“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.
In Episode 95 Mark Baldwin, Orion Occupant Protection Specialist, talks about crash testing of the Orion spacecraft and why it is important to keep the crew safe during some of the most critical moments of their mission. This episode was recorded on April 24, 2019.
Transcript
Gary Jordan (Host): Houston, We Have a Podcast. Welcome to the official podcast of the NASA Johnson Space Center, Episode 95, Spaceship Crash Testing, a Crash Course in Space Safety. I’m Gary Jordan and I’ll be your host today. On this podcast we bring in the experts, scientists, engineers, astronauts, all to let you know what’s going on right here at NASA. So, if you’re familiar with us, you may know we’ve had a couple of episodes about the Orion Spacecraft, the one that will be traveling into deep space, carrying humans. We’ve covered a variety of topics, a lot of them focusing on the more human side of things. Keeping them alive and comfortable, protecting them from radiation and learning how to deal with emergencies if necessary. That’s a lot of human spaceflight, thinking of what could go wrong and then solving the issues ahead of time. And that’s what we’re going to be talking about today. This topic is called occupant protection. It’s basically thinking of ways that Orion could put stresses on the human body during different phases of flight, like launches and landings. And thinking of ways the crew inside could be injured. This could come from vibration, or acceleration, even hard impacts. And then, super smart people get together and design parts of Orion to make sure the crew is safe. So, today, we’re talking about the biomechanics of it all and even what biomechanics is with Mark Baldwin. Mark is one of those super smart people helping to solve these issues. He has a background that goes deep into figuring out how to keep people safe. Anatomic modeling, kinetics and kinematics, ergonomics, and crash testing for plane, trains, and automobiles, and now spacecraft. This guys has strapped himself into a vibration table for Orion testing for 7 hours, over the course of two days, all in the name of good engineering. He’s an Orion occupant protection specialist for Lockheed Martin. So, here’s a crash course on occupant protection and biomechanics with Dr. Mark Baldwin, enjoy.
[ Music ]
Host: Mark, thank you for calling in all the way from Littleton, Colorado today, I really appreciate your time.
Mark Baldwin: Yeah, it’s my pleasure.
Host: So, if you’re thinking about, and this kind of struck me, if you’re thinking about just fun engineering jobs, crash testing has to be up there for something you see and think, yep, that’s what I want to do for the rest of my life. Is that kind of how you started with your career, or did you kind of take another path?
Mark Baldwin: No, there was nothing early in my childhood that directed me toward crash testing. But when I was an engineer, I did have an interest in things, how they moved, how they worked, kind of the underlying reasons things functioned. And then, in my undergraduate at Purdue University, I started in mechanical engineering. But I definitely had interest in another aspect of engineering, which was biomechanical engineering. And that is a unique form that really takes mechanics and applies it to the body. It was only later when I got into industry that I got exposure to crash testing and crash test dummies. And it was really interesting. Of course, the first time you see a big test and how fast everything occurs and things flying off or things breaking, you think wow, that was pretty intense. So, that was really the origin of where I am now.
Host: Yeah, it’s a very visual thing and it’s just super cool to watch. And that’s kind of where I wanted to start. You said you started with mechanical engineering and then went into this biomechanical and I kind of wanted to start there. Can you tell me a little bit about what that is, biomechanical engineering and biomechanics?
Mark Baldwin: Sure, yeah. Actually we need to start with mechanics and mechanical engineering, really. And you can break that down into generally three categories. The first would be how things are designed. And that really comes down to the shape of things, the size of things, how things fit together. In spacecraft development, a lot of that comes down to the computer aided design and laying things out. can we fit all this stuff physically into the vehicle? And then there’s motion. Things that move, kinematics. On a spacecraft there are lots of things that are actuated. So, either a valve opens, or buttons are pressed, or even pyrotechnics, small explosions that occur to release something. And of course any time you have motions, you’re going to have certain loads associated with that motion. And then that gets to the third piece the strength and the stress. So, a lot of people don’t know those terms, but in general, that’s how a material can withstand external environment. So, what type of load is applied to those parts in the spacecraft. And I’ll give you an example. In terms of the human, strength you can think of as how much strength is in your arm. So, let’s just take your bicep. If you hold out a platter that has 100 pounds of cookies on it and you’re holding that straight in front of you, you can think of I have a certain amount of strength in my arm to support that 100 pounds. Now, stress is a common output we look at in engineering, to see if that part, in this case, our bicep can withstand the amount of load put over that certain area. So, you bicep would be a cross sectional area if you cut your bicep in half. Now, if I’m strong enough to support that 100 pounds. The strength is greater than the stress and I will not see a failure. Now, if I take my son, Dylan, who’s 8 and I ask him to hold the same plate of 100 pounds of cookies, now he has a much smaller cross sectional area for his biceps. Same force. And if his arm is the same length, now all of the sudden he has a lot more stress and his arm will fall, and he doesn’t have enough strength. So, in that case the stress exceeds the strength. And that’s when things break. So, on spacecraft, same kind of thing, when the stress is higher than the strength of the material, or the part, then you can get catastrophic failures. So, it’s really those three things. The design, the motion of things, and the strength, and stress. That’s all mechanical engineering.
Host: Yeah, it’s like if a job needs to be done, what you’re doing is basically you’re solving that problem. You’re trying to figure out what’s the best way that I could solve this problem and make sure on the strength and stress side that it’s going to be reliable in solving that problem.
Mark Baldwin: Yeah, absolutely. Yeah. And there are multiple teams of people that do these things. So, it’s a big collaborative effort. Both on the Lockheed Martin side, and the NASA side to ensure that we’re really addressing these three aspects of mechanical engineering. So, then back to your question about biomechanical engineering, that’s where it gets interesting. So, in general biomechanics, or biomechanical engineering is, take those same fundamentals of mechanical engineering, and now apply them to the body. The challenge there is that of course there are no parallel or perpendicular surfaces. There are no right angles in the body. All the materials are pretty much nonlinear. And then, people come in different shapes and sizes and different body strengths. So, you’re going to have inherent variability. As in everybody is different. So, you can’t just apply one set of loads or environments to one person and expect a different person of a different size to be able to withstand that same environment.
Host: Yeah, that makes things a little bit harder, because now you not only have to solve that problem with the mechanical engineering part, now add the human you’ve got to not only solve the problem, but you have to make sure that the human is going to be okay when the problem is solved. And then that it’s flexible enough that you know multiple types of people can survive it, or it works for them, is that right?
Mark Baldwin: Yeah, yeah. And so, then if we look at now applying this whole biomechanical engineering to Orion, specifically and to keeping the astronauts safe, to be able to do all those things we need to look at how to protect the human in a variety of different ways, right? We need to provide surfaces that support them, that limit that motion, and that keep those external environments that are applied to the vehicle to a level sustainable by humans without injury. And that’s really the crux of my job. And also what makes it interesting, because then I get to work with a large variety of people, both on the NASA and the Lockheed side. So, that’s for example the crew systems team, Lockheed Martin crew system team in Houston designing the seats that maybe the Orion crew survivability systems team, the suit guys at NASA JSC, the human factors folks against stress and other mechanical analysis teams. All that stuff needs to go into what we consider for astronaut safety and assessment of weather an injury is going to occur or not.
Host: So, like for let’s take an abort for an example. You’re on your way into space and something happens, and the abort system is supposed to carry the crew module away with the people inside safely. So, from a mechanical side, you’ve got to make sure that it actually pulls it away from a speeding rocket, okay, that’s fine. But from the human side, you’ve got to make sure that it does it in a way where the humans are safe and going to be okay as well as the crew module.
Mark Baldwin: Yeah, absolutely. And so, that’s the trick of it. Now, we’ll get to it later, but that’s the whole purpose of our Ascent Abort number 2 test that’s coming up later this summer. And really, from that test, it’s my job along with others to understand and characterize that environment. Now, keep in mind that’s one test. We can collect data on that test, but a real abort can occur in any number of says. And so that’s where as an engineer, I have to take the one data point I have and then understand how that could possibly change. And then I could analytically put in different size people and then carry it forward to that assessment of potential injury.
Host: Yeah, it seems, I think the way I’m kind of describing it and they way you’re describing it, it does seem pretty straightforward, but I think there’s more to it. But so before we kind of go into the Orion part, let’s just kind of expand on this biomechanics part. You know where did this all start? Tell us the history about biomechanics and why this is important.
Mark Baldwin: Yeah, so it really is a relatively a recent field of engineering, in that let’s say by the 1950s we started seeing automotive accidents in which people were not surviving. Right? We had vehicles that went fast enough now to impart a load, potentially beyond what the body could handle. At that time, very little research had been done. There were limited animal studies trying to characterize impact. But the one person that would probably be credited as the grandfather of impact biomechanics would be a guy named Colonel John Paul Stapp. He was actually a physician within the Air Force. This was in the 1950s. And if you Google him, you can look up on YouTube John Paul Stapp 46.2 Gs and what that means is envision this, in the ’50s your boss comes into a Monday morning meeting and he says, all right team, here’s what we’re going to do. We’re going to strap me to a rocket sled. And I’m going to go down a track at 630 miles an hour, and then you’re going to stop me within 1 second. [laughter] Everybody in? Would blow your mind, right? You’d think this is insane.
Host: Yeah.
Mark Baldwin: But the reality is, at that time, remember this is the ’50s, they didn’t understand what a human body could take. Now, he didn’t just jump into that. He actually did a number of impact tests where he strapped himself into a seat and then he just slammed the seat and arrested it quickly. And he flails forward, but he’s okay. Well, they worked themselves up to this rocket sled test. And you can see the video on YouTube, but what he did was he said, all right. I’m going to put myself in this situation because I want that datapoint. This could end badly, but we need to understand. And as part of the Air Force, he was really thinking of the entire air crew. Before we expose and ask our pilots to be exposed to ejections and crashes, I’m going to understand this. So, he strapped himself in, put a helmet on and he went shooting down this track at Holloman Air Force Base in New Mexico. At the time, he was considered the fastest man alive at 632 miles an hour. He stopped like I said within 1 second. That imparted 46.2 Gs. So, that’s 46 times his own body weight. Nearly 8000 pounds when he stopped. And when he stopped, he had broken ribs. He had a hernia. He shattered his wrist, his eyes hemorrhaged. He was temporarily blinded. His eyes were full of blood, and he fractured his tailbone. However, he survived. And that datapoint to this day is one of the most extreme exposures, intentional extreme exposures that survived. And that later populated a limit for what we consider people can take from just an acceleration exposure standpoint. Now, keep in mind he was well protected. He had a huge harness on and a helmet, etcetera. But he put himself at risk to make that point.
Host: Yeah, the idea is you know how much can the human body withstand. And this guy put himself through the most extreme circumstances possible to like you said, get that datapoint. But now what can we learn from that? I think you know one of the first things I think of is, all right, well if we’re going to design a system, let’s make it so that it doesn’t exert 42Gs on a human body, right? I think that’s probably fair.
Mark Baldwin: Yeah.
Host: Yeah. So, then I guess a lot of that got taken into human spaceflight then. Because if you’re talking about, you know we kind of referenced an abort scenario, but even launches and stuff like that, you just, you don’t want to have that much force on a person.
Mark Baldwin: That’s right, but keep in mind and this is one thing that’s probably not clear is there is a certain amount of impact that you can take without damage. And then there’s certain levels of damage within the body, and certain types of damage within the body that can occur. And the interesting part is now it depend on which direction you load and by how much. A lot of people ask me this question. When we have an abort, let’s take this ascent abort case. Everybody asks well me, well are they going to pass out. Well, the answer is not necessarily. It’s very much a function of how intense that acceleration is, or the magnitude of the acceleration, and then how quick it occurs. And that’s one thing that after Stapp was done with his research, a guy name Jim Brinkley who was a civilian working at Wright-Patterson Air Force Base in Dayton, Ohio, he during the Vietnam era wanted to address a little bit more dedicated to directionality and that magnitude what the limits were. So, he took Air Force cadets, put them into his own sled test. They didn’t go anywhere close to 46 Gs, but what he did was he placed them at different orientations. So, head up, head down. Frontward, backward and started to vary the magnitude and the duration of those pulses and by doing that, he was able to start to fill in the blanks of what could the human body take if you were well supported, if you had a full harness, if you had a helmet. And so, from that we developed what’s called the Brinkley Model named after Mr. Brinkley. And that gave us, we’ll call it a first cut, or the first level of understanding of when I go to look at any and all of Orion mission throughout the mission, any high G level events, I can use this Brinkley Model to characterize that acceleration in any direction, in any seat, and get a sense of whether I’m going to induce injury. I don’t know what the injury is going to be. I just know that maybe an injury could occur and how severe that injury might be.
Host: Yeah, so ever just before spaceflight, Brinkley was looking at this, I guess short duration acceleration sort of phenomenon. And I think you know we were in the middle of like you said the Vietnam War coming up in the ’60s here. You know, I’m guessing like a lot of, there were already systems of jets and other kind of spacecraft where they exposed to these high Gs. You know what were those systems doing to these soldiers. Did they not really realize until after Stapp and Brinkley was investigating this, like oh, this is probably you know the way that we’re looking at humans and the mechanical side of things should probably be in sync.
Mark Baldwin: Yeah, so that’s where the story gets a little more interesting in fact. Because what they found were Air Force pilots would rather crash their planes into the ground than eject. And you can say, well why is that? And it’s because the spinal injury rate was unacceptably high. So, the pilot basically made a calculation that I would rather crash and take my chances than eject. Well, clearly that’s a terrible design, but to be fair, what they didn’t realize is these accelerations are one portion of the picture. There is another aspect which is what’s the direction of loading relative to sensitive parts of the body. So, now instead of looking at just acceleration, now let’s start to hone in on parts that could be injured, such as the cervical spine at the base of the skull. Does the helmet contribute that, adding mass to the head contribute to that And so, they started to dig in a little bit deeper? And that’s what is really more the secondary level that we use today. So we still use Brinkley, as that first pass at acceleration assessment. But once we do that, we need to now look at Orion specific hardware and that means the seat, the suit, the harness. How do all those pieces fit together and will any of those contribute to now a localized injury, let’s say at the head or neck.
Host: Yeah. Yeah, so I guess before we really dive into all of these different components. The seat, the suit, the helmet, and all that, for specifically Orion, you know let’s talk about you know where these injuries can come from. You know, what are we looking at if you had to break it down of the main sources?
Mark Baldwin: Yeah, so in 2013, NASA solicited a variety of experts in the field. So, academics, we brought in the Air Force, we brought in the Navy. And we posed the same question. What do we need to really be looking at for human space flight? And really this was rewriting the book for any and all man-rated capsules or vehicles. And so, at that time, there was already a quite established body of work done in the automotive industry, and Air Force to assess localized injury. So, we got to the deeper layer of what could be injured and how. So, in your car that you drove to work today, every part of that car has to conform to a certain set of automotive standards. And those, when you run a crash test will assess the likelihood of skull fracture by hitting your head on any part of the vehicle. A neck or cervical fracture that could in part forces in moments right below the skull. There’s chest, there’s pelvis, there’s any parts of the body that would be sensitive to either localized or acceleration loading now become adopted as part of the standard. Because we needed to understand these things, especially because spacecrafts are not cars. Now, we’re putting, and if you look at the interior of the Soyuz, you can see how astronauts are placed in more of a fetal posture, plus they’re reclined back relative to the ground. Very different than what you would see in your typical vehicle—or automotive vehicle. So, now we have to take into account the specific configuration for any and all spacecraft. And how the helmet interacts with the seat, the harness, and as you land, whatever your environments are; whether it’s hitting the water after a splash down, or during an abort, now you have to start looking at each of these pieces of information in those environments against what are established limits.
Host: Yeah, okay. So, let’s see if you’re looking at all of these different elements of how, you know all of the different sources or I guess you can say locations of the injury, you know what can really cause this injury especially when it comes to space flight. You know I’m thinking abasically abort is a good scenarios, but even like major traumatic things. Like can a launch be one of the sources, or you know, acceleration, vibration, what are we looking at?
Mark Baldwin: Yeah, so it really does fall into three different categories. The first would be vibration. And vibration is not very intuitive to most people because you don’t experience it in everyday life. And yet, the shear nature of vibration, I mean it goes up and down. Your loading will switch direction. The magnitude and the duration of that just like impact matters quite a bit and then whether it’s applied head to tail, or chest to back, those kinds of things also make a difference. So, we have to look at vibration from as soon as they light the rocket, all the way through ascent. And then of course, during abort, the abort motor will have a much different vibration profile than your typical ascent. So, that’s—number 1 is vibration. Number 2 is sustained acceleration and we consider that anything that occurs and lasts for longer than half a second. So, that would be like your centrifuge testing and G lock, when you’re pulling Gs in an airplane. We have certain limits that were characterized back in the Apollo days to understand okay, when does somebody pass out? And then, third is the short duration acceleration, really impact and that’s the Brinkley Model. And for the localized injuries we can get into crash test dummies and what those do and that’s really our key to be able to understand and characterize when a localized injury might occur.
Host: Yeah. Yeah, let’s go through those three types of injuries that I guess you said starting with vibration. I mean I’m trying to imagine myself, maybe on like a ride, some kind of rollercoaster ride where I’m vibrating intensely. I can’t imagine being vibrating so intensely that it has bodily harm, but I’m sure there are scenarios. You know, what is so bad about vibration, why is this a concern for us?
Mark Baldwin: Well, so first of all, going back to what I started with, the mechanical system, the body as a mechanical system, you can imagine that all these tissues from rigid bones to soft tissues like the heart, they all have unique mechanical properties. And in terms of vibration, we refer to a resident frequency. And that means something that at a certain frequency, will start to resonate, will start to move anh amplify an input. So, the body is sensitive to different frequencies. And so, to understand that fully, and understand that within the spacecraft environment, there’s really no substitute for human subject testing. And so, back in the ’60s the same test lab that did the impact testing of the air cadets also strapped them to vibration tables. So, if you go on YouTube, bioastronautics research government archives, you can see some of these tests. And these guys were heroic. Because they were trying to establish the limit of what somebody could take under vibration. And it wasn’t just random vibration, where that frequency changes. So, you’d be moving in and out of sensitive frequency. These were sine sweeps which means you are going up and down at a specific frequency. And if you go to the video, you see these guys, it looks like they’re just trying to hop up and down off the table. They had them laying on their back. And the way they conducted these studies was really interesting. I sure wouldn’t want to do it now, but they basically put them at a certain frequency, and then they started turning up the volume, if you will. The gain on these frequencies. So, these people went from just giggling a little bit to really bouncing and getting airborne with only that belt holding them on to the seat. And they basically kept these guys going until they hit the switch and said stop. So, it was really intense. But they captured that data, and that data today is what we use, the limit of do not exceed on Orion.
Host: So, yeah, well I mean first of all, yes, I think brave is a good word that you used to describe these guys. Because I certainly wouldn’t sign up for that test. Hey, shake me as violently as you can. Let’s test the limits of the human body. But you know what did we learn? What can the human body withstand? What happens when we get to those higher levels, and those higher gains of vibration, what’s going on?
Mark Baldwin: So, yeah what happens at that, the more extreme levels is you start to lose the ability to take a breath. Like your lungs are being compressed and expanded too fast and you can’t breathe. Other things they found were pain in the head, headache. So, it’s almost like you’re shaking your brain inside your skull to the point where it really starts to hurt. Of course we don’t want to go anywhere close to that level at this point. And certainly for not the durations. So, building upon the approach that they took back in the ’60s we wanted to answer that same question specific to Orion. So, in 2016 I was working with colleagues at Johnson Space Center in the human engineering group and we developed a plan. We said, you know we’re not going to go to the extreme levels, but we do want to characterize what it’s like for our astronauts to ride Orion. So, I suggested, well, let’s put together a plan, let’s get a real seat, let’s get a flight like suit, and oh by the way, I’ll go first. You can strap me into the seat. And they said sure, Mark, you’re a perfect dummy. [Laughter] So, they brought me down to JSC, we had it all set up. We did those same sine sweeps, but we didn’t go nearly the same amplitude as the guys in the ’60s did, because quite honestly, we didn’t need to establish that limit anymore. I didn’t want to be shaken to the point where I couldn’t breathe.
Host: Yeah, you already had the data.
Mark Baldwin: Right, but we actually were interested in collecting data to build a model. So, interestingly, I’m going to live on as a stick figure model in our vibracoustic analyses. Because we used the data collected on me to make a little stick figure version of me and put it in our analytical really big, complicated model. But what was great about that test was, kind of like you, Gary, I didn’t really have a great understanding of what does vibration feel like, you know what hurts, or what is really so intense that I can’t handle it? And so, by going first, I said let’s get me in there, let’s run different tests. Let’s see what this feels like. And as an engineer, went back to the, I really want to understand how is this going to affect the crew? So, they strapped me in the seat for two days in a row. I spent 7 hours in a seat. We went through a variety of different tests. We did sine sweeps, but we also simulated both lift off and the most extreme parts of the ascent, which it’s called buffet, but that’s when the vehicle is starting to shake across a variety of different frequencies. And then going back to the sensitive part of the human body, we wanted to make sure that nothing was going to be damaged, or I didn’t feel head pain or anything like that. And as a fun aside, the thing I was most worried about was we had high speed video focused on my face and as we were doing these tests, visors down. And I was really nervous about throwing up inside the helmet, because that would have been caught on video. I never would have lived that one down. But turns out I didn’t throw up.
[Laughter]
Host: Well, okay so it looks like the sources for vibration for Orion are liftoff and this buffet, like this time during ascent. There are the primary sources of the most violent vibration. So, tell me, you experienced it. What was it like? What did it really feel like?
Mark Baldwin: So, for the most part, when the crew are going to be on, in our case it will be the space launch system. You know, they’re going to be 300 feet up above where the flames are coming out of the bottom of the rocket. You would think that’s far up, but you have to almost look at a rocket and a capsule as just a stack of springs, right? You’re sitting on metal that is all capturing a lot of this structure born vibration. Way down below you, but it’s transmitting all the way up into the seat. By the time it gets to the crew, you know, ascent as you go, is what we call random vibration, as in you’re moving in and out of certain frequencies and amplitudes, so the severity is changing constantly. And really actually, the test series was to focus on legibility. Could we read the display units? And interestingly, so I had this display unit suspended over my head as I was being shaken to what we considered an ascent and even that buffet, that most severe part. And I could read the displays just fine. And at times the displays would blur ever so slightly and then snap right back into focus. And that’s an illustration of the effect that it’s having. Because it’s random, sometimes you’ll tune into the eyeball or the head. But it will move in and out quickly. So, it really was not, it was not uncomfortable at all. It was kind of neat, honestly to hear as well as feel that input to the crew. And we came out of that series with a lot of confidence that you know, not only will our crew be able to read the display units, but they’re going to be quite fine.
Host: That’s good and that’s actually an important reason to conduct the test in the first place, rather than just sort of assume or predict what’s going to happen, put yourself in the scenario, test it out and see oh by the way, whenever you’re launching you’re going to feel the vibration, but you know you’ll be able to read the screen. It might come in and out every once in a while, but it’s going to work out for you.
Mark Baldwin: Yep. That’s right.
Host: Yeah. All right. So, that’s vibration, which it’s super interesting, and that’s just only one phase of the flight, though. The biggest sources there are liftoff and ascent, but what about the sustained acceleration. Where’s that coming from?
Mark Baldwin: Yeah. So, sustained—we’ll talk about the ascent abort trajectories for AA2, but the way that works is the vehicle is going to be pulled away from the rocket. So, the Orion crew module will be separated, and while the accelerations are severe right in the beginning, you’re still not quite done. You still have to do a reorientation to put the bottom of the vehicle, the heat shield side first, because that’s what hits the water. Then you have to go through a series of parachutes deployments and each one of those releases a packed parachute on the vehicle. It inflates and then the crew module is just dangling and spinning underneath. We’d like to control that to a level where you know you’re not going to pass anybody out. But sometimes parachutes fail. In the case of a pad aboard, you have very little time to get all of the parachutes out. So sometimes you have to skip a few and go right to the main parachutes to open all those up before you hit the ground. So, we work with the guided navigation control folks, at both Lockheed Martin and NASA to assess how much acceleration you would feel in the seat, and then along which direction, and we have these charts and we can look at each one of these types of environments throughout the entire re-entry and all the chute sequences and confirm that yeah, you might be spun for a little bit but you’re not going to pass out.
Host: Yeah. Yeah. And we will get into the ascent abort and exactly what’s happening there, but it sounds like that’s going to be the source for this sustained acceleration that’s longer than half of a second.
Mark Baldwin: Yeah.
Host: Yeah. But then the short duration one, I think this can come from several different sources, right? The impact sort of Brinkley Model sort of thing, where are these coming from?
Mark Baldwin: Yeah, so if you go through the mission sequence, the first possibility you could see this would be an abort. Like I mentioned, you could have an abort on the pad. Now, the abort motors were designed to get you away quickly and safely. But like we mentioned earlier you can’t do it so fast that you liquify the crew in the process, right? So, there’s a limit to the G levels that you want to keep during that abort. And now, on the pad, you can imagine you’re not moving, versus you’re going really fast during ascent you have to do the ascent abort. It has to operate in both ways and it also can’t overload the crew, both during ascent and pad. So, that’s one major thing to look at. Pretend, we get all the way around, we do our mission, we’re coming back through. Now we have a shoot deploy sequences. Those can impart a jerk onto the vehicle. And the weird thing there, the vehicle may be oriented in different ways, right? You actually come in on Orion upside down and backwards. And through a series of maneuvers then you get feet first and down. When those shoots deploy, though, you may be still spinning as the next step deploys. So, we have to look at directional acceleration there. But the magnitude is generally a lot lower. The last thing is landing. And so, in my job I really focus on about 2 seconds of an entire mission, an entire two week mission, I spend all my time looking at abort and landing. Because that’s when the accelerations are the most severe. And landing is really interesting because it is unique to space flight, because the—our capsule and others are going to land in the ocean. If we have an abort, we’re not done yet you’ve still got to land in the Atlantic. If you have a nominal re-entry in the Pacific, we have to land, and we could land under a variety of conditions. There’s winds, and waves, and then you know anybody that’s done a belly flop off a diving board, you know that if you land flat, that hurts a lot, right? So, we don’t want to land too flat. And we also don’t want to land too steep, such that we roll over. So, we spend quite a bit of time and have done a series of really interesting tests to characterize, not only how does the vehicle respond to landing, but how do the crew respond to that acceleration in each of the seats.
Host: Yeah, you know that’s funny that you describe that in the entire duration of the space flight, you’re really focused on a few seconds, but these are a very important few seconds.
Mark Baldwin: They are.
Host: Yeah, yeah. So, tell me what are you doing to test this I guess we’ll focus on landing for now, landing in the water. How do you actually get a feel for what that’s going to be like?
Mark Baldwin: Yeah, so this is where the collaboration between Lockheed Martin and NASA really worked well. So, let’s back up a little bit. Several years ago, we didn’t really have a great sense of how Orion, when it hit the water would translate to local seat acceleration, so we could do those Brinkley and the crash test dummy assessments. So, instead we started out with faking it, where we put a seat on a sled and we went to that same location, Wright Pat Air Force Base that put humans in the seats and we simulated what we thought was an acceleration profile based on some preliminary drop tests with a very crude version of the vehicle, a boiler plate. And we had run tests with a full scale boiler plate at NASA Langley. They built a dedicated pool, a 20-foot pool under what they called the Gantry, which was used back in the Apollo days. And the Gantry is really neat, it’s this 200 foot tall structure that they can pick up a 20,000 pound vehicle, raise it up to 100 feet, swing it and then drop it into the water and let it smack. And we can do that under controlled conditions. We can either turn it around, or we can tip it forward, or we can make it flat for that belly flop. So, we spent quite a bit of time, and we thought through this. We said all right let’s first start with the simple boiler plate, doesn’t have to be a fancy vehicle. Let’s just drop something in the water and characterize those accelerations. So, we did that. Then we took those accelerations and we translated that over to the sled tests at Wright Pat Air Force Base. Then we started testing dummies inside, crash test dummies, inside of suits in our seat. And started running those tests. So, we’re starting to build this understanding of how does the whole vehicle acceleration during landing relate to the localized injury potential at the crew. So, as we did a couple of those preliminary series we said, well why don’t we just put the whole thing together and do this for real. So, in 2016, again with the NASA Langley Team and the Lockheed Martin Landing Team, we developed a plan of 10 different tests. Now, this time the tests had a lot more fidelity to them in that we used and recycled what we called the ground test article which was of medium fidelity. It had an interior much like the structure of the real vehicles. But it allowed us to put in real seats and what we call the crew impact attenuation system and I’ll get to that in a second. It allowed us to put in a small and a large crash test dummy inside a spacesuit and then drop that whole thing in the water multiple times. And so, there’s actually a picture of myself and Ricky Barr from the Orion Crew Survivability Systems at NASA JSC. We were in the vehicle, stuffing the dummies into the suits. And that picture made it into “National Geographic” in November 2016.
Host: Oh, that’s cool. So, yeah, essentially to summarize, you’re basically throwing this module, basically what is to be the Orion in the water, seeing what the crew is going to be really up for when it comes to a landing and all these different scenarios. And then putting, you know, this test dummy, this article that’s seeing where the loads are going to be put, right? So, you know of throw him in different directions, put him in a suit, basically, replicate the scenario of what the crew is going to be and then see, is this where the design element comes in where you’re like okay, we need to put the seat this way, we need to make sure the suit has this sort of material, or is situated it this way for the comfort of the crew. You know, what are some of the ways you’re designing for successful Orion mission come in?
Mark Baldwin: Yeah, so that’s where all of this goes way beyond me. Right? Some of the teams that I mentioned before, the guys developing the seat, the Lockheed Martin Crew Systems Team, the Orion Crew Survivability Systems, that’s the suit guys. So, Rick and I flew to Langley to make sure we set all that stuff up inside the vehicle, as close to flight as we could get it. Then, another interesting thing that folks may not know about, the impact attenuation system. So, on Apollo, all three people were strapped to a single couch. That couch was suspended inside the vehicle via these struts. And those struts were meant to stroke the couch if you hit hard enough. Well, on Orion we actually started out with a similar design, we got 4 crew on Orion, but the struts were kind of bulky and in the way, we didn’t want those. So, we said, well wait, can’t we do this better? So, we took a page from another industry, the helicopter industry. So, Blackhawk Helicopters, the pilots that sit in those front seats, they actually, when they hit the ground, because the impact is so severe, the seats are designed to physically translate down a series of rails and you can end up through the floor, by design, through the floor in a Blackhawk and the floor is cut out. What that does is it reduces the severity of the acceleration especially on the spine, right? That’s the most sensitive part of the body that you want to protect. So, helicopters have been crashing for years and years, they’ve evolved this technology and we say, well why don’t we borrow some of that technology and put it into Orion. So, we did and not only that, but instead of everybody being tied together, which wouldn’t give the same acceleration to a small lightweight crew member as a big crew member, we said why don’t we de-couple each of the seats, why don’t we develop an impact attenuation system along the spine that can be tuned per the person’s mass. And then everybody sees a comparable acceleration. Doesn’t matter if you’re minimum 94-pound, or you’re maximum 243-pound crew member, everybody will see the same acceleration if you have a hard enough landing to stroke that. So, what we did is we put those units inside this test series to see if it would work. And lo and behold when we hit just right, and we loaded up the spine, we saw our system do exactly what we wanted it to do, which was stroke along the spine and limit that acceleration and that load to the cervical and the lumbar spine.
Host: That is awesome. So, this goes back to your basic description of what biomechanical engineering really is all about, is this flexibility when it comes to the crew members. And this system, correct me if I’m wrong, basically what you’re doing is you’re making each seat, knowing who’s going to sit in that seat, you’re making it so that a crew member of this mass, you kind of tweak it up a little bit and it is specifically designed to I guess decrease the acceleration in the event of an impact for that specific crew member.
Mark Baldwin: Yep. That’s right. That’s right. And while we were making this change, I’ll illustrate one of the most interesting days I had on the program, I get a phone call and it’s a guy name Milt Heflin who basically had my job 50 years ago. He was an Apollo engineer that was the landing engineer and the impact attenuation system engineer. And this guy totally nice guy, he was great. But he was kind of grilling me a little bit, like do you know what you’re doing buddy. In a really nice way, but at the same time, I took him through everything I just described and said, you know what, we felt like there’s new technology we’re going to leverage it, we should put it in. And I got the thumbs up from him, and so basically, I was like success. You know I passed the test.
Host: Well, that’s the idea, right? The idea is yes there’s a lot of great lessons we can learn from the past because other people have done great research as well, but let’s take this already great technology with like you said the helicopter technology which has been crashed over and over a lot of good data there. And you can basically take that into human spaceflight and make an even better system that’s going to make it safer for the crew. And that’s the ultimate goal is the safety of the crew.
Mark Baldwin: Yeah, yeah. And let me take that one level deeper. So, we have a dedicated group of about a half a dozen people within occupant protection. And we started this group with a large group but then we kind of refined it down to a subset of members. And some of those members have been really instrumental in helping us. So, the suit guys at JSC, Dustin Gohmert, and Rick Ybarra and Jeff Suhey, they’re helping us understand all the features of the suit. Because when we go back to this acceleration environment, and now we put a heavy helmet and a bulky helmet on a body that is landing and hitting the water, we’ve got to make sure that that helmet does not now impart a load on the neck to overload the sensitive portion, which is the cervical spine. I think folks remember the Dale Earnhardt NASCAR death. That was a basilar skull fracture because the added weight of his helmet twerked his neck right at that sensitive location and overloaded it. That’s where that stress exceeded the strength. We’re trying to prevent that. In addition, we’ve recruited folks like Dr. Nancy Currie who was an astronaut at JSC, and she is 5′ 2, a total bad ass. She is the most awesome person you would ever meet. [Laughter] But she has been really helpful to make sure we keep in mind as we’re doing these assessments, as we’re testing, as we’re doing analysis that we don’t forget that you have to make sure this system works for the shorter stature crew members, and the tall, and the small, the lighter weight and the heavier. So, we spent a lot of time focusing on not just running a single test. And this is where the tools of today actually are beyond what the guys could do in Apollo. We can run analyses. So, myself and other analysts, Jeff Somers, Chuck Lawrence, Jacob Putnam, and Martin Annette we run what’s called LS-DYNA, it’s nonlinear analysis. And we replicate as close as possible, either those sled tests or the full scale water drop test with the small, and the large, and the medium size crash test dummies. And from those dummies, you can think of it as a bit of a transfer function. You put an acceleration in and then outcomes from the models now, forces and moments at the sensitive areas. Whether it’s the neck, or accelerations at the head. And that gives us answers that will tell us, did we induce a neck injury. Do we have a skull fracture? Do we have traumatic brain injury? We can now look at all of that stuff and not just for the test that we ran, but now we can run all sorts of different environments, that could occur, that we can’t go run 10,000 tests, but we can run 10,000 models and collect all those answers and then get a pretty holistic picture of what the risk is for any size crew and in any situation.
Host: Yeah. And this kind of goes back to that biomechanical engineering, that flexibility. But also kind of highlights, you know why testing is important and why testing over and over again is important. Because the truth is that people come in different shapes and sizes.
Mark Baldwin: Yes.
Host: So, you need to accommodate that. And it makes engineering I’m sure for you a little bit more difficult, but it is worth it because really the idea is to protect as many astronauts as possible. And I’m sure that this could be translated to other places too. You know, you’re getting really good data you can share that.
Mark Baldwin: Yeah, and as we go forward, so that’s let’s go back to Ascent-Abort-2 test if now’s the time.
Host: Yeah, go ahead.
Mark Baldwin: Yeah, so we, as a program we need to understand these external environments as much as possible. But you can imagine an ascent-abort test is not cheap. And we can’t do a lot of them. So, we have to use this combination of tests and analysis of that test. And then analysis of things we couldn’t test to try to fill in the blanks. So, Ascent-Abort 2 similar to the very first water impact test, we have a crew module on there that’s fairly simple. It doesn’t have seats; it doesn’t have crash test dummies or anything in it. But we do have a bunch of instrumentation in and around the crew module and the launch abort system. We’re going to take that vehicle up to 31,000 feet. We’re going to initiate the abort. And the whole thing is going to be over in 1 minute. But the sequence we go through is going to help us ground our structural model. So, this is more classical mechanical engineering, where we’ll understand the vibration, we’ll understand the stress. We’ll understand all those forcing functions. The things external to the vehicle, and we’ll ground our models. Then, analytically, I can take what we just learned. And now I can drop in any size crash test dummy, or any size stick figure mode, remember based on my under vibration, and we can scale that to be large and small. And then assess, okay what would it have been like had we put somebody in that Ascent-Abort 2 test.
Host: Yeah, there you go. Ascent-Abort 2 you’re not going to put the crash test dummies on there, but you’re getting good info on what the environment is like, that’s the idea right? So, you can do your own tests. Here’s the data, not go do your own tests.
Mark Baldwin: Absolutely. And that’s where the analyses and the computational power we have today makes that approach much more sensible, as opposed to Apollo, the only choice they had was to throw the vehicle in the water as many times as they could and record all the data. We can do all of that, I can run a million different landing cases in less than a week.
Host: Nice. Yeah, that’s really, really important, you know efficiency, obviously. But so you’ve got this Ascent-Abort 2, you’re going to get some great data from what it’s like to abort in the event that the vehicle is already on its way to space and then is aborted. You got this, you got water impact testing. You got the sled test. You know what else do you need to test, or really is this going to give you a nice package to present to, you know the Orion folks or whoever to say, we’re ready to fly.
Mark Baldwin: Yeah, so it’s the last I think major extreme system level test that we’re going to do, we’re not quite done though, right, so the next big whole mission test is called Exploration Mission 1, EM1. That is going to be a lunar flyby. We’re collecting data on that. In fact we have a seat and a mannequin and a suit that going’s to ride in EM1. But we’ve opened the aperture beyond just occupant protection for that test series. Right? Of course we’re going to get structural data. Of course we’re going to go through the paces of the mission profile. But inside the cabin we’re also going to add radiation torsos that are provided by the German Space Agency. So, we’re actually collaborating on EM1 to try to make sure we address not just injury but radiation exposure. So, it’s kind of cool, we’ve got two radiation torsos that are going to go in the bottom two seat locations. One of them is going to have a vest provided by the Israeli Space Agency to protect one of the German Space Agency torsos and the other one won’t have a vest. So, we’re going to kind of get a with-and-without comparison of the exposure as they do the lunar flyby. And that’s all baked into EM1.
Host: Yeah, this is what I love about human spaceflight is all the international collaboration that comes with it. It’s pretty cool to see all these people come together and do great things especially on EM1, which is going to be awesome. And especially for you because this is the last really big you know piece of data that you need for this occupant protection thing before you get to that, you know we’re ready to fly thing, which I believe is EM—Exploration Mission 2, if I’m right.
Mark Baldwin: We are, yeah, we do have two more checkpoints. We’ve got more sled tests we’re going to run; we’ll call it the final Orion spacesuit. The final Orion seat. We’re going to go back to the same location. Now that we’ve completed these full scale water drop tests and abort tests, now we’ve got that acceleration profile from those tests. And now when we run a sled test, we can come really close to reproducing what that environment looks like in the seat. But we can spend a lot of time and get high speed video and a lot of measurements now on our crash test dummies now put inside what we’ll call the final flight suit seat design. So, that’s still upcoming.
Host: A lot of great stuff coming up. Wow, Mark, this was very fascinating to hear all the different elements that go into really just a few key moments of human space flight, but extremely critical. And I think this was a fantastic overview. So, Mark I really appreciate your time to bring us through this biomechanics and this spaceship crash testing today.
Mark Baldwin: Sure, thanks for having me.
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Host: Hey, thanks for sticking around. So today we talked with Dr. Mark Baldwin about occupant protection and crash testing and biomechanics; I hope you really enjoyed it. If you are not done with everything we have to talk about about Orion, we have plenty of other episodes. You can check out Episode 66, called “5,000°F,” that one was on Orion’s heat shields; you can go to Episode 69, which was “Navigating Deep Space,” on navigation and communication; Episode 75, that had, talked about radiation shielding; Episode 79, on, it’s called “Livable Space,” it was on life support, and, life support systems and environmental control; Episode 84 we talked about propulsion, and there’s plenty more to come. Actually, if you go deeper, back, on Episode 62 we dive into AA-2, the mission we talked about during today’s podcast, the ascent abort mission; Episode 28 we talk about living in Orion for three weeks; and Episode 17 is just general Orion. And again, there’s more to come. If that doesn’t satisfy your need you can always go to nasa.gov/orion to see what they’re doing right now. Otherwise, if you’re looking for more audio content, nasa.gov/podcasts has a lot of good stuff. For social media, stay up on the latest on the International Space Station, Orion, and Johnson Space Center pages of Facebook, Twitter and Instagram, use the #askNASA on your favorite platform to submit an idea for the show, just make sure to mention “Houston, We Have a Podcast.” So, this episode was recorded on April 24, 2019. Thanks to Alex Perryman, Norah Moran, Pat Ryan, Gary Napier and Jessica Vos. Thanks again to Dr. Mark Baldwin for coming on the show and taking the time out of his schedule from, all the way from Littleton, Colorado. So, we’ll be back next week.