Mr. Holland: I think that is a very good point. There is a danger here, especially if we conduct a classified program, that we will be operating in isolation and out of touch with a lot of closely related work. This would argue for an unclassified program, as free as possible, so that information can be exchanged with other scientists in meetings of the kind you conduct. Dr. Shreve: Satellite programs seem to be limited by perigee to about 120 to 150 miles, the Ash Can program similar things to 20 miles, roughly. We might well use the ingenuity that has been put into the satellite program by way of instrumentation and measure many of the things in this height realm between the two regions so that we have an integrated understanding from satellite measurements on down to the ground. Dr. Otting: Most importantly, you are measuring the same thing by two independent means, and if you get the same answer you feel better about it. I think if you can do this in some cases it would just be an independent check. I think the region in this more or less transition region from a continuum region of 100,000 feet where you can fly, and so forth, to 500, 000 feet, where you would get into the molecular region for sure, is a tough one to sample because it is a transition, but by the same token it is important. Lt. Ahearne: I'd like to point out a few of the reasons why people in my business are interested in this type of thing. One of our major interests at the present time is the area around the D-region, in particular the area of about 40 to 80 kilometers. We are interested in the impurities present at these altitudes which might affect recombination rates or various air chemistry reaction rates, The studies that have been done indicate that impurities 10° to 10° may be more important in determining the methods by which electron recombination occurs or attachment occurs than has been appreciated before. these altitudes. At the present time, we know little of the impurity concentrations at We hope in the future to have fairly decent means of simulating conditions in the laboratory to study recombination rates. Unfortunately we are now faced with the unpleasant realization that we don't know exactly what to put in our containers to have this recombination proceed because we are not really sure what the impurities are. Another important thing is the ability to verify or improve on some of the theories that have been developed on methods by which these particles do settle down from the extremealtitudes. This is impor- tant for people in the Rover programs or similar programs who will be forced to inject a certain amount of impurities during operation. They are very interested in trying to find out where these go. We are interested in being able to determine what type of capability we must have for a detection program for detonations in space. In this light, detection does not look very promising when we consider the long time which is postulated for fall down into the region in which we now sample. We are essentially saying now that we may be able to tell 20 years from now whether a test occurred out in space today. This is of little use to us. However, if we can have a capability of detection at high altitudes and understand what the settling process is, we will have a greater confidence of being able to tell in a short time. I was extremely interested in the point that was raised by Sandia people about the winds at high altitude and the rise of the debris to extreme altitudes. This is of tremendous 169