Dr. Ladner had a chance to talk with Layne Carter from NASA recently. During his 28 years at NASA, Mr. Carter has worked on the development, design, delivery, and operation of the ISS Water Recovery System (WRS), which includes the Water Processor Assembly (WPA) and Urine Processor Assembly (UPA). His current role is the ISS Water Subsystem Manager, for which he is responsible for the ongoing operation of the water management and WRS on ISS. In addition, he is the co-Lead for NASA’s Advanced Exploration Systems (AES) Wastewater Processing and Water Management team, which has the responsibility for developing the technologies to be used for NASA’s future manned missions.
Immediately everybody thought, “Wow, that looks like peanut brittle,” because it had actually … it had formed on the back wall, the hotter surface in the evaporator because calcium sulfate has a retrograde solubility curve. Then, on return, it had broken up and just kind of tumbled down into the bottom of the evaporator, at least in 1G. So we just scooped it out, put it in a glass jar, and set it on a table and titled it, Urine Brittle.
Layne Carter
On this episode, you will learn,
- How urine is recycled so astronauts can drink it. Yes, drink it.
- How the Russians are helping with the Station’s overall water balance, and
- How urine brittle, not to be confused with peanut brittle, was a problem NASA had to overcome.
Transcript
Speaker 1:
The Outfall Podcast exploring the hidden edge of our natural water world and our infrastructure.
Robert:
Hey, this is Robert. Welcome to it another episode of The Outfall. Today we’re heading into space, 254 miles above the earth to be exact. This is where the International Space Station rotates around the earth every 90 minutes. The station is huge, about the size of a football field, but on this episode we’re going to focus in on one critical system. This system enables all the incredible science to happen that sustains life in the station. What is it? It’s called the water recovery system. On this episode, you’ll learn how urine is recycled so astronauts can drink it, yes, drink it, how the Russians are helping with the station’s overall water balance and how urine brittle, not to be confused with peanut brittle, was a problem NASA had to overcome. Amy and I join Dr. [Ladner 00:01:12] in his office at Clemson University to hear, laugh, and discuss his conversation with NASA’s own [inaudible 00:01:24].
Lane:
If it were just pee, that’s one thing, but this is astronaut pee, right?
Amy:
The creme de la creme.
Lane:
Exactly.
Robert:
So you gave us an overview of their urine processing system. Let’s take a listen to some of what he said about that.
Lane:
Well, on the space station, we have two primary waste streams that we deal with and that’s obviously the crew urine and then the crude latent, which is just the water vapor that they perspire and respired into the atmosphere that’s collected by condensing heat exchangers that also serve to maintain the cabin temperature that condenses out that crew latent. So those are our two primary waste streams. We’ve got to do water recovery because it’s just an unacceptable cost to resupply all of the water. We’ve estimated that the cost to resupply a kilogram of mass is on the order of $68,000.
Dr. Ladner:
Wow.
Lane:
You can do the math pretty quick and realize, yeah, you can’t possibly just resupply all of your water. So instead what we do is a water treatment system. So we take the urine, we put it through a rotary distiller to make distillate and we combine that with the condensate of the crew latent and put that through what we call our water processor assembly. That has some adsorbent in it, some ion exchange resin. That takes out the bulk of the dissolved species. What isn’t effectively removed are volatile organics, like methanol and ethanol and such as that, so the [inaudible 00:03:05] are strict requirements for both total organic carbon as well as microbial. We have a catalytic reactor, and that runs at about 267 Fahrenheit. So, we oxidize whatever residual organics are in the process water, as well as sterilize it. What comes out is pristine drinking water.
Dr. Ladner:
One of the first key things that I found really amazing was the discussion about energy, because you do a lot with water and wastewater, right Amy?
Amy:
Mm-hmm (affirmative).
Dr. Ladner:
And energy is a key thing, right?
Amy:
Absolutely.
Dr. Ladner:
Isn’t a lot of the wastewater treatment plant upgrades that we do is to reduce their energy use and things like that?
Lane:
Sure.
Dr. Ladner:
I asked him, “What about energy on the space station?” And he essentially said, “We don’t care about energy.”
Amy:
Different problems in space.
Dr. Ladner:
Right.
Lane:
Power consumption is a little bit of a tricky parameter for us. When we were originally evaluating technologies, power consumption was a bigger issue. We tried to weight it rather heavily. Now I’ve realized since I’ve gotten onto the space station, we have plenty of power, so as long as you don’t use too much, then it’s not an issue at all and we don’t use too much. So that really hasn’t factored into any of our decision making. A better example is our oxygen generation assembly because it does use a lot of power, several thousand watts. So when we originally designed it, we implemented day night cycles because when the space station is actually facing the sun, then the solar rays are obviously … we have more power capacity, and so we thought, “Oh, we’ll run it while we’re facing the sun. When we go to the dark side of the earth, we’ll shut everything down.”
Lane:
What we found out is, “Nope, you don’t have to do that,” because they still had plenty. Whether it was day or night, it didn’t matter, so we just run the OGA all the time and don’t even think twice about it. So, as long as you don’t go beyond the limit, you’ve got all the power you need.
Dr. Ladner:
So they just have big battery banks that are …
Lane:
Yes, yes.
Dr. Ladner:
Okay. [crosstalk 00:05:23].
Lane:
Power has just never been a limiting factor. What really drives technology selection is mass resupply and reliability. It’s really about how much mass do you have to launch off of the planet? That really just drives everything, and so if you have a system that’s not reliable and you have to fly more spares, or the other critical factor actually is crew time. If you have something that the crews got to work on a lot, then we don’t like it because we don’t want the crew doing maintenance. Crew needs to be doing science. That’s what pays the bills. So those are really the critical factors. Power consumption is something we never think about.
Dr. Ladner:
All right. So the next crazy thing was a discussion about Russians. Obviously, on the international space station, it’s international and they have Russians and Americans. It’s interesting, the Russians didn’t have their own urine collection system and urine processing system. So, what do Russians drink on the international space station?
Amy:
Vodka?
Dr. Ladner:
I wouldn’t doubt it, actually.
Amy:
American’s pee.
Dr. Ladner:
Yeah, they drink American pee. Of course, we-
Amy:
We drink their …
Dr. Ladner:
Russian pee too. Yeah.
Lane:
Typically, we would need to resupply. Right now, on average, we’re really not having to do a lot of resupply because the Russians are also on the space station. They have a condensate processor that they use for drinking water, but they don’t have a urine processor. They’re in the process of getting one ready. Hopefully later this year they’ll be successful on that venture, but right now we get all of their urine as well. That makes up our deficit, so we’re pretty much even on our water balance right now because we’re processing all of the Russian urine. It’s community.
Dr. Ladner:
Okay. Has it ever been separate?
Lane:
No.
Dr. Ladner:
Oh, okay, so that’s just a method that I must have picked up along the way somewhere.
Lane:
Yeah. No. Yeah, there’d be no credible way to do that. I don’t think the crew … I don’t think they care if … if you can get comfortable with drinking your own urine, you can get comfortable drinking your neighbor’s urine as well.
Dr. Ladner:
If you’re comfortable drinking your own urine, you’re comfortable drinking other people’s urine. What better call for peace in the world is there than this understanding that the astronauts drink each other’s pee? If the Russian astronauts can drink American pee and vice versa, can’t we all just get along?
Amy:
Forget dreams of holding hands and world peace. Let’s just all sit around a table with each other’s pee.
Dr. Ladner:
There we go.
Lane:
Could you do that? Could you drink each other’s pee?
Dr. Ladner:
Absolutely.
Amy:
Under those circumstances.
Lane:
You could? Come on.
Amy:
If I had an option of a bottled water, I think I would take that one, but with limited resources, yes.
Dr. Ladner:
You would drink.
Amy:
I would.
Dr. Ladner:
Well, the crazy thing is that most people are drinking someone else’s pee.
Amy:
That is a excellent point. We are all drinking someone’s people.
Lane:
We’re all downstream of someone.
Dr. Ladner:
All downstream of someone. I remember living in Illinois, the Illinois river is what received the wastewater from the Stickney plant wastewater treatment plant, which is one of the biggest plants in the world. Where does that wastewater go? Straight down the Illinois River to the Mississippi to St Louis, and then down to New Orleans. They call it defacto wastewater reuse because that’s what we’re doing. We reuse water. I would rather have a really powerful system to purify the water instead of our ad hoc defective systems that we have right now.
Dr. Ladner:
Now, another crazy thing that came out in this discussion is the interplay between oxygen and urine or oxygen and water.
Lane:
Now, it’s the main system.
Dr. Ladner:
Really?
Lane:
Yes.
Dr. Ladner:
So most of the oxygen that the astronauts drink is coming from electrolysis of water.
Lane:
Yes.
Dr. Ladner:
Interesting.
Lane:
Yes. We do have oxygen, pressurized oxygen tanks that we also fly to station. Initially, it was oxygen that was transferred from the shuttle, but since we ended the shuttle program, now we fly up tanks. They’re called Norris Tanks, nitrogen oxygen resupply, that provides pressurized either oxygen or nitrogen. They’ll transfer those over to the oxygen tanks and then that pressurized oxygen supply. We do use that also for the water processor because I use gaseous oxygen as the oxidant in that catalytic oxidation reactor. We use a minuscule amount, but then that’s also used for makeup oxygen periodically, but the overwhelming majority of the oxygen that the crew consumes is from the OGA.
Dr. Ladner:
Okay. That’s amazing. Now, what do you need nitrogen for? Nitrogen is mostly a [crosstalk 00:10:51], right?
Lane:
Primarily to make up the for atmospheric leakage. So even though-
Dr. Ladner:
Oh, really?
Lane:
Yeah, even though the modules are very, very tight, you still have permeation, they’re still non metallics, and so you’re still going to have some limited gas permeability.
Dr. Ladner:
A little bit of oxygen leak … or nitrogen leak, [crosstalk 00:11:09].
Lane:
Atmospheric leak, right. So, that’s what the nitrogen is primarily used for is to periodically repressurize the space station.
Dr. Ladner:
Wow. Very cool. So in other words, in a way, they’re sort of not only drinking their urine, they’re breathing their urine. Talk about world peace.
Amy:
Absolutely.
Dr. Ladner:
Now we’re super excited, not just about the pee, but you know, when you have number one you got to have number two to deal with too. What do they do with the poop? You guys remember what they do with the poop?
Robert:
It was totally different than what I thought.
Dr. Ladner:
Yeah.
Amy:
I thought they would extract the moisture somehow.
Dr. Ladner:
I thought so too.
Amy:
But no. No. Just a poop cannon, flaming poop cannon.
Lane:
We don’t do anything with the feces. That is something that we are looking at for exploration because there is a good bit of water still captured in the feces that we would like to get back. I can’t remember the exact number, but I think it’s almost a liter per day for a crew of four. I’m not certain on those exact numbers, but that’s approximately it. So again, you think about it, that’s a lot of water for an exploration mission. Right now though, the feces is just collected in fecal collection bags and then they go into one of the trash modules and burned up on reentry.
Dr. Ladner:
Oh, they are?
Lane:
Right. So we don’t do anything else with them.
Dr. Ladner:
So not only are the astronauts drinking their urine, but all of us down on earth are receiving the outfall?
Robert:
The outfall, oh, clever.
Dr. Ladner:
Or what’s the nuclear term?
Robert:
Fall out. Fall out.
Dr. Ladner:
That’s what it is.
Robert:
Not outfall, but fall out.
Dr. Ladner:
All right, so he had an awesome story about, not peanut brittle, but another kind of brittle. Let’s see what he had to say about this.
Lane:
After we initially ran the urine processor on the space station, we found out the hard way about the elevated calcium concentration in crew urine and microgravity, again, due to bone loss. I think most people are familiar with this now, that in microgravity, without the resistance that you get here on earth, the bones start to excrete calcium because it just doesn’t need as much calcium as was in there, that is removed from the body in the urine. So if you get more urine in the … if you get more calcium in the urine, when you start distilling out the water, that calcium and sulfate start to precipitate and that’s what happened to us after, just … it wasn’t long, four or five months of operation initially on the space station. I guess this would be back in 1989, so the distiller clogged, we didn’t know exactly why at the time.
Lane:
We brought it back down, popped open the centrifuge or the evaporator and looked inside. Sure enough, there’s this calcium sulfate precipitation. It’s kind of this dirty brown color. This was right around Christmas time and immediately everybody thought, “Wow, that looks like peanut brittle,” because it had actually … it had formed on the back wall, the hotter surface in the evaporator because calcium sulfate has a retrograde solubility curve. Then, on return, it had broken up and just kind of tumbled down into the bottom of the evaporator, at least in 1G. So we just scooped it out, put it in a glass jar, and set it on a table and titled it Urine Brittle.
Dr. Ladner:
Urine Brittle.
Lane:
Yeah, Urine Brittle. As far as I know, nobody ever tried it.
Dr. Ladner:
Think there’s a market?
Amy:
There has to be. He said it looked tasty. Sell it beside the astronaut ice cream.
Robert:
Yeah, forget astronaut ice cream, right?
Dr. Ladner:
But what struck me, they are losing their bone density, but that is actual mass that’s leaving their body. So you have to ask, if you lose mass out of your body, through which orifice does it leave? In this case, they’re losing calcium and it’s leaving with the urine. So they’re literally peeing out their bones as they lose that mass.
Robert:
Yeah, I never thought about that.
Amy:
Wow.
Robert:
Have you, Amy?
Amy:
No.
Robert:
No.
Amy:
No. Interesting.
Dr. Ladner:
I definitely hadn’t thought of that either. Now the other Russian, U.S., sort of interesting debate that was happening, when they combine the two modules, I’ll let Lane tell us about it a little bit, but the Russians had their way of doing things and we had our way of doing things. A key difference was the concentration of carbon dioxide in each of the modules.
Lane:
It’s interesting, the Russians actually do think it should be higher, or at least some of the Russian specialist. So they like for it to be like over three. They think it’s more healthy. This has led to a little bit of dissension on the integrated space station since we have this Russian segment, this U.S. segment that are attached and we do have active inhalation between the two. So we’re trying to drive it down because we understand the health effects of it and the Russians are saying, “Well, that’s really not that critical.” It’s been an issue that we’ve had to address in the last couple of years. Everybody’s in a pretty comfortable state now as far as how we’re going to keep it around two and a half. We’re also, though, developing new and better technologies for CO2 removal because it’s … even though I think it’s the approach that we’re using right now on station, everybody’s comfortable with, they also acknowledge for long duration missions, they think we need to do better.
Dr. Ladner:
World peace again, right? If we could all just agree on what the right CO2 level is, then we’d be a lot better off.
Robert:
CO2 and our water, right?
Dr. Ladner:
It all … the international space station is just this microcosm about getting along with one another.
Amy:
Distills things down to the basics.
Robert:
Oh.
Dr. Ladner:
There you go.
Amy:
What you breathe, what you drink.
Dr. Ladner:
Yeah, it’s all shared. We just have to find a way to agree on how we’re going to share it all.
Dr. Ladner:
Then, I thought it was super cool, Lane’s perspective. He is not thinking about just orbiting earth in the space station. He wants to do bigger and better things. Let’s let him tell us a little bit about that.
Lane:
We have an approach, or I should say a system, on space station right now that definitely longterm is viable. Is it the best approach? I certainly hope not. In fact, I’d be real disappointed if we’ve already figured out what the water treatment approach should be when we leave the solar system, because we’re going to pull that off at some point. It might be a hundred years from now, but I don’t think we’re there yet. So what we’re trying to do, actively, is to identify what is the next upgrade to this water treatment system? So what we have today certainly works. What we need to improve upon, as I was saying before, is mass resupply, and then just overall liability. We can’t be heading outside the solar system until we have a technology and a design that we have absolute confidence in, and how to effectively keep it maintained for long duration, even to get to Mars, we feel we have to do better. That’s what we’re working on right now, honestly, is reducing mass resupply and improving the design to improve reliability. We’re going to keep pursuing that and be opportunistic about new technology upgrades that we think will help us in that regard.
Dr. Ladner:
Anyway, he was a great guy, great conversation. Yeah, it’s fun to listen.
Robert:
So, Did you have to convince him to do the interview? Was he pretty easy to convince?
Dr. Ladner:
Yeah, he was all for it, I think. I don’t know if the rest of the technical sessions at the talk weren’t doing it for him and he wanted to do something else, but especially for a novice interviewer like myself, I think I was really happy that he was gracious enough to do it.
Speaker 1:
Love this episode of The Outfall? Head over to iTunes to subscribe, rate, and leave a review. We appreciate it. You won’t be sorry. Thanks.
Robert:
Have you heard the one about the three holes on the ground?
Amy:
No.
Robert:
Well, well, well. We’re done.
