A conversation with Robin Beck, an engineer at NASA’s Ames Research Center in California’s Silicon Valley who develops, designs and tests heat shield materials.
Transcript
Host (Kimberly Minafra):You’re listening to NASA in Silicon Valley episode 88. I’m Kimberly Minafra and this week our guest is Robin Beck, an engineer here at Ames who develops, designs and tests heat shield materials. Robin talks about the different types of thermal protection systems that are needed for a variety of space missions, like the Mars Insight Lander Mission that launches in early May.
Now let’s listen to our conversation with Robin Beck.
Host: Tell us a little bit about yourself. What’s your background, and how did you actually end up at NASA?
Robin Beck: Well, I’m hometown, so born in San Jose. I went away to school to Santa Clara.
Host: Oh, wow. Quite far.
Robin Beck: Santa Clara University. Yeah, seven miles. And then I went all the way 11 more miles to Stanford for grad school.
Host: Okay.
Robin Beck: So I’ve always been in this area.
Host: Right.
Robin Beck: I’ve always worked probably within a square mile of here.
Host: Really?
Robin Beck: Yeah.
Host: That’s interesting.
Robin Beck: And all of my years at several different companies, but always very close to this area. I started in defense so I worked for a small defense company for a very long time, and that’s where I learned about heat shields.
Host: Really?
Robin Beck: And ablative materials.
Host: What were they doing? Were they working on that, too?
Robin Beck: Well, I talk about it’s as a joke as “bombs and bullets,” but it was for entry vehicles that had to go really, really fast and be protected, and so we did nose-tip materials that had to ablate and heat shield materials. Very high heating. Very high-pressure environments. And so, we learned a lot about the kinds of materials that would protect those kinds of vehicles way beyond often what NASA uses.
Host: How did you get that though?
Robin Beck: Get to NASA? Well, it’s interesting. How did I get to that?
Host: Yeah. Were you studying that in school?
Robin Beck: Well, heat transfer. Fluid dynamics. Combustion. All of that feeds in to ablative materials, it turns out. We got a little bit of it in what happens when you blow gasses into a boundary layer, so transpiration cooling.
Host: Right.
Robin Beck: And that’s really part of what ablative materials do. And so, a lot of that was understanding those equations that was from school. Most of the actual understanding of the materials themselves, and how to model them, and how they behave was on-the-job training from the perennial expert at the time who was Bernie Laub, who eventually came to NASA Ames.
Host: Wow, okay. Okay.
Robin Beck: And so, school got me really, the technical background and the right set of tools —
Host: Fundamentals.
Robin Beck: Absolutely, the fundamentals. To understand what the equations of state were. What was going on. And then understanding how the individual materials responded was from working with experts.
Host: So ablative, what is that, exactly?
Robin Beck: An ablator is a material that basically, changes state during — and in doing so, thermally protects the aeroshell that’s underneath carrying whatever it’s carrying. For us here at NASA, it could be carrying people. It could carrying science experiments. It could be carrying a rover that’s carrying science experiments to Mars. And so, it’s a material that will protect. It’s a thermally insulating material. However, it needs to go beyond just insulate. Our insulating materials like the materials we use for shuttle can’t handle the kinds of heating rates that some of these other vehicles see. And so, an ablator is pretty cool in that it has a reinforcement. So it can be anything from glass, or woven carbon, or all kinds of things like that.
Host: Like an extra layer of protection?
Robin Beck: Right, well, it’s the structural part.
Host: Oh, okay.
Robin Beck: And that’s infused usually with some sort of resin. Whether it’s a phenolic or a silicone. That’s what fills the spaces between that actually helps it be more insulating. The beauty of an ablator is at lower heating rates or even at high heating rates, but starting at lower heating rates the energy gets in, and the resin starts to decompose.
Host: Burn away then?
Robin Beck: Well, it will turn from a solid to a gas.
Host: Oh, okay.
Robin Beck: Yeah.
Host: That’s interesting.
Robin Beck: And so, and some of them are particularly amazing in that while that’s happening they absorb a lot of energy.
Host: Right.
Robin Beck: So the act of turning from the solid to the gas absorbs energy which keeps it from going —
Host: Oh, wow, right.
Robin Beck: — into the material deeper, right. So it’s actually absorbing energy at the location in-depth where it’s decomposing. Then those gases that form, since they are in-depth away from the surface, are actually formed at a cooler temperature than the actual outside surface.
Host: Oh, okay.
Robin Beck: So they flow through what’s now, a char layer and actually, are transpiration-cooling that char so they’re actually, cooling the char slightly. Then they blow in to the boundary layer which thickens it. Which lowers the heating. So you get all of these benefits from that gas being formed which takes energy. The gases flowing through the hot char which takes away energy. And then those gases flowing in to the boundary layer which also, lowers the incident energy to the surface. So there’s all this benefit of the actually active charring depending on the material. Phenolic uses up a lot of energy to decompose. Silicon, not so much.
Host: Right, so different materials have —
Robin Beck: Right, right.
Host: — different properties that allow —
Robin Beck: Exactly.
Host: — it to react to the environment.
Robin Beck: Exactly, and the way that they work are different, but the process is similar in that, even if it’s silicon which doesn’t seem to absorb much energy at all while it turns to gas, the gas still is cooling the char layer, and blowing in to the boundary layer.
Host: Which is what you want it to do.
Robin Beck: Absolutely.
Host: Keep the actual cargo or whatever —
Robin Beck:Exactly. Well, right, it absorbs that energy that’s being conducted in and keeps it from conducting further. Now, you’ll still have some of it going in, but a lot of it is used up in all of those processes.
Host: So this basically, is how you were working before you got to NASA then. You had all of that knowledge then.
Robin Beck: Exactly.
Host: Wow.
Robin Beck: And what was happening was we were coming to the end of shuttle here and returning to an Orion-type vehicle, right?
Host: Right, which was the capsule, yeah.
Robin Beck: Which was back to ablated materials. NASA had really moved away from ablators other than for science missions to planets — they still were using them there.
Host: The foam stuff?
Robin Beck: Right.
Host: Okay.
Robin Beck: But for any of the work for human-rated missions they were only looking at low-Earth reentry, so they didn’t need anything beyond just the pure insulators — the tile or coated tiles. Those kinds of things. And so, since NASA was returning, after about 40 years, to needing to understand ablative materials my expertise worked out to be a benefit to be coming here. So I started at NASA in 2006.
Host: Okay.
Robin Beck: So I haven’t been that long compared to a lot of other people.
Host: A lot of people here.
Robin Beck: Right.
[Laughter]
Robin Beck: But I started in 2006 just as the Mars Science Laboratory was running in to difficulty with anomalous behavior in arc jet testing of their heat shield material. The material that had flown to Mars on every other science mission, NASA had assumed and planned to use that same material for MSL which was bigger and had much higher heating than anything had flown before it. Not so much, much higher heating, but high shear, turbulent flow.
Host: Just so people understand. Mars Science Lab or now that we know it’s the rover on it, Curiosity —
Robin Beck: Curiosity, right.
Host: When it was coming in, landing on Mars, it’s a higher velocity so that’s the shear you’re talking about?
Robin Beck: Well, it’s two things. The velocity was fairly similar —
Host: Similar to the previous rover missions?
Robin Beck: — to the previous missions. However, it was a much larger aeroshell.
Host: Oh, that’s right. It is a bigger —
Robin Beck: So the flow, when it first hits the stagnation point, so it hits where it starts. And then it flows over the shape of the body, right? Well, this was coming in at an angle of attack so it had a very long running length on the lee side so it just kept going and going. Well, laminar flow after a while turns turbulent. And so, it really was the first time that for missions to Mars we had to really consider turbulent flow. The onset of turbulent flow and now, materials and high shear.
And so, the material that had been used is a great charring ablator that really isn’t designed for very, very high heating. There’s a lot of glass content, and you end up with a melty-flowy-type heat shield. If you get beyond certain environments, and once you have something that can melt, and you have a high shear environment you truly have melt flow.
Host: Which can damage the craft, right?
Robin Beck: Well, the thing that bothers me about a melty-flowy heat shield is that as that glass melt flows around the shoulder now, everything gets cold. So my question is, “What happens? Does it re-solidify? And that’s right where it has to separate or the heat shield has to pop off. And so, would it inhibit — ?
Host: It could be blocking the mechanism.
Robin Beck: Right, but beyond that we had some very anomalous behavior. I just happened to be here. I was pulled in on the team and then we started actually, an extremely rigorous redesign and repurposing of changing the material that was going to be used. We were the tall pole in the tent for a very long time. The highest risk was the heat shield obviously. And so, we did a lot of tests, and a lot of analysis, and a lot of design. We actually redesigned, machined-built and had the heat shield ready in 18 months.
Host: Wow. Oh, my God.
Robin Beck: Our heat shield was ready to launch when we were supposed to in 2009.
Host: That’s insane.
Robin Beck: And so, but yeah, all of —
Host: It’s hard to think you could build all of that first and now, analyze everything. And then redesign everything.
Robin Beck: Absolutely.
Host: Get all the sign-offs on everything.
Robin Beck: Right.
Host: In that short amount of time.
Robin Beck: Right. It was the first tiled, ablative heat shield.
Host: Wow. Wow.
Robin Beck: And so, there were a lot of risks after shuttle with gap-fillers and, “What do we use?” The good news is we weren’t flying humans. We were flying a machine. flying—
Host: Yeah, a little bit of possibility there.
Robin Beck: Yeah, cargo and flying a rover so we had the flexibility of a little more risk.
Host: Absolutely.
Robin Beck: But we also had a very robust material that we were going to fly.
Host: That’s exciting to hear.
Robin Beck: Yeah, it was.
Host: You could accomplish this major task.
Robin Beck: It was a lot of fun. It was very harrowing.
Host: Stressful?
Robin Beck: Yeah, and the good news was that it was successful.
Host: I bet you didn’t sleep much.
Robin Beck: Right, but it was very harrowing and scary that would we make it? And then the fact that as we were ready to deliver the heatshield a lot of the other systems I think that were hiding a little bit behind the big elephant in the room — the TPS — it turned out that there was a lot of the other systems that weren’t ready to fly. And so, there was the launch delay of two years.
Host: Wow.
Robin Beck: Yeah.
Host: Now, how did you guys test this new heatshield for the mission?
Robin Beck: We tested in —
Host:Because you mentioned there was testing, but what is that, really?
Robin Beck: Right, right. Well, there’s always going to be thermostructural so we want to make sure that as the aeroshell itself, if it flexes does the material break?
Host: Right, right.
Robin Beck: So we had those kinds of testing. We tested at elevated temperatures. Not very high temperatures, but elevated for those kinds of issues. We also tested at very, very high temperatures though. Aerothermal environments in our arc heaters. And at AEDC where we could get some very high shear as well in their arc heater facility.
Host: And what is that facility called again?
Robin Beck: Arnold Engineering —
Host:It’s a non-NASA facility, but a partner?
Robin Beck: It is an Air Force. It’s at Arnold Air Force Base in Tullahoma, Tennessee.
Host: Oh, wow. Way out there.
Robin Beck: Yeah. And so, they have an arc heater facility. They have three different arc heaters there. And then we have ours. Theirs is more designed for defense side, so higher pressures. And then we have the space entry-type things with the lower pressures and very high enthalpies. So the combination of the two we were able to piece-wise test the high heat flexes. The high shear. The right pressure ranges and expose the TPS to a lot of different environments because we had very heating, but we also had areas of very low heating. And it turns out, with our gap-filler those were the more stressing for the differential in the recession. Where the heating was low, the gap-filler would stick up.
Host: Oh, really?
Robin Beck: It would swell and the TPS around it would be ablating. And so, we had to look at the flow —
Host: Yeah, figure out how to —
Robin Beck: — over these fences where things were sticking up.
Host: In terms of the actual facilities especially, with the one here at NASA Ames you said an arc jet? What is that like? Can you explain what happens in there briefly or at a high-level?
Robin Beck: Right.
Host: Is it like a wind tunnel or how does that work?
Robin Beck: Sort of.
Host: Okay.
Robin Beck: Air is heated through a long tube where an electric arc, it truly is a very, very high amperage. Voltage. High voltage electric arc shooting down through this column of air.
Host: Like a lightning bolt? Kind of like that? It sounds like it.
Robin Beck: I like to describe it that way. It’s lightning in a tube that’s heating up the air. The arc jet people don’t like it to be referred to that way. It’s very controlled.
Host: Okay.
Robin Beck: It’s spun up so it’s the electrical energy is coming from an anode to a cathode, and it is spinning, and it doesn’t touch the walls. And the air flows through, and it heats it to an extremely high temperature.
Host: Wow, like what you would see in other atmospheres? Like our own? Does it mimic different planetary atmospheres?
Robin Beck: No, because at that point it’s not going fast, right?
Host: Okay.
Robin Beck: So as you heat it and you send it now through a nozzle that accelerates it, and we get very high velocity, high-temperature air. Now, people ask me, “Well, we’re not flying in to air at Mars. We’re flying in to mostly CO2.” We have found that especially, for the for the carbonaceous materials if we know how much oxygen is available we can go from testing in air —
Host: And simulate that.
Robin Beck: — and calculate what’s going to happen in CO2. There are few facilities that can do limited testing in CO2 and with that, we can verify it.
Host: That’s pretty cool.
Robin Beck: We can also, with some of our facilities we can vary the amount of oxygen. Even though we’re just using oxygen and nitrogen we can vary that amount of oxygen and see that, “Yep, available oxygen will react with the carbon and make the surface recede chemically,” and we can thermochemically predict how that surface is going to recede.
Host: Wow, that’s crazy. Lots of really cool facilities that not a lot of people realize NASA has.
Robin Beck: Oh, definitely. Definitely, and they’re even used to look at a lot of different things so that the aerodynamics of MSL, of that capsule, was studied in a ballistic range. Also, in our wind tunnels the parachute was tested. The MSL parachute was tested in the NFAC [National Full Scale Aerodynamics Complex]. The big wind tunnel.
Host: Right.
Robin Beck: Looking at radiation. The shock layer radiation and what happens in the wake was studied in our EAST [Electric Arc Shock Tube] tunnel which is a shock tube tunnel, and they tested in CO2.
Host: Wow, okay.
Robin Beck: So there are a lot —
Host: A lot of cool things we’re doing with Mars exploration.
Robin Beck: A lot — a lot of testing went on for MSL, and that information has fed in to the current missions.
Host: Absolutely.
Robin Beck: Some of that information from the shock tunnel and from instrumentation on MSL fed in to some of the analysis that was done on InSight which is our next lander that’s going to Mars.
Host: So Mars InSight.
Robin Beck: Yes.
Host: Okay.
Robin Beck: It will launch in May this year.
Host: Okay.
Robin Beck: And then it’s also feeding in to how we’re designing or evaluating the design for Mars 2020, which is the next rover from the U.S. The next rover going to Mars.
Host: When you are talking about materials you have a plethora of varieties to work from based on where you’re going? Can you use the same type of material for basically, all spacecraft that are coming in to an atmosphere or how does that work?
Robin Beck: Well, for Mars up until MSL the same TPS was used basically, because it met the requirements. You really need to understand your environment. Just first of all, what gases are going to be there obviously, but how fast are you going in? So from that you do the computational fluid dynamics. How hot are the gases going to be? How high is the heating going to be? How long are you going to be at heating so that you understand the heat load?
There are materials, the glassy materials that can’t go above a certain heat load so that’s your first hint. “Oh, well, it’s above anything about 100 or so watts per square centimeter,” you’re going to want to stay away from a glassy material and go to a carbonaceous material. Depending on the heat load and the heating rates the density. There are a whole lot of different flavors of combinations of carbonaceous reinforcement and phenolic, for example. So anything from —
Host: And what’s phenolic? You’ve mentioned it a couple of times. What does that mean?
Robin Beck: Phenolic is a resin.
Host: Oh, okay.
Robin Beck: It’s a type of resin. And so, conventional — again, reentry going fast and hot — heat shields are made out of full-density carbon phenolic so they are made out of carbon cloth that’s woven, and laid up, and laminated basically. And it’s impregnated with phenolic. Our heat shield for MSL was made out of PICA — which was phenolic-impregnated carbon ablator — but that carbon ablator, the carbon reinforcement was a very low-density structure. And so, that was one-sixth or so of the full-density carbon phenolic.
Host: So it’s lightweight, thin —
Robin Beck: Right.
Host: — but very protecting.
Robin Beck: Right.
Host: Wow, that’s crazy.
Robin Beck: Right, and now, if you needed to go faster, hotter that might not have been the best solution at pressure. It’s a low-density, brittle material so it’s going to be limited on what kind of pressures it can take. We’ve been developing 3-D woven. Basically, carbon and phenolic mixtures that are mid-density, lower-density so there are a lot of different variations on a theme that can be used to design a TPS. When you’re dealing with missions that can’t take the risk you’re typically not designing a new material.
Host: You’re going to reuse something that works?
Robin Beck: You’re going to go with something that’s flown. You’re going to go with something you have heritage on so that you don’t have that added risk that some missions can absorb and others can’t.
Host: Right. Well, that’s good that you have at least some samples that work.
Robin Beck: Absolutely.
Host: And missions that have proved the technology.
Robin Beck: Right, and a lot of the PICA and a similar material with a silicone where they impregnate shuttle tile with silicone that’s called SIRCA. That those two materials were invented here at Ames quite a few years ago. And so, the fact that we developed them. We developed the models to predict how they respond. We understand how to design with them, and we can use them. Especially, now that they’ve flown. And they’ve flown both ways. A single piece of PICA was flown on Stardust.
Host: What’s Stardust? That sounds cool.
Robin Beck: Stardust was a probe that returned —
Host: Stardust?
Robin Beck: It did. It did. I think it was a comet dust.
Host: Oh, okay.
Robin Beck: But I’m not positive.
Host: Makes sense.
Robin Beck: It brought stuff from space.
Host: So that material is —
Robin Beck: And that came in hot and fast.
Host: Wow.
Robin Beck: It was a very small, little probe. Less than a meter in diameter, but it came in hot and fast.
Host: Wow.
Robin Beck: And so, we knew how the material responded that way, but we had never flown it tiled. Well, now, for MSL we’ve flown it tiled, and that was much lower heating than Stardust so we’ve got a wealth of data on that type of material, and we know how to use it.
Host: Now, in terms of MSL would that same thermal protection material be suitable for say, Orion or another spacecraft going to Mars with humans, or can you scale that up just because you know it works, or does it mean the payload is going to change coming in hot? Do you have to change it up?
Robin Beck: Well, for an Orion-sized vehicle going to Mars, yeah, absolutely.
Host: Okay.
Robin Beck: But it has to come back so coming back is much hotter and faster. We were looking at that, and we learned a lot from the beginning of the Orion design’s early days to where we are now in that probably yes, PICA could work. We haven’t flown it on a manned vehicle.
Host: Right.
Robin Beck: And so, it takes a lot to qualify a material for a manned vehicle.
Host: So that means you’re going to have to adjust even that type of material because you haven’t gone both ways with it. MSL went one way so you were good to go.
Robin Beck: Right. Well, and it was lower heating.
Host: And lower heating.
Robin Beck: But that’s the thing. The entry for going in to Mars was much, much lower heating than it would be coming back.
Host: Coming back, yeah, that makes sense.
Robin Beck: Right. It’s going to come back much faster, much hotter, and it’s coming in —
Host: At a different trajectory, too, right?
Robin Beck: — to a much higher density gas, right?
Host: Right.
Robin Beck: It’s coming in to Earth’s atmosphere so the heating is much, much higher. PICA could take it.
Host: Okay. Go, PICA.
Robin Beck: Yes, it could take it, but there you still have gap-fillers, and all the things that are troublesome in designing. It would require a lot more testing and a lot more development.
Host: Yeah, because you think about different shoes for different types of weather or different activities. The same applies for these materials —
Robin Beck: Correct.
Host: — for different spacecraft missions. Different environments. Obviously, the weight of the spacecraft. It all plays in to adapting and making sure you have the right materials.
Robin Beck: Correct.
Host: You’re working on InSight which is coming up here. What other type missions are you preparing for or that you can talk about?
Robin Beck: Well, I’m working on InSight.
Host: It’s done basically, though.
Robin Beck: The spacecraft is being shipped to Vandenberg now, I believe.
Host: Wow.
Robin Beck: I’m working on Mars 2020, and that is a nearly build-to-print from MSL. It’s a new rover, and new insides. New stuff going in. More instrumentation, but the aeroshell and TPS will be the same as what was built for MSL. But it’s going in, in 2020. We had to do all of the trajectory analysis, the heating, the thermal analysis, and TPS sizing to ensure that as-built is enough material. So each mission is different. While it’s possible you can use the exact same spacecraft and spacecraft design you still have to prove it. You still have to do the analysis and do the sizing to make sure that your design is viable for that mission.
Host: Wow, yeah, that takes a lot of research first before you can even think about putting the materials together, right?
Robin Beck: Right, right.
Host: Do you see a lot of similarities between the materials that you used to work on for your previous position before coming to NASA and now or is it completely different because of the missions we do?
Robin Beck: No, it’s very similar. Again, the physics behind ablation is the same regardless of the materials. And the fact that we’re doing so much with carbon and phenolic whether it was full-density 2-D carbon phenolic that I started. Now, using low-density versions of that for NASA. And, in fact, NASA used some of those materials for their Venus missions. They used the full-density carbon phenolics for Venus missions. It’s still the same physics. And so, it’s a really good fit to go from the one environment to the other. So I had the right understanding of the materials.
And then it turns out that some of the materials that we were developing in that defense company for low-density materials and RF transparency actually flew on MSL. We used it on MSL.
Host: Really? That’s awesome.
Robin Beck: And we’ll fly again on Mars 2020.
Host: Mars 2020. Cool. Now, thinking about the materials themselves so we can visualize this in our mind are you talking about rigid, hard, bulky material that you attach to the bottom of, or on the belly of a spacecraft or are you talking about softer, squishier material? What is the texture are we talking about? You said something about woven something?
Robin Beck: Right.
Host: So what are we talking about?
Robin Beck: Even the woven once it’s impregnated it starts out as being moldable because it’s a dry-woven cloth.
Host: Oh, it’s cloth?
Robin Beck: It’s thick. Well —
Host: Sort of?
Robin Beck: — it’s a structure. It’s a dry-woven structure because it’s three-dimensional. We’ve done stuff even with felt. With carbon felt so you can mold the felt when it’s dry, but phenolic which is what we’ve intended for those materials to impregnate with, phenolic is rigid. So once we impregnate we have a rigid material. The material for Orion is rigid. Again, even the 3-D woven material that we’re developing here, we mold the dry cloth or the dry structure, we mold it. And then we impregnate such that we get much better properties rather than starting with something thick, and flat, and cutting out from it.
Host: When you can get it molded already.
Robin Beck: If we can mold it we can have the good properties everywhere normal to the surface rather than only in certain areas.
Host: Right. That’s pretty cool because I can imagine you’re cooking a lot.
[Laughter]
Host: It’s like putting all these layers on top of each other. How long does it take to even make a piece of material like this? Is there an average between all of them or are some created or developed faster than others? It sounds like you can do it in 18 months.
Robin Beck:Well, we weren’t inventing the material.
Host: Oh, okay.
Robin Beck: Remember, we already had PICA. That was already invented, and we understood that it was what we were going to be working with billets of the material. And we were cutting curved parts out of rectilinear billets so we understood the variation in the fiber direction and the properties. To start from scratch it takes a lot of years.
Host: Really?
Robin Beck: The 3-D woven work now had been probably — oh, I’m going to give the wrong answer so —
Host: Yeah, a few years?
Robin Beck: Well, more than three years.
Host: Oh, wow, okay.
Robin Beck: In developing the weave and designing the weave. And then the impregnation and figuring out how much to put in. How much impregnate to put in so how much phenolic depending on what properties you want and what kind of heating. The 3-D woven that we’re using, that we’re developing right now is for high-energy entry. So it’s for very high-energy. High temperature environments so it tend to have a higher density than PICA. It can take higher pressures. It can do a lot more than PICA can. And so, it’s for again, different missions than we’re —
Host: Deep space missions, right?
Robin Beck: Right, right. Missions that PICA can’t do, really.
Host: So in terms of your challenges what do you see are some major challenges to protecting spacecraft from extreme trauma entering a high, extreme atmosphere or temperature?
Robin Beck: Well, I think our biggest problem is that most of our spacecraft — we’re getting better — there are more and more requirements for instrumentation, because unless you have a failure where you want the forensics to figure out why you failed, “Oh, look at that thermocouple was really hot.” Typically, the missions themselves, as long as you designed it right, they don’t care how hot it got as long as their payload got where it supposed to go.
Host: Safe.
Robin Beck: Right. And so, we margin, we add. “Okay, here’s our predicted heating.” We multiply that.
Host: Yeah, you’ve got to have some padding, right?
Robin Beck: Right. Then we do our sizing and we margin that up. We could margin ourselves out of being able to fly. As we get to hotter environments, higher energy environments, because we don’t have the data we could end up being too heavy. Well, we can fly one pound of science because we’ve got 99 pounds of TPS in structure because we’re not really sure how hot it’s going to go, and we don’t want to overheat. So we have all these big margins.
And so, I think the more data we get — MSL had the heat shield — the forward heat shield — instrumented. This time Mars 2020 will have similar instrumentation spread out a little bit differently on the heat shield, but it will also instrument the back shell because the back shell is huge. We even margin higher there because we really don’t understand the separated flow field and how much heating we’re going to see.
If we can get that instrumentation, and that will feed in to the next mission. As we get more and more data about our missions it will feed forward to the next. Help us adjust those margins and not over-design so much. I really do think that over-design might be what kills the mission.
Host: Oh, absolutely.
Robin Beck: “Oh, well, we can’t do that because the TPS will be too heavy,” or, “We can’t make it thick enough because of the requirements that we’re calculating with all these huge margins.”
Host: Wow. What a fun job to be actually designing the safety aspect of getting a spacecraft to and from a mission. Literally, you’re the gatekeeper, if you will, for how these are getting back to Earth or at least going to other places.
Robin Beck: Yeah, going to a planet.
Host: And it works. You’re like, “Oh, my God, it works.”
Robin Beck: Right. It’s embarrassing in that people ask me, “How is Curiosity doing?” It’s like, “I don’t know.”
Host: You’re just worried about it getting there.
Robin Beck: Well, I could have been delivering a load of concrete. For me, my job was done when whatever we were sending landed. Now, all the science and everything which that was the purpose. Nobody cares about the heat shield. It’s garbage now on Mars, but without it we couldn’t have landed the rover. And so, my husband looks and sees what Curiosity is doing way more than I do because I did my job because we got it there. And then somebody else has to worry about going and doing the science on the planet.
Host: That’s pretty fascinating though.
Robin Beck: Right, but it’s only a few minutes.
Host: You were probably nervous.
Robin Beck: From Mars it was seven minutes.
Host: Right, yeah. You’re scared to death, I’m sure, watching this reenter, or at least seeing the trajectory.
Robin Beck: Right. As we were getting the information back during the entry for MSL, for Curiosity we were listening to information that was 14 minutes old.
Host: Oh, my gosh, that was stressful.
Robin Beck: Remember, there’s seven minutes of entry, and we were getting the pings 14 minutes later. So it was long-landed before we even knew it really started, right?
Host: Wow.
Robin Beck: So it was a little harrowing, and it was surprisingly right on the mark. Every ping that we got was exactly when we expected it.
Host: That’s wonderful.
Robin Beck: It was one of those moments where we were down near Hollywood because we were at JPL watching all this. “Are we sure?” All the theorists who say that we didn’t really go to the Moon.
Host: Yeah, they’re all down there, too, I’m sure.
Robin Beck: Exactly, so it was just so perfect, as we were hearing the pings that, “Okay, it’s done this. Okay, heat shield separation. Whoo-hoo. Oh, that parachute deployed,” and all of that. It really was happening right on schedule and so, it was very exciting.
Host: Awesome. Well, I’m sure Mars InSight is going to be just as thrilling. The whole world is going to be watching this, I’m sure.
Robin Beck: Yeah, and that one, it will just sit there. It’s a lander. It doesn’t roll.
Host: But still, the fact that it can make it.
Robin Beck: But it’s doing a lot of science. It’s doing seismic measurements. It’s drilling down, and doing seismic measurements, and everything else. And so, yeah, that one will, it will launch in May.
Host: Arrive?
Robin Beck: And land around Thanksgiving.
Host: Oh, okay. Another one of them?
Robin Beck: Yeah. I think Thanksgiving weekend or right after Thanksgiving it will land.
Host: And you’ll be thankful it made it.
Robin Beck: Exactly. Exactly.
Host: That’s fantastic. Well, I think the only other thing I would ask is how does it feel to be the — you actually have to review everything. Every spacecraft that we have as far as heat-shielding, right? Is it Ames or your team here that has to at least have some thumbprint on?
Robin Beck: Right. We’ve been involved as either oversight, or validation and verification, or direct design for some missions for each of the spacecraft that have required TPS. We’re the TPS Center of Excellence. And so, we’ve been involved with that throughout the years. Obviously, before I started here and through the missions that I’ve been involved in.
Host: Thank you so much, Robin, for joining us and telling us all about thermal protection materials and spacecraft coming in and out of atmospheres. I think it’s phenomenal that you get to work on that.
Robin Beck: Oh, I’m really enjoying it. Thank you for having me.
Host: Absolutely.
Robin Beck: I had a good time.
Host: Yeah, so well, hopefully, we’ll get to talk maybe after Mars InSight.
Robin Beck: There you go, yeah.
Host: That would be fun to hear what you’ve got and, of course, get ready for Mars 2020.
Robin Beck: For Mars 2020, yep.
Host: Absolutely.
Robin Beck: That’s the next one. All-righty.
Host: All right, thank you.
Robin Beck: Sure, thank you.
Host: You’ve been listening to the NASA in Silicon Valley Podcast. If you have any questions, on Twitter, we’re @NASAAmes and we’re using #NASASiliconValley. Remember we are a NASA podcast, but we aren’t the only NASA podcast, so don’t forget to check out our friends at “Houston We Have a Podcast” and there’s also “Gravity Assist” and “This Week at NASA”. If you’re a music fan, don’t forget to check out “Third Rock Radio”. The best way to capture all of the content is to subscribe to our omnibus RSS feed called “NASACasts” or visit the NASA app on iOS, Android or anywhere you find your apps.
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