Broadcast 3681 Greg Meholic

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Guest:  Greg Meholic:  Topics:  Fusion for energy and propulsion, fission propulsion, fusion mission trades, fusion fuels, challenges, market demand, compact power, R&D, NASA and more.

 

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We welcomed Greg Meholic back to the show to discuss The Aerospace Corporation fusion work plus the state of fusion energy and propulsion development.  Our discussion included a look at fission energy for propulsion plus near the end of the program our guest commented on a few exotic propulsion concepts, EmDrive and the Mach Thruster research being done by Dr. Woodward. 

Regarding fusion, Greg assessed the state of development for it along with the different types of fusion fuel being researched. As you will hear, there are several potential fusion fuels with a reactor needing a special design based on the fuel.  Greg drew an important distinction between fusion for propulsion and fusion for energy.  One fuel he spent time talking about more so than others was He3 found mostly on the Moon.  Don't miss all of what he said about this fuel and why it was both a potential high quality fuel but a very challenging fuel to use.  Greg also explained and talked about Q Factor and the difference temperature makes for either energy or propulsion. 

Our first caller was Bill wanting to know about the overall fusion TRL.  Greg had much to say in response to this question.  He talked about the BWXT Nerva Design, a Russian example, then he explained the difference with today's Nerva design as compared to the original one a few decades ago.  A listener sent in a note asking Greg if human spaceflight to Mars would be a driver for fusion.  Don't miss his surprising answer to this question. 

Fremont John called to inquire about the Direct Fusion Drive concept by Princeton Satellite Systems.  This turned into a major and important part of our discussion so be sure to hear all of it.  In addition, I am working to bring people from Princeton on The Space Show so stay tuned for those developments.  As part of this discussion, He 3 came up again as did some of the challenges in using this potential fuel.

Ft. Worth John called regarding some of the preliminary comments made regarding the Woodward Mach Thruster research and EmDrive. More about these possible propulsion formats came later.  John talked about making tritium through the process, a sort of breeder reactor, plus he suggested that there might be a momentum transfer through relativity.  In addressing the Woodward Mach work, Greg said the thought the effect was a vibrational effect from the process Jim was using in his research. This seemed to be a consensus opinion from others familiar with his research. Greg thought it might be interesting to scale it up and see what happens but that has never been done.  At this point, we took a phone call from Jim Dewar, a former and frequent Space Show guest. 

Dr. Dewar wanted to talk about the possibility of using gas cores for fusion.  Greg said Marshall Spaceflight Center was working on a similar concept.  Be sure to hear all of this important discussion with Dr. Dewar and Greg.  Their discussion included talking about high ISP and how to achieve it. In referring back to the mach thruster work, Greg too thought the effect was a vibrational artifact but thought the research was valuable and worth doing.  He was not as supportive of EmDrive but you listen to what he said about it.  Regarding the Woodward Mach Thruster work, EmDrive and other topics, post your thoughts and commentary/questions on our blog.  We would like to know how you see things in these areas. 

Later Greg was asked for his "pet rock" propulsion theory. He mentioned a faster than light concept he called "Trispace."  He mentioned it being part of a science fiction book, "To Sleep In A Sea Of Stars." (www.amazon.com/Sleep-Sea-Stars-Christopher-Paolini/dp/1250762847/ref=sr_1_1?dchild=1&keywords=To+Sleep+In+A+Sea+of+Stars&qid=1619994642&sr=8-1).  Greg also told us about the author and how his theory was worked into this award winning science fiction book.

As we were coming up on the end of the program, Greg was asked if the mach R&D would continue when Dr. Woodward was no longer with us.  Greg had some thoughts on that but of course nobody knows and everyone wants Jim to stick around for a long long time.  Our guest was also asked about a timeline for nuclear to Mars.  The late 2030 was mentioned as he talked about research having been going on since about 2016.  He thought we might see nuclear power demos in space around the mid 2020s.  He ended the program by again stating the need for successful mission trades for nuclear propulsion of any kind.  Earlier he said those trades do not yet exist today.

Please post your comments/questions on our blog for this show.  You can reach Greg Meholic through The Aerospace Corporation or me.

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30 Apr 2021 Greg Meholic
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