From Earth orbit to the Moon and Mars, explore the world of human spaceflight with NASA each week on the official podcast of the Johnson Space Center in Houston, Texas. Listen to in-depth conversations with the astronauts, scientists and engineers who make it possible.

On Episode 234, John Blevins details NASA’s Space Launch System rocket ahead of the Artemis I mission. This episode was recorded on February 15, 2022.

Transcript

Gary Jordan (Host): Houston, we have a podcast! Welcome to the official podcast of the NASA Johnson Space Center, Episode 234, “SLS.” I’m Gary Jordan and I’ll be your host today. On this podcast, we bring in the experts, scientists, engineers, and astronauts, all to let you know what’s going on in the world of human spaceflight and more. NASA is returning humans to the Moon, and we’ll put the boots of the first woman and the first person of color on its surface through the Artemis program. To get there, NASA is building its most powerful rocket yet, the Space Launch System, or SLS. We had conversations about this rocket early in the podcast’s history; Episodes 41 and 42, if you want to check them out. I think it’s about time for refresher and even better yet, a deeper dive into the vehicle’s construction and components. To do so, we’re talking with none other than Dr. John Blevins, Space Launch System chief engineer. Advanced degrees in mechanical and aerospace engineering, and decades of experience at NASA, working on rockets and propulsion, make him the right guy for the job. I’m very excited to learn more about this rocket, so let’s get right to it. Enjoy.

Host: John Blevins, thanks so much for coming on Houston We Have a Podcast today.

John Blevins: Hey, glad to be here, Gary.

Host: Awesome. Um, what a job you have, John, I mean, of, of this is, it’s, it’s quite an impressive title, chief engineer of NASA’s mega-rocket, the, the Space Launch System. Um, just pulling back and just recognizing that, uh, how does, how does that make you feel to have that level of responsibility for something so grand and so important?

John Blevins: Well, quite frankly, Gary, it’s, it’s an honor; you know, there are really thousands of engineers, uh, across this country, uh, that are working on this rocket, uh, on the return to the Moon for our nation and really for the world, and I’m just really excited to be in a position where I get to represent them and, and, uh, just kind of help discern the technical path for this rocket. So it’s, it’s quite an honor, quite frankly, and it’s humbling because some of the best people, some of the smartest people in this country, are working on this rocket.

Host: I can only imagine the people that you get to work with, but you’ve been, you, you, part of the reason you have this job is because of your decades of experience and your schooling and, and you, you spent a lot of time working and thinking about rockets. And I wonder if there was something early in your childhood that sparked that, because it seems like it was something that, like propulsion and rocketry, it’s something that you stuck with. So was there something early on, uh, that sparked your interest that made you want to pursue it so passionately?

John Blevins: You know, I grew up with a passion to fly. That’s, that’s really what I grew up with a passion: every time something would go overhead, uh, I just wanted to see that, uh, and, and very early on, actually, I, I, took to, uh, light aircraft, you know, uh, flying in light aircraft. And then, then I went to, uh, on a school tour when I was young and, and it was at Arnold Engineering Development Center. That’s Arnold Air Force Base in Tennessee, and they test a lot of supersonic stuff, right? And so, they had airplanes that were supersonic. They had rockets that were supersonic, uh, models that were sitting outside in the wind tunnel. And I said, man, I, I want to do this. And so ultimately, what I got into was doing the aerodynamics for supersonic vehicles, including this rocket. And that led to this great opportunity to do this. But I, I do love rockets. That’s a great way to put it. There are these sparks in our lives that kind of lead us down different paths and it’s, uh, it, it’s man and machine, uh, it’s flying. That’s really what, uh, what made me, uh, excited about it.

Host: Well, so, so in school, you, you got degrees in mechanical and aerospace engineering, but I wonder, I wonder what you did and, and what, what you focused on? Because I think from, in each of those respective areas, you can go into a lot of different places, but what were you doing to hone your skills in the area, in the areas that you were interested in?

John Blevins: Well, you know, uh, my advice to all the, the, the people that are going into undergraduate is just solve the problem that’s right in front of you. You know, that’s how we ended up going, uh, to the Moon the first time with Apollo — those guys did not grow up dreaming of going to the Moon for the most part, and I know some of them; uh, they, they ended up dreaming of jet aircraft and flying things and, and they were at the right place at the right time, uh, when we did that. And so, my philosophy is first just to make sure you’re doing a good job at whatever you’re doing. Uh, and so, uh, in that undergrad, that was the way to go. And then I had that opportunity, uh, after designing cars for a few years, I decided to go to grad[uate] school and that’s when I said, hey, I want to do some supersonic flying things. And actually, the first thing I worked on was a big missile, which is not too different. And, uh, and then after that in grad school it just got down to rockets and I’ve had a wonderful career and great time at NASA.

Host: And you did end up exploring that passion for flying, right? You became a, a pilot.

John Blevins: Oh yeah. You know, I, I really can’t stop that, right? So, uh, I, uh, I bought an airplane and learned to fly along the way. And then I, I decided the next step was, uh, you know, to get the instrument rating and the next step was to get a commercial rating, and then I became a flight instructor and, and then I became a multi-engine flight instructor and then I became an instrument flight instructor. And, and so, yes, I’m actually multi-engine airline transport pilot-rated, and I fly frequently, and, and it’s just a, a great passion of mine.

Host: Well, I, I certainly envy you, you’re working on a lot of cool things and you’re exploring your passions. It’s certainly a great way to live. And, and it’s, it’s one of those things that you’re working on so hard, John, that I want to talk about today, it’s, it’s the Space Launch System. Really want to do a dive, deep dive to really understand this rocket. Um, uh, and, and especially where we are today, because we’re coming up on Artemis I very closely. So let’s start from a high level. John, just, what is the Space Launch System?

John Blevins: Well, the Space Launch System is really a heavy-lift launch vehicle, right? We’re the, we’re the large truck that takes payload into deep space. Uh, you know, it is unique in, in the heavy-launch area, not just, uh, uh, really for today’s time, but really for all time, because this is the, the rocket since Saturn V that we start, thought about man, uh, uh, humankind when we fly this rocket for the first time, we’ve, we’ve thought about all the things, the human rating requirements to make sure the men and women that fly this rocket are well taken care of from the very beginning. And right, so, it’s unique in that, you know, we’ve looked at reliability, redundancy — which is much different than reliability and where it should be redundant — from the very get-go. Uh, we’ve looked at where we need aborts, where we understand the rocket’s behavior, um, the full capability of the rocket, what, what it means and what we would call an enclosure rate and a statistical performance metric to make sure that, uh, you know, that up to a five-sigma that we accomplish what we say we’re going to accomplish. Because what you don’t want to do is, is, uh, is, is put some men and women on there to go to, uh, say the Gateway that we’re going to build out near the Moon and have a module on there and not be able to achieve that mission. So from the very beginning this was built to human rating standards. It’s just a unique, uh, heavy-lift capability. And, and as you pointed out, we’re about at the Artemis I missions; this is a very mature build, uh, and design, uh, a lot of heritage and uh, capable components that we put together here to make a great rocket.

Host: And, and we’re, we’ll spend some time going into those, uh, what those heritage components are and, and we’ll, we’ll, talk about it from the ground up. But keeping, keep, starting at a high level, keeping it there for just a bit, you talked about, it’s, it’s a big, big, heavy-lift capable rocket, um, that’s going to get us to explore, to explore the Moon, to explore beyond. Um, why? What is so good about a big rocket that allows you to do the things we want to do?

John Blevins: Well, it’s really in part about safety, right? You know, if you have to assemble things in space, if you have to, uh, if you have to connect, you know, it’s hard enough to connect at, uh, on planet Earth at the Five Guys to have lunch, right? Uh, but if you’re going to deep space and, uh, and you can imagine the radius as you go out, uh, into orbit, and have to connect things, we do it, uh, when we do that, it limits our launch window, it limits our capability, you can actually end up wasting missions, right? You can send some things like cryogenic propellants, and then if you have to dock with those later, and you have a, a reason you can’t launch, like weather, uh, then you might miss an opportunity. But for us, we’re going to carry everything in the one system. And, and that was done on Saturn, uh, largely for safety, and we’re doing it on our rocket, uh, for safety as well. And so, we, we want to carry the people and the things those people need in order to achieve the missions for exploration. That’s first to the Moon, as you pointed out, uh, in the Artemis I and subsequent planned Artemis missions, but that’s beyond the Moon eventually as well.

Host: All right. Um, now you, you guys are thinking long-term. Exactly that, right? So, so we’re talking about Artemis I and we’ll, and we’ll talk a lot about that mission today, but, but just thinking ahead, what the, the design of the Saturn V, you have considered that in mind a sort of an evolution, uh, and, and the way that you have it, uh, spread out over time is in these things called blocks. Uh, now what’s the logic there. What are the blocks? What, what are the different blocks and what do they help you achieve over time as the design matures and grows?

John Blevins: Well, the real, uh, eventual goal of the block upgrades is really to provide more mass, more cargo capability, um, to, to the Moon. Uh, you know, they’re logical in the sense that, uh, in certain cases like, uh, you know, the big booster upgrade, that’s the Block 2, that’s kind of the ultimate block, we’ve got a lot of that hardware. You know, we built booster cases early in the shuttle program. We recovered those boosters, we flew them. Uh, and now we’ve decided to expend them. We’ve decided to fly them and, and due to our flight rate we’re going to drop them, and so a good logical path is to create a, a more lightweight, a better structure for the booster that’s not built on reusability, you know? For the solid rocket boosters for the shuttle and for most vehicles, when you try to do recovery, the recovery actually drives the design, it drives the mass into design, it’s your highest dynamic pressures. And, and so for us, we can now focus on just that ascent mission. We can design just for that, and we can optimize, and we can provide more cargo, uh, with what we’re going to do, uh, and the Block 2 for the composite boosters. Uh, but between now and then, there’s a upper stage, uh, change that we’re going to make. That’s a huge change for us. Uh, and it really is an upper stage. Right now, we have an in-space stage that we’ve got on top of the rocket. And then when we go to that, you know, high Mach number, upper stage, it’s also an in-space stage that just provides us a lot more lift capabilities. So each one of these block changes have, uh, mass performance as the center capability that we’re trying to achieve with each block upgrade.

Host: And the more mass, uh, you know, beyond just, OK, you can bring more stuff, you can bring heavier stuff, but is that, is that really the ultimate goal here is, is as you bring more stuff, it helps you to achieve your mission and really get the best bang for your buck out of a single launch? Is that, is that the idea through the evolution of, of the program?

John Blevins: Yeah, it really is. Uh, you know, uh, there, there are other ways that you can try to do a lot of mass and SLS is going to be capable of those as well. If we, if we went to, you know, docking scenarios with multiple missions but, but the reality is if you can take it all at one time, you save a lot of CONOPS, a lot of concept of operations, that can be risky and dangerous for the crew. And so, uh, we do want to take as much as we can at one time. And, and, you know, just like, uh, you know, you mentioned the Saturn V, Gary, uh, you know, when they first started, they didn’t have the capability to take the rover, right? That came later. And, and if you look at the, uh, mass performance, even though they stayed, uh, identical to everybody’s vision on the pad, when that thing rolled out, they said, oh, that’s, you know, that’s Apollo 11 and the, you know, keeps rolling out, and eventually, they’re like, OK, there’s, you know, Apollo 17; but in the, in the interim between those, uh, missions, they were able to improve the mass performance. And so the last vehicle was much more capable than the first. And we do that with other vehicles, just like we do it with aircraft evolution and others. So, so it’s kind of that standard aerospace, uh, evolution of capability that we’re looking for, but we’re making these block upgrades are significant. Uh, and there’s engine upgrades in them, uh, for the, the main engines. Uh, and there’s the boosters. And then there’s that upper stage. And those are just huge block upgrades for us.

Host: Now, you talked about some, uh, you know, reliability and redundancy being at the core of the design of the SLS, making sure, uh, that this thing is a safe vehicle. And, and even, even just the whole idea of a large rocket, one of the core reasons there is safety. Uh, I wonder though, you know, building a, a giant rocket has to come with just some baseline challenges: as you scale up with in the terms of the rocket and the amount of propulsion that you bring, there has to be some risk that’s introduced to, to having such a large design. So, high level, when, when you’re tackling the, this, this design, when you’re tackling this, this super-large mega-rocket, what are some of the initial challenges that you have to overcome, uh, to get to where you want to be ultimately, the safe, redundant, reliable vehicle?

John Blevins: Well, you, you hit on something that most people don’t see there, Gary, and that is when you have a tremendously large rocket, you’ve got issues just based on size. Uh, and, and some of those are just transportation, right: having dedicated, a dedicated barge to carry the core stage, uh, to wherever we’re taking it. And, and, and typically, that’ll just be directly from the Michoud Assembly Facility, uh, down to, uh, Kennedy Space Center, just like we did the [space shuttle] External Tank and this is a similar diameter, but, uh, you know, for all the listeners today, I would challenge you to go get a picture of the shuttle and then put a two-scale picture of the Space Launch System beside of it, and you’ll say, oh my goodness that, that SLS is huge, uh, comparatively. And so just, just, uh, so one, just, uh, transportation; another is picking it up, right? It’s, it’s not a light vehicle. It’s, uh, it’s going to hold 700,000 gallons of, gallons of cryogenic propellant. And so, using a crane. Uh, rolling it out to the pad: we do use the historic, uh, crawler-transporter that hasn’t been really taxed like this since the Saturn days. And so, transportation is certainly, uh, one of the big things. You know, there is something to our advantage, uh, here with scaling rockets, and we, you know, we knew this when we started, uh, you know, the rocket back in 2011, and that is, as you scale up you, you can achieve higher, uh, mass fractions, higher performance, uh, in terms of propel, or your, your payload, uh, to the overall mass of the rocket. For all, all, all that effort of picking up and moving and, and, uh, assembling these incredibly heavy pieces and, and doing that does have a payoff, and that is that rockets scale favorably to propellant mass fraction as they get bigger.

Host: And so, the, um, the ground support infrastructure that you’re saying is one of the challenges to, to supporting such a rocket that has been built up over time. So, so just the snapshot of, of where we are today, John, on being able to support Space Launch System manufacturing and transportation, to start, you know, building these rockets and, and putting it into a sustainable, long-term, repeating program, what are some of the ground support infrastructures that we have in place right now to be able to do this long-term?

John Blevins: Well, you, you’ve hit on one of the things we’ve been working on really hard for ten years. And in fact, I, I like to say that, uh, we haven’t just been building the rocket, we’ve been building the system to build the rocket. And so, the first one took a, you know, it was a pathfinder, it took a long time to get through its process, uh, and now it’s at Kennedy Space Center in the VAB (Vehicle Assembly Building), and it’s about to roll out, uh, under the, the crawler-transporter that I mentioned. That crawler-transporter was used in the Saturn program, and then also in the shuttle program. Uh, we’ve completely redone a mobile launcher. We’ve redone the water systems for the mobile launcher. Uh, we’ve redesigned the tower. Uh, so the ground system, the ground support equipment, uh, is a, is completely modified: in fact, we’re building a new one for the future blocks right now as well. And so, all of that infrastructure is what we’ve been building for ten years. Uh, you know, the, the first one takes a while to go through all of its paces, and quite frankly, the second one’s coming in right behind it, right?

Host:Yeah.

John Blevins: We’re, we’re finishing up at Michoud, this starts at the factory. You know, Gary, it starts right at the different factories, uh, with ground equipment and how we test there. And then we take it on to Kennedy. The system at Kennedy is, is really ready. I, I’ve sat in the, uh, the, uh, the LCC, our Firing Room 2 launch command center, and, and, uh, you know, they’ve remade that, it’s completely different, uh, software and a completely different setup, and it’s very efficient and, uh, and we’re ready to go.

Host: Big deal, big deal. Now let’s go to the rocket. Right? So, um, if we’re looking at the components, we talked about, we were going to do a deeper dive into this. I’d like to start from the base of a rocket, closest to the ground, and go all the way up top. So let’s, let’s start at the base, um, with the engines. Now, as I understand it these are the same shuttle engines, just you guys maximized the performance of these engines, more so than, I guess what was even realistic, right? It’s like a hundred, it’s like over a hundred percent efficiency improvement or something like that, right? So, so there’s four engines. What, what are these engines that we’re using?

John Blevins: Yeah, these are, uh, flight heritage engines, you know, during shuttle, uh, we, uh, we flew engines — in fact, we didn’t build too many, we flew them and then we’d bring them back and, and we’d reuse them. And, and we had 16 engines, uh, that were flightworthy when the, the shuttle program, uh, was, uh, ended, and, uh, we’re using those 16 engines for the first, first four flights of this, uh, vehicle. And so, let me, let me talk about those engines. You know, they’re, they’re the engines that the world knows the best, uh, and I mean, the world. Uh, we’ve got more test time, we’ve got well over a million seconds of test time on these engines. We had dedicated facilities during the shuttle program to test these, it was called the MPTA, the Main Propulsion Test Article. It tested everything in the line of the shuttle. Uh, and, and, and we continue to test these engines, uh, mainly because we’re changing some things, we’re making them cheaper, uh, we’re, as you mentioned, we’re making them higher performance. We we’ve got this, uh, performance metric we call rated power level, and that goes back to the original space shuttle main engines. And so, during the shuttle program we kept bumping up against that rated power level to the point where we got to a 104% of rated power level for those engines. So greater than the metric that we used as a baseline for power, and we were able to do the 104% and then bring those engines back and inspect them and then reuse them. Um, and, and now we say, well, we’re, we’re going to build these cheaper, and we’re going to get rid of these ones because of our mission profiles. And so we’ve, on the early flights, we have moved that performance up to 109% of that rated power level. And then the engines that follow are already in the test cycle — in fact, we’ve tested these up to much greater than that in case we need that. But for this first mission and for, uh, the immediate subsequent missions, uh, all of these flight heritage engines we’re going to run those at about 109% rated power level, is a max operating. And we’re going to do that most of the mission. So it’s, uh, pretty exciting the way we use these, uh, space shuttle main engines. They’re, they’re very powerful. You know, there’s a lot of, there’s a lot of, um, misunderstanding about power and thrust. They’re actually not the same thing, uh, you know? And, and they’re technical definitions. So it’s not something we can change or, you know, our emotion doesn’t affect whether they’re powerful or not, but the space shuttle main engines are incredibly powerful. And part of that is because they use a low molecular weight propellant, hydrogen. And so when they put out an exhaust it is, it is going faster, the velocity, not only is it around Mach 7, the Mach number means something different in a lighter molecular weight fluid, it’s a higher velocity than we would typically see if it were air or if it were hydrocarbon or another engine. So they’re extremely powerful engines, and they do produce a lot of thrust. They produce about a half a million pounds thrust each. Uh, and so, uh, just an incredible set of those for those on the base end, uh, of the vehicle. And, uh, and as I mentioned, uh, several of these engines on the first flight, one of them was even used for a Hubble servicing mission, we didn’t, we didn’t cherry pick these engines, we just picked four out of the 16. Uh, but last week we went through a Flight Readiness Review and I got reminded of the wonderful heritage of these four engines. So, uh, it’s good stuff on the bottom of that rocket.

Host: Oh, wow. And you’re talking about the one for Artemis I, right? You’re saying those four are ready to go for the first launch.

John Blevins: Uh, they’re attached to the rocket, we’ve articulated the nozzles; in fact, as you probably know, we, uh, did a full-duration firing of those, with those same engines at Stennis Space Center, uh, in preparation for the first flight.

Host: Big deal, big deal. Now they’re attached, we’re talking about the bottom of the rocket; there’s a, they, of course are supplied by an incredible amount of liquid hydrogen and liquid oxygen, being supplied from, and correct me if I’m wrong, the core stage, which also has a lot of other features to it. This is a very important stage. This is, this is what’s going to do, uh, you know, it’s, it’s the base, the anchor point of the rocket. So what’s, what’s the core stage, what’s in, what’s in this very important segment?

John Blevins: Well, you know, the core stage is the newest hardware. I, I want to point out that the core stage is maybe more complicated than it looks. If you take all the functions that you’d have on a rocket, or maybe even the shuttle if you think about the orbiter, you know, all the avionics and, and, and, uh, the command central, if you will, a lot of that is on the core stage. The flight computers, uh, they’re on the core stage. And it’s more than just, uh, a tank, right? In, in the shuttle, we had an external tank attached to the side, but we had all of the lines, ducts, valves, all of the complicated, uh, uh, propellant flowing hardware on the inside, generally, of the orbiter. In this case, uh, it’s on that core stage. So the core stage is a completely new structure. Um, it, it’s really neat because we built it for those loads that we’re going to see later on with the different block upgrades. Uh, and it, and it used some new technology. You know, it used some things that were developed even at NASA, the, you know, friction stir welding was developed in the ’80s at NASA. And so instead of fusion welding we used friction stir welding. Uh, and these are the thickest aluminum tanks that have been done, friction stir welding. And this is the largest cryogenic tanks ever built, you know: 700,000 gallons of cryogenic, liquid propellant. It’s, it’s, uh, it’s really an amazing, uh, beast. And of course it’s covered, uh, with thermal protection system, just like we did on shuttle, uh, in order to, uh, prevent ice buildup as well as to keep that blow-off to a minimum as we sit on the pad and prepare to launch.

Host: OK. So you got the, you got the tanks, you got the fuel lines, and then, uh, you, you talked about the brains, too, right, there’s, there’s a bit of avionics in here. What are they doing?

John Blevins: Well, you’ve got the brains, the flight computer, you know, um; the, the, the vehicle doesn’t do anything the flight computer doesn’t tell it to do, right? You’ve got these nozzles on the back end, you’ve got boosters that are attached, uh, off to the side that I know you’re going to want to talk about.

Host: Yeah.

John Blevins: But even the boosters do what that, those flight computers tell it to do. And more than that, we have rate gyros, we’ve got redundant rate gyros, that are in different areas of that core stage that are telling the flight computer what’s going on with the vehicle. So the flight computer, and there’s three of them, and they will, they’ll read, uh, the information from all of this information; we’ve got, uh, what we call operational flight instrumentation, uh, we’ve got certain engine flight instrumentation, it’s a little different, we’ve got, uh, developmental flight instrumentation — now that’s not to the flight computer, that’s just for us as an engineering community to make sure the rocket’s doing what we asked it to do, and that we’re good for the next flight. But, but it takes a lot of that information, and it takes specific data from say, the right rate gyro assembly or the inertial navigation units, uh, and it, and it, it takes that and has voting logic in case one of those devices fails, and then it tells the rocket what to do. And the rocket does what the flight software tells it to do. The, the, the flight software and, and in my opinion, is the, is it’s the integrator of the rocket. Uh, the, the rocket will only do what the software tells it to do.

Host: Mm-hmm. And you read my mind, John, of, of what I was going to tackle next. Uh, you know, the, the core stage, we talked about the engines doing, having a lot of thrust, but, uh, a lot of it’s going to be helped by the solid rocket boosters that flank both state, both ends of the, uh, core stage. And, and those are also I believe, uh, shuttle heritage and, and they do a lot of, uh, they do a lot of the work for, for the first phase of this flight.

John Blevins: Yeah. You know, the boosters, uh, they’re based on heritage, they’re a little different than heritage.

Host: Got it.

John Blevins: The propellant is from the heritage family. That’s really a good way to look at it.

Host: OK.

John Blevins: And the steel cases that we’re using, uh, those are heritage. We’ve got different avionics over there controlling certain things. Uh, we’ve got some different placement. We don’t have parachutes on the top of these, uh, as we did in the, in the, uh, in the booster, uh, for shuttle. And they’re taller, we’ve got another segment; we’re getting more impulse out of this. But you have it exactly right, Gary: you don’t get off the ground without these boosters. Uh, you know, if you like the main, uh, engines on the core stage, and you don’t like the boosters, then the boosters serve as a test stand, right? You just sit there and, uh, and you just burn propellant and, uh, you know, out of the, out of the core stage. And so, uh, the booster guys are very proud of that. We definitely need them. And, and, and it’s not, uh, recognized by everybody but when you’re setting there, you know, the core stage is really suspended by the boosters, the boosters at the forward area have the thrust carry-through where their thrust gets carried into the rest of the rocket assembly. We, we take that thrust out at the top of that rocket. And so, you know, a, a, real engineering way to look at it is that core stage and all of the rocket is actually hanging on the boosters, right? The boosters are the support, which is touching the mobile launcher, uh, at, uh, its support post, uh, prior to liftoff. And so, uh, so the boosters are incredibly important. Uh, you know, I mentioned the power of the, uh, the space shuttle main engines, but there’s another real, uh, issue for any rocket and that is the requirement for the thrust to the weight to be greater than 1. So now I’ve thrown gravity into the equation, right? So weight is that mass times, you know, gravity, and so, we’ve got to have more thrust, uh, pointed up than we do weight. And it’s those boosters that overcome that requirement for us. And they do an outstanding job. They’re extremely reliable. Um, we, we’ve set it up, uh, you know, based on our heritage with shuttle, and, uh, it’s, it’s, uh, it’s really something to see if you’ve, if you’ve never seen a launch with a, a big solid like that. Uh, it’s, it’s, uh, it’ll light up the sky.

Host: Uh, it’s on my bucket list, John. I never, I, I actually was, came, came a little late to the space game and never saw a shuttle launch. So I’m going to be relying on you to, to help me out with seeing SLS get out, get off the pad.

John Blevins: Well, we’ll get you a good seat, Gary.

Host: [Laughter] I see, I’m leaning on you. I, I hope you’re able to do it. Uh, um, but, OK, so, so we’re talking about the first stage, right? We talked about, uh, core, we talked about the solid rocket boosters. Uh, for Artemis I, on top of that is, is a stage called the ICPS (Interim Cryogenic Propulsion Stage). Now, what is this?

John Blevins: Yeah. So I’m going to, I’m going to even back you up down the rocket just a hair. There’s an adapter that the ICPS kind of sits mostly in, and it’s called the LVSA, Launch Vehicle spacecraft Adapter…uh, or Stage Adapter. And so that, that, it’s a cone and, and really, you know, we, we, jokingly sometimes say, it’s the, uh, you know, it’s the largest, uh, you know, size change adapter, you know, for plumbing in the world, but it, it has some functions as well. We’ve got some instrumentation in there. It passes through a lot of, uh, our developmental flight instrumentation equipment. And everything that’s going to talk to Orion has to go through all these stages. But if you were to look inside of that, that cone, that LVSA, you’ll see most of this stage you just mentioned, the ICPS, the Interim Cryogenic Propulsion Stage. And the reason that, uh, we call it that is because we knew from the very start that that was just going to be, uh, our first few flights — uh, we kind of went back and forth, how many do we fly with this ICPS? You know, we like the ICPS. It’s a great partner to us. Uh, this is a piece that we bought from ULA (United Launch Alliance), we, we basically modified an upper stage that they use, so it, it gives us some added benefit and safety to the first flights because we know how it’s going to fly. We’ve got some heritage with that. It uses a single RL-10 engine, which is, uh, an expander cycle, hydrogen oxygen engine that’s been around since the early ’60s. Really one of the, the, uh, well, probably the longest successful engine program, um, in the history of the world, really, is the RL-10. And so, um, and so it’s got that very, very reliable engine, and it’s a well-known stage, um, with all of its hardware, the lines, ducts and valves. It gave us longer time to develop a new stage that was more capable, uh, later on in that Exploration Upper Stage, but for this first mission we’ve got that ICPS; really excited to have ULA as a partner doing that.

Host: Yeah. There and they are going to help us out with the first, I believe it’s the first three missions, right, ICPS, before we, and then all, all helping us get ready for the, and that was the other one you mentioned, the Exploration Upper Stage, right? That’s how it’s, that’s the cadence?

John Blevins: That, that sure is. You’ve got that nailed, uh, shut there. It’s, uh, three flights with ICPS and then the fourth flight we go to the Exploration Upper Stage.

Host: Now I did skip over the, you, you caught me there, the launch vehicle stage adapters. So that is very important. Does that change when you change the upper stage from the ICPS to the, to the Exploration Upper Stage, or, or is the adaptor help you in both cases?

John Blevins: No, it does change, actually. We’ve got a, uh, we’ll have a — piece we’ll call the inner stage, be able to be constant diameter. Uh, we’re using that diameter, that core stage, to set our design guideline for that Exploration Upper Stage. You know, uh, you get a little bit of drag, it’s not hugely significant on a big rocket, but you get some environments and some drag, some shock waves, every diameter change; uh, you do get some stability added, but, you know, uh, with, uh, shock waves down the vehicle, but, but ultimately we decided to go with a constant diameter for that next stage. So it’ll be the same diameter, uh, as that core stage. So it looked like one big piece going up until it gets to an adapter for the capsule at that point.

Host: Got it. Got it. OK. Um, all right. So catch me again if I’m, if I’m skipping some stages of this rocket as I’m going up. But as we’re going up the, uh, ICPS, uh, and then that’s where you hit the, uh, Orion and the service module. So, so all of this, right, is to, is to carry payloads. It’s to carry the, uh, the payload which is ultimately Orion and the service module. There’s some secondary payloads, too, but, uh, that’s really, what’s sitting on top of this vehicle. Unless, correct me if I’m wrong if I skipped, if I skipped another stage there.

John Blevins: Well, you, you know, you know, I can’t let you dis any of the rocket, right? That’s what the chief engineer does, defend the honor of the rocket. There, there is a, uh, piece that doesn’t look like much to anybody when you’re looking at the rocket, you say, hey, that, uh, that stage you bought from ULA, it’s a certain diameter and, and the, um, Orion capsule is just a little bit bigger than that. And so, we’ve got this, we do have this piece called the Orion spacecraft adapter, and it’s, it’s actually more than you think. We said, hey, we can do something with this little area in here, and so what we did is we created an area that has CubeSat launch capability. And so, we can put numerous CubeSats in there, and we have those for the Artemis I mission. In fact, they’re from all over the world for Artemis I mission. We’ve got some from Italy and Japan, we’ve got several all over the country, JPL (Jet Propulsion Laboratory) has a CubeSat in there. And so, uh, that, you know, for a rocket this big, carrying something pretty small, uh, doesn’t affect our performance. And so we just set a ground rule and said, hey, we, we want to carry some payloads for science, we want to help that community out. We’re heading to a unique destination, and so, we planned in three bus stops, three different locations that will drop off CubeSats on the Artemis I mission. And then, uh, you know, the subsequent missions haven’t been fully nailed down on what we’ll do, uh, inside that volume, but there is that little volume there, and it gives us the capability to carry really pure science missions. It’s kind of a neat thing.

Host: Very cool. OK. I’m skipping all the adapters, but they’re very important to, and to your say, some of them serve multipurpose, which is also very, uh, very important to some of the objectives of this mission. Uh, secondary objectives as well. Now on top of everything you got, we talked about Orion and, um, and the service module. On top of that is I think to, to round it all out is the launch escape system. And that’s, that’s the very pointy tip of, of what makes up the SLS.

John Blevins: Yeah. And, and of course, uh, if you’re riding on this thing, it’s not an insignificant part at all, right?

Host:Right.

John Blevins: It’s, uh, it’s been tested, it’s extremely important. Uh, I’m really glad we have a rocket that has that capability. Uh, we even saw not so long ago, just a couple years ago, uh, that the escape system was used on the Soyuz, right? We had an astronaut, an American astronaut flying and, uh, you know, that abort system was used. Uh, you know, it’s pretty important for any rocket to have some kind of capability to get off if able, you know? Shuttle, shuttle used a, uh, maneuver called return to launch site. Um, but because it didn’t have an immediate abort system, we considered it, uh, a little bit more dangerous. And so, I’m glad we we’ve got something here to make sure the crew can get off to safety if we get an indication that we’re not flying safely.

Host: Very important. Absolutely. Um, that’s, so that’s the SLS, right? From base to the very tip. Um, we cover most of the major components. Now, I think what’s interesting, uh, because, John, when we first kicked this off, I, I pointed out you were the chief engineer, but you mentioned you were working with thousands of people around, around really, definitely the United States, maybe even the world, uh, to, to put all of the different components, all of these different pieces together. And that’s what I wanted, wanted to explore next was, um, you know, you have this, this big rocket; we talked about a lot of different components, um, but they all have to come from different places, uh, to, to be built, uh, put together in the, uh, Vehicle Assembly Building and then ultimately rolled out to the pad for launch. So where are some of the major, uh, locations, contributors; how, how is this thing, how is this gigantic rocket being built and then shipped over to the Kennedy center, Kennedy Space Center for assembly?

John Blevins: You know, with the rocket this big, quite frankly, we hit just about every state and we do hit numerous countries, you know, with nozzle materials and other things.

Host: Mm-hmm.

John Blevins: But let me hit the big hitters with you, Gary. You know, we’ve got, uh, we’ve got some really good partners here that are, uh, somewhat legacy aerospace companies that have done an outstanding job. And let me start the way you started, you know, those engines that are attached to the core stage, uh, you know, a lot of the manufacturing for the components of those engines happens out in California, near Los Angeles. Uh, those sub-assemblies are sent to Stennis Space Center where those engines are put together and they’re tested and verified and then they’re shipped over to the Michoud Assembly Facility. And this is where we build the core stage. You know, at Michoud Assembly Facility which, which was really built during World War II, you know, if, uh, you guys know the Higgins boats, during World War II, uh, you know, the ones that landed on D-day? That facility that built all those Higgins boats, um, is the facility that we used to build the Saturn V and the facility we use to build the external tank for the shuttle, and it’s the facility now that we, we use, uh, to build the core stage. And so, those engines are, uh, integrated with the core stage where the core stage is built. Uh, as far as that core stage built by Boeing, um, uh, I, I don’t know if I mentioned but it’s, uh, Aerojet Rocketdyne builds those engines, uh, out, you know, the sub-assemblies out California and then assembled at, uh, Stennis. But, uh, Boeing is the, is the provider for that core stage. And, uh, and what Boeing, um, uh, does is they, they roll in sheets of aluminum and they roll out a core stage. And so it’s truly a factory, uh, that way, it’s, it’s, uh, there are some pieces that are bump-formed in other places but by and large, you get these big flat sheets of things coming in and they’re, they’re milled, and they’re welded and vertical assembly weld there. And so, there’s a lot of operation at the, uh, Michoud Assembly Facility. We call it MAF. Uh, for the booster side that we talked about, uh, those segments are cast, uh, in fact, we’ve actually built, uh, we’re just yesterday we cast one of the segments for the fourth flight of the Artemis missions. We’ve already finished casting all the segments for the first three and some additional segments for what we call flight support boosters, uh, which are, uh, witnesses for us, to make sure our manufacturing process is going the right way. We’ll test some, some of those on the ground just to make sure that we’re building these rockets the way we want. And that’s out in Promontory, Utah, just north of Salt Lake, uh, great partner out there, Northrop Grumman. Uh, they do a wonderful job. They’ve been doing this, uh, for us during the shuttle program, uh, with other names, uh, that in their background before they were Northrop Grumman. But it’s the same folks that did that, but they also do a lot for our country otherwise. They build, uh, different solid rockets for, whether it’s science missions or even, uh, even for DoD (Department of Defense) missions. And so, they, they do a wonderful job out there. And then, and then we’ve got, uh, on top of that, we’ve got that LVSA I mentioned; that’s actually a, uh, built, uh, largely at the Marshall Space Flight Center, assembled; it’s a company called Teledyne Brown. Huntsville, Alabama, provides that and the TPS (thermal protection systems) is applied on-site at Marshall Space Flight Center. And then above that, we’ve got the ICPS, which is, as I mentioned, it’s a modified stage, uh, from the Delta heritage line for ULA. And that’s built in, uh, Decatur, Alabama, where they build rockets, um, for the, uh, ULA, uh, team. Uh, and then of course, on top of that, we’ve got the OSA (Orion Stage Adapter), that’s actually, again, uh, built in Huntsville, Alabama, and, uh, and integrated there, and then shipped down to Kennedy Space Center. And, and you mentioned that that key there for our ground system guys, that putting it all together in the VAB, the VAB is just, it’s an incredible resource. It’s, uh —

Host: Yeah.

John Blevins: — the largest building you’ll find. And, uh, we got to get you down there, Gary, so you can see a launch.

Host: Another one of my bucket launch things — bucket list things, is as I’ve never been to the VAB. So I’m, I’m absolutely relying on you for, for all these lifetime experiences, John, but, um, amazing, right: you talked about so many contributors across the U.S. and, and a lot of different companies all contributing to this, to this fantastic vehicle. Now, now you, you mentioned a couple of things along the way, right? Uh, manufacturing is one thing, actually building the rocket, getting it out to the pad, rolling it out; but you mentioned a couple of instances where you want to have ground test equipment, you want to be able to verify that, that things are being built the way you want it to be built, and then of course, all along the way, as you’re designing this, you got to test…test, test, test, right? So what, what have we done so far? Right now, we’re recording this in February of ’22; what, what have we tested so far to make sure that the SLS is ready for its first launch?

John Blevins: Well, most everything, to be quite frank about it, uh, Gary; we’ve tested almost everything individually and then as an integrated system is what we’re going through now. In fact, as I speak, uh, we’ve got a team in the VAB that’s testing out, uh, the FTS, that’s the flight termination systems. That’s the systems that the range, the 45th Space Wing of the Space Force, uses in order to make sure the public is safe in the event that the vehicle flies the wrong direction, right? If, if all else fails we do need to make sure the public’s safe. And so, um, and, and, and all rockets that launch from anywhere have those systems. And so we’re testing those out right now, today. Uh, so let me, let me kind of go in reverse order, actually; it might be more fun for you. Uh, it might not be, but I, uh, I love testing, so you may have to cut me off here and, and, uh, it’s your podcast, so you step in, but —

Host: No, take it away. Take it away.

John Blevins: All right. Well, testing is, is, uh, what a chief engineer loves, uh, any, any chief engineer should just be involved in the testing. In fact, I spend most my time over the last six months down at the VAB, the Vehicle Assembly Building, uh, down at Kennedy Space Center. And so for the last, really, um, six months we’ve been doing, um, a little bit more than six months, we’ve been doing what we call ITCO, that’s Integrated Test and Checkout, and that’s where all of these different systems have come together for the first time, and, and a lot of this, um, and it’s going smoothly, it’s going exactly like we planned. We did a lot of testing that we, um, that we expected to do that really saved us development time and money. Uh, like for instance, I’m going to give you one of my favorite tests and that’s called the modal test. And, uh, and every time I spell “modal” in a document, somebody corrects me and says “model,” but it’s not model test, it’s modal, it’s dynamic response. So we literally shake the vehicle. We had, and, and in fact, we shake the vehicle, and we shake the mobile launcher, and we do it at different positions at different frequencies. And, and so we, we have these known input shakers that we put on this vehicle and we measure, and measure the response of the vehicle at different places with strain gauges and accelerometers. And, and so we get this dynamics of the vehicle and what that tells us is how well we can control the vehicle. And let me just go ahead and report to you that controllability is good. It also tells us what our loads are going to be and how we radiate those loads. And let me just tell you on that one, the finite element models we use to predict the loads were verified through that testing so we expect that to, uh, all be good. In fact, that’s all cleared for launch. Uh, that’s a test that historically has been done with a full flight hardware set that was essentially wasted for that test, and so we, we decided to do something a little bit different, you know, we’ve got shakers that you would use on a bridge, right? You, you know, for anybody that’s old in the audience, they saw the Tacoma Narrow Bridge videos, at least, uh, where there was an aeroelastic event, there was a response to a wind gust on a bridge, and it just shook itself and, and tore apart. And, and, and the phenomenon is a little bit different, but very similar that can occur on a rocket when it’s flying through the atmosphere, or even while it’s sitting on the ground and a wind gust goes over it. And so we test that aeroelastic type response by putting that known forcing function in. In fact, the shakers that we use are generally used to shake bridges when they build them in order to verify their, uh, capabilities. So we’ve done that testing. Uh, we’ve, we’ve done testing to make sure all the systems work together, to understand the latency in the electronic components — you know, if we send a signal, uh, we’ve got the clocks all synced up for our data acquisition units, uh, we’ve just been doing a lot of integrated sequential testing, uh, along the way. And, and a lot of that’s verification, right? You know, you, and, and, and the funny thing is the things that you don’t think you’re testing are sometimes what tells you, hey, I need to look at this component again, or, or, or whatever, like when we boot it up, uh, you know, the viewers may know we booted up one of the engines, which we had already run to full duration, and we had a little bit of a hiccup in the, in the start transient. We’ve solved that now, we’ve replaced that, we understand why that occurred. Uh, but it’s those kind of things on a big system, uh, that you need to check out before you fly. And that’s what we’re doing. Uh, even right now, in the next big test, uh, staying with that integrated testing, will be called the wet dress rehearsal. That’s where we, uh, we, we literally do a wet dress, if you will, for, um, for launch. We will go all the way through, um, automated launch sequence, switch over, uh, we’ll be pressurizing the tanks after we fill them up, we’ll be looking at strut articulation — you know, when you put cryogenics in a big tank like this, it shrinks a little bit. And so, all of those things are taken into account. We’ve got targets on the vehicle. If you’ve seen the vehicle, I need, you get, get you down there for this too, Gary, you can see the VAB, but you can get two of your bucket list items out all at once, and that would be seeing the wet dress and the VAB. And, uh, and, and so there’s targets and we look at those difference in targets and we measure the difference. But, but before you pull me off the stage, I just want to say that testing is the backbone of any rocket. We started testing in 2011. When they made the announcement for this vehicle to get going, we were already getting ready for wind tunnel testing. I was the wind tunnel guy. I helped make those first models. I was in the wind tunnel. I didn’t miss a wind tunnel test until 20-7, well, actually 2018, when they pulled me into the chief engineer’s office; they pulled me in in 2017 but I, I kept going to the wind tunnel test until they, they got me doing a bunch of other, uh, different things. And so, um, uh, so we’ve done a lot of testing. We’ve fired, uh, rocket motors, uh, in wind tunnels in order to check out base heating. And so we’ve just done a lot with, uh, the, with testing. And that’s how you verify a system that’s very complicated that you cannot test until you fly fully.

Host: Yeah. But, but it gives you that confidence, right? And that’s, that’s what I’m hearing from, as you’re going through, you’re — checking to make sure things are good. That’s, that’s the idea here. And, um, and, and you excitedly reported that you passed these major milestones and, and I think it just overall increases your confidence and everybody’s confidence, really, that, that, about the performance of this vehicle, which is, which is ultimately good. Um, I don’t want to leave testing quite yet, uh, because this is, is a very important and exciting topic. I did have a question because we haven’t on this podcast, haven’t covered the Green Run yet. And I know that was a big one. Uh, so can you describe what that was? And uh, and what was the result, uh, at the end of the Green Run?

John Blevins: Well, now, now we’re talking my language. This is great. Uh, so I, I got to be in the, uh, the test center, certainly for Green Run, but let me, let me say Green Run was really a series of tests. You know, it’s a little bit misunderstood.

Host: Right.

John Blevins: We took the core stage up there and we said, hey, this is the first time we’ve got these different test objectives, and so, it was a series of, of really eight very specific tests with a lot of subtests. Uh, we even did the shaking up there, too. We shook the core stage only, suspended by a crane. Uh, and so, that was a, just a great test to get started with all of those tests, uh, at the, uh, at the Stennis Space Center. Uh, you know, the one that’s visible, obviously, as we get to the end, you know, we tested out the flight computer systems for the first time and we went through and we tested the TVC (thrust vector control) systems, we just gimbled like crazy, and, and if you watch the Green Run we did it while they were firing too. But, but the culmination was, uh, that we, uh, that we, we fired the, the rocket engines, we fired the RS-25s. And so, we, when we were doing the, uh, the cryogenic portion, the tank op[eration], we, like you find with a big system we found some of our valve timing was a little bit of an issue to us. And so, we, we kind of stood down, uh, and we had to do that again. And so, the, so when we did the wet dress the second time, uh, we went in and we, we kind of took a risk, we said, hey, I’ll tell you what, we think we’re getting better at this, and let’s go ahead and go to an engine firing if we get all the way down to that point, we’re ready for that. And so the first hot fire was actually not the main goal of that test. That test was a wet dress; uh, we were all sitting in the firing room. I had the privilege of sitting by John Honeycutt, who is our program manager. And, uh, somewhere around test minus, you know, um, 20 seconds, he said, “I think this thing might actually, you know, go off today.” And so, we did, we got through that and, and by the way, it’s T minus six seconds when those engines starts up, because the T minus time is mimicking the launch minus time, and so those engines did fire up. Um, there were some hydraulic pressures that we had not accounted for right and so we stopped after, um, 60-some seconds and we started vectoring the engines. And then, um, and then we did it again, and we did it to eight, eight and a half minutes because we felt like that was the right thing to do. And the second test just went off without a hitch. And that’s what you want, you want a quiet day. And in fact that second long, uh, duration test, uh, you know, I’d like to say it was boring, except for the fact we had 700,000 gallons of propellant about to be expended over an eight-minute period coming out the back end of a rocket. Uh, and except for that historic event, it was really a boring day. We didn’t have any things going on with the rocket, we were just monitoring the systems and going through the checklist. And that’s why we test, and that’s why we get ready for this launch in the same way. And, and, uh, we might have a good quiet launch day as well. So, but, uh, but it was great; that, that, that Green Run gives us a great deal of confidence. And what is really also significant about that is, it is the newest hardware. There are complicated pieces, and let me speak to complication. You don’t make a rocket any com, more complex than it needs to be. Uh, we don’t want it to be complicated, but it’s going to the Moon so it is complicated, it is complex. But it’s only as complex as it has to be. There’s only as many lines of code as there has to be in the flight computers. There’s, there’s only the complexity that’s required by the mission. We try to make things simple as possible. That’s how you get mission success.

Host: Understood. Now, now, and you’re talking about confidence, right? You’re talking about making sure that it’s mixing that efficiency with that reliability, um, the redundancy with — all of the, with, with your, what you’re talking about is making sure you just have what you need, and you’ve tested it and you’ve tested it, tested it, you verified it, you got some confidence; ultimately, though you need to fly it. And at its core, really, the first flight, Artemis I, is truly a test, right? We want to see, make sure everything works before we put humans on board. So we’ve talked Artemis I from a lot of Orion perspectives and a lot of the testing and verification that’s, that’s going to be, uh, uh, performed as part of that mission, uh, on this podcast. But specifically for SLS, you’ve, you’ve talked about a lot of the major test objectives that have passed. But, but zeroing in on Artemis I, when you, when you walk away from that mission, what is it exactly that you are verifying? What are the key things that you want to demonstrate when it comes to the SLS on Artemis I?

John Blevins: Well, first let me speak as an agency. What we really want to verify is the function of the heat shield on Orion. That is our number one test objective —

Host: Right.

John Blevins: — for that flight, right? That’s what’s keeping our crew safe. We’re all working together regardless of program to keep our crew safe. So as, as a partner to the Orion program, our job is to put them in an orbit that at least achieves a high-speed re-entry one way or another. Uh, but for the SLS, uh, program, there’s a lot of things we want to, to verify. And it, it, it’s all the way from the liftoff acoustics, right, as you lift off you’ve got water, that’s going in the hole and you’ve got a certain amount of drift, uh, that may occur depending on the lens of that day. And you’re going to be measuring all the way up the tower and on the vehicle, what are the reflected acoustics? Those reflected acoustics right off the pad drive a lot of vibration. And in fact, the largest vibration is not when we pass through transonic, but it’s when we get off the pad, generally, at least for the things in the lower half of the rocket. We’ll be looking at that. As we get to transonic, there’s a lot of things to verify in transonic flight. We we’re even going to do some maneuvers with the rocket, we call them program trajectory inputs; those program trajectory inputs are we, where we perturb the rocket to a known state. Like, we jitter, if you will, the, the nozzles on the back end, put it in a different angle of attack, and then we watch the response of the rocket. Uh, those, those things give us confidence for future flights as well, and the stability of the control systems that we have. We’ve got sensors on the outside to take a look at the unsteady loads that occur. We call that buffet during transonic. We’ve got quite a few of those transducers and that’s something that affects particularly multi-body rockets a lot. And so we’re, we’re going to verify that. We’ve got sensors on the base as we go up, we actually have the boosters and we’ve got the engines and you’ve got a lot of heating and so you want to make sure you understand what the base heating is. It’s easy to mitigate as long as you know it, we put cork on the bottom and do that. And then we’ve got the separation system, we’ll have a lot of visual evidence of what occurs when we separate the boosters from the core stage. Uh, then we go up and we’ve got other separation events. We, the panels come off of Orion and, and we’ve kind of looked at that as a keep out zone. And so we’re going to do that. And then as we get up, uh, we shut off the main engines and we get ready for a perigee raise maneuver; we separate, uh, even, even where the core stage comes in, we’ll be observed very closely by our assets on this flight. Let me say one thing, Gary, that can be misunderstood about flight, too.

Host: Yeah.

John Blevins: Both tests and flight go together. You cannot develop a rocket with just test flights, and you can’t develop a rocket with just ground tests. But the advantage to ground, and let me give the example that an aerodynamicist would give: when you’re on the ground and you’re at a wind tunnel, say at Ames Research Center in California, or Langley [Research Center] where we’ve done a lot of our testing, I can test every Mach number and angle of attack that I need to during transonic; every one; I can make it in very fine increments of Mach number, I can, I can do every quarter-degree or every tenth of a degree angle of attack as I go through that transonic buffet range, and I can get those environments. And that is something I cannot do in flight. On the other hand, there are things in flight that may be a little bit different than what that ground simulation will do. But when I fly through transonic, I get one angle of attack at one Mach number. And that’s why for a full flight envelope, if you were just to build, say, 20 SLSs and just fly them to get that aerodynamics, that wouldn’t be nearly as much data as the 10,000 data points that I have from ground testing. And so, it’s both of those together that give us the confidence that we are ready to fly humans — men and women, going back to the Moon for the first time in over 50 years — for the next flight. So it takes both of those together. It’s not just one. The test flight is critical and they, there are some things, like that Orion heat shield, that we absolutely want to do, but make no mistake: they’ve taken that Orion heat shield to the Ames Research Center arc jet test facility and they’ve evaluated to the best they can what they think the properties of that heat shield are. And so, both of these tests work together and the shortcuts that can be taken on one or the other will cost you in the end. And so that’s why we’re very keen on doing, doing both a good set of ground tests as well as a good set of flight tests.

Host: Very, very important. And you mentioned just how, you know, you’re stressing how critical these tests are and, and even your story of just the wind tunnel test, for example, just, you wanted to go to all of them, you wanted to be there. Um, and for, for one reason or another — A, tests are cool — you know, but, but also just the, the importance of them, right? And so I wonder for Artemis I, being that it’s a, it’s a, it’s a flight, it’s also a test, um: where are you, where, where will you be sitting and what will you be doing for, for Artemis I?

John Blevins: I’ll be sitting in the, uh, the Launch Control Center down at, uh, Kennedy Space Center, in Firing Room 2. Uh, it’s my job to represent all of those great engineers that, uh, will be working that day on the Space Launch System, uh, for any problems that arise. You know, we’ve given our technical input to our ground system folks, and we’ve said, hey, if it, if it’s within these parameters, if the temperature at the engine is this, and if the pressure over here is this, and you don’t lose that sensor, uh, you’re good to fly. But in addition to that, we, we form a team that day, and I get to lead that team. Um, and I’ll be sitting in the firing room making sure that I talk to the launch processing engineer and the launch director, uh, to make sure that they know our vehicle’s ready to fly. The purpose for us doing that is we may see something that we haven’t seen, uh, in testing, and we may be able to tell them like, oh, that temperature is OK, or if you cut on that heater, we can, we can, we can get back in the box that we need to do. And so, as the, uh, original in-manufacturer of that vehicle, you might say, uh, we’ll have our crew on board. And, uh, as I mentioned, the smart folks are working for me on that day, giving me a lot of information, and then I get to feed that information to our launch director.

Host: And I, and, and John, I wanted to end with this, um, because we’ve talked about a lot about SLS. We’ve talked about all of the different components, all of the different contributors. You, yourself mentioned that you’re, you’re backed by thousands of engineers around and, and I just want to take a moment to, to reflect on just where we are right now. Uh, we’re coming up on Artemis I. It’s right around the corner. You have years, uh, of hard work behind you, um, from the design, development, construction, testing of this rocket. Just sitting in this moment right now, uh, thinking about that and what we’re about to do, we’re about to, we’re about to test this rocket that’s going to return humans to the Moon and, and that era is, is, uh, right around the corner, it’s not too distant, it’s, it’s, it’s right here; um, just how does that make you feel, just, uh, thinking about it in this moment?

John Blevins: Well, I’m quite frankly, I’m honored to represent, again, all those engineers, but more than that, our country. You know, there are, there are things that mark, you know, great civilizations throughout all of history, and, and they tend to be art, uh, which, you know, our country has a great deal of that; um, science, which all of us did something scientific to get here; and exploration. Art, science, and exploration. Those are the things that great civilizations and countries, uh, do, and they, they do them independently and they do them together. And this one is together. This is a, this is an international effort. And, and so, to, to explore, to go back, uh, to the Moon, to send the first women to the Moon that haven’t been, I think this is a, this is the cusp of, of, of a sustained exploration effort, um, that’s going to serve our, not only our nation but the world well and how we view each other and how we view the world. And so, I’m just, I’m just honored to be a part of that.

Host: Beautiful, John, and we’ll end right there. Thank you so much. Uh, John, I, I learned so much about, about the SLS. Just, I too, am very excited for, for what’s about to come, uh, and, and all, and very appreciative of all the hard work that’s gone into getting us ready, um, for, for Artemis I and then also beyond, building up an infrastructure that’s, that’s, that’s meant to last. So I appreciate you coming on, uh, the podcast and, and describing this and, and — thank you very much. And I, and I wish you the best for the couple of months to come until we get this thing off the ground.

John Blevins: All right, Gary. Well, I’ll see you at the VAB and at the launch, hopefully.

Host:[Laughter] I’m holding you to that. Thanks, John.

John Blevins: [Laughter] Thank you.

[Music]

Host: Hey, thanks for sticking around. I really enjoyed talking, talking with, uh, John Blevins today. What, what an incredible guy and, and he’s got a lot of knowledge about the SLS. I certainly learned a lot and I hope you did, too. Check out the latest at NASA.gov. Make sure you, uh, check out the Artemis program and specifically the Space Launch System on NASA.gov. There’s a lot of resources that you can, uh, read, uh, to dive even deeper into very specific topics about that rocket. Um, that’s certainly where I went to learn more, uh, and to build some outline for this podcast, and so, there’s, there’s, uh, you can go pretty far, uh, make sure you check it out. We, uh, talk a lot about human spaceflight on this podcast, and we got a lot of episodes related to Artemis. Go to NASA.gov/podcasts, find us, and then over on the side, on the left side, you can click on a collection called, uh, “Artemis Episodes.” Uh, and you can dive deeper into specifically everything Artemis, from the SLS to the Orion spacecraft and more; uh, we’ve, we’ve done a number of topics and you can listen to them in no particular order. Of course, there are other podcasts across the agency that you can listen to, make sure you check them out as well, NASA.gov/podcasts. To talk specifically to us, we’re on the NASA Johnson Space Center pages of Facebook, Twitter, and Instagram. Just use the hashtag #AskNASA on your favorite platform to submit an idea or ask a question for the show; make sure to mention is for us at Houston We Have a Podcast. This episode was recorded on February 15th, 2022. Thanks to Alex Perryman, Pat Ryan, Heidi Lavelle, and Belinda Pulido. And of course, to Laura Rochon, Tracy McMahan-Mayhan, and Nicole Brandon. And of course, thanks again to John Blevins for taking the time to come on the show, give us a rating and feedback on whatever platform you’re listening to us on and tell us what you think of our podcast. We’ll be back next week.