While pursuing a master’s degree in aerospace guidance, navigation, and control theory at UT Austin, Terry Hill got an opportunity to work at NASA JSC as a primary investigator on a project his educational advisor was conducting. This led to him being accepted into the Aeroscience and Flight Mechanics division as a graduate co-op in 1998, and an offer of full-time employment in 1999. Since then, Hill has worked on a variety of projects including the Orbital Space Plane, the STS-114 Return to Flight mission, the navigation software for space station assembly missions, and the X-38 Crew Return Vehicle. He is currently developing NASA’s next-generation spacesuit as the Engineering Project Manager for the Constellation Spacesuit System.

NASA Tech Briefs: How did you come to pursue a career with NASA?

Terry Hill: I originally was in college and part of the graduate co-op program. My professor had gotten me in the door at NASA through a contract he had at the Johnson Space Center. Through the process of working here under contract, the powers-that-be liked the work that I did and encouraged me to get into the graduate co-op program. Upon completion of my graduate co-op program they had me converted to a full-time employee. That’s how I got in. It was not part of the grand, master scheme of things in my life; it was a very pleasant surprise.

NTB:What year was that?

Hill: I became full-time in the spring of 1999.

NTB: You have a master’s degree in aerospace guidance, navigation, and control theory, and in your 12-year career with NASA you’ve worked on a variety of projects including the orbital space plane, developing and testing tools for the STS-114 Return to Flight mission, navigation systems for the space station assembly missions and X-38 Crew Return Vehicle (CRV), and avionics hardware for the space station and CRV. How did you go from that background to designing spacesuits?

Hill: That’s a very good question. Actually, my career was a very torturous path mostly driven by programatics – as one program wound down, I would be transferred to a new program. A series of events after the tile repair activity for the return to flight missions concluded, that was when the ESAS (Exploration Systems Architecture Study), which was the precursor to the Constellation program, was going on. The branch that I was working in developed EVA tools and spacesuits, and at that point in time they had a need to start supporting their next-generation spacesuit development project. So, given my skills with project management and experience with hardware development over a ten-year period, management decided to place me on this spacesuit task.

Actually, given my aerospace background, you get a broad education on all of the different engineering disciplines, which is ideal for spacesuit development because, you know, a spacesuit is a vehicle. If you get a leak, you’ve got propulsion [laughs]. But given that background of all different systems, they thought it would be a good match, and it was.

NTB: I imagine you’d have to be knowledgeable about a broad range of disciplines – fabrics and materials, pressurization, thermodynamics…

Hill:That’s correct, yes

NTB:How different are the spacesuits worn by today’s astronauts from those worn by Neil Armstrong and Buzz Aldrin when they walked on the moon 41 years ago ?

Hill: Well, as you know, there’s a guiding design principle that form follows function, so in a lot of respects they’re the same. But in some respects they’re a lot different. For example, the lunar suits that were used by the Apollo crew all had pressure, they all had radios, they all had life-support systems, they all met thermal requirements. Now, some of the key differences are the type of material that was used for thermal management, and also some of the mobility elements. For example, the Apollo suits didn’t have a lot of bearings and joints, per se, so that’s why you saw them kind of loping across the lunar surface. They found that much easier than trying to force the suit in 1/6-gravity to try to conform to their natural walking motion.

Today’s suits, where we are allowed to deal with weight constraints or mass constraints, we add in a mobility element, which allows a much more natural movement for their bodies. Of course, for the next-generation suits we’re looking at advanced materials for fire protection and protection on launch, thermal management on Abort to Earth-type environments, and also next-generation thermal management for, like, Mars.

NTB: Will these spacesuits be very different from the ones currently being worn by astronauts in, say, the space shuttle program?

Hill: Again, a lot of the form follows function. For the spacesuit architecture we developed for Constellation, it’s a modular system. What that means is, historically we’ve had a different suit for every design environment – for example launch, entry, and abort. We’ve got the orange spacesuit you have now, the launch suit. For microgravity operations you’ve got the EMU (Extravehicular Mobility Unit) suit, which is fantastic for doing microgravity operations outside of the space shuttle, or constructing space station, or catching satellites, or what have you. And then you’ve got the Apollo suits, which are better for extraterrestrial activities.

Now, for the Constellation spacesuit, the challenge for us is to merge all of those different design environments into a single suit system. So what we came up with was an architecture that is modular, which would allow you during the course of any particular mission to reconfigure the suit to match the environment in which you’ll be operating.

NTB: What are the most important things you need to consider when designing a spacesuit for long-term deployment in space?

Hill: That’s a good question because a lot of it is lifecycle cost, which is driven by the design and how you maintain the suit, and the logistics of the flow of hardware, and all kinds of stuff. But more on mission profile, long-term deployment. What you’ve really got to look at is reliability and how human needs require that spacesuit. What are the impacts on the crews and their daily lives while on a mission?

Of course, the environment we’ll be operating in is a key factor in that as well. You have to think about what location you’re going to because dust on the moon, or dust on an asteroid, is vastly different than what you see on Earth or Mars, so you have to take that into consideration. If you’re going to multiple destinations with a single architecture, then, of course, you have to identify the worst possible scenario and incorporate many of those requirements very early on.

NTB: How do you test the ideas you’re working on to make sure they’ll perform satisfactorily in space.

Hill: Another good question. That’s a very key thing in what we do here at Johnson Space Center. We have analogs that go on here, outside on our back-lot, where we have “rock piles” – actually medium fidelity analogs – that simulate a lunar environment and the Mars environment. Also, we have our yearly trek out to Meteor Crater in Arizona where we do long duration EVA excursion analogs, where the terrain is very similar. You’ve got the crater terrain, you’ve got the rocks and you’ve got the ejecta and lack of vegetation, and an arid environment so we can test the thermal systems. So a lot of that is very similar to what you might expect to find on the moon or Mars. It’s even more applicable to Mars. So we do that type of testing in an analog environment.

Also, we have the zero-g aircraft – or the microgravity aircraft – that we take and test our designs in. That will allow you to get about 20-30 seconds in reduced gravity, so we can design our experimental test suits in incremental formats such that we can see how they might perform in microgravity or reduced gravity, depending on how fast the aircraft falls. The rate of descent will dictate the type of gravity situation you’re trying to simulate.

In addition to that we can just do air laboratory pressurized testing to test the pressurized performance of the suit, and also at Johnson Space Center we’ve got several vacuum chambers where we can test the vacuum response or a combination of thermal and vacuum environments that we might see at a destination.

NTB: Have there been any major breakthroughs in spacesuit technology recently, or has it been more of a gradual evolutionary process over time?

Hill: It’s been a gradual, evolutionary process that’s mostly driven by the budget and funding available. There has not been a tremendous focus placed on spacesuit development, so it’s been an evolutionary process over the years to basically meet the needs of the current program.

NTB: Aside from keeping our astronauts alive, of course, what are some of the most important performance characteristics the spacesuit of the future will incorporate?

Hill: It can be. Yes, it can be, particularly in the area of a microgravity environment where you’re not really holding on to anything, so if you have to struggle too much, it becomes a bit of a chore.

But more than that, we are expecting to go out into space for longer and longer missions, so we have to really address the design requirements as such, to minimize the maintenance requirements and also increase our reliability, and more importantly make it such that you’re not fighting the suit the entire time you’re wearing it, because that really does tax the astronauts if they have to wear a suit for 8 hours and the suit is fighting them the whole time due to the pressure and the torques involved.

NTB: What impact, if any, will the proposed cancellation of the Constellation program have on spacesuit development at NASA?

Hill: Well, that’s a difficult question to answer. In an ideal world, assuming the funding is similar to what we have now, the effect would be minimal because the very nature of our architecture, to be able to handle all different mission requirements within a single suit architecture for a single mission – the modular aspect of it – the fact that we design our architecture to be modular and be reconfigurable in a multi-destination mission, positions us ideally for this flexible path.

When you think about it, the environment around an asteroid is very similar to that of the moon. You’ve got very sharp dust, very low gravity, no atmosphere, and the thermal extremes are very, very similar. So in that aspect, it’s the same. You still have to launch and land, so that aspect is the same. And we were designing our architecture to go to Mars eventually anyway, so that aspect is the same. So, as the old saying goes, “The more things change, the more they stay the same.” That’s how we think we’re positioned.

NTB: Do you envision any of the technology you’re developing for spacesuits having other potential commercial applications?

Hill: You know, that’s a good question in as much as a lot of that you can’t predict, because you don’t go into it with commercial aspects in mind. Now, having said that, currently we’re using a lot of the commercial aspects in our designs. For example, the fire protection cloth in garments, we’ve been using Nomex for years and years, but now there are companies out there designing fireproof fabrics for firefighters that are t-shirt-weight material. We’re looking at incorporating that type of stuff.

With regard to our tech development – our technology development program, where we’re looking at developing thermal aerogels and flexible aerogels, then you expect them to be used in any number of applications here on Earth. Because if you can make aerogels that are highly efficient and flexible, such that they don’t break apart when placed in tension, or even compression, then you’ve got all kinds of aspects for any type of environment here on Earth where you need to have thermal management. That’s just one example.

We’re also looking at lunar applications of heads-up displays that you can use inside the helmet. That could be used by the military, or even by the everyday Joe, depending on what our everyday lives with electronics is going to be 10, 15, 20 years down the road.

For more information, contact Terry Hill at This email address is being protected from spambots. You need JavaScript enabled to view it..

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