CLASSROOM: Guests: Classroom: Dan Adamo, Jon Goff, Dr. John Jurist, Dr. Jim Logan. Topics: This Classroom program was an advanced in-space propellant depot discussion. Please note that you are invited to comment, ask questions, and discuss the Space Show Classroom program/guest(s) on the Space Show Classroom blog, http://spaceshowclassroom.wordpress.com. Comments, questions, and any discussion must be relevant and applicable to Space Show Classroom programming. We welcomed back our Classroom co-hosts Drs. Logan and Jurist and our two propellant depot experts, Jon Goff and Dan Adamo for a comprehensive graduate school level two hour discussion about propellant depots. Also note that that as part of our upcoming Space Show webinar series, we did test video streaming during this program but as I said, we did not archive the video stream. We will let you know when our next video streaming test will take place. During our first segment, Dr. Logan set the tone with his opening statement when he said that resource pre-emplacement was essential if we were to go beyond LEO with chemical rockets. Dan said the ISS was already a depot that transferred hypergolic bipropellant fuels. This opened the door to cryogenic fuel transfer and a comprehensive discussion about boil off and the goal of reaching Zero-Boiloff Cryogenic Storage of the fuels in space. Much was said about this, the energy needed to separate hydrogen and oxygen and why cryogenic storage was necessary in space. We discussed some options were a depot to be located on the surface of the Moon but the issue of having sufficient power available for the separation is a significant one. Launch windows, departure schedules, and depot locations were discussed. We also talked about the idea of placing the depots in convenient places to attract multiple suppliers though this presents significant challenges with space traffic management problems. In our second segment we started with a listener question about using NOFBX and would it significantly help to reduce the complexity of a depot. Jon Goff responded to this question. Dr. Jurist brought up the issue of launch schedule reliability were it necessary to have between three to six flights including crew rendezvous happening within a specific time frame. Both Dan and Jon referenced the Target NEO conference from February 2011, specifically the Chel Stromgren paper, "Getting to the Starting Line -Launch and Assembly Reliability for Deep Space Missions" (www.targetneo.org/Sessions/Session%203/TargetNEO-Session3-Stromgren.pdf). During this segment, we discussed boil off rates and what this actually means regarding propellant losses and economic hits. One of the recurring issues during our discussion focused on NASA Technology Readiness Levels (TRL). SpaceX heavy lift was discussed in the context of propellant depots as was heavy lift in general. Bigelow hotels were also mentioned in the context of depots but there was also a discussion of why it might be too risky to put depots too close to human operated space hardware. As our discussion was drawing to a close, our guests talked about the road forward. Each of our experts and our co-hosts provided short summary statements and as you will hear, each differed so don't miss what each said. We welcome your comments and questions so post them to our Classroom blog for this program. If you want to email a specific guest, send your note to me and I will forward it to the person of your choice.