NASA Edge | Game Changing Entry, Descent and Landing, Part 1
NASA EDGE gives an in depth look at the latest Entry, Descent and Landing (EDL) technologies being developed at NASA. Chris Giersch is joined in studio by Steve Gaddis (Game Changing Development Program Manager) and Michelle Munk (EDL Principal Technologist) to discuss the game changing nature of EDL, while Blair and Franklin interview Mike Barnhardt (Systems Modeling), Mark Shoenenberger (MEDLI-2) and Joseph Del Corso (HIAD-2) in this first part of two episodes on EDL.
Game Changing Entry, Descent and Landing Part 1
CHRIS: Welcome in NASA EDGE, an inside and outside look at all the things NASA. We’re joined by Michelle Monk and Steve Gaddis, how are you guys doing?
CHRIS: And we have a very important topic today, and that’s going to be EDL or Entry, Descent and Landing. Michelle, you are the principal technologist for EDL, what is Entry, Descent and Landing?
MICHELLE: Entry, Descent and Landing is how we get a spacecraft from the top of the atmosphere to planetary surface. So the Entry part refers to atmospheric flight, most of it, and then we have descent and landing, which is usually propulsive and get us down on the surface safely. We do D and L on the places that don’t have atmospheres like the moon or asteroids but usually we talk about EDL when we talk about atmospheres.
CHRIS: So Michelle what is your role as principal technologist for EDL?
MICHELLE: I look across all the admissions that NASA has coming up that will use Entry, Descent and Landing on any planet, and I look at the technologies we’re going to need for those missions and I bring them forward to the Mission Directorate for starting funding.
CHRIS: So you have a need in the EDL world, in the community, you are coming up with the technologies that are needed for future missions. So you take some of those technologies that maybe are less mature, hand them off to you, and then you make sure those technologies—
STEVE: Design, develop, test and evaluate.
CHRIS: Is that is a pretty easy task trying to figure out?
MICHELLE: Not at all. I have to look at the human missions that are coming up, so sending humans to Mars. I have to look at the scientific missions that are coming up in all the destinations, the scientist want to go to, and I have to kind of rank those and prioritize them, and figure out where they are in terms of maturity, and what the best infusion point will be, when is the first mission that can use that technology. And then, I have to figure out what is the best program within STMD for the investment. Is it better to have a University work on it or a small business, or is it better for a game changing program element.
CHRIS: And your job is really hard because we’re going to be talking about a suite of EDL projects over the next two shows, because there’s so much content in—
STEVE: There’s a lot of content—
CHRIS: You can’t do this in one show.
CHRIS: This is going to be part one of two parts. So how do you manage all that?
STEVE: Well one is, it’s hard, but it’s also fun, and we got excellent technologist leading everyone of these activities. So we all work together, and we all know that we need these technologies so we’re motivated to see them be successful.
MICHELLE: We’re very passionate community.
CHRIS: And all the interviews that we’ve done, you guys are definitely passionate, now the first one that we’re going to be talking about is ESM or Entry Systems Modeling, what is that about?
STEVE: So that’s the first part of it where there’s, they develop these models and simulations to understand how the technology works and how it will be beneficial at a system level. It is very crosscutting against all the projects, and the plan is to take that data, and then infuse it into the projects.
CHRIS: Blair had a chance to go out to NASA Ames Research Center to talk to Mike Barnhart, who is the integrated EDL systems lead, let’s check it out.
BLAIR: Mike, tell me a little bit about Entry Systems Modeling project. What is it?
MIKE: So that entry systems modeling project is tasked with developing a lot of these technologies that are coming from lower technology readiness level, things like academia and trying to bring them up to a level so that we are ready to help them.
BLAIR: So in this particular situation, we’re talking about EDL projects, and so you’re actually helping them raise their technology readiness level?
MIKE: That’s right, so any of these things, you know, Orion, Mars 2020, Mars InSight, anybody that’s flying anywhere in the solar system and they need to enter an atmosphere, you have to go through an Entry, Descent and Landing phase. And we don’t have all those problems solved. We don’t have all those technologies built, and so we’re continually trying to improve on our existing technologies and also renew with new ideas, and that’s the real purpose of Entry Systems Modeling Project.
BLAIR: How do we get the data we need to improve the EDL process across these missions?
MIKE: Right, so there’s a lot of different things that we can do. We have ground facilities which we rely on a lot, so we have arc jets that we do for material characterization and developing models for material response. We have our shock tube to a tree used to develop radiation models. We have wind tunnels that we use to build aerodynamic models. The dynamic motion of a body as it’s flying, that sort of thing. We need to know all of that in order to have a successful entry into a planetary atmosphere. So that’s the simplest thing that we have access to everyday. And then we also have, you know, some amount of flight data. So there is the Orion EFT1 flight last year, which was very successful, and we can use that to take our models and look at our predictions, and then try and back out you exactly how well are we doing quantifying, you know, how well are we predicting that.
BLAIR: You used a lot of data from the Apollo era. Are you able to use data from things like MSL and more recent missions to help because I know we have limited data on entry?
MIKE: Yes, so you know, MSL is a really great example because we flew MEDLI on MSL, and that allowed us to get some of the only data that we’ve had on entry at Mars. So heating data, pressure data, which we use to reconstruct the aerodynamics, is fantastic tool for us. But there’s a lot of challenges there as well. So it’s really, you know, it takes a village. You need to have your computational models because they’re the only thing that’s going to access the true flight space that we have here on the ground. We have ground facilities that simulate parts of the flight space, and then ultimately, you have a little bit of flight data, and your goal is ground to flight traceability. Let’s predict what we do on the ground. Let’s predict what we do in the air, and let’s see, you know, how far apart are we so that we can quantify when we’re designing the next mission exactly where we think will be.
BLAIR: Are you sharing that data with all the different EDL potential systems that are being developed?
MIKE: Absolutely, absolutely. Everything that we do in the Entry Systems Modeling Project is for the greater good. We work very closely with academia. So we’ve got University partners that we are sharing this data with to help improve our models. We share it with other projects. So with radiation modeling we’re working very closely with the inside project, and OSIRIS REx projects because they had issues with radiative heating on their back shell. So they call us because we’re the radiation modeling experts, and they say, “Here’s our problem. Tell us, how worried do we need to be,”—
BLAIR: Be worried, be very worried.
MIKE: We’re always looking to help everyone else around the Agency, and that’s really what Space Technology Mission Director is all about right is trying to help the other Directorates with the technology that they’re going to need.
CHRIS: That’s a great interview with Mike Barnhart. I mean it really kind of gives you the flavor of how difficult EDL really is. If you can’t characterize it and model it here on the ground, you’ll never be able to land.
MICHELLE: That’s right.
STEVE: And you can’t test an entry system on the ground and get the flight like data that you need to design.
CHRIS: And that’s a challenge because–but with MEDLI, on MSL, that was a game changer, wasn’t it?
CHRIS: I mean, you actually, for the first time where able to actually see the health of the spacecraft as it was entering atmosphere.
MICHELLE: Right, as engineers, you know, it’s great that we succeeded, but I want to know if I got an A+ or a C- on the design. So the MEDLI data allowed us to actually know how we design the vehicle.
CHRIS: And based on that MEDLI data, what were the results, they were pretty good, aren’t they?
MICHELLE: They were fantastic. But we found some things that we didn’t know. Radiative heating is important at Mars and at the scale of MSL we didn’t recognize that before.
CHRIS: And now since it was such an important mission for you guys, now you’re going to take it to the next level from MEDLI 2 to for Mars 20/20.
STEVE: For Mars 2020, yeah, we’ve got that going and right in the middle of their preliminary design phase. They’re going to put some new measurements on the back shelf.
MICHELLE: Yeah, they were actually at Aberdeen proving ground last week doing some testing to see where to put the pressure measurement on the back of the vehicle that we had. It’s really exciting to get this new data in the back shell and using new sensors.
CHRIS: Well you know, Blair had a chance to sit down with Mark Schoenenberger, who is the reconstruction lead, which—I’m going to ask you about that, when we come back—I never heard of a reconstruction lead—but we’re going to learn more about MEDLI 2—let’s check it out.
BLAIR: So Mark, when you think about the differences between MEDLI – 1 and MEDLI – 2 it’s interesting because MEDLI 1 the M stood for MSL, Mars Science Laboratory. Now it’s Mars 2020, you guys caught a break, you get to use the same letter.
MARK: We still get to use the same letter. I think it will just be shortened to Mars EDL Instrumentation, and hopefully continue for a bunch more MEDLI’s, MEDLI 3, 4. We can always call it Mars.
BLAIR: Just perfect. It’s nice little series you got going.
MARK: Yeah, and we are great data.
BLAIR: Now, I’m wondering though, in terms of technology and in terms of how you’re growing MEDLI, I mean MEDLI – 1 was a very successful mission as far as the data we got back. What are we expecting for MEDLI – 2?
MARK: For MEDLI – 2, it’s really to dig in and look at the pieces that we couldn’t quite get for MEDLI – 1. The instrumentation there was to really, it was the first time we’ve flown instrumentation since Viking, to get pressure and heating data. So we really try to capture the whole event, and to do that, especially for pressures, we had these transducers that could see the peak high-pressure when you went through the hypersonic phase, you are really slowing down around Mach 18, and then as you slow down, you really start getting a noise there with the kind information you can get, the signal was just really weak, it’s sort of like using your bathroom scale to measure the ingredients for a cake. There’s not a lot of resolution there. So you don’t really trust those measurements.
BLAIR: That’s about how my cakes turned out.
MARK: So what we did here now is to use more of a postal scale for pressures. So we’re measuring down the low range, when we’re flying supersonically, right when we get near to parachute deploy, we’re spending a lot of time just, kind of slowing down, flying at the same altitude, but you’re really at terminal velocity, you are not slowing down really well.
BLAIR: Now is that pretty much in the part of the Descent, if you will, that where you’ve burned away most of the heat show that you’re going to in the process?
MARK: Yeah, all the heating is over, and you’re still a little warm and things are kind of winding down, but yeah, all the exciting heating stuff is over, and you really just trying to bleed off energy until you get down to a condition, let’s say for the parachute, and so any error in your prediction of how that vehicle slows down or your prediction about the atmospheres going to end up being on the day at Mars can lead to being far up range or far downrange, your landing ellipse and how you target it, you need to account for that. So if we can get better data to characterize the aerodynamics, we can tighten that up and land in even smaller spaces.
BLAIR: Which is always the goal right? Trying to find out exactly where you need to land. So Mark, how is the instrumentation different on MEDLI – 2 from MEDLI – 1?
MARK: So at least, from my experiences with the pressure side, MEDLI – 1 was really designed to capture the pressure all the way through entry. So it had this nice high maximum pressure could measure. What we really want to do for MEDLI – 2 was to look for the low pressures right before shoot deploy. We’re going to be coasting there, slowing down from say mach 4 down to mach 2, for a minute, 100 seconds or something like that, and that as to the landing ellipse, any error in aerodynamics. So the transducers, we put more of them on the heatshield and they’re in the lower range with a much better resolution at those low speeds so we can pull out things like winds and we can get a better estimate of the drag, and we also have a pressure transducer on the backside. As you slow down, get down to supersonic speeds, the pressures on the back shell become a big contributor to the total forces acting on the capsule. It’s really hard to predict actually what those pressures are. So with some truth on the backside that can really help us nail down the total behavior of the capsule as it’s flying at those slow speeds.
BLAIR: It seems like we’re getting an awful lot of good data on the things are happening during EDL and Mars, especially from MEDLI and MEDLI – 2, are we able to, in the future, may be translate what you’re doing here to potential different atmospheres or different EDL’s and circumstances?
MARK: Absolutely. So MEDLI – 1 definitely demonstrated, and it was the reason I think we have MEDLI – 2, was it became the model of how you put an instrument package on a heatshield, how to work with the project to do it, so they’re not scared about putting holes in there, within heatshield that’s designed to get the rover on the ground. We have a process now to do that. So you’ll see missions going to Venus or Jupiter, Titan those kinds of things they’ll all have instrumentation during entry, and NASA has the confidence to require that because we did so well with MEDLI – 1 and hopefully again with MEDLI – 2.
CHRIS: You know, Mark really did a nice job discussing MEDLI – 2, but I have to ask the question, in all my years at NASA, and talking to subject matter experts from all 10 centers, what is a reconstruction lead?
MICHELLE: Reconstruction is really important after a flight, so understand exactly how and where the vehicle flew, and without the proper data, it’s really hard. You have to make some assumptions. So for instance, before MEDLI, when we didn’t have an independent pressure measurement, we had to assume something about the aerodynamics of the vehicle in order to figure out how it flew. Now, that independent pressure measurement, we can nail it, and we don’t have to make any assumptions. So reconstruction lead is really key to understanding how we did.
CHRIS: I see, I learned something new everyday. I had no clue.
STEVE: Yeah, he comes back with that flight plan and where the data is along those flight, and it’s very important.
CHRIS: Now, speaking of that flight plan with MEDLI – 2, can you take the data from MEDLI – 1 and kind of show what the flight plan is going to be for Mars 2020 or is that a completely different flight plan?
MICHELLE: It’s a lot the same because it’s the same shape, size vehicle, the mass would probably be a little different. They’re using the same Entry, Descent, Landing System, but the atmosphere, obviously, will be a little bit different. The entry velocity will be a little bit different because of the different year, but largely, you know, we’re going to use all of our MSL simulations as the basis for where we start on 2020.
CHRIS: Now I noticed, Steve, with Game Changing, you take technologies, and you take them from a technology readiness level. We always talked about that one through that nine scale and you’re in that middle range—
STEVE: Middle range about 3 to 5 or 6—
CHRIS: Right, so but with MEDLI, since you have proven, you have a fight underneath you, and then you’re working on MEDLI – 2, is that still considered—it’s still not space ready—
STEVE: Yes, it was like what Michelle was telling you was we learned so much from MEDLI – 1 that we want put different kinds of transducers to get the lower pressure range. We want to understand that the back shell pressures and the radiation rates. So we learn so much. So it’s not really just a repeat of MEDLI – 1.
MICHELLE: Yeah, we have totally new sensors, knowing what we know from MEDLI – 1, we’ve moved a lot of our sensors so we have kind of the same number of channels of data but we’ve distributed them differently on the fore body and then moves on to the back of the vehicle.
CHRIS: Well speaking of a new mission, we also have now, instead of MEDLI – 2, we also have HIAD – 2.
CHRIS: Which is a Hypersonic, Aerodynamic, Inflatable Decelerator.
MICHELLE: Inflatable, Aerodynamic, yes.
CHRIS: And let me do it again—it’s Hypersonic, Inflatable, Aerodynamic Decelerator—
STEVE: Bravo, bravo!
CHRIS: So that’s a completely different type of EDL system from MEDLI – 2.
STEVE: It is.
CHRIS: Franklin had a chance to sit down with the project manager, Joe Del Corso, and we’re going to learn more about HIAD – 2, so let’s check that out.
FRANKLIN: So Joe, we’re talking about HIAD – 2, tell me what has changed since HIAD – 1.
JOE: So we’ve had a number of changes, the first one was we upgraded our thermal protection system. In HIAD – 1, we use the generation one thermal protection system, which was somewhat capable. It’s a low temperature capable, basically, something on the order of 1000 to 1100°C on the surface. For HIAD – 2, what we’ve looked at is a much higher temperature capable materials, much more flexible and lighter weight. So now we’re using custom-built silicon carbide materials as an outer fabric, we’re using cots materials and some custom materials for our insulator systems, and then on the backside for the gas barrier, you have woven fabric systems with PTFE film wrapped around. Our inflatable structure is also being upgraded, and then the other thing that we’re doing is we are working on scalability. We’re focusing on trying to get to 12-meter scale. In order to do that, we got to upgrade a lot of our equipment. We got to work on something as simple as just picking up one of the gore seems, takes a lot of development, a lot of careful coordination. So what we’re focused on is not just upgrading our materials but also upgrading our handling techniques, our manufacturing techniques.
FRANKLIN: Tell me about the HIAD timeline from the time it was,
FRANKLIN: conceived, to where we are right now at HIAD – 2.
JOE: So HIAD has been in development, previously it wasn’t on HIAD, but it’s been in development now for almost a decade, and we still have probably another four years-worth of work to do to get us to human access to Mars. We started out in 2006, doing material testing, and really all we were doing is we were doing low level, trying to learn how to test fabric systems so that we could simulate an atmospheric entry condition. We were learning how to learn in the early phases. We had IRVE-1 happen. Unfortunately, there was a launch vehicle anomaly. So we lost that, but what it did do is enabled us to put in place IRVE-2 flight test, people had enough confidence in what we we’re doing that they allowed us to build ability to print. That went up on the sounding rocket, launch our Wallops, and it was incredibly successful, proof of concept. We had an inflatable structure but no real TPS at the time, Thermal Protection System. Following the success of IRVE-2, we started up what we currently know as HIAD which is the Hypersonic Inflatable Aerodynamic Decelerator project. During the project, we were doing all the lab scale development, small-scale, little samples, we had learned how to test, do the initial testing. Now, we were taking it through a maturation process, getting it ready for flight again. The third flight that we flew out of wallops again is called IRVE-3, that was a much higher heating condition and it was the first chance for us to actually test a Thermal Protection System with our inflatable structure. After the success of IRVE-3 and the closure of the initial HIAD, we attempted to fly an orbital entry flight test called THOR, Terrestrial HIAD Orbital Reentry flight test. Unfortunately, due to the ORF-3 failure, we had to cancel THOR, and we went back to the ground developed effort. But unlike the first two ground development efforts, the third one wasn’t focused on learning how to test or testing materials were developing materials. It’s focused on scaling. So we did small-scale in the early development phases, and now we’re scaling to something more applicable for human access to Mars.
CHRIS: Now the cool thing I understand about HIAD-2, you guys have a partnership with ULA? Let’s talk about that.
STEVE: So about a year ago, ULA announced that they wanted to use HIAD technology to recover their boosters as part of their new business model, you know, affordability. And so we’ve been working on the flight demonstration with them over the last year and a half.
MICHELLE: Yeah, and that would be at the 6 meter scale, which is about half way to what ULA would need for their full booster recovery, 12 meter that Joe talked about on the video, and it’s also the right scale for us to do, maybe a Technology Demonstration Mission leading up to putting humans on Mars.
CHRIS: So the idea that you’re using this HIAD technology to recover the first stage of ULA rocket.
CHRIS: And so is that going to be recoverable, is that going to sort of land in the oceans, is it going to land on dryland house, how is that going to work?
MICHELLE: They actually want to snatch it out of midair with a helicopter, and then to minimize any refurbishment costs.
CHRIS: Wait a minute, so you’re going to have this booster coming down, with the HIAD deployable shells, and then helicopters are going to come and just kind of grab it in midair?
STEVE: Yes, it will come in. It will have a catch hood, and the helicopter will come, it’s a modified helicopter obviously, that’s the plan.
MICHELLE: We’ve not air snatched anything of that mass, yet, so that’s a little bit of technology development as well.
CHRIS: I just hope that you go back to your ESM folks and do some modeling of that snapping because—
MICHELLE: Reconstruction of the booster trajectory.
CHRIS: Reconstruction lead, will be a part of that too?
CHRIS: Well, we’re looking forward to seeing that in action because that will be something to see when that actually happens.
MICHELLE: That will be awesome.
CHRIS: And also, with HIAD, which is a win-win, not only for ULA, but for NASA, NASA gets a demonstration out of it, but then it kind of matures that technology to move on to an eventual test in Mars?
CHRIS: Awesome. I’ll tell you what, we’ve come to the close of just part one of EDL, I mean, we’ve covered a lot of technology today, and then on the next show, we’re going to be covering even more technologies.
STEVE: Yeah, we should be talking about ADEPT and 3D-MAT and HEEET.
CHRIS: And now, with regards to 3D-MAT and HEEET, that’s more of the more material side as opposed to the big system side, isn’t it?
CHRIS: I will come forward to that, and so stay tuned. We’re going to be talking more about EDL. You’re watching NASA EDGE.(c)2016 NASA | SCVTV