Main Engine Cut Off - T+10: Logan Kamperschroer on the Current State and Near Future of Storable Propellants

Episode Date: June 29, 2016

This week I talked to Logan Kamperschroer, a Graduate Research Assistant at the School of Aeronautics and Astronautics at Purdue University. Logan’s research focuses on hypergolic rocket fuels—specifically the push to move away from the toxic storable propellants (hydrazine and its derivatives) to “greener” alternatives. We talked about the current state of storable propellants, and where things are going in the near future. Logan Kamperschroer Hypergolic Propellants Laboratory | Home SpaceX Pad Abort Test - YouTube LMP-103S: New Process for Production of High Purity ADN (PDF) AF-M315E: GPIM AF-M315E Propulsion System Sigma-Aldrich Email feedback to [e-mail] Follow @WeHaveMECO Support Main Engine Cut Off on Patreon

This week on the show I have something a little different than my typical format. This is the first of the interview shows. I thought it would be interesting to talk to some people in the industry from time to time, whether they're in the industry or just related to it, or doing something interesting related to spaceflight and exploration, or any of the topics that we bring up on the show from time to time. So we'll have more interviews in the future as different events happen, as I come in contact with different people that might be interesting to talk to on this show. But first up, we have Logan Kamperscher. He's a graduate research assistant at the School of Aeronautics and Astronautics at Purdue University. His research is focused on hypergolic rocket

fuels and specifically the push to move away from toxic storable propellants like we use today with hydrazine and its derivatives to greener alternatives that we might use in the future. So we're going to talk about the current state of storable propellants as well as the near future and where we could see things going over the next decade. I do also just want to apologize up front for any technical issues we might have with Skype. The audio seems to be dropping in and out, as is typical with Skype, but we will do our best to make sure that we can hear everything for the podcast. So thank you very much, Logan, for coming on the show. As a little background so that other people know kind of how this started, Logan sent me an email a couple weeks ago about one of the shows and kind of was talking about

things that he was working on that might be interesting topics for the show. And that's when I said, hey, why don't you come on and we'll talk about these things. So this was kind of serendipitous in a way to get us together. So thank you very much for coming on the show. Maybe to start, just tell us a little bit about yourself, maybe a little bit about what you're working on. I know you can't get too in-depth on that. All right. Well, thanks for having me on the show.

I'm really honored to be the first guest and never thought that this would happen, but I really appreciate it. A little bit about myself. I grew up in the Chicagoland area. That's where I'm from. And I am currently studying aeronautical and astronautical engineering at Purdue University in West Lafayette. I interned at Expo Aerospace, which you might

have heard of, in Mojave, California, back in 2014. I graduated with my bachelor's degree from Purdue in 2015, and then went into the master's program in rocket propulsion. And my research is on storable propellants, storable rocket propellants, which is a topic that I'd like to talk with you about today. So I feel like at some other point, XCOR would be an interesting topic to talk about.

I'm sure you've been following along with some of the stuff that's been going on with them recently. We don't have to get too often to that today, just because I don't want to sidetrack from what our topic is. I know that one of the things you brought up was that storable propellants are kind of in an interesting spot right now where there's a lot of change going on, or at least a lot of research going into new and different kinds that we haven't used in the past

that could have some pretty big effects over the next couple of years. But if you want to give us some background on that with how we got here today. So just for everybody that doesn't know, a storable propellant is the contrast to a cryogenic propellant. So your liquid hydrogen and liquid oxygen systems, that would just boil away if you left them unchecked. With a storable propellant, you can just leave it in a tank, on the shelf, whatever you want, and it'll be ready to go when you need it. on the shelf, whatever you want, and it'll be ready to go when you need it. So you can imagine, say, a missile silo that has 20 years of sitting there without being used at all.

But it needs to be ready at a moment's notice. So for the guy designing that system, you know, storability is a really huge concern. So within the category of storable propellants, there's really two subsets. There's the monoprops, which use your, you know, single liquid and decompose them. An example of that would be hydrogen peroxide that was used on the mercury capsule for their attitude control. Now, the hydrogen peroxide that you or I could buy at pharmacy is around 3%. The stuff used in the monoprop and rockets is over 90% concentrated peroxide. Another example that's still in use today is hydrazine, which is a chemical used in the pharmaceutical industry

for making pharmaceuticals and in the polymer production industry. Both of those, when you expose them to a catalyst, they very quickly and energetically decompose. So now you can see the advantage of using these sort of fuels is that they're incredibly simple. You can have just a fuel tank that you don't need to worry about keeping cold. You have a catalyst bed somewhere downstream of your system and you just have a belt that

you can control your entire rocket with. Simple on-off run belt. Now I'm oversimplifying a little bit, I understand. That's essentially it. And then the second category of storable propellants is biprops. So these are like your typical launch vehicles that have a separate fuel and oxidizer. Now I work specifically with hypergolic biprop. These are combinations of fuel and oxidizer that combust on contact with each other without requiring any other

separate source of ignition. All other biprops require some kind of spark or torch, match, whatever to get it started. So the hypergolic or hypergol for short reactions tend to happen incredibly quickly, like on the over milliseconds. So your blinking has your eyes closed for over 100 milliseconds. And your typical time for like a hypergol fuel oxidizer when they contact or when they combust is around three milliseconds. So we could back-to-back 30 hypervolve ignitions and if you blink you'd miss all of them that's pretty amazing yeah so in my work we we use very high speed uh high resolution cameras high speed data acquisition systems that can resolve those events at the time scale you have thousands of hertz thousands of frames a second capture every little detail about what's

happening in something that's over, you know, just like that. It's nothing to do here. So going a little bit into the history of hypergulls, the hypergulls have really been around as long as biprop rockets have. So Robert Goddard, you know, the first guy who launched a liquid-fueled rocket, he worked on hypergulls back in the 40s. The Gemini capsule's RCS was one of the first systems to use the now most commonly used hypergolic propellants. The fuel, and I understand this is a mouthful, is monomethylhydrazine, which I'll call MMH,

and then the oxidizer is nitrogen tetroxide, which I'll call NTO for short. So historically, hypergols were used for their very short response times and high reliability. So the space shuttle, when it was flying, used MMH and NTO in its orbital maneuvering and attitude control systems. You can imagine trying to dock with a space station being just a few meters away, the ability to do several really quick hot-off pulses that could be really precise delta-b and make it so you don't crash full steam into the station. Another example, the Apollo Lunar Module used the reliability of hypergols to ensure that

their ascent engine would start so that they could leave the moon. The astronauts and the NASA scientists both knew they didn't want the remotest possibility of having to fix a broken ignition system while on the inner surface. So they needed something that would go when they needed to go, and Hypergols were their answer. So that kind of brings us to where we're at today, which is the storable propellants. We use monoprops, hydrazine, peroxide to a lesser extent. Hydrazine is the big one, and then the Biproc combo of MMH and MTO.

They're both used extensively today. There's some other hydrazine derivatives that are also being used, but those are the big ones. SpaceX uses MMH and MTO for their Draco thrusters currently on the Dragon capsule. They also use it on their larger Super Dracos

that are on the Dragon too. Anthony, have you seen the SpaceX Catabot test? That is one of my favorite videos over the last couple years, because I love to watch how fast the Dragon 2 is accelerating by the time it's to the top of the frame of the video. I'll put that in the show notes, because if you haven't seen that video, you should definitely go check that out. A thing to note on that video is right at the end, shutdown of the engines. There's a little orange cloud that you can see coming out of the engine. And that's the oxidizer, that's NTO, the themes that it gives off, nitrogen dioxide.

But it's a really impressive video and it really shows the power behind hydrogels. There's a lot of power in those propellants. Orbital ATK also uses MMH-NTO for their Cygnus spacecraft. Long duration satellites use these propellants. For instance, the James Webb Space Telescope will use hydrazine and NTO to maintain its orbit out at L2. to ask how China's Long March rocket, their next-gen rocket, is going to stop using hypergols in the future. And I think that really leaves only the Indian Space Agency as the only one left using hypergols at launch, which was a really popular thing to do back in the day. But there's a reason that most people are bailing it out, and that's because what I haven't mentioned yet is that hydrazine, MMH, and NTO, all three of those

are really, really toxic. So, NTO, for instance, reacts with any moisture that's on your body or in your body to form nitric acid. It's not good for you. Hydrazine, MMH are both carcinogens. OSHA puts their exposure limit

for working with MMH at less than one part per million. So you don't want to be anywhere near that. Anytime that people are working with these propellants, the technicians that are fueling the spacecraft need to be in full personal protective equipment. Basically a hazmat suit with a hose providing the same air to breathe from outside. So the difficulties that this puts on normal operations like transportation of fuel, storage, loading propellants, it's a huge time and money thing.

And let alone, it's a huge environmental concern. If there was a spill, you know, the environmental concern is pretty crazy. But that is exactly where some propulsion engineers and some chemists really see an opportunity so the at uh at kennedy space center down there i was down there uh for the first launch of orion i was part of the nasa nasa social for that launch and they were taking us on the tour um and we actually got to go see the hazardous payload processing facility which is where everything that has to be loaded up with hydrazine

or the related things that you're talking about has to go through just to deal with the handling. Like you were saying, all of the different hazmat suits you got to wear, every precaution you have to take when you're loading it up for launch. So is that, you know, with these new generation of fuels that we're talking about, is this something that is going to go away completely or is just going to be made better yeah uh that's exactly what people are working towards and um so in different industries kind of you know all over the world there's a push to go green you hear that all over the place and storable propellants really aren't any different

so the hope is to find something that's safer to handle than the current propellants in use today that I've been describing, but the tough part is not sacrificing on your engine's performance. Ideally increasing your performance, but that's a tough thing to do. a substance of very high concern. That's what they called it. So this led ESA to fear that the future of hydrazine might be restricted in some way. It's just like how the fears of vans on Russian-built engines has pushed the development of American-made engines. The potential for a European van on hydrazine has pushed the development of alternatives over there.

So they've been looking at a monoprop. It's memorably named LMP-103S, for anyone who wants to look it up. And it would be a replacement for hydrazine, basically a one-to-one replacement, which is really nice. So the initial calculations and testing really show promise. It has a higher ISP than hydrazine. It's also significantly denser than hydrazine. So you're able to put more mass into the same size tank that's a pretty important part too because if we think about uh you know what we've talked

about a lot is the upgrades to falcon 9 over the past couple months have been thanks to densification of the propellant in that uh where they're putting more propellant in the same amount of volume and that was something that took their performance to a ridiculous level above what they were seeing before with the falcon 9 so if that's like a side effect benefit, you know, you listed that as the last benefit of that thing. But you might be burying the lead a little bit on there. Yeah, it's definitely something that in my field, it's something that we can really point to as this is a great propellant in that department. It's density ISP is better than MMH-NTO, it's better than hydrazine. That sort of a thing is something that propellant engineers really look for

in their fuels. And yeah, that note with SpaceX, it's exactly what they're trying. It's the exact same thing. They're able to get a lot more performance out of the same volume of fuel. So back to storable propellants real quick. In the US, I mentioned Europe, in the US the Air Force Research Lab has developed a monoprop also hoping to replace hydrazine in US systems. So keeping with the tradition, they memorably named their fuel AFM315E. So you can see sort of a trend there with community fuels. But this fuel also has performance on par with hydrazine, and it is again much denser, so it leads to a more volumetrically efficient propellant loading, which is something that

is obviously a pretty huge benefit. So NASA plans to fly a demonstration mission of that AFM-315E on a Falcon 9 Heavy in 2017, and they hope to prove that that sort of propellant works as expected in space. So those two fuels, the one from the Air Force and the one from ESA, are both monoprops, and they could very well replace hydrazine in the coming years. I can totally see that happening. Working to find a green alternative to hypergolic Biprops is still ongoing.

The main difficulty in that is, aside from their acute and chronic toxicity, MMH and NTO are really, really good rocket fuels. They're hyper-forming, a lot of energy there, quite high density, so they're tough to beat. Finding an alternate combination that matches on performance is difficult to start with. But add on top of that, that the majority of things that you or I would consider safe, safe enough to call a green alternative to these fuels, we consider it safe exactly because they don't spontaneously combust with other things. Right. We're trying to find a safe explosion.

Exactly. It's really challenging to match those ignition delays of three milliseconds and something that's really, really reactive in the combustion chamber, but then is essentially benign outside of the combustion chamber. That's a pretty tall order for anybody working on that problem. And that's exactly what I work on. So the lab that I work at here at Purdue is working on that problem. And that's exactly what I work on. So the lab that I work at here at Purdue is working on that problem. There's numerous other researchers around the world who are also looking at that problem. But with the entirety of chemistry available,

it takes some well-educated guesses, a lot of trial and error, and a little bit of luck to find a hypergall that has a real chance of getting flown in space. That's really the goal of anyone working on these sort of cloud projects, and it's what keeps us going every day. Just talking about the potential uses for these different propellants in the future, we talked about China's phasing

out their old generation of rockets. Their new generation is going to have I think it was Kerolox the last time I looked. And a lot of the newer upper stages that people are working on, ULA is working on their new ACES upper stage, which is going to have some better cryogenic storage. It's going to be using, it's kind of a crazy system where it uses this kind of smaller motor to keep things cool enough to be stored for longer periods of time. We have things like SpaceX working on their Raptor upper stage, which is going to be methane driven. There's a lot of

work into these more energetic upper stages. And I'm just wondering what, you know, in particular, the uses of these other hypergolic propellants that we're talking about, where are they going to fit in over the next five to 10 years? Yeah, I find that at ACE's upper stage from ULA, their idea is that it'll fly on the Bolton booster and that it would use the boil-off gases of hydrogen and oxygen to generate vehicle power, which would eliminate their batteries, their onboarding batteries. And then also in their reaction to coal thrusters, so they'd completely eliminate hydrazine from their equation using only hydrogen and oxygen, just their normal propellants. They claim that their system will be able to support up to one week-long duration emissions, which is quite impressive for a cryogenic system. So I can see that if successful, the ACES stage and the Raptor upper stage will take a little bit of a bite out of the market share of storable propellants. But for satellites that are in orbit for several years, I still think storable propellants are the way to go.

So on that front, I know that some of the recent satellites that have been going up, specifically a Boeing satellite bus that they've been selling recently, has been using solar electric propulsion. And I know that's still very early days. There's been just a hand few of satellites that have went up with that. A lot of them are still using the propellants we're talking about today. But is there any thought on whether solar electric propulsion will actually take away a lot of the usage of these propellants? Or is it something that's like the benefits that we're talking about, where

you're going to be able to fit more of this in the same amount of volume? Are those benefits going to outweigh any other benefits that people would be looking at in other areas? I see the reason that we've been talking today is because we see the future of both of us as being really fluid right now that it could go in a bunch of different directions and it's on the verge of some significant changes so the push to go green in monoprops and biprops is very strong and there is some real progress being made and it would be nice if you have a design for a spacecraft that uses hydrazine and if instead

of loading it with hydrazine, you load it with AFM315E and it's ready to go. No need to redesign your spacecraft in any way. It's just a one-to-one switch out. I think that's something that there's a lot of progress being made and that people are really looking towards and hopefully will have flying soon. Like I said, I could see the ESA I could see the ESA propellant being used as a hydrazine substitute very soon. But with the technological advances being made, you know, all the time in aerospace, like ULA's ACES system and the advances in electric propulsion and solar propulsion, there's a lot of opportunities for designers

to look at alternates to the current status quo and i think it is an exciting time to be a space designer and a propulsion designer because you do have all these options one thing i'm wondering i was kind of thinking about this all day getting ready to talk to you and uh you know we're in this kind of small sat movement right now where you're able to build satellites at a very small scale that are pretty powerful just because we've been miniaturizing things for so long. And, you know, that led to a lot of things like different academic programs using CubeSats and other things like that to do research kind of as ride-along payloads on these different launches and things like that. But, you know, none of them are going to go through hazardous payload processing when they're these kind of almost throwaway satellites.

I'm wondering if a fuel is developed that's safe enough, and that's maybe not some of the other ones where we're talking about finding a safe explosion, but something that is storable and pretty safe to use, if that would lead to use in the smaller sats where it's, you know, you don't have as much to go through to actually get something into orbit with all of that propellant aboard, if that's something that could be useful in the small sat space, you know, a few years from now, and we start to get small satellites with the capability of maneuvering and orienting themselves and, you know, doing the on-orbit operations like the larger satellites have been doing for so many years. For sure, yeah.

If you go on the internet, if you go on sigmaaldrich.com, they're a chemical supplier, you can buy hypergallic green fuel that you can use in a normal laboratory setting. You don't need for a positive pressure hazmat suit, anything like that. You just have on your lab coat gloves, and they'll sell it to you for a comparable price. It might even be less, I don't know, to MMH and NCO. So you could feasibly, if you're making a CubeSat, you could buy those propellants and load them yourselves in your backyard, and you're ready to go. And that's, I might have undersold how the health benefits and how, you know, we're trying to find something that is that controlled explosion in a rocket chamber

but that we can handle outside of the rocket chamber just fine. And there is a lot of work being done still to get that performance match, but a keepsat isn't necessarily trying to maximize its ISP. It wants something that you can load easily and not have to go through that whole hazmat procedure. And that is something that has been done, and that is an option today. You could easily get those sort of tools and load them today. I find it interesting that when you were talking about the history of all of these different propellants and how we got here, you skipped from 1972 straight to today. And I feel like that's a

common theme right now in the industry where it was kind of just status quo for two decades almost, maybe even three decades in some cases. And there's all of this new upheaval happening. And I think mostly everyone that is talking about that is talking about SpaceX, Blue Origin, people doing things differently, you know, in visible ways where it's these giant launch vehicles that are going up and coming back down and landing. But really, this is a trend that's across every part of the industry. You talk about launch vehicles, you talk about propellants like this, even the miniaturization like we were talking about with smallsats. There's so many different cases where things have been static for decades and now have seen a lot of change. So is there kind of a similar feeling in terms

of hypergolic propellants, storable propellants that we see with all of the upheaval that SpaceX brought to the launch market? There definitely is a push as of late to have green hyperdellic propellants, green historical propellants in space soon. We have a good timetable for that. But the look into alternate propellants, MMH and NTO, like I said, were used first on the Gemini spacecraft, which was back in the 60s. And since then, they have been the propellants of use. And there have been people since then looking into new propellants to change those and haven't come up with a good enough propellant combination to replace those systems.

So I don't want to make it seem like we started working on this a couple of years ago as SpaceX started getting going and as Blue Origin started getting going. It's been a long process of people looking at a bunch of different options, the entire library of chemistry, you know, maybe this chemical will work. We test it. No, that wasn't good enough. Maybe this chemical will work. And you can see how long that would take going through every chemical.

chemical will work and you can see how long that would take going through every chemical yeah and this is definitely stuff that you can't do you know you can't really do in environment tests until you've got all the way out to your operating environment so it's not something that is as easily testable as you know like we've seen with blue origins test flights where they can fly these things pretty frequently uh this is something that has a longer life cycle so it's makes sense why these things have taken longer to get going yeah and. And it's exactly the problem. You don't want to find out that your storable propellant only lasts a year. You have loaded it into your spacecraft. That needs to last for five years or whatever. So you need to do that minimum of five years of testing. And that means that your testing program is a minimum of five years long plus

all the rest of it so it is definitely a very difficult problem to tackle there's a lot of smart people working on it and i at least have some hope for the future that we'll find something are there any other uh just general i know we probably only have a few minutes left but is there any other particular project or program in general in spaceflight that's that's of interest to you or any other topics that kind of, you know, you always find yourself reading about or interested in? I know we talked about ACES a bit as something that is just like a very new way of thinking about it or new way of using, you know, excess, boil off kind of, you know, in a way that is helpful for the mission at large. Is that something that in general you like that kind of, you know, using what is there already to help out your mission?

Sure. The thing that I found interesting about ACEs and with their new upper stage, with ULA's new upper stage in general, and this goes back to my XCOR point that I know you wanted to get back to. So XCOR uses piston engines instead of turbo pumps to pump the propellants into their combustion engine. And the ACES engine, or the ACES upper stage, is going to use a piston engine made by Rouse, which is a grossing company. And that's what's going to power everything. So I think that as well as a kind of paradigm changer thinking differently than everybody else. Everybody else

is using turbo pumps. Why aren't we using piston pumps? There is a reason but if you can work around that reason then there's a lot of things that you can do with that sort of system and I like that style of thinking. SpaceX is definitely doing it. ULA is doing it to a certain

extent. Blue Origin is definitely doing it and it's an exciting it to a certain extent. Blue Origin is definitely doing it. And it's an exciting time to be in the industry and see, you know, all of these different directions that we can go and kind of have the horizon in front of you and you can just go in any direction. That's a good point about ULA using, you know, something different than everyone else is doing. Because I know I haven't been like too kind to them in the past about the way they're going about their problems in general, but there are these hints of, of ways that they're

thinking outside the box entirely, uh, and kind of doing their own thing. And that's one that to me has a lot more promise than, than some of the other things that they're working on right now. So that's really cool to hear about. All right. Well, we probably are just about out of time, but thank you again for coming on. And we will probably talk in the future, maybe, you know, as the NASA mission gets closer to launching. We can have you back to talk about that. Yeah, it sounds like a good time. Thank you. And with that, that's all I have for the show today. I hope you enjoyed the interview

with Logan. If you have any feedback about what we talked about today or any ideas for future topics or interviewees, please email me, anthony at mainenginecutoff.com. I'd love to hear from you. I will put some show notes together with links of things that we talked about in the course of the interview. You can find those at any time at mainenginecutoff.com. And again, I do apologize if we did have any audio issues today in the podcast, and I will be working on improving the interview setup as we do more of these in the future. So thank you very much for listening, and I will talk to you next week.