Broadcast 1843 (Special Edition)

28 Aug 2012 Dr. Anita Sengupta
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Guest: Dr. Anita Sengupta. Topics: Entry, Descent, & Landing for Mars, Venus, propulsion, parachute issues, & more. You are invited to comment, ask questions, and discuss the Space Show program/guest(s) on the Space Show blog, http://thespaceshow.wordpress.com. Comments, questions, and any discussion must be relevant and applicable to Space Show programming. Transcripts of Space Show programs are not permitted without prior written consent from The Space Show (even if for personal use) & are a violation of the Space Show copyright. We welcomed Dr. Anita Sengupta, Senior Systems Engineer at JPL in Entry, Descent & Landing (EDL) Advanced Technologies Group to discuss EDL for Mars, other planets, and much more. In our first segment, Dr. Sengupta described conditions relevant to Mars and landing an object on the planet. We talked about the Martian atmosphere and what an EDL team needs to consider and design to land any payload on Mars as well as humans. We also learned that EDL for a different size payload would be different than what was used for Curiosity, probably needing new systems. We talked about supersonic parachutes & parachutes in general, addressing parachute materials, velocity, parachute violent extremes, the speed of sound & much more. Another topic was testing on Earth to make sure the devices work on Mars. Dr. Sengupta explained how such testing & Mars simulation is done on Earth. Other landing techniques such as airbags were mentioned along with retro rockets. During this discussion, our guest did a great job of explaining the various forces and physics involved in landing & how each of these forces must be dealt with for a successful landing. We then talked about landing a payload on Venus and just how different Venus is to Mars. The same for our Moon and the moons of Mars, Phobos & Deimos. Listeners sent in questions about the rover debris being left on Mars as well as wondering if there were other ways to explore Mars than using rovers. John called to inquire about first stage reusability & our guest talked about doing the "trades" (running the numbers to see if reusability is economic or not). Doug called to talk about orbital transfer vehicles, aerobraking, and more. This led us to a discussion about larger launch vehicles, the need to dissipate lots of energy on reentry, and why larger areas with drag are preferable. In our second segment, I asked about software programs we might use for the basic type of analysis Dr. Sengupta had been discussing. Note her recommendations. We then talked about plasma propulsion and ion thrusters. Dr. Sengupta had much to say on this subject including ion thruster fuel, costs, ISP, and again, the importance of doing trade studies for a mission to determine the best methodology/economics for the mission. Our guest also talked about the lower ISP Hall ion thruster which was also lower in cost but with substantially more ISP than a chemical engine. Also in this segment, we talked about the Dawn mission & Vega, a possible Europa mission & the use of nano satellites for the Europa mission. Doug called back regarding ion propulsion fuel, xenon, iron, lunar fuel, etc. As our program was ending, Anita mentioned the Orion parachute system tests she works on & the new Mars mission InSight. Several times during the program, Dr. Sengupta stressed the need to do the trade studies regarding mission planning to determine the best economics & cost effectiveness for the mission. Many of you have heard on The Space Show that if one does not "run the numbers," it is impossible to know if what you want to do is economically & mission productive/viable. On Oct. 28, Dr. Jurist is doing a special webinar with his interactive Excel spreadsheet on rocket/mission planning. It is essential to be able to do this in mission planning. Trusting your beliefs, gut, & preferences are not the way to go so watch this webinar if you can. Please post questions/comments on our blog.

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