IV. FUTURE DEBRIS INJECTIONS R. S. Claassen, presiding (C) Some Aspects of the LASL Rover Flight Safety Program L. D. P. King Los Alamos Scientific Laboratory The ultimate usefulness of nuclear reactors for rocket powered space flight does not depend only on the technical demonstration of a reactor which has satisfactory thrust and performance characteristics. Of equal importance is that one can demonstrate beyond any doubt, to government agencies concerned, that all public safety requirements are met. One must not overlook the fact that unsolved safety problems can seriously slow down the ultimate use of nuclear rockets and may require changes in design concepts. The potential gains from the use of nuclear energy in space must be evaluated in comparison to the risks of physical or financial damage. It is the responsibility of governmental bodies to regulate and evaluate hazards to the public in such a way as to minimize the risk and maximize the gain. It should be the responsibility of the technical staffs of research organizations involved in the nuclear rocket program to supply the necessary technical data for a correct evaluation of the safety problems. The Los Alamos Scientific Laboratory recognizes the variety of skills and general complexity of the safety problems arising from the use of nuclear rockets. Since the successful completion of the Kiwi A series of propulsion reactor tests, the technical feasibility of nuclear rockets motors has been demonstrated, In- creased effort on solving the safety aspects of flight and operational use of such devices now requires additional effort. A Rover Flight Safety Committee has recently been formed at the LASL with the express purpose of studying and coordinating the contributions the laboratory can make towards the solution of nuclear rocket flight safety problems, Substantial work dealing with Rover safety had already been done at the laboratory prior to the formation of the committee, but this was done more or less on an individual interest rather than a laboratory wide responsibility basis. For example, the classified document, LA-2409, Nuclear Safety Aspects of the Rover Program, was issued in March 1960 and has provided most of the presently available reactor technical data directed towards Rover safety considerations, The Rover Flight Safety Committee has been working on a program which seeksto identify safety problems which can be foreseen and evaluated so that a suitable experimental and theoretical program can be pursued. In particular, the LASL will be concerned with aspects of reactor core operation and design, An effort is being made to place emphasis on those items which appear to have the greatest urgency. The most difficult, and probably the most important problem at present, appears to be the disposal of a nuclear rocket reactor core and its components on return from orbit or ballistic trajectory when the point of im- pact is not known. be modified, This is particularly true if the present safety rules required of the engine contractor cannot The requirement that no reactor or large fragments thereof re-enter and impact on the earth's land masses may be troublesome or impossible to guarantee under all conditions. 97