Broadcast 3114 Marc Gibson

The Space Foundation Conference

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Guest:  Marc Gibson; Topics:  The NASA Kilopower Reactor Development Project, higher power planetary missions, human spaceflight issues, RTG's nuclear safety and more.  Please direct all comments and questions regarding specific Space Show programs & guest(s) to the Space Show blog which is part of archived program on our website,   Comments and questions should be relevant to the specific Space Show program. Written Transcripts of Space Show programs are a violation of our copyright and are not permitted without prior written consent, even if for your own use. We do not permit the commercial use of Space Show programs or any part thereof, nor do we permit editing, YouTube clips, or clips placed on other private channels & websites. Space Show programs can be quoted, but the quote must be cited or referenced using the proper citation format. Contact The Space Show for further information. In addition, please remember that your Amazon purchases can help support The Space Show/OGLF. See   

We welcomed Marc Gibson to the show to discuss the NASA Kilopower Reactor Development Project.  Please note that his reviewed paper has been posted on the blog for this show.  You can also find his paper, "NASA's Kilopower Reactor Development and the Path to Higher Power Missions" on the web.  I strongly recommend you read this paper before listening to this interview.  In addition, you can find out more about the project at  We started the first segment of our two segment 88 minute discussion with Marc introducing us to the Kilopower Project designed to provide more power for the needs of higher powered space missions by using a small reactor that does not generate much launch mass.  Marc both described and explained the Kilopower Reactor, compared and contrasted it with an RTG and talked about solar electric power (SEP) and the limits for using SEP as one moves further away from our sun.  Some of the issues talked about included the U235 fuel used for the small reactor as compared to Plutonium 238 for the RTG.  Marc then described the recent Nevada test site ground test for the Kilopower reactor (KRUSTY), testing it in a vacuum, , plus our guest said a few times during the interview that the test was a big deal.  Marc described the power range for the Kilopower Reactor so don't miss this important early part of our program. 

Several emails were received during the program.  Jack sent in a note asking for more information and an explanation of a Sterling engine.  Marc had much say about the Sterling engine and its potential efficiency running as high as 35-40%.  Don't miss Marc's comments on this subject.  Dr. Doug sent in several emails.  One asked about using the reactor for ISRU propellant manufacturing.  Doug's question led to a lengthy and at times complex response from Marc so by all means, listen carefully and don't miss it.  The Uranium 235 fuel for the Kilopower Reactor came up several times as did the half-life of Uranium.   Listener Shirley sent in a note asking if the reactor could also be used for station keeping for say the ISS or a satellite.  Also, life extension for planetary missions and other space hardware.  Again, don't miss what March said in his reply. 

Additional listener emails were received during this segment.  Kim sent in a note asking about shielding protection for crewed missions in open spaces on the Moon or Mars.  Marc had much to say about shielding and the options so don't miss his reply.  Doug asked about the SEP distance limitations from the sun.  Tony sent in an email asking about the Kilopower Reactor size and if our guest had been in touch with Dr. Zubrin regarding the Kilopower Reactor project. Marc said he had not been in touch with Dr. Zubrin.  Listener Ben sent in a question about the nuclear fear issue.  Marc suggested this was much less of a fear generating project than other nuclear space projects so listen to what he had to say on the subject.  Other topics included comparisons of the fuel used for an RTG as well as the Kilopower Reactor and then he was asked if the Kilopower Reactor generated nuclear waste.  The answer was no but don't miss the explanation.  Before the break, Doug asked about the BFR and related topics but we talked the Kilopower timeline and the KRUSTY Test at the Nevada Test Site.  Just before the break, I asked our guest if he thought the Kilopower Reactor might someday be available for commercial missions.   Don't miss his response, it might surprise you.

For the second segment,  we talked about NASA budget issues for the project and if the budget was secure or at risk.  Marc had much to say about the project costs so far and the efficiency of the program.  He thought the budget  was secure.  I think you will be impressed by what his team has accomplished for the costs he talked about with us.  We thank Tina for asking the budget question.  Next, Carl asked about the size of his Kilopower team and if it was international.  We then took an email question form Randy who wanted Marc to explain depleted uranium and why it was being used on the project.  Near the end of the program, Henry asked if they were sure the reactor would work in space given space was not the same environment as on Earth.  Don't miss what Marc said in response to this question.  Nancy followed it up asking him about his microgravity experience which he had previously mentioned when they were doing various microgravity tests for the reactor.  Marc got to experience and work at both lunar and Mars gravity and Nancy wanted to know his preference.  As we were nearing an end to the program, another Carl mentioned Marc's engineering background and wondered if he learned the nuclear stuff on the job or if it was part of his academic engineering studies.  He said OJT but listen to all of what he said on this point.

Please post your comments/questions on TSS blog.  You can reach Marc through me or his Kilopower Reactor paper posted on the blog.




The Kilopower Reactor Development Program

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14 May 2018 Marc Gibson
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