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The Space Launch System Part 2

Season 1Episode 42Apr 27, 2018

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. HWHAP Episode 42

space launch system liftoff

launch cam top view uhr2

“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.

Houston, we have a podcast

Transcript

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.

Host: Right.

Paul Bookout: Yeah. And, you know, for SLS, there’s still a lot of work at KSC being performed too. It’s just not the launch vehicle and all of its hardware for EM1. It’s KSC has to go through a redesign on a lot of their components. As David just said, the VAB and all the platforms to be able to reach the hardware where you’re stacking SLS. Also, the crawler transporter that takes the mobile launch platform, which has the SLS rocket on — originally, the Saturn V rocket — has to be upgraded to fit the SLS rocket. So, in addition, out at the launch pad, they’re redoing the flame trenches, re-bricking them because it’s going to have a lot more powerful rockets since the S, you know, since the shuttle program. In addition, they’re, they have to have a lot bigger water suspension system, you know, because at a lot more power than what shuttle was going through.

David Smith: Called rainbirds after the sprinklers. Big rainbirds.

Host: Rainbirds.

David Smith: Yeah, they kind of go, click, click, click, click, click, on the lawn, but this time, they do it on the engines and stuff.

Host: Oh. [laughs]

Paul Bookout: So, you know, the water suspension, suppression system is to help with not just the heat but, also, the sound that these rockets, engines, and solid rocket motors, when they ignite, they’re very loud. They send out a shock wave. And if you didn’t have the water there to suppress or dilute that sound, that would just bounce back off the hard surface up into the vehicle and could damage the vehicle. So it’s just not for flame. It’s also to protect the vehicle from itself on the acoustics.

Host: Okay. That’s the, so that’s the suppression system?

Paul Bookout: Correct. The water that you usually see that starts a couple seconds right before ignition.

Host: Actually, I think we do have some audio of that. I don’t think this one’s quite as loud as a hot fire test, but let’s listen to that. This is what the suppression is going to sound like.

[ Engine Sounds ]

Host: And those are the, that’s the clicks, right? That’s the, I guess it’s basically just like a giant–

David Smith: Sprinkler system.

Host: Sprinkler system. Yeah, yeah, yeah.

Paul Bookout: Yes.

Host: Rocket-size sprinkler system. So you’re going to take it from the VAB, and I wanted to get, circle back on that because I think I was calling it Vertical — is it Vehicle Assembly?

David Smith: Vehicle Assembly.

Host: Vehicle? So I was getting that wrong. It’s Vehicle Assembly Building. You bring it out to a launch pad, and is it going to launch on the same pad that the Saturn V was launching?

David Smith: Yes.

Host: Okay, so that’s 39–

David Smith: In fact, I think — well, I’m not sure if it’s A or B–

Host: A or B.

David Smith: But the one that we, that NASA kept, they totally revamped the equipment underneath that concrete mound.

Host: Yeah.

David Smith: And it’s, there’s a lot of [inaudible] and electrical equipment that’s there in, the remnants from Saturn V, there’s still a rubber room. If you know, that’s where the, if someone was trapped at the pad, you’d have a safe place in there. So that’s still in that same area, which they’ve now made a historic area, which is kind of interesting. But they, for the first time in 50 years, have to clean out all the old equipment, totally revamp that launch pad for SLS. So it’s brand new and ready to go. It’s really impressive.

Host: So the, what’s being suppressed over at this launch pad by that suppression system, is it, is the solid rocket boosters, right, and then are the engines firing at the same time?

David Smith: Yes.

David Smith: These RS-25–

Paul Bookout: Correct.

Host: Engines?

Paul Bookout: So–

Host: Everything’s all at once?

Paul Bookout: Right. Actually, the — sorry. Actually, the main engines ignite first because we want to make sure all of those are operational and working at peak efficiency because once you start the solid rocket motors, you got to launch because you can’t turn off solid rocket motors. So you want to make sure your other four engines are operating nominally, and then you ignite your solid rocket motors.

Host: So we’ve done some testing with the, with these, the main engines, right? The RS-25’s?

Paul Bookout: Correct. Yes. Also, we have done full-scale testing of the solid rocket motors out there at Orbital ATK in Utah, where they actually constrain him, lay him on the ground sideways, and constrain him, and actually fire, do test fires out there at Utah.

Host: Ooh, I’ve seen that. They actually had a HDR video I think of that — high dynamic range or something.

Paul Bookout: Yes.

Host: Yeah, and it was super cool to see. But then, also, just the test itself, actually–

Paul Bookout: Yeah, I’ve been out there for a couple launches, and it’s kind of unique because, with shuttle launch, you listen to the sound, and it’s, you know, launching, so it’s, after just a few seconds, it, the sound’s gone. Where solid rocket motor is, it’s operates for two minutes, so you’re sitting there feeling that whole sound, you know, [laughs] for two minutes, and it’s a really exciting experience to be out there.

Host: How did it feel? Did it feel like you were at a loud concert, or even worse than that?

Paul Bookout: Well, you’re usually about a mile or so away.

Host: A mile, okay.

Paul Bookout: So, you know, just for safety reasons and everything.

Host: That’s, yeah.

Paul Bookout: So you kind of get to see it off in the distance a little bit, but, yeah, you still feel it and hear it, yeah. And it’s kind of unique because you see the smoke, the engines fire off, and the smoke coming out, and then, a couple seconds later, that’s when you feel it. So–

Host: How about the RS-25’s? Do you feel those too, or not as much? Were out at the RS-25 test?

David Smith: Yeah, yeah. Well, the static firing, yeah, you feel it in your, you can get close for that, and you feel it in your stomach. I mean, it’s very visceral, the shaking of your, of that sound, so, yeah, you won’t forget it once you’ve had it.

Host: That was the sound we played earlier, right?

David Smith: Right.

Host: Okay. I think the one we still have is the solid rocket booster, I think. Okay, let’s play that one. This is the one that Paul was talking, the one out in Utah.

>> T minus 10, 9, 8, 7, 6, 5, 4, 3, 2, 1, fire.

[ Engine Sounds ]

Host: Okay, so that was the test from out in Utah, and if you really, if you turned up the volume on your, on the podcast, you can really feel it. I listened to some of, I would listen to this in the car or hook it up to a nice speaker because you can really feel it there. So those, that’s all of those — the solid rocket boosters, the RS-25, and the suppression systems. So let’s go back to the stages and sort of recap the, I guess the stages of all of these engines firing. What’s that look like?

David Smith: Right. So, you know, the term “stage” means that you have a single entity that provides an impulse for a period of time and then is thrown away.

Host: Okay.

David Smith: So in the olden days, so that would be Saturn, you know, you’d say Saturn was a three-stage vehicle, right. It had the first stage, the second stage, and then third stage was the injection stage that took, you know, Apollo and the land to the Moon. For both shuttle and for SLS, we really don’t, can’t call it three stages because these stages work together, which is kind of like they’re two-and-a-half stages. So what that means is the core, and, as Paul said, the core starts a little bit earlier, but they’re essentially the same time. The core and the booster, the solid rocket motors, boosters, excuse me, turn on at the same time. So they’re ignited, and that’s the one-and-a-half stage–

Host: Okay.

David Smith: Because what happens? After two minutes, the boosters fall off and the core continues, so that’s the half stage, in a sense, the boosters. Now, the core continues. And then, finally, the core is expended after eight minutes. It’s disposed of in the ocean. And then, you have the upper stage — in this case, the second of the one-and-a, two-and-a-half stages — fires to get you to your destination. So you could still call it a three-stage system, but because some of the stages work together they’re not really separate stages. So it gets a little confusing. So that’s why you really don’t hear, that’s why people use the term “upper stage” these days and not “third stage” or “second stage” [laughs] because even the expendable vehicles have multiple solids on them, and so they have the same issues. So that’s the difference in staging today. And it’s more effective to do it this way as well.

Host: It’s more effective, I guess is it from the perspective of, oh, you can turn this off, you want to make sure everything’s working? Is it I guess more reliable? That’s why it’s more effective?

David Smith: Well, it’s more effective because you use the power where you need it. At, you know, at sea level, you need the most thrust, so you combine everything together to get you out of the gravity well of Earth. So there’s an efficiency with that system that, you know, is improved, is an improvement upon what was done for Saturn and other rockets before then?

Host: Okay. So how about the, we’re talking about different configurations too — Block 1, Block 1B — and how they’re going to be different and just sort of evolve. Paul, I think you said you had some secondary payloads I think on 1B.

Paul Bookout: Yes, that we’re planning for.

Host: That we’re planning for, okay.

Paul Bookout: So, you know, currently, on commercial launch vehicles, CubeSets usually don’t have propulsion sets, and they’re really going to low Earth orbit or geosynchronous orbit.

Host: Yeah.

Paul Bookout: And they’re pretty much just deployed in those locations, so they don’t need a secondary or propulsion system to get to where they need to. On EM1, this is the first opportunity for a secondary payload to be able to have propulsion systems and going to get access to deep space because we’re giving them the initial thrust or velocity to get out going to the Moon or into deep space. They only need smaller propulsion system to change their trajectory or where they want to go. So it’s, you know, this will be the game changer for secondary payloads. I mean, this is first-time opportunity for these small, little, shoe-size, shoebox-size payloads to be able to get out into deep space.

Host: Yeah, and do some great stuff — orbiting the Moon, land on the Moon. You got some–

Paul Bookout: Right.

Host: Great stuff happening in some of these–

Paul Bookout: Right.

Host: Secondary payloads.

Paul Bookout: As I mentioned in Part 1, EM1’s kind of discovering that, well, they really want to be a little bit bigger so they can have a little bit larger propulsion system. So instead of getting off at we call bus stop one right in the middle of the Van Allen belt, they’d like to get off at bus stop two or a little bit past so they don’t have to worry about the radiation effects on their systems as much. But they can’t do it because they don’t have the propulsion system big enough to change their direction that they want to go. So on EM2, because it’s a more powerful rocket, there’s opportunity for additional mass allocations for secondary payloads. The mass allocation is the mass that’s left over that the primary or co-manifested payload doesn’t need the full capability of the rocket, so we can use that additional up mass for secondary payloads. So we’re offering actually from a 6U- up to a 12U- and even a 27U-size secondary payload.

That’s huge for secondary payloads wanting to be able to get out into deep space. This allows them to have more power systems, more advanced telemetry, communications, and especially larger propulsion systems so they can get out into different destinations and do all this great science that they want to do in these smaller, less expensive packages.

Host: Actually, that blends in nicely to drawing comparisons with SLS to other heavy-lift rockets because SLS is going to be gigantic and take these very, very large payloads. What’s the difference between SLS capabilities and some other heavy lift rockets like Delta IV Heavy or Falcon Heavy? Why wouldn’t you use just the heavy rockets? Why do you need SLS?

Paul Bookout: Existing commercial rockets, they’re not destinations going into deep space. They’re mainly going into low Earth orbit or geosynchronous orbit. So for a secondary payload to get out into deep space, they’d have to be pretty big, you know, to have a propulsion system larger than a 27U. So the uniqueness of flying on SLS if you want to get out into deep space is that you don’t have to have a huge satellite or, and propulsion system. SLS is providing that initial kick or velocity to get you out in the general direction you want to go. And then, you’d have a smaller propulsion system to be able to get out there. So overall, it’s a lot less expensive. And again, SLS is giving these small CubeSets the opportunity to get onto deep space.

Host: And also, the fact that it’s human rated, right. The fact that you can actually put people on it and bring them far into space, right?

Paul Bookout: Right.

Host: Kind of a big thing.

Paul Bookout: Definitely, yes.

Host: Is it the only one that’s rated for human, for deep space?

David Smith: Well, it’s the only launch vehicle today that’s being designed specifically for that. There’s–

Host: I see.

David Smith: You could make the argument that a Boeing CST-100 capsule flying on a Falcon, excuse me, on a Atlas is a human-rated system. It’s not really. It’s an amalgam. And by the way, that’s aimed at LEO. So they–

Host: I see.

David Smith: You know, it, yes, we are the only ones that are being, designing specifically for that, and it’s for safety reasons.

Host: So it has to really meet these standards. It has to be redundant. It has to, and the SLS is the big, deep-space rocket that has the standards, has the capabilities, and is going to get you farther.

David Smith: Right.

Host: Ultimately.

Paul Bookout: Exactly. And, you know, to be that safe vehicle for launching humans into space, deep space, you know, we have to have these built-in, redundant systems. We have to do all these testing throughout the whole build of the system. You know, of course, that’s a little penalty that we have to have additional mass to be able to have this redundancy, have this extra safety aspects of this vehicle. So that, of course, goes right in against being able to have a larger mass, up mass capability. But we’re doing this for human exploration, not robotics exploration, so we’re, we have to take those extra steps to make it safe.

Host: That’s right. So what’s the benefit of having this large up mass versus just launching a bunch of rockets with smaller masses?

David Smith: Right. We, what’s often not fully appreciated is, for human spaceflight, for long duration, you can put together a whole bunch of little modules for humans, but think about it like this: Every time you put together a module, it has to have a hatch. Maybe it has to have two. It has to have a life support system. It has to have a power system, a thermal system. It has to be able to operate autonomously until another small module is joined to it. So you can make a lunar orbiting platform or a Mars deep-space transport out of many small modules brought up over time for that many vehicles, but the problem is it becomes sub optimized. You end up paying maybe 50% more mass for all the structure you don’t really have to have. Plus, now, you have many duplicative subsystems for many modules that have to all function flawlessly together and have to wait in space while other modules come up over time and to be joined together. So when you think about this, coming up with this giant, origami-type space station that’s deployed over years from many small modules compared to one flight or maybe two flights bringing up a very large module that does everything in one reliable, tested on the ground type of human habitation system, it becomes almost a no-brainer, right.

[laughs] If you want to make sure your people are alive over time, you really want that kind of system. Only SLS right now is sized to do that. Other guys can certainly deliver those pieces, but they’d be a lot smaller and you’d have these issues that we just talked about.

Host: That’s right. And I guess it kind of opens up some opportunities for just, because you can have a larger up mass, because you have more space within the fairing to put things–

David Smith: Right.

Host: Now, you have a lot less constraints because even — I’m going to go back to James Webb, right. James Webb is a wonderful telescope, but it was constrained by what it can–

David Smith: The volume of the fairing.

Host: Yeah, so it had to come up with this folding technique to pretty much fit inside the fairing. Otherwise, you couldn’t launch the satellite. But I guess you can design, you have a little bit more freedom of design with something a little bit larger, right?

David Smith: Or if you wanted to scale up the James Webb design, let’s say that was the perfect design for telescopes–

Host: Yeah.

David Smith: You could make a telescope that’s five times larger with the large fairing that, you know, larger fairings that SLS could fly. So it opens up a whole, either you can have a non-origami type, folding-out type telescope, and it’s all great, or, if you want to still do that, it gets you something even larger. So the scale is, the current fairing is, in some cases, the ten-meter fairing would be five times larger than the largest existing fairing today–

Host: Whoa.

David Smith: If we could produce that. And that’s, you know, we’re talking a seven-story building could fit inside that ten, you know, [laughs] that long, the long, ten-meter, diameter, meter, diameter fairing.

Host: All right. Just launch my house into space and just–

David Smith: There you go.

Host: Kind of get a nice view.

David Smith: Well, it’d be your condo building that it would launch–

Host: [laughs] Condo building.

David Smith: Not your house.

David Smith: Even bigger.

Host: Yes.

Host: So I kind of wanted to end with just sort of a scope of, we’re kind of setting up a scene for what this rocket is capable of. Looking towards the future, and, David, you kind of pointed towards this, was this is a 50-year rocket, right. This is something that we’re planning on using for a long time for many missions. How do you see this rocket being used? Like, take us into the future. What is this rocket going to give us?

David Smith: So, you know, obviously, the lunar orbiting platform would be the first step. Let’s–

Host: Yeah.

David Smith: Improve the technologies in our backyard we call the Moon. We use those technologies then to extrapolate a system that can go to Mars safely and start, you know, bringing Mars into this human ring of habitation in our solar system. Some of the more exciting things in tandem are these robotic missions. There’s the idea that we can send, because we can go so fast, we, so fast into the deeper reaches of the solar system, that within a five-year mission, we can send out a telescope that could go 200 astronomical units out from the Sun, and actually come back and aim at the Sun, and use the Sun as a gravitational lens to see exoplanets on the other side of the Sun. So we could make the world’s largest telescope by having one lens on one side of the Sun and using the Sun’s gravity as the other lens, and now seeing planets like we could’ve never seen them before, all because SLS can send that telescope out in a time frame that we can actually operation a mission, versus, you know, remember, Voyager took 30 years to get outside to, close to the heliosphere. So, you know, it’s a, it’s such a game changer that the real issue with SLS is we haven’t thought about all the stuff we can do with it yet, you know.

It kind of bends our imagination in a new way that we haven’t been thinking of. Another example is interstellar probe. Again, sending something beyond the heliosphere now. You know, instead of the Voyager drifting out there over 30 to 40 years, we can send something out there in 20 years to break the barrier and see what’s on the other side of the heliosphere. And we can do that in an active manner versus we’re just getting little pulses from Voyager now still coming back. We can be much more active in that. So a lot of places like JPL are investigating the capability of SLS in ways that we never even thought of recently. So we’re just on the very edge of discovering what we can do with the system.

Host: Unbelievable. And this just kind of opens up the plan for exploring beyond low Earth orbit, right. You’ve said the first step for human exploration is going towards the Moon, but now you have a bunch of Moon missions. You kind of develop your skills. You got this Lunar Orbital Platform, the gateway that’s going to bring us, the truck stop [laughs] that we call it–

David Smith: Right.

Host: Is going to take us further out. And I’m guessing this will be used for the future human missions too beyond this first step.

David Smith: Well, if we go to, we talked about I think in the earlier episode, nuclear thermal propulsion.

Host: Yeah.

David Smith: If we’re able to employ that for human transport, we can reduce times to where we can send people maybe even ultimately beyond Mars. So, but only SLS with its capability to loft both mass and volume, when the nuclear, this nuclear thermal propulsion requires large amounts of hydrogen, which requires volume, only the SLS can give us that capability to even see if some of these technologies are usable, versus just relying on the same old technologies as the last 50 years. So we have so much promise in front of us with this.

Host: Unbelievable. You guys are getting me all excited for what’s to come. I just want to take a time machine, and jump, you know, 20 years into the future, and just see this rocket has done.

Paul Bookout: Yep, you’re not the only one.

David Smith: [laughter] Take us with you.

Host: Yeah, that’s–

David Smith: We want to be there too.

Host: Unbelievable. Hey, David and Paul, thank you so much for coming on, and kind of describing the SLS, and really spending so much time so we can do this in two episodes because there’s so much to this story. And honestly, this was the first time that I’ve actually gone into this much detail for the rocket, so I really appreciate you getting on. And for the listeners, please listen to Parts 1 and 2 and get the whole story of what this rocket is all about. Guys, thanks again for coming on. Houston, we have a podcast.

David Smith: You’re welcome.

Paul Bookout: Thank you very much for having us.

[Music]

Host: Welcome to the official podcast of the NASA Johnson Space Center, Episode 2, Can You Hear Me Now? I’m Gary Jordan, and I’ll be your host today. In this podcast, we’re bringing in the experts — NASA scientists, engineers, astronauts, pretty much all the folks that have the coolest information, the stuff that you really want to know. [inaudible] We’re talking everything from extraterrestrial [inaudible] to the unknown [inaudible]. So today, we’re talking space communication networks with Bill Foster. He’s a ground controller– Hey, thanks for sticking around and listening to the whole full story of the Space Launch System. This was Episode 42, Part 2. If you haven’t listened to Part 1, go back. You can listen to some of the more components about EM1 and then just some general ideas about what SLS was. Otherwise, you can go to some social media channels and website.

We’ll start with the website — www.NASA.gov/SLS. That’s where you can get the latest and greatest. Otherwise, you can follow some social media accounts on Twitter. It’s @NASA underscore SLS. On Facebook, it’s NASA SLS. Or you can actually go on the web and search “SLS Mission Planner’s Guide,” and it’s a document on the web that you can download and just learn everything about the rocket, some of the constraints. And that was actually one of the things that Mr. David Smith worked on. So we’re really looking forward to the launch of the first SLS. Glad you were able to join us on today’s podcast to listen about the rocket and some of the missions and capabilities of the Space Launch System. If you have any questions, just use the #askNASA on your favorite platform for the NASA Johnson Space Center accounts on Facebook, Twitter, and Instagram. You can submit a question or an idea for an episode that you want us to cover here on the podcast. Just make sure to mention it’s for this podcast, Houston We Have a Podcast. This episode was recorded on March 20th, 2018 thanks to Alex Perryman, Rachel Craft, Laura Reshawn [phonetic], Kelly Humphries, Pat Ryan, Tyler Martin, Bev Perry, and all the folks at the Marshall Space Flight Center for helping to put this together. Thanks again to Dr. Paul Bookout and Mr. David Smith for coming on the show. [inaudible]