Deep Space Design: The Search for Future Space Construction Materials

17:14 minutes

The NASA budget passed for this year is $1.3 million higher than the previous year, and includes $55 million to develop a deep space habitation module. Ars Technica space editor Eric Berger fills us in on the other areas covered in the space ledger.

Plus, what tools and materials might be used in constructing future space habitats? Journalist Bruce Lieberman discusses inflatable spacecrafts and engineer Gianluca Cusatis describes how to mix up a batch of Martian concrete.

A block of Martian concrete made out of Martian soil simulant created by engineers at Northwestern University. Image courtesy of Northwestern University
A block of Martian concrete made out of Martian soil simulant created by engineers at Northwestern University. Image courtesy of Northwestern University

Segment Guests

Eric Berger

Eric Berger is Senior Space Editor at Ars Technica. He’s based in Houston, Texas.

Gianluca Cusatis

Gianluca Cusatis is an Associate Professor of Civil and Environmental Engineering at Northwestern University in 
Evanston, Illinois.

Bruce Lieberman

Bruce Lieberman is a freelance science writer based in San Diego, California.

Segment Transcript

MANOUSH ZOMORODI: This is Science Friday. I’m Manoush Zomorodi, sitting in for Ira Flatow. Last month, right before the holidays, NASA received an end of the year gift from its secret Santa, a bigger budget. Congress approved the space agency’s funding. A $1.3 billion increase from last year and nearly 800 million more than the White House had requested. So what’s covered in the budget and how does this funding outline the goals of NASA?

My next guest is here to take us through the accounting. Eric Berger is the senior space editor for Ars Technica. He’s based out of Houston, Texas. Hi, Eric.

ERIC BERGER: Hey, good afternoon Manoush.

MANOUSH ZOMORODI: Hey there. So why was there an increase in the budget this year? That seems like very counter intuitive.

ERIC BERGER: Well you may recall that at the end of 2015 Congress, both Republicans and Democrats, kind of came together with a deal. And as part of that they came up with some more money for the overall budget. And NASA has a lot of friends in both the House and the Senate. And so, both chambers kind of have their favorite parts of the space agency’s budget so when it came time to allocate money NASA did pretty well.

MANOUSH ZOMORODI: So can you just break it down for us? What areas within NASA actually got a boost?

ERIC BERGER: So the biggest winner in terms of the overall budget from what the President proposed was the space launch system. This is the large rocket that NASA is building and it says it’s part of its journey to Mars. That got a nearly 50% increase in its budget, more than $600 million than the President sought.

MANOUSH ZOMORODI: And were there any areas that were overlooked, that didn’t receive as much funding?

ERIC BERGER: No. Pretty much every area got what it wanted. There had been a lot of controversy earlier in the year because the House and Senate budget responses basically to the President had provided less money in two key areas. One was commercial crew. This was the effort to replace the space shuttle and the American reliance on Russia for transportation. And so Bowing and SpaceX are building these vehicles.

Both houses of Congress had basically provided $300 million less than the administration sought. Then the other issue was Earth science funding. There’s some skeptics, or deniers, in Congress who, you know, do not believe that humans are causing climate change. And they had actually underfunded the Earth science budget by nearly half a billion dollars.

MANOUSH ZOMORODI: Can we go back to the Russia point that you made? So basically, up until now, we’ve been using the Russians to get into space, is that right? Or for the last–

ERIC BERGER: Since 2011.

MANOUSH ZOMORODI: Since 2011. OK. So this was an attempt to sort of take back power, if you will, to get us into space.

ERIC BERGER: Yeah, it’s an effort to do a couple things. First of all, it is an effort to launch humans from America’s soil again. And NASA had been saying it was on track to do that by the end of 2017. It said if it did not get full funding for commercial crew this time that that date was going to slip into 2018 or beyond. So basically it was putting Republicans in the House and the Senate in the position of if they didn’t fund it they were going to look like they were willing to spend money on the Russian defense program.

MANOUSH ZOMORODI: OK. So it all comes back to politics. I mean the other thing that you mention in your article, which I found fascinating, which was that the budget includes few very specific deadlines. And one is to have a Lander on Europa, which is Jupiter’s moon, by 2022. I mean that sounds pretty ambitious. And I understand it’s because of a particular Republican.

ERIC BERGER: Yes. So each– the Senate kind of has their favorite things and they like the big rocket, the space launch system in the house. There’s the chairman of the appropriations subcommittee, he’s a guy from Houston named John Culberson and he’s really interested in the moon, Europa. Now Europa is this fascinating place. It’s covered in ice, it’s bathed in radiations from Jupiter’s surface, it creaks, it kind of goes up and down, it feels this massive gravitational pull from Jupiter.

But beneath the surface is an ocean. You know, there’s more water on Europa than there is on Earth. And there’s a heat source because you have this title flexing of the core of Europa. And so if you’re going to look for life that’s living now in the sources today that’s probably the best place to look.

MANOUSH ZOMORODI: I mean that sounds fascinating. But in your article about the mission you say that NASA’s administrator, Charles Bolden, only grudgingly accepted this mission. Why would that be?

ERIC BERGER: Well, there’s a couple reasons. First of all, he and Culberson really don’t see eye to eye that well. He was, Bolden was, appointed by a Democratic President. And they have different priorities. He also didn’t want to take on another big ambitious mission. This is probably a one to $2 billion mission and so he wasn’t sure that he was going to get funding through 2022 or 2023 launch date.

MANOUSH ZOMORODI: So and is he like, OK, fine we’ll go to Europa now?

ERIC BERGER: I think so. I talked to Culberson after the budget deal and apparently they sort of came to an agreement that, OK, we’re going to do the Europa mission. So now we’ll see in next year’s budget whether NASA and the President really ask for as much money as it needs, which would be a couple hundred million dollars.

MANOUSH ZOMORODI: You had also written about investment in the space launch system. Lot of money that NASA’s putting into that. Can you tell us more about that?

ERIC BERGER: Yes. This is the big rocket, a heavy lift rocket. And NASA initially was told to have it ready by the end of 2016. The launch date has now slipped probably until 2018. And we’re probably seeing also slippages in terms of putting people on it, in the Orion spacecraft. And so Congress is stepping up saying, here’s more money, you know, please try to stick to these launch days. But then you have other people in the space community saying, this rocket program is so big and so expensive that the delays are inevitable regardless of how much money you put into it.

MANOUSH ZOMORODI: Fascinating stuff. All right. Eric Berger is the senior space editor for Ars Technica. Thank you so much, Eric.

ERIC BERGER: My pleasure.

MANOUSH ZOMORODI: So in the NASA budget, $55 million was put aside to build a deep space human habitation prototype. This is a ship that a crew could live and work out of, maybe on the way to Mars. The destination isn’t set yet but the deadline for the prototype is 2018. NASA has just two years to figure out a model for this shuttle.

And the agency has been quiet about any blueprints but researchers are already thinking big. What might a deep space habitat look like? And how could you build a habitat right on the surface of Mars? My next guests are here to talk about this deep space design and the future of space construction.

Gianluca Cusatis is an associate professor of civil and environmental engineering at Northwestern University and Bruce Lieberman is a freelance science writer based out of San Diego. So Bruce you’ve talked to engineers who are building these types of shuttles and they say that there’s a great future in inflatables. Inflatable spacecrafts. I mean, is that kind of like a bouncy castle that one might have had a kid’s birthday party? Because I got to say that’s what I’m picturing.

BRUCE LIEBERMAN: You know, I was thinking about how to describe these. And these are not party balloons. They’re– when you think you of these you might think of astronauts bouncing around in these giant party balloons. But that’s not what it is. It’s a rigidized inflatable habitat that has numerous layers of protection and thermal blanket covering. And this is something that could be conceivably attached to a propulsion system that would give astronauts a lot of living space on their way to a destination, whether it’s an asteroid, or Mars, or the moon.

MANOUSH ZOMORODI: And what are the advantages then to like an inflatable? What’s wrong with metal? What’s the plus side?

BRUCE LIEBERMAN: Well, Bigelow Aerospace is the company in North Las Vegas that is working on this technology. And the way they market this technology is that it has a few really great features. It’s cheap, it’s relatively cheap compared to other modules. It’s light weight, it’s compact, and it has some advantages to aluminum pressure vessels as far as radiation protection.

When high energy particles from the sun or cosmic rays hit a metal pressure vessel it creates what’s called secondary radiation. Which creates this shower of subatomic particles that can enter astronauts bodies and create damage. So a fabric or inflatable habitat would not create as much of this secondary radiation. And so there would be less of that.

MANOUSH ZOMORODI: Is it kind of like Kevlar or something? The fabric.

BRUCE LIEBERMAN: So the actual construction of the habitats is proprietary. So NASA and Bigelow wouldn’t say exactly what it’s made of. But it is supposed to be a Kevlar like fabric that would help protect astronauts from orbital debris that’s orbiting the earth and then also micro meteoroids. But that would not have anything to do with the radiation protection.

MANOUSH ZOMORODI: OK. I want to just know, how big an inflatable can you actually make? Because the crew would need to be in these things for quite some time right? Like I assume that comfort factors in somehow.

BRUCE LIEBERMAN: That’s right. So right now Bigelow is anticipating the launch of a test habitat that would be docked to the International Space Station for two years. And that launch was supposed to happen around early September. But because the SpaceX Falcon 9 rocket exploded shortly after launch in June, the launch of this test module was postponed until sometime this year. That’s called the Bigelow expandable activity module, or BEAM. B-E-A-M.

And this is fairly small. But the operational habitat, which would advance if BEAM is successful, would be 330 cubic meters. And if you consider that, that alone is about one third of the room that the entire space station now gives astronauts.

MANOUSH ZOMORODI: So massive then.

BRUCE LIEBERMAN: Yes. Yes, it would give astronauts a lot of space for in orbit operations or if they’re heading somewhere. Like I said, like the Mars, or moon, or something.

MANOUSH ZOMORODI: So Gianluca, I want to ask you, you came up with a recipe for actually making concrete in Mars, on Mars. How did you get interested in this idea?

GIANLUCA CUSATIS: So the idea came from previous research in NASA where they were exploring settlement on the moon. And because, you know, you don’t think about shipping cement, and water, and gravel, which are the main component of concrete here on Earth. They explored using sulfur to bind and to glue together the lunar soil.

And so a few years back, based on this early work, we started to look at what this idea would be if extending to be used on Mars. And so I had a student of mine went buying some martian soil. Believe it or not, you can buy.


GIANLUCA CUSATIS: It’s similar. You know, it’s similar. It’s not really a martian soil.


GIANLUCA CUSATIS: And then sulfur. And the technology is very simple. You melt the sulfur, it becomes liquid, and then you mix with the martian soil, and then it hardens and it is a solid possible construction material.

MANOUSH ZOMORODI: So just tell us a little more. What is the optimum mix then that you found?

GIANLUCA CUSATIS: So that was a surprise that in our discovery. While regular sulfur concrete, typically you have about 20% of sulfur in the mix. We found with specific mineralogy of the martian soil, you need a 50-50 proportion with the martian soil and sulfur to get optimal performances. But the surprise was also that with those proportions the performance of the material was higher, or relatively higher than the usual concrete that we use here on Earth.

MANOUSH ZOMORODI: You mean it was stronger than?

GIANLUCA CUSATIS: It was stronger. About twice as strong. And which is interesting because if you adjust that also for the gravity because, you know Mars is about one third of what we have here on Earth, we calculated that you have a strength that is compatible to the one that we use here on Earth to build skyscrapers. So that was very interesting. I think.

MANOUSH ZOMORODI: I mean it sounds kind of like you came upon the perfect thing. What are there any drawbacks about using and producing this concrete on Mars?

GIANLUCA CUSATIS: Well yes, there are drawbacks. So the one that is also plus is the fact that, you know, being still sulfur based it melts back to liquid if you heat it up. So in a case of fire or high temperature definitely that is not something that you want to have in your house.


GIANLUCA CUSATIS: And that is the reason why we don’t use sulfur concrete here for structure application on Earth. However for especially the first settlement on Mars, I think the first thing is going to have to be to have shelters, right. And people are thinking even about the ice as a possibility for shelters on Mars. So I think this fire resistance, which of course you need to have in, you know, a building, might not be the first priority when humans will go to Mars. So, yes.

MANOUSH ZOMORODI: I’m Manoush Zomorodi and you are listening to Science Friday from PRI, public radio international. So Bruce, let’s go back to you. Are these companies looking into using these habitats on the surface of Mars? Or well, why not the moon? Why Mars or the moon?

BRUCE LIEBERMAN: I think that Bigelow does envision habitats on the surface of the moon or Mars. I think that’s pretty far away as far as becoming a reality. Right now the BEAM needs to be tested. And it really needs to go through a series of tests to prove its viability. So once that happens, then they’ll test this B 330, which is the 330 cubic meter habitat. But eventually, far in the future, there could be something on the surface of Mars or the moon. But that’s, I think, pretty far in the future.

MANOUSH ZOMORODI: So Gianluca, would it protect against radiation? Because as we heard earlier that that’s a problem for people out there.

GIANLUCA CUSATIS: Right. Well, concrete in general is a good shielding for radiation, so definitely. We haven’t done specific research on that, but I imagine that would be a good material for protection from radiation. And certainly is going to be a good material for protecting from debris, and meteorites, and impacts that you might have on the surface of Mars.

MANOUSH ZOMORODI: Have you heard anything from NASA about your concrete mix?

BRUCE LIEBERMAN: No. We haven’t.


GIANLUCA CUSATIS: No. The old research really was unfunded. Was all the motivation of one of my students. So this is a testament of excellence of our students. Who was interested in this work and she– her name is Lin Wan. And she did both the research that she was supposed to do and this research on the side. But we’re waiting. So we hope we can continue this research. There’s still a lot of open questions. As a matter of fact our research answered a few questions, but there are more out there still to be answered.

MANOUSH ZOMORODI: And can you just let our listeners know, you had mentioned that they’re Mars concrete mix simulate available to regular people. Can you tell us just a little more about that for people who are curious?

GIANLUCA CUSATIS: Yes. So that is a product that NASA developed awhile back. I think they do that for also other planets. So they try to mimic the same chemical composition and particle size distribution of these soils, of these materials. And, you know, you go on the internet and you can order and then they ship it to you. It’s expensive. You know, I think a few pounds of that was for $500. Yes, $500. But you can buy.

MANOUSH ZOMORODI: OK, so I’m not going to do it my kid’s next birthday party. That’s going to be the craft that we make then I guess. And so Bruce, when you have heard about this concrete mixture does that make you think that there’s a lot of research and trial and error is going to have to happen before we actually build these things?

BRUCE LIEBERMAN: Oh yeah, absolutely. I mean to do these construction projects on another planet would be a huge, huge undertaking. And we have to get humans to Mars first to see how they do there and how they work in the environment before we can build anything obviously.

MANOUSH ZOMORODI: Gentlemen thank you both so much. Gianluca Cusatis is an associate professor of civil and environmental engineering at Northwestern University. Bruce Lieberman is a freelance science writer based out of San Diego.

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