Broadcast 1951 (Special Edition)

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Guests: Dr. Haym Benaroya, Dr. John Jurist. Topics: Engineering space structures, hardware, and habits for LEO, the Moon, and Mars. Please direct all comments and questions regarding Space Show programs/guest(s) to the Space Show blog, 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. If you want to view the video webinar, please visit We welcomed our main guest Dr. Haym Benaroya and co-host Dr. John Jurist to our first Space Show webinar for 2013. As Dr. Benaroya is a mechanical and aerospace engineering at Rutgers University and well known for lunar architecture and engineering structures, we asked Dr. Benaroya to take us behind the scenes for a look into the engineering needed to have something in LEO, on the surface of the Moon, or Mars. Dr. Benaroya prepared a special .pdf presentation for us which is on The Space Show blog per above. I urge you to follow along with the .pdf slides as Dr. Benaroya discusses space engineering. During the first half of this two hour five minute webinar, Dr. Benaroya started out by discussing some of the basic issues in space engineering including gravity. He started with Slide 2 and talked about each item and the engineering considerations associated with it, both here on Earth and in space. As you will hear, not only are the engineering considerations significantly different between Earth and space, but many are also different from one another depending on if the project is in LEO, on the Moon or Mars. Make sure you follow along with him using his slides. Listeners, Dr. Jurist, and I asked Professor Benaroya many questions about lunar based habitats, LEO habitats, shapes, pressure forces, regolith issues, heat issues, and more. Referring to Slide 5 Dr. Benaroya talked about gravity issues and concerns. Slide 6 was about lunar dust issues, tidal forces, seismic concerns. We compared seismic reinforcing in San Francisco or other terrestrial earthquake zones to what would be needed on the Moon. The subject of engineering for extreme and rapid temperature changes came up for LEO, the Moon & Mars. Dr. Benaroya suggested many times during our discussion that we would need to use ISRU given the high cost of getting materials to space. In this first segment, other topics included the potential afforded lunar engineers by having a Lunar Space Elevator available and even a lunar bulldozer! The subject of heavy lift came up as it always does on these programs and all of us talked about fewer larger launches as compared to many smaller launches, even using depots. Doug called in to argue for the Falcon Heavy. As Dr. Jurist pointed out, putting mass on the Moon is about 10% give or take of the rockets IMLEO mass capability. In responding to Doug, both Dr. Jurist & Dr. Benaroya illustrated the difference between the Falcon Heavy and SLS regarding landing a specific mass on the Moon. Just before the segment ended, in responding to a question from Dr. Jurist, Professor Benaroya suggested that each person on the Moon would need about 20 times his or her weight in mass on the lunar surface for around a six month stay. To determine the most cost effective way to get the needed infrastructure and mass safely to the lunar surface, lots of issues go into the trade studies to determine the best approach, including launch vehicle choice. In the second segment of our webinar, we took a call from John in Florida who wanted to ask Dr. Benaroya about his earlier comment about using magnesium on the Moon as a type of rebar in lunar concrete. We next talked about reliability, power sources, competing technologies and design issues. One of the issues brought up was the need to design the structure to be successful during the design phase, not just the completion stage. This was a most interesting discussion, don't miss it. One of the points he made was that we can't test structures in space like we can on Earth so engineering design issues must be considered & dealt with for space that would not be encountered on Earth. He talked about the preferred shape for a lunar structure and advocated the arch as in Slide 21. Our professor then talked about design standards here on Earth, the fact that we have none for space so all of the Earth standards are extrapolated to work in space though we have no history for doing this. Also, he talked about using four to five times for a safety factor where on Earth the safety factor might be more like 1.5 or 1.6. We also talked about confidence intervals. While on Earth, something may be done with a CI of 95% or higher, he suggested that on the Moon or in space the CI would more likely be pretty low, around 70 or maybe 80%! He cited dust design as an example of what he was talking about as dust is not a big factor in terrestrial engineering but it will be on the Moon or Mars. Doug called again to advocate inflatable structures rather than the engineering and building of structures. Prof. Benaroya suggested that they may be used early on but that most of the studies show their primary advantage to be in transportation because on the surface they have to be made rigid. This is another discussion you don't want to miss. Near the end of our webinar, advanced manufacturing for the future was discussed. Dr. Benaroya talked about advances in robots, layered manufacturing and 3D printing. He explained how these can really change the game for space structures, engineering, manufacturing, and costs. Near the end, questions came in as to why the Moon instead of Mars, the 7-8 year time lines mentioned by the lunar companies and Mars One as well as wanting to know if space engineering was strictly an academic project or if it was being worked real time by companies that can actually make hardware. As you will hear, it’s a combination of both at this time. Dr. Benaroya kept talking about time lines 2-3 decades long and I asked him about speeding that up and the short time lines for the lunar and Mars One group. He did not think the shorter time lines were feasible. See what you think after you hear his and Dr. Jurist's comments on emerging company time lines. Dr. Benaroya concluded by pointing out the popularity of these subjects in both undergraduate and graduate classes and the importance of student research and its benefits. Please post your comments/questions on The Space Show blog above. To email Dr. Jurist, do so through me at You can contact Dr. Benaroya at



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17 Feb 2013 Dr. John Jurist, Dr. Haym Benaroya
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