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NASA Edge | Scalable Technologies

Uploaded 06/23/2016

Scalable Technologies

NASA EDGE is back in studio to look at two of NASA’s major Technology Demonstration Missions, Green Propellant Infusion Mission (GPIM) and Evolvable Cryogenics (eCryo). Chris interviews Associate Administrator for the Space Technology Mission Directorate Steve Jurczyk about how NASA develops and tests new technologies. Also interviewed on the show are Chris McLean (GPIM Principal Investigator), Hans Hansen (eCryo Project Manager), Monica Guzik (Gas & Fluids Systems Engineer), and Greg Zimmerli (Research Aerospace Engineer). Check out the show to learn how these technologies may become an integral part of all future space flight missions and why the co-host’s new energy drink (TRL-Zero) will never make it to market.





Green Propellant Infusion Mission (GPIM) and Evolvable Cryogenics (eCryo)
– Steve Jurczyk
– Hans Hansen
– Steve Jurczyk
– Hans Hansen
– Chris McLean
– Monica Guzik
– Greg Zimmerli


CHRIS: Welcome to NASA EDGE.

FRANKLIN:  An inside and outside look.

BLAIR:  At all things NASA.

CHRIS:  Hey, we got a great show lined up today.  We’re going to be talking about two cool technology demonstration missions.

BLAIR: TDMs, we covered them in the past, great ones, Deep Space Atomic Clock, Medley, LDSD.

FRANKLIN:  LDSD or space brakes.

CHRIS:  That’s great.  I like your phrase.  But on today’s show, we’re going to be focused on GPIM and eCryo.

BLAIR: That’s right, GPIM which is the Green Propellant Infusion Mission.

FRANKLIN:  And eCryo is the Evolvable Cryogenics.  And we’re talking about freezing somebody like in Star Wars with carbonate freezing.  This is dealing with fuel.

CHRIS:  Yeah, that’s a good point.  You know, before we get to GPIM and eCryo, I had a chance to sit down with the Associate Administrator for the Space Technology Mission Director, Steve Jurczyk.  And I asked how GPIM and eCryo fits into his portfolio.

CHRIS: So Steve, we’re talking about two really cool Technology Demonstration Missions today but before we get to these missions, let’s look at the overarching theme for Space Technology Director, what are you all about?

STEVE: We run the crosscutting technology program for the agency where we’re developing revolutionary transformative technologies to enable the future missions for NASA.  I really try to enable not only more capable robotic missions but also a human exploration of the solar system.  Our technologies cut across a lot of areas and we have these eight trust areas and they range from everything, from advance in-space propulsion, to advance power systems to environmental control, and life support systems, and even precision navigation.  And so, those are the capabilities that we’re going to need particularly if we’re going to do human exploration of Mars.

CHRIS:  Now, we have two cool ones, the first one of course is GPIM or the Green Propellant Infusion Mission.  Tell us a little bit about that and how that fits into your portfolio.

STEVE: Yeah.  So, GPIM is part of our propulsion system portfolio.  It is leveraging technology that we developed by the Air Force which is a green propellant that is not only safer for the environment but also provides higher performance for propulsion systems.  So, it’s been a great partnership not only with the Air Force but with Ball Aerospace & Technologies corporation and Aerojet Rocketdyne and it’s just an example of a very cross-cutting technology, one that can be used in not only space craft developed for NASA missions but missions for other government agencies and the commercial industry in general.

CHRIS:  And the other technology demonstration mission is eCryo.  Where does that fit in your portfolio?

STEVE: Yeah.  So, that’s also a propulsion system technology completely different though.  What we’re trying to do are a couple of things: one is cryogen, hydrogen and oxygen are very low temperature and if you don’t insulate them in a system, they boil off and it just goes away.  You can’t fill the tank up fast enough to keep it full which, so we’re trying to develop technologies to insulate the systems, so we can store propellant in orbit and they are also developing technology transfer from a delivery spacecraft to another spacecraft.  So, this gives you operational flexibility.  You can have upper stages, stay longer in orbit and re-fire them for more mission agility and also, it’s part of our architecture to launch system and reuse then in space.  So, you use up the fuel but it stays in space.  You send up a fueling system and you refill them and use them again.

CHRIS:  So, is it fair to say, Steve, that at STMD, you’re looking at technologies that maybe relatively new that you’re just starting out maybe as a paper study but then you have some technologies that are more mature that already for space flight?

STEVE: Yeah.  So, our programs are organized like that.  So, we have a set of early stage programs, Space Technology Research class or research with Universities.  So, that tends to be what we called lower technology readiness level.  And then we have what’s called NASA innovative advance concepts.  And we do a solicitation every year and we get proposal from everywhere, NASA centers, universities and industries and we get some really interesting kind of way out concepts, things like laser propulsion and mining asteroids for fuel and water.  And so, not many of them go on to the more mature projects but it’s really great to see the innovation that we get.  And then we have the game change development program which takes some of those ideas that are kind of way out there and matures them and then the ones that pan out of the game changing move on technology demonstration missions like GPIM and eCryo.

CHRIS:  So, you’re the guy to go to, that has invented the light saber, warp drive.

STEVE: Yup, we’re always looking for warp drive.  If the energy had zero mass and zero volumes, those are things we’re always looking for.  So, yeah, if I had somebody has  Unobtanium out there, we want it.

CHRIS:  Look guys, I got to say I really enjoy talking with Steve but he lost me in that last part. Unobtanium I’m not down with the time.


BLAIR:  Well, I mean you know, it’s a good reference.  It’s a reference to Avatar.  That’s what they’re mining on Pandora.


BLAIR:  So, I give Steve a little bit of credit for actually

FRANKLIN: Showing us his Sci-Fi chops.

CHRIS:  I would’ve had said Vibranium and Adamantium and that’s more – you know.

FRANKLIN: Yeah. Your more on that Marvel line.

BLAIR: As interesting as Marvel is and as much as we love them, the technology we’re going to talk about today, though, is still very cool and not hopefully unobtainable but very attainable, Green Propellant.  It’s green and it’s environmentally friendly, friendlier than what we currently used.  But the real expert on Green Propellant is Chris McLean at Ball Aerospace.  And I had a chance to sit down with him and get all the details about the Green Propellant Infusion Mission.

BLAIR:  So Chris, I’m very excited about this Green Propellant Infusion Mission but what is exactly is Green Propellant?

CHRIS:  Well, Green Propellant is a non-toxic fuel relatively speaking compared to heritage in space propulsion technologies like hydrazine and hypergolics.  What makes it really green is the fact that it has a very low vapor pressure.  You can put a container of this stuff on your desk and there is no evolution of nasty species that might mess with your breathing and get into your airways and stuff.  And actually, the toxicity of the liquid itself is really low.  It’s something you can almost drink but not quite.  We’re also able to ship it to FedEx across the country.  We don’t have to have it in explosion-proof containers.

BLAIR: Could you say ship me some Green Propellant for my desk back at NASA?

CHRIS: Well, that’s a nice idea and we’ve been asked to do that before, however, it is still an explosive.


CHRIS: So, even though it has a low-explosive paneling rating for shipping, it’s something you’d probably want sitting around all the time.

BLAIR: Obviously, it’s good to be green and obviously conscious in that way here on the planet.  What kind of benefits does that add for space travel?

CHRIS: The green benefits aren’t really part of the space application.  It’s for when we’re handling and unloading it and protection to the technicians and engineers that worked with this stuff.  When you’re working with this fuel, you really don’t have to worry about exposure to it.  If you spill some, you can clean it up with water and rags and things like that.  When we’re in space, the benefit is the performance of this fuel.  There are two things about this propellant that make it outstanding in paired Heritage fuels.  One is the performance is significantly better for a monopropellant.  If you look at hydrazine system, which is similar to what we’re doing in terms of single fluid in rocket engines attached to that, this thing has 50% better performance.  So, if you can imagine your car had enough gas in the fuel tank to 100 miles for that same fuel tank, you go 150 miles for this fuel.

BLAIR: You basically turned it into a hybrid vehicle.

CHRIS: Right, pretty much, pretty much.  And some of the other benefits are, when you look at deep space mission, there are times when with the hydrazine system, you need to have heater power going all the time to keep the propellant from freezing because if it freezes hydrazine or any of the traditional propellant freeze, it expands like water, like ice in your ice cube tray and it will break lines and things like that.  With this fuel, it goes through glass transition phase and does not expand at all.  So, for certain power critical applications like going to the South Pole of Mars.  Here’s an example if you want to land on a comet, if you want to be there for a while, you could save energy and put it into the electronics and things that need that energy and not spend the resources keeping the fuel liquid because you don’t have to do that.

BLAIR: So, what exactly is infusion of the Green Propellant Infusion Mission?

CHRIS: When we look at technologies that are employed on spacecraft, spacecrafts are high-dollar assets especially the big geo coms.  You could talk at a half-million dollars and more for an asset like that.  So, in order to use the technology like this and take advantage of the performance benefits that are offered by it, you need to demonstrate that first.  Almost every spacecraft that you would look at, let’s say, “Well, has that flown before?” you know, “What’s its history?  What’s its heritage on orbit?  What is our experience base with it?”  So by flying this technology on this spacecraft would build that experience base.  A lot of it, in my mind which kind of surprised me as I went through this process was realizing, you know getting range safety familiar with it and loading people saying, “Hey, this is a new fuel.  We haven’t had a new fuel go through some of the processing steps since 1972.”  So by the time we’re done with this mission, we would characterized this fuel on orbit on a spacecraft, demonstrating that we can do all of the Heritage applications and propulsion for spacecraft and moving it around, de-saturating momentum wheels and pointing the spacecraft and things like that.  And so we can say, “Hey, this technology is ready.” It’s ready for use on other applications and as people start proposing spacecraft down the stream.  They can say, “Hey, in my catalogue, in my toolkit of things, I can put it in this proposal under the spacecraft.”  Green Propellant has been demonstrated so we can use that.

CHRIS: You know I think this could be the first time, in my recollection, that the word green is used –

FRANKLIN:  Are you sure?


BLAIR: He’s really struggling with the certainty on this.

CHRIS: I think this is the first time that the word green is used in conjunction with a space technology.  Is that fair to say?

BLAIR: I think that is fair and additionally, all of the environmental benefits of this mission really take place here on earth but when they go to space, they’re not compromising any performance which is really awesome in terms of this being a good technology to be developed by NASA.

FRANKLIN:  Speaking of going in space, we’re actually going to cover the launch of GPIM along with the Deep Space Atomic Clock next year on a live show.

CHRIS: Yeah, I’m looking forward to that because I think that launch is going to take place down at NASA Kennedy which we love covering –

BLAIR: Absolutely.

CHRIS: The launch is live.


CHRIS: Now, speaking of technology, now we talked about GPIM, great technology but now we have to shift gears.  We have another technology we need to talk about which is Evolvable Cryogenics.

BLAIR:  Right and I had a chance to sit down with the eCryo program manager and my genius twin brother, Hans Hansen, to learn all about the many aspects of eCryo.

BLAIR:  So Hans, I notice you have a lot of moving parts in the eCryo program but there are a lot of things that are e this or e that, you know.  So, I’m wondering what exactly is eCryo?

HANS: So, eCryo is Evolvable Cryogenics.  So, we’re looking to try to build on cryogenic fluid management technologies or CFM for in-space applications that can be scaled up to an upper stage or potentially a depot down the line or even Mars applications.  We’re looking either demonstrating technologies for the first time or how can we scale it up to a larger scale, so that it can be infused into a mission.

BLAIR:  Now Hans, correct me if I’m wrong but I always understood cryogenics as sort of that process where you freeze the astronauts so that they can live longer in space on their trip to Mars.  That’s not what’s going on here?

HANS: No.  We’re not looking at cryogenic for that application.  We’re looking at it for –

BLAIR:  So, there is an application to do that?


BLAIR:  I’m sorry, go ahead.

HANS: We’re looking at using cryogenics in storing fuels.  So, the reason we’re using cryogenics is to have a very high-energy efficiency so that you can get the most bang for your backer, that’s gas mileage if you will.

BLAIR:  It’s important is space, too, I guess.

HANS: Yeah, especially in space because every pound matter, so what we’re looking is we try to see how can we be more efficient with storage of these fuels because they have to be stored in such as cold temperature.  We’re trying to prevent the fluids from boiling off, so you don’t lose your fuel on your way to your mission.

BLAIR:  Now, I was looking at your logo and I notice you have a veritable plethora of acronyms there.  Maybe it should be e-acronyms as your title.

HANS: Yeah.  We have some talented team members who came up with the bunch of these acronyms but, yeah, we – our modeling effort is DIVAT.  It’s Development In Validation of Analytical Tools.  That’s what we’re doing our modeling and simulation of the physics.  We’re also working on IFUSI.  It’s Improved Fundamental Understanding of Super-Installation.  So, we’re looking at a coupon level, multi-layered installation technologies that are used on spacecraft and upper-stage tanks for a long-duration mission to try to extend the mission duration from a couple of hours to maybe potentially even months if you’re going to a Mars application.  SHIVER is our largest element of our project.  It’s a four-meter tank where we’re going to be testing liquid hydrogen-type applications applicable to an upper-stage.

BLAIR:  And what about RFMG, what’s that all about?  I try to guess but I can’t.  I can’t quite get a handle on.

HANS: Yeah.  RFMG is our Radio Frequency Mass Gauge.  Once you get up in space in microgravity, you don’t have level-sensing opportunities, so we’re trying to use radiofrequency to gauge how much fluid is in a tank.

BLAIR:  You definitely want to know how close you are to “E” when you’re ready to head back from Mars.

HANS: Yeah.

BLAIR:  What about IVF?

HANS: So, IVF stands for Integrated Vehicle Fluids.  This is a ULA-based propriety technology that we’re looking at doing some testing and assessment of the technology to see if it’s applicable for the base-launch systems, exploration upper-stage.  We’re doing testing and analysis and modeling to see if it can save potentially a few thousand pounds of mass for the SLS program.

BLAIR:  So essentially what you’re saying is if eCryo is successful, that eventually, we’ll have a lean mean space flight machine.

HANS: Yeah, we’re trying to get as efficient as we can with our fluid management.  The whole eCryo project is trying to understand how fluids operate in microgravity environment.

BLAIR:  One of the things that Hans also said is they’re trying to get this technology to the point where they can actually test it in space because once you know that the technology actually works in flight, then it can be a part of every NASA mission coming the down the line and that’s really the goal of this technology demonstration missions.

CHRIS: And just like Hans said –

BLAIR:  Wait the minute, I’m sorry.  I forgot.  I got to mention this because Hans, my twin brother, actually told me that I needed to be sure that I made this point, okay?  I made the point in the interview, it’s ridiculous, and NASA is explicitly not involved in cryogenic research of that kind which is ridiculous.

CHRIS: Right, right.

BLAIR:  But then, last night, I was thinking, when I couldn’t sleep, I was like, “eCryo, think about it in sci-fi, never good idea.”  Not once do you watch a sci-fi movie where they have cryogenic sleep and you think, “Man, that’s technology we need.”  It’s always problematic, right?  So, not only does NASA not do it but it’s not even really helpful in the sci-fi community, right?

CHRIS: Continue on, so if you remember in his interview with Hans, eCryo has a bunch of smaller projects that are kind of under the umbrella of eCryo.

BLAIR:  That’s true.  That is true.

CHRIS: And one of them is called SHIVER.  I had a chance to talk with Monica Guzik, the lead engineer for SHIVER.  And the cool thing about this is we had a chance to go out to the Plum Brook facility which is about an hour for GLENN in a building called B2 where they had thermal back chamber.

CHRIS: So Monica, SHIVERS, every time I hear that I get called.  What’s that all about?

MONICA: Well, we did that on purpose.

CHRIS: Okay.

MONICA: We’re dealing with very cold stuff, with cryogenic liquids but SHIVER stands for Structural Heat Intercept Installation and Vibration Evaluation Rig.

CHRIS: Okay, that’s a mouthful.  So, you have to explain that to me.

MONICA: So, what’s going on here is we’ve got liquid rocket propellant tanks and they’re cryogenic which means really, really cold and we’re storing cold liquids.  So, what happens when you have a cold liquid is anytime you get heat in, you start boiling it off, just like water on the stove.  For us, boiling off is not a good thing because that means that we’re losing fuel.  Imagine trying to go drive to California with a leaky fuel tank and no gas stations in between.

CHRIS: Right.

MONICA: You’re never going to get there.

CHRIS: Okay.

MONICA: We have the same situations.  So, we’re trying to plug that leak by preventing the heat from coming in.

CHRIS: And what are you using to prevent that leak?

MONICA: So, we’re doing it two things, and that’s right in the name.  We’re using Structural Heat Interception which means that we’re actually cooling the structures.  These tanks have to be held up by something and they’re attached to really parts of the spacecraft.

CHRIS: Right.

MONICA: So, we’re trying to cool those attachment points, so that we reduce the heat coming through them.  We’re also using installation to try to prevent radiation that’s coming in from the surrounding space environment.

CHRIS: Okay.  So, what kinds of materials do you use to insulate the tank?

MONICA: What we’re using primarily is called multilayer installation or MLI.

CHRIS: Right.

MONICA: So once you’re in orbit, you know you don’t have air or anything hitting it.  Your primary source of heat is what we called radiation.

CHRIS: Okay.

MONICA: Radiation is heat coming in for a really hot source and kind of transmitting from that source to its surface.

CHRIS: Right.

MONICA: We prevent that by using highly-reflective sheets.  You can think of as almost like a mirror that reflecting that heat away and preventing that heat from getting in.  So, we have layers of what we called mylar which is actually just a type of really, really thin plastic.

CHRIS: Right.

MONICA: And we coat them with aluminum or some other reflective material on both sides.  And they end up looking a lot like really, really thin tinfoil and we layer these up and we separate each layer by something that doesn’t conduct a lot of heat and is really lightweight and it actually looks like the veil material that a bride would have on her wedding day.

CHRIS: Oh, okay.  I guess what you go to determine is how thick that installation is around the tanks?

MONICA: Right.  The more layers you add, the less heat can get it.  But that means you’re also adding more material which is more mass –

CHRIS: Mass, right.  So, there’s a trade off.

MONICA: So, there’s a mass trade, right.

CHRIS: Okay.

MONICA: Because mass is money when we launch.  So, we’re trying to save mass without adding too much.

CHRIS: I mean I can only imagine what the launch vehicle is taking from the pad, it’s shaking, it’s vibrating, I mean there’s a chance that material can come off.

MONICA: Yes, there is.

CHRIS: So, do you have to do testing to make sure it stays on?

MONICA: Yes, we do.  And that’s that vibration.  The ‘vir’ part of it is the vibration evaluation that we’re looking at.  So, what we’re going to do first is we’re going to test here in this B2 chamber.

CHRIS: So, this is a thermal vac?

MONICA: This is the thermal vacuum chamber.  It’s called B2.

CHRIS: Okay.

MONICA: And so here, we can test very large.  We’ve actually tested full rocket stages here before and it actually is capable of live fire rockets but we’re not going to do that here.  We’re going to keep everything from burning up.

CHRIS: So, how do you actually do a thermal test?  If I put your simulated tank in here, you got to close the door somehow, and so how do you heat up the temperature so it’s in space conditions?

MONICA: Right.  So, one thing that’s funny is since we’re so cold, actually just the temperature we’re at right now, we’ll heat up the tank.

CHRIS: Oh wow.

MONICA:  So when we talk about it, we’re going to take this tank, we’re going to close it, and you can sort of see the top of what we called a cryoshroud behind me and what we do is we can run either liquid or gaseous nitrogen through the tubes that are embedded in the shroud and those tubes – well, we can set –so that there’s a certain temperature that mimics what we’ve encounter in the space environment.  And it may in fact be colder than the air around us right now but it’s still very, very warm compared to the liquid in that tank.

CHRIS: You’re not really worried about the thermal test on launch, right?

MONICA: Right.

CHRIS: This is more in transit?


CHRIS: Okay.  But then on launch, you’re worried about vibrations?

MONICA: Right.  So once we do our first thermal test and we see how this perform, when we know it’s working, when it’s good, it hasn’t shook or anything, we’re going to take it over to our facility called the Reverberant Vibroacoustic Test Facility.

CHRIS: Okay, right.

MONICA: And we put it in there and there’s a whole bunch of what looked like big speakers on the wall and they can emit vibration sounds, acoustic sounds, to the levels that we’ve encounter in launch.

CHRIS: Okay.  And that would typical for the launch vehicle that it’s going up on.

MONICA: Exactly.

CHRIS: Okay.

MONICA: Yes.  And we actually have some of those launch profiles already and we’re going to use those when we do our testing with the SHIVER tank.

CHRIS: I’ll tell you what, it seems like the SHIVER is an extremely important program for the journey to Mars because if we want to send humans to Mars one day, we don’t want to boil off, we don’t want to lose the propellant and so, really, you have critical role to making sure that there’s enough propellant to get to your destination.

MONICA: Definitely, yes.  So, you could imagine if you’re trying to go somewhere and you run out of fuel half way there.  It’s bad enough if you’re in the middle of nowhere in the country but it’s really bad if you’re in the middle of space on the way to Mars.  So, you definitely need to make sure you have fuel in the tank there and back.

BLAIR: So, as processing this interview with Monica, as I’m looking at it and evaluating, I kept thinking with this idea of boil off, this kind of cold, kind of boiling in space kind of temperature, I was thinking, “Well, that doesn’t make sense to me because water like boils at a hundred degrees Celsius and that’s like hot.”  So, that’s hot.  It’s very hot.  It’s very cold in space.  So I’m wondering, how are things boiling off in space?  Is there something on the spacecraft that’s so hot?  I may have missed it.  She may have addressed it but I’m just curious if you dealt with this.

CHRIS: Different liquids had different boiling points.  So just like you said with water, water boils at a 100 degrees Celsius or 200 degrees Fahrenheit, right?  So, we’re talking about cryogenic fuels.  We’re talking about really cold temperatures in the -300 to -400 degrees range, right?  So, it doesn’t take very much to boil those liquids off.  So, if you have something a little bit warmer than that, it could boil off.

BLAIR: So, warmer is relative term, warmer than that extremely cold, so going from extremely cold to just slightly less extremely cold equal boil off.

FRANKLIN: This is where the multilayer installation comes in because you have to make sure that you maintain the temperature inside the tank so that you don’t get them boil off.

BLAIR: And so, you just keep like slapping layer, after layer, after layer, after layer, after layer on there, until you get that sucker nice and comfortable, so there’s no uncomfortable boil off.  So, okay, I got it.  Now, that’s interesting, right?  That’s a total interesting topic.  Here’s another question, because I’m wondering if you’re curious like I am.  Have you ever wondered especially we’re out of fuels, have you ever seen that ISS when the astronauts are up there and they’ve got the little water droplets and they’re floating around and everything, and it’s cool, right, it’s fascinating.  Have you ever wondered what happens to the fuel in the tank – when it’s full, I get it.  You know there’s no room for anything to move around but if you start to use that fuel visit, does it turn into a little globs and start floating around inside the tank?  Does that happen?  Is that possible?

CHRIS:  That’s a great question.

BLAIR: Exactly, which is exactly the question I brought up with our good friend, Greg Zimmerli who’s actually working on a way, a technology, to find out how to measure fuel inside the tank when it is floating around inside there.  Let’s check it out.

BLAIR: Greg, before we get into the radiofrequency element of your program, I’m just curious, I understand there’s a challenge in measuring the quantity or amount of fuel in a tank in zero gravity.  What is the challenge?  What’s exactly going on here?

GREG:  Well, 1G or in Earth’s gravity, the fluid settles to the bottom of the container, so we’re able to use what we call a level center to sense how much liquid is in the tank.  But in zero gravity, surface tension forces other things like that.  They can move the fluid around inside the tank to places where you’re not sure where it’s going to be.  So, we’re working on a technique that can measure the quantity of liquid in the tank no matter where it is.

BLAIR: No, correct me if I’m wrong and believe me, most of the time I am, but it seems like it’d be kind of tricky to put anything that emits any kind of frequency in a fuel tank because it might be combustible or something.  How are you accomplishing this?

GREG:  The technique we’re using, the radiofrequency mass gauge, we put an antenna inside of a tank and we transmit a range of radiofrequencies through the antenna.  Those frequencies emit radio waves inside the tank and it creates modes, natural electromagnetic modes, inside the tank and we measure those modes with a special instrument.  It’s very low powered.  There’s no danger with the technique.

BLAIR: So, have you don’t any testing on this technology so far?

GREG:  We have.  We’ve done a lot of testing here at Glenn Research Center.  We’ve tested the technology in liquid hydrogen, liquid oxygen, and liquid methane.  We’ve tested it on the parabolic aircraft.

BLAIR: Ah, yeah, that’s for the lower gravity situation –

GREG:  The low G, right.  So, we get about 20 seconds of low gravity on the parabolic aircraft.  We weren’t using the cryogenic fluids but we were using room temperature stimulant fluid for those.

BLAIR: Well now, it’s interesting you mentioned all those different test fuel.  Did they behave differently in zero G?

GREG:  In zero G, they’ll behave a little bit differently because the surface tension of all those fluids is a little bit different.  For example, water has a very high surface tension but liquid hydrogen has a very lower surface tension.  So in that respect, they’re different but the only real difference for the radiofrequency mass gauge is a property called the dielectric constant which is –

BLAIR: Alright.  You just move above my grade of understanding but–


GREG:  Maybe I should say the index of refraction of the fluid.  For example, glass in water slows the speed of light at different rates for example, okay?  So, these fluids also slow the speed of light in a known way.  That’s called the index of refraction of the fluid.  So, the radiofrequency mass gauge is sensitive to that index of refraction.  It slows down the speed of light; it changes these mode frequencies of the tank in a way that we can predict.  So, we measure those frequencies and then we compare those to some simulations that we do on the ground ahead of time and then we use – it’s almost like a digital fingerprinting matching type technique, okay?

BLAIR: Yeah.

GREG:  So, we compare the spectrum of the tank that we measure with what we’ve calculated and we find the best match and then that tells us approximately how much fuel is inside the tank.  The technique actually works relatively quickly.  We can engage a tank in a few seconds for example.  So, you could engage as often as you want.  You could have a real-time engage showing how much liquid is in the tank.

BLAIR: This is really exciting.  I love this but I’m curious now, how are they measuring it now?

GREG:  So, for the cryogenic propellants, there is no way currently to measure how much fuel is in the tank when it’s in low gravity.  So, we have to resort to secondary techniques with bookkeeping, for example.  So, we know how much fuel we started out with or how much propellant.  We know how much we’ve used when we do engine burns, things like that.  So, it sort of an accounting techniques.  We called the bookkeeping technique.

BLAIR: Wow.  So, it seems like this technology will actually go a long way and not just being more efficient but giving a lot of confidence to mission planners in terms of knowing how much fuel they need and how much they have at any given moment.

GREG:  That’s right.  It’s sort of an enabling technology.

CHRIS: Is it fair to say that as you increase the size of the tank, you scale it up, that you have to put more antennas inside the tank?

BLAIR: Scale up more antennas?  My first impression just based on Greg’s expertise and everything and listening to him in the interview and just my overall thoughts to the whole process would be no more – you don’t need more antennas.  What you really need bigger antennas.  Scale up bigger antennas.  You don’t need more antennas, just bigger antennas.

CHRIS: Okay.  As we wrap up the show, we talked about two great –

BLAIR: Wait!  Before we get to the end of the show, I’ve got more stuff from our good buddy Hans, who’s got more information.

CHRIS: Okay, go ahead.

BLAIR: So Hans, you have some very key information and I was supposed to mention it earlier, I think I did but I don’t think I did a good enough job, so I just want to go through it really quickly here.  He says that all these things in eCryo in the various parts like in FUSI and SHIVER and DIVAT which is a modeling component that we did not talk about, these are not just like all similar groups that are studying.  They’re studying at a different phases.  So here what he says: he says they’re testing at the coupon level with IFUSI, that’s a smaller level, they’re doing scalability with SHIVER, and then they’re performing predictive modeling with DIVAT all moving toward getting that space test eventually, so they can proved in space and, therefore, put in future missions.  Thank you.  Through email, last minute communication nailed it.

CHRIS: Okay.  So, as we wrap up the show, we talked about GPIM early in the show and remember in the interview with Chris McLean that he –

BLAIR: Great guy, great guy.

CHRIS: He was the –


BLAIR: He looks like the bad guy and Hero’s. Remember the guy with the glasses turned out to be the good guy.


CHRIS: So, remember that Chris said that he couldn’t get a hold of some Green Propellant Infusion Mission –


CHRIS: It’s peachy color.


CHRIS: What is that on the table?

FRANKLIN: What is that?

BLAIR: This, my friends, energy drink.  I was concerned that I would not be able to perform to scale, scalability, with these TDMs, so I went out and purchased an energy drink, so I would have the caffeine –

CHRIS: Okay, good.

BLAIR: To do well in the show today.

CHRIS: So, that’s not GPIM.  I just want to clarify it because you can’t drink it.

BLAIR: Nobody can drink GPIM.

CHRIS: Okay.

BLAIR: That’s bad, it’s not healthy.  It’s something that you could get close, you can spill in the shop and wipe with a sponge or something like that but you wouldn’t want to make it a beverage on like a drink list or you wouldn’t want to bring it to parties or you wouldn’t want to offer it to your friend or you wouldn’t want to give it to someone who’s thirsty because that would be cruel.

CHRIS: Are you done?

BLAIR: I could be.

FRANKLIN:  You’re watching NASA EDGE, an inside and outside look at all things NASA.

CHRIS: That better not be GPIM.

BLAIR: Oh no, no, it’s just an energy drink.  Who would drink green propellant?  It’s not good for the environment inside your body.  It’s bad.  It’s not green for the intestines


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