Terry Hill, Engineering Project Manager, Constellation Spacesuit System, Johnson Space Center, Houston, TX
- Monday, 01 November 2010
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.