NTB: Could the water recovery technology your group is developing, which involves converting urine and other types of wastewater into clean, potable drinking water, someday be applied to places here on Earth where clean drinking water is in short supply?
Ewert: Well, the applications and conditions are very different in space and in remote areas on Earth, but the principles are the same, so yes, there are many parts of the work that we do that could help out on Earth as well. In fact, several members of our team have been involved with efforts outside of NASA, such as Engineers Without Borders.
NTB: Do you envision any other potential commercial applications for the technology your group is developing?
Ewert: I’m sure there are many. One that comes to mind is what we call a lightweight contingency water treatment system that can take seawater, or even urine, and make it into potable water.
NTB: What impact do you think President Obama’s proposed cancellation of the Constellation program will have on the Exploration Life Support Project?
Ewert: Well, I don’t want to speculate too much on that, but there’s still a big emphasis on research and development within NASA, and specifically in closed-loop life support, so we believe we’ll have lots of good work to do, and that we’re already doing. No matter how we explore space in the future, if we do it with humans their basic life support needs will be the same, so we have that knowledge and we plan to be ready to support those kinds of missions.
NTB: Before becoming the Exploration Life Support Group’s Deputy Project Manager in 2007, you led their Systems Modeling and Analysis Group for a number of years. Tell us about that position and some of the tools you used to model proposed life support system designs.
Ewert: That was an interesting experience. We generally tried to help guide the technology projects by doing systems analysis and searching for the best technologies to develop. We developed one spreadsheet tool called the Advanced Life Support Sizing Analysis Tool, or ALSSAT, which allowed us to rapidly evaluate many different technology options for different proposed mission scenarios. It actually does mass balances and calculates mass, power, and volume of the life support system hardware based on mission requirements.
We also used industry standard software to perform more detailed dynamic analysis. Another thing we developed was a document called the Baseline Values and Assumptions Document that has been widely used by researchers both inside and outside of NASA. It kind of helps fill in the blanks for some of the conditions and requirements that future technologies will see so that the technology developers know those parameters before the actual programs have developed their detailed requirements.
NTB: About 10 years ago you invented a solar-powered vapor compression refrigerator system that operates without batteries or external power. Tell us about that invention and how it works.
Ewert: Well, I was working on thermal technology development at the time, and we actually integrated 3 types of cooling system with solar photovoltaic panels. They were a thermoelectric cooler, a Stirling cooler, and a vapor compression cooler. The vapor compression unit turned out to have the best commercialization potential since that cooling technology is already widely used on Earth. The novel thing that a colleague named David Bergeron and I did was to integrate the vapor compression cooling system with the solar panels and an ice thermal storage system using a new algorithm programmed into a microcontroller that allowed the compressor to run at variable speeds, depending on the amount of sunshine available, and to store the cold, if you will, as an ice block for periods of time when the sun is not shining.
NTB: You’re also involved with a company that has licensed the technology from NASA and is commercializing it, correct? How’s that going?
Ewert: NASA has spoken with several companies interested in the technology and one license agreement has already been signed. That company is working first on a battery-free vaccine solar refrigerator. There are other applications as well, for self-sufficient refrigerated shipping containers, for example, or maybe vending machines that are off-grid, or ice makers, that could come out of this, so I think the commercialization is going well.
NTB: What would you say have been some of the biggest technical challenges to achieving more widespread commercialization and use of solar energy?
Ewert: Well, cost and the intermittency of the solar resource are always challenges with solar energy, so I believe that smart integration of the technology is the key. For example, if you can make use of the existing insulated cabinet of a refrigerator and just improve that, as we did with the solar refrigerator, and run an existing compressor in a way that maximizes the capture of solar energy, and look at the system as a whole, then I think you have the best chance of a successful product.
Another place I see this happening is with building-integrated solar energy systems. I think a renewable energy future is coming, and I think NASA is kind of helping make that possible.
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