fallout data that we have obtained, what difference it makes what the structure of the mesosphere is and what the mixing rates are in the mesosphere. What difference would it make in our estimates of the length of time it would take for the debris to get to the ground, its distribution on the ground, and the doses that people might get from it? I believe it does make a very substantial difference. The rhodium experiment brings out the un- certainty from the data we have now as to whether the mesosphere residence time is 5 years or 20 years. This would make a lot of difference for some of the nuclides that are involved in the aerospace program. Dr. Shreve: Before I call for the next panel member I want to comment on his talk last night and how much I valued it. I think it is very easy, when you turn your eyes toward scientific implications, to be caught in the romance of outer space and to speak rather glibly about the possibilities. What I valued about his comments last night was his qualification concerning the kinds of things that might appear possible. He pointed out someof the difficul- ties which might be encountered because of what man-made debris has already done to these altitude regimes. Until we can really check the reaches of man's influences, we may have a rather tough job of resolving what we might term natural in a background of man's contribution to the realms. Dr. Martell: I have already had much more than my share of an opportunity to speak. There were a couple of points that I meant to touch on last night that have not been mentioned in the meeting but perhaps are worth considering. No one has said anything about the priority of different experimental applications of interest to the DOD, AEC, and geophysicists. There are a very limited number of tracers that one can use. One can agree whole- heartedly with Col. Russell's suggestion about using a multitude of tracers so that one can get the details of the ablation history and the completeness of the ablation. But, unless this experiment were going to be conducted on a small scale with very small amounts of material, you might be wasting a large proportion of the limited few tracers and thereby might eliminate the possiblility of carrying out some other experiments. Let's presume that the application of high-altitude sampling techniques becomes an important method for work in connection with a moratorium violation. In this period, could we afford to carry on experiments of the type described in the Orion program which would confuse the short-lived activity component in the high stratosphere rather seriously? It seems that we have to have some sort of central committee to consider and review all the experi- mental areas of interest and all applications of interest, and to consider whether we should expend our best long-lived tracers, recognizing how this might confuse other applications or other experiments. If we are going to carry on experiments of this kind in the atmosphere, then certainly the Russians and other nations can do similar things. They already have bigger missiles and their experiments might more generously contaminate the high atmosphere with similar tracers. We have always felt that a few good long-lived nuclear tracers or a few selected nonnuclear tracers should be reserved perhaps for international geophysical types of experiments to study atmospheric behavior. This is the only means of controlling the experimental possibilities on an inter- national and cooperative basis. Such things might be worked out through such agencies as the World Meteoro- logical Organization or the National Academy of Sciences. This is a consideration perhaps more immediate to some of the people I am associated with at GRD than to many of you, but I think the air has to be cleared in this area. There has to be some kind of coordination within our own program and, in some few cases, on a much broader basis. Lov