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Guest: Dr. Ajay Kothari. Topics: Rocket reusability, 1st 2nd stage reusability, space tourism, & more. Please direct all comments and questions regarding Space Show programs/guest(s) to the Space Show blog, http://thespaceshow.wordpress.com. 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 www.onegiantleapfoundation.org/amazon.htm. For those listening to archives using live365.com and rating the programs, please email me as to why you assign a specific rating to the show. This will help me bring better programming to the audience. We welcomed Dr. Ajay Kothari to the show to discuss first stage and full rocket reusability. During the first segment of our 1 hour 44 minute discussion, Dr. Kothari opened with references to his April 14, 2014 Space Review article, "Robust and Reusable." I suggest you read this article and have it handy as a reference as you listen, http://thespacereview.com/article/2490/1. Dr. Kothari explained his model and analysis process to evaluate the costs and economics for rocket reusability options. Our guest goes through his models and scenarios for us, notes that they are only for TSTO rockets (2 stage to orbit), plus he identifies his analysis and software tools. His analysis led him to understanding the importance of the First Unit Production Cost (FUPC) and how this is a killer without a high rocket launch rate. Dr. Kothari then talked about the possibilities for space tourism. As you will hear, he thinks much more of orbital tourism over suborbital tourism which is understandable when you see his costing, price points, percentage of net income being spent on the flight, & a few other parameters. When asked if he thought orbital space tourism would be the economic driver for rocket reusability, he said he thought it had the potential to be a significant contributor to it. Listener Paul asked him about the reusability penalty due to added mass for a reusable rocket. Ajay said they addressed that in their model and suggested a reusable rocket capable of the same payload and destination as an expendable would need to be 2-4 times the size of the expendable! John from Ft. Worth was a caller with many questions but near the end of this segment, he asked for Ajay's thoughts on the SpaceX reusable system and process. Our guest thought highly of the SpaceX effort, process, and concept. We also talked about both flyback and boostback options. In our second segment, Dr. Jurist called in and addressed efficiencies in the learning curve which benefit expendables over reusables though our guest was quick to point out that after decades we still cannot build on these learning curve efficiencies to move further out with expendables in technology and cost reduction. Dr. Kothari and John spoke about the flight rate b/e point which is largely unknown. I then asked our guest about full rocket reusability and his ideas for a hypersonic second stage to orbit and back. Dr. Kothari spent time with us during the balance of our program discussing his concept. We even discussed point to point transportation as a result of this model and he suggested the innovative idea of combining limited orbital space tourism with Point to Point to make it more acceptable. Don't miss his explanation of this idea. Tim called in wanting to know about landing large payloads on Mars , possibly using inflatables or magnetic fields generated by a hypersonic in the Martian atmosphere. Doug was our last caller asking about rarefied gas flow & possibly returning to Earth from the Moon with a lighter weight heat shield, even what bouncing off the Earth's atmosphere meant for Earth capture of the incoming spacecraft. Our guest talked with him about this along with steady flow or steady heat conduction. To conclude our discussion, Ajay summarized his models that closed the business case for orbital space tourism, including the one model that could not close. Note the parameters he talks about for each model. For more information, check out Dr. Kothari's website for Astrox Corporation (www.astrox.com). Please post your comments/questions on TSS blog above. You can reach our guest through me.