can stay there with very little power using a xenon solar electric propulsion system. The second part might be a habitation module. This isn't where the crew are going to, they're not going to live here full time. Again, it's a way station, so it's a place they can hang out, refresh themselves, get food, change clothing, who knows on their way to the Moon. Then, they're going to have an air lock that allows them to do servicing on perhaps landers and other kind of equipment that comes into that gateway.
And then, also, a place for logistics modules to come to resupply this service plaza so that, for the long term, it can service people going to and from the Moon. So that's probably the first part, and that looks like that would be something that would be in the early 2020's, and that's where the current administration seems to be focusing us is on doing lunar first to be prepared for Mars later.
Host: Okay. It's kind of like a small truck stop.
David Smith: It is.
David Smith: It is--
David Smith: Think of it as, yeah. [laughs] Yeah. And it should be kind of looked at that way as it's a way station to greater and better things, either the Moon or Mars.
Host: Yeah. That's right. You can shower. You can, [laughs] you can service it. It's got a--
David Smith: Get your eggs and steak.
Host: Yeah.
David Smith: You know, get your car repaired. Refuel. Get some gas. Tow truck is even there to maybe save you if you have a probably on the Moon. So really, it's a good deal. It's kind of like a lighthouse and service plaza all put into one.
Host: But not only will the SLS get us there. It's actually going to get the LOP-G there, right? It'll actually--
David Smith: It'll assemble it.
David Smith: It'll assemble it.
Host: In pieces. Now--
David Smith: Yeah.
David Smith: If we were to do it the best way, instead of doing it in smaller pieces -- and by the way, it's going to do this just using the trunk section underneath the Orion. So the co-manifested payload is what these little elements of the station are going to be. If we were, if we could, it'd be best to just make one giant chunk and put in the, into a fairing, but the way I think the program is unfolding, to use crew to start with, is to bring the station in pieces that the crew can assemble at that location.
Host: So going back to the previous episode, Episode 41 -- if you haven't listened to it, go back -- and that was the first part of our conversation, but going back to this co-manifested payload, we're talking about primary payloads, co manifested, secondary. What's the co manifested?
David Smith: Yeah, the co manifested, again, is the ten-ton capability that is the trunk space underneath Orion that's going to fly on the Block 1B SLS. So in contrast, if you took off the Orion and its trunk space and put a large fairing on top, you get a primary payload that could be 40 tons the Moon. So it's ten tons the Moon is co manifested, or it's maybe 40 tons the Moon as a primary payload. And the secondary payloads are payloads of opportunity. They kind of fit in little, tiny spaces that are left over. They aren't filled up with other kinds of stuff.
Host: And that's where Paul comes in--
Paul Bookout: Yes.
Host: Right? [laughter]
Paul Bookout: That's my world.
Host: That's right.
David Smith: So after Lunar Orbiting Platform-Gateway, one of the early missions that's been envisioned is taking a probe to the Europa, the moon, icy moon of Jupiter. What's so neat about this mission is that SLS, is we have to loft this payload and get it to Jupiter in two-and-a-half years, where a current ELV -- Atlas, Delta, even a Falcon 9 Heavy -- couldn't do that in more than seven years. So we're going to cut five years off a trip. Now, what does that mean? Well, one, it means that you're getting quicker returns to the science community. You're helping people not spend their whole career on one science mission. You have younger people come in, work on a mission, do it quicker. And if it costs $100 million a year to maintain a cadre of ground controllers watching this thing, think of the money that you're saving over time if you can eliminate five years of that mission. Plus, the risk of that hardware traveling through space. So this is a real enabler for Europa. In fact, SLS is the only vehicle that can bring it there in that kind of time.
Host: Unbelievable. Is it a bigger payload because it's a, it's SLS, or is it just--
David Smith: Well--
Host: It gets it there faster?
David Smith: In this case, Atlas could fly the same mass of payload, which is very large, by the way, but it would take over seven years.
Host: I see.
David Smith: So it had to take a whole bunch of gravity assists around the Earth and Venus to get it there where SLS can send it there directly. Now, to your point is the New Horizons mission, which was the mission to Pluto, I think it was 120-kilogram payload that was finally delivered there after like ten years. In that case, SLS couldn't get you there any faster, but it could double the payload to over 250 kilograms of delivered payload to Pluto. So it just depends on the trajectory and the position of the planets when you do this, on what value you have, but the fact you can do it quick is a unique attribute that only SLS can bring right now.
Host: [laughs] Unbelievable what this rocket is capable of. And I kind of wanted to go back and kind of visit the rocket itself, where, the history of it. Where did we start with some, building some of these pieces, and kind of where are we now? So if we can just sort of start at the beginning, whenever SLS was proposed, and we're going to hammer in the first nail, I guess. It's a little bit more complicated than that, but where did this all begin?
Paul Bookout: Yes. Of course, the primary design was based off of the shuttle heritage. You know, we're taking components that the shuttle used, the propulsion aspects of it -- the [inaudible] motors, the external tank, and the space shuttle main engines -- and utilizing, upgrading, making more powerful the, those components and assembling the core stage. So that's kind of where the history of where SLS is coming from. So we want to use that existing technology, again, upgrade it, make it better. Also, the manufacturing facilities that go into making these components are in existence, so we want to still utilize that, save money, save schedule to move forward with the SLS rocket.
Host: Okay, and so it's kind of, that makes sense, right, because it's, you have, okay, this is a core stage that works. These are components of the shuttle that worked. Let's just sort of fit it and to meet these requirements of building a giant rocket that can take payloads anywhere in the solar system.
Paul Bookout: Exactly.
Host: And humans too. It's human rated, which is a huge component of this whole thing.
Paul Bookout: Definitely.
Host: So it's, where is it being built? Is it one location?
Paul Bookout: No. Actually, overall, there's 44, over 44 states--
Host: Oh, wow.
Paul Bookout: That different components are going to be, are being built in. So this is America's rocket.
Host: Yeah. [laughs]
Paul Bookout: So it's not just NASA's. It's being built all over. You know, there's more than 1000 contractors working on this, in addition, of course, into, in addition to NASA. The core stage, which is the prime or contractor is Boeing, they're building that in Michoud, which is outside of New Orleans. The engine prime is Aerojet Rocketdyne. They're being developed, or manufactured, or refurbished down at the Stennis Space Center. And then, when they're done, they'll be shipped to Michoud for integration with the core stage. And then, that core stage with the main engines would be sent back to Stennis for testing because Stennis is the primary testing facility for NASA--
Host: I see.
Paul Bookout: For rockets. The boosters is the Orbital ATK. They're actually manufactured just north of Salt Lake City in Utah. And it's kind of ironic that the, it's very close to the Golden Spike, where the east and west railroads met when they were building the transcontinental railroad, was very close to that because the motor segments are used in the rail system to ship down to KSC from ATK, Orbital ATK out in Utah.
Host: Oh, okay. All right.
Paul Bookout: So--
Host: I like that.
Paul Bookout: A little history there. [laughs] And the upper stage, of course, where, as Boeing ULA, which is a direct purchase from them for that. And that's being built in Decatur, Alabama.
Host: Wow. All over the place is absolutely correct, so--
Paul Bookout: And again, those are just the primary elements. All the subsystems to that are spread out all over the United States.
Host: So what is currently built, and then what's on the ticket to be built?
David Smith: Well, right now, the core has been built three times so far. The weld confidence article to make sure that friction stir welding is appropriate because it's the world's tallest, biggest weld fixture--
Host: Oh, wow.
David Smith: Down at Michoud, so we had to test that first. Then, they're building test articles. And then, the flight hardware. The test articles right now are up at Marshall, so there's this new barge -- actually, it's the same barge they used for shuttle Pegasus. They had to make it a lot longer, so they cut out the middle and put in a new middle section. And that just shipped up, the core section up to Marshall, where it's going under, undergoing static testing. The engine section's already been completed. The testing of that's been completed. And the intertank, the sections between the hydrogen and oxygen tank, has just arrived at Marshall Space Flight Center for testing. The hydrogen and the oxygen tanks will arrive later this year for testing at Marshall too, all for static testing, where they're put under a load to simulate their launch conditions. So this is the largest structural testing campaign since shuttle in the 1970's, and, you know, since this is probably a 50-year rocket, this is really laying the foundation for that kind of generational spacecraft capability that we're building for the Moon and beyond. The upper stage, the exploration upper stage, the NASA one is currently being worked on in design phase, but the ICPS that Paul talked about earlier, the interim cryogenic propulsion stage, is finished and down, already been tested and shipped down to KSC.
The engines, the new engine controllers are hot fire tested at Stennis already, and I might even hear a sound of that in a minute. And the boosters, as we talked about, were built in Utah but had full, two full-scale static firing tests at the Orbital ATK facility so far. Core stage and booster avionics testing are undergoing at Marshall right now in specialized, in a specialized, integrated avionics test lab. So the testing is going forward. It's really quite a test campaign. Working on EM1 right at the moment, but, in parallel, getting ready for, I'm sorry, Block 1 to start with, and, in parallel, working on Block 1B for the EM2 mission maybe in 2022.
Host: So I'm, I want to understand the full scope. That's, there's a lot of different elements, a lot of different parts of the testing. What are some of the main things that you really want to test? It sounds like structure is one of those things, and how do you do that? How do you test the structure?
David Smith: There's a new static test facility at Marshall that's been developed where you essentially set them up vertically, and then you put a load down on the stage, and you do it in many different angles to make sure you can understand not only is it going straight in flight, but if starts experiencing some kind of skew because of the engines, so it undergoes quite a bit of testing that way. That's obviously, the structural modes are the most important. And when we talk about human spaceflight hardware, what that really means for structure is that you test it to a factor of 1.4. So it means there's a 40% margin on the capability of that structure, which is not something that expendable launch vehicles have to worry about. So our rockets are generally a little heavier, a little stiffer, a little more capable, but we do that to provide more margin for the crew in case of emergency. So that's the biggest part of that structural test that's going on right now at Marshall.
Host: That goes back to your point, Paul, about one of the main parts of testing this and building SLS is the fact that it is human rated and you have these extra constraints for making sure that safety is and redundancy is one of the primary concerns of building this rocket.
Paul Bookout: Exactly, yes.
Host: Unbelievable. So the other part is the engines too. You're actually firing the engines. And it's a hot fire test. What's that?
David Smith: Well, that's, the shuttle engines are going, they're installed into a test [inaudible] at Stennis. They're put through the same paces as if they were being launched in the vehicle. And remember, some of these engines haven't been test fired in eight years, seven, eight years.
Host: Right.
David Smith: So it's real important to make sure that they're still, still have the quality that we are looking for at the same time they have a new engine controller. So the controller, the computer that runs these engines have been upgraded from the shuttle days. So it's the first time those two have been mated together. So real important testing. We have I think up to 15 of those engines in inventory, so they're going to be going through those until they, at, probably in the mid-'20's, replacing with a new build of the shuttle engine. So right now, we're still going through the old engines with the new controllers installed.
Host: Actually, we do have some audio from that that I really want to play. It's, this is the hot fire test at Stennis, so if you're listening right now, be prepared because it's going to be very loud.
[ Engine Sounds ]
Host: So that was the hot fire test, and what, you're looking at what components?
Are you looking at temperature? Are you looking at propulsion, efficiency? What are the main things that you really want to get out of this test?
David Smith: Well, I think the biggest one is, how's the turbo machinery going? You know, if you have turbine blades going at like 3000 rpm and you're spitting out all that fuel at the same time, how is that working out? Is it meeting all the parameters? Is, like you said, that's the temperature? How does it run through its life cycle for that eight-minute burn? That's a long time to run an engine.
Host: Yeah.
David Smith: So especially, you know, before we launch, you know, the shuttle only had three of these engines firing. Now, we're going to have four of them. So again, that's a unique configuration. So making sure, [inaudible] how these engines will play together will be an important part of the test as well.
Host: Did you ever get to see any of these tests in person -- structural tests, hot fire tests, anything like that?
David Smith: Yes.
Host: Is it really, really loud?
David Smith: Well, the Stennis tests, you can get really close to it--
Host: Oh, really?
David Smith: Because, you know, it has the flume that comes out the side. And you can get close to a cyclone fence. In fact, you can taste the exhaust because, you know, oxygen and hydrogen comes together and forms water.
Host: Right.
David Smith: So that, and you have the sprinkler system that's cooling it down. So you get both the sound, right, you get the visual of the flames, and then you get the taste. [laughs] So I don't think you can do that anywhere else. You certainly can't get the taste at Kennedy, so Stennis is really a remarkable opportunity when they do those test fires there.
Host: Does it -- I'm imagining like a hot shower or something, just like really--
David Smith: Well, remember, Stennis is pretty humid because it's in Mississippi, so--
Host: Oh, yeah.
David Smith: It's going to feel like a hot shower, but, [laughs] yeah.
Host: Okay, so I'm, a curious thing -- how does a hot fire test taste?
David Smith: Yeah, it has a taste to it.
Host: [laughs] So what about the flight hardware for EM1? Where are some of those components?
Paul Bookout: Right now, the Orion stage adapter, that's where the 13 CubeSets are going to be housed during launch on EM1.
Host: Oh, yeah.
Paul Bookout: It's currently at Marshall Space Flight Center. And at the end of, beginning, I'm sorry, of April, it's planned to ship down on the Super Guppy, which is a large carrier aircraft, down to KSC for processing. And once it's down there when we're about six months to launch, that's when the secondary payloads will be integrated into that before stacked on the vehicle. The interim cryogenic propulsion stage, of course, is finished. It was, again, up in Decatur and is already down at KSC doing other final preps on that. The launch vehicle stage adapter, the primary structure is complete, and they're doing spray foam insulation on the vehicle right now. Again, that's also to help with acoustics aspects of the inside of that, inside of the LVSA.
Host: Oh, that's right.
Paul Bookout: The core stage, of course, the major components, as David said, the tank, the different tanks will be set up, sent up here for testing. And once they're done testing, they'll be sent back down to Michoud and assembled. And then, the main engines will come over from Stennis and assembled into the full core. That's the liquid oxygen, liquid hydrogen inner tank and the engines. Then, it'll be sent back over to Stennis. As David mentioned earlier, each engine, it would be separately tested, but then all four of these will be tested as, in flight configuration down there at Stennis. So we're running them through the full cycle of, as we're integrating. We're testing as we're putting it together.
Host: That's right.
Paul Bookout: So we understand that, as we assembled it, is it still operating the way we expected it to?
Host: So then, will you, will it be built at Kennedy because that's when it's going to be launched?
David Smith: Assembled.
Host: I'm sorry, yeah.
David Smith: It's built in Michoud, tested at Stennis, and then assembled at Kennedy.
Host: Assembled at Kennedy.
Paul Bookout: So the solid rocket motors, again, all the segment are, the five segments -- total of ten, five on each side -- have already been cast. They're in final prep for shipping down to KSC on the rail system. And then, just at, similar to shuttle program, once they've reached KSC, they'll be stacked in the VAB one segment at a time, and then the core stage will come in and be connected in the center between them. Then, you have your upper stage or the ICPS, where, I'm sorry, you'll have your LVSA, launch vehicle stage adapter. Then, you'll have your Orion -- let me just start over. Once the core has been installed, then you'll have the launch vehicle stage adapter installed. Then, you'll have your upper stage or the ICPS. And then, on top of that, you'll have the Orion stage adapter where the secondary payloads are. And then, Orion will come in and make, complete the stack.
Host: All in this, in the Vertical Assembly Building?
Paul Bookout: Yes. Yeah. Remember, it will built to assemble the Saturn V rocket, and--
Host: Yeah.
Paul Bookout: We're about that same size, so [laughs] there's plenty of room in there.
Host: That's right. It's, going back to that, actually, I don't think we've talked about it on the podcast. The Vertical Assembly Building is, as you can probably tell from the way that this is being assembled, it's gigantic. But it's so big, right, that it has its own weather system that you have to kind of worry about, right? Is that right?
David Smith: Yeah, it's--
Paul Bookout: Yes.
David Smith: Tall enough where, you know, everything that gets up in there can form its, it could rain a little bit sometimes--
Paul Bookout: Yes. Form clouds up there.
David Smith: Yes.
Host: Wow. And then, the, you have these giant doors that's going to open, and then you'll just sort of roll the rocket out.
David Smith: But one big change is, if you recall, so it's really interesting. You know, a lot of that building was not changed from Saturn V. They only used two of the bays. There's four for shuttle. So they took out the platforms that were for Saturn and put in some shuttle platforms. But for Saturn, excuse me, for Block 1B, they had to do a lot more changes to that. So they had to replace all the platforms for that, and they actually removed a whole bunch of Saturn V, your equipment that had been left, abandoned in place. So it's, that building has really changed from what it was during the shuttle era.
Host: So it's really been reconstructed to fit the SLS. That's really the main--
David Smith: Yes.
Host: The thing that's going on right now in the VAB. Is it--
David Smith: Right.
Host: Is it completed, or is it still going on?
David Smith: The platforms are completed.
Paul Bookout: Completed.
David Smith: For [inaudible] 1, Block 1.
Paul Bookout: For Block 1, okay.
https://www.nasa.gov/johnson/HWHAP/the-space-launch-system-part-2RAPPORT DE LA NASA
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