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Aviation History
1961
1961 - 1469.PDF
F.JGHT, 12 October 1961 573 er gines, producing thrust from the energy liberated in a combustion p ocess, were limited in specific impulse by the obtainable tempera- tu'es of combustion and by the relatively high molecular weights of th,1 combustion products. Chemical systems could produce thrust ai specific impulses up to 5001b of thrust for each pound of propel- la-u flow per second, and this level of specific impulse was insuf- ficient for extensive manned missions to be accomplished prac- ti. ally. Several systems had been proposed to provide high specificimpulse motors through the application of nuclear energy. The two which were receiving major emphasis in the United States werethe nuclear heat transfer rocket (Rover) and the nuclear-powered ebctrical propulsion systems. Of these two, the greater emphasiswas placed on the nuclear rocket engine. The present objectives of the nuclear rocket programme, MrF.-nger stated, are to provide the necessary technology and experi- ence for the ultimate utilization of nuclear rockets in a wide varietyo! space missions. As such, the programme involves ground tests of reactors, the development of the NERVA (Nuclear Engine forRocket Vehicle Application) engine, plans for flight-testing a nuclear propulsion system, an extensive safety programme, andwork in areas of advanced technology. Justifying Nuclear Propulsion The justification for the development of nuclear rocket propul-sion systems is found in the analyses of manned planetary missions. The exploration of Mars, for example, would require a spacecraftweighing 9,000,0001b in an Earth orbit, if chemical propulsion exclusively were employed for the trip to Mars and return. Suchspacecraft weights may be totally impractical whereas, if nuclear rockets were used, the weight of the spacecraft would be reduced tosome 900.0001b. Economic analyses indicate that the money saved on a single trip to Mars using nuclear propulsion would be morethan enough to pay for the development costs of nuclear rockets. Without even questioning the relative practicability of building9.000,0001b and 900,0001b spacecraft in orbit around the Earth, therefore, one can conclude that nuclear propulsion is desirable—and, indeed, necessary—for manned interplanetary flights. The advantages of nuclear propulsion for a variety of missionswas recognized as long ago as 1955, when the Los Alamos Scien- tific Laboratory in New Mexico began studies and experiments todemonstrate the feasibility of reactors for nuclear rockets. These efforts led to the KIWI-A series of reactor experiments in 1959 andI960 which were conducted at the Nevada test site by LASL. The success of these KIWI-A experiments provided the technicalbasis for expansion of the programme to meet the broad objectives of engine development and flight testing. To provide the proper management of the expanded nuclearrocket programme, the responsibilities for the programme were vested in the Space Nuclear Propulsion Office. This office reportsto both the Atomic Energy Commission and NASA, thereby com- bining in one office the responsibilities of both agencies for nuclearpropulsion developments. After the formation of the SNPO, an industrial contractor teamwas selected to develop the first nuclear rocket engine, designated NERVA. Plans for additional reactor experiments—the K1W1-Bseries—were established and the necessary reactor test facilities have progressed towards completion. In addition, design and con-struction cf the facilities required for the nuclear engine develop- ment programme has begun. For some time, methods of flight-testing nuclear engines havebeen under investigation in a study programme known as RIFT I Reactor In Flight Test). Early next year an industrial contractorwill begin development activities on a RIFT vehicle to meet the objectives of achieving flight testing in 1966-67. On current ideasthe initial flight test will be accomplished using a Saturn-class first stage to launch the nuclear system on a short-range, ballistic flightdown the Atlantic Missile Range. After such flights have been accomplished it is expected that more extensive testing involvingescape missions and orbital starts will be attempted, leading to operational space applications. Safety is one of the major concerns of the nuclear rocket pro-gramme, and mission profiles and launch operations are being carefully examined to uncover the possible sources of hazards tolaunch crews and the general public. Systems to ensure safe opera- tions will be provided during the course of the programme leadingto flight testing. The remaining sessions on Tuesday were devoted to the fourthcolloquium on the law of outer space (which we hope to report in a forthcoming issue), energy conversion, astrodynamics (optimiza-tion theory and landing guidance) and a panel discussion on high- performance combustion systems.Among the papers presented were Development of Nuclear Power in the United States for Space Applications by Lt-Col G. M.Anderson and Cdr D. L. Jarrell of the Atomic Energy Commission, Dynamic Flight Vehicle Power Systems by George Sherman ofUSAF Systems Command, Space Power Sources by Thermo- electric and Thermionic Emission Processes by P. H. Egli of theUS Naval Research Laboratory, Optimum Soft-landing Trajectories by L. J. Berman of Massachusetts Institute of Technology, andTerminal Guidance and Control Techniques for a Soft Lunar Landing by B. A. Kriegsman and M. H. Reiss of Raytheon Co. Also included, as an appendix to The Social Impact of Communica-tions Satellites presented by Arthur C. Clarke before the space law meeting, was a reprint of a 1945 article published by our sisterjournal Wireless World. Written by the same author and entitled Extra-terrestrial Relays, this paper is believed to be the first everpublished on the subject of communication satellites. At a National Aeronautics and Space Administration receptionthat evening Dr L. R. Shepherd of the British Interplanetary Society presented Dr Wernher von Braun with a Gold Medal ofthe Society. The first papers at the congress on the subject of bio-astro-nautics were presented on Wednesday. October 4. They included Psychological Approach to the Study of Fatigue in Space Flight b\Lt-Col David G. Simons of the USAF Aerospace Medical Center. Psycho-Physiological Reactions to Weightlessness as observed onsubjects during recent Bio-ballistic and Bio-satellite Experiments by Harold Von Beckh of the USAF Missile Development Center.Some Results of Physiological Reactions to Space Flight Conditions by Oleg G. Gazenko and Vladimir I. Yazdovsky of the USSR,Flight Safety Systems for Advanced Manned Space Missions by T. F. Heinsheimer of General Dynamics Astronautics, and theintriguing On the Possible Existence of Intelligent Living Beings on Other Planets by Rodolfo Margaria of the University of Milan.The previous days" sessions on space law and high-performance combustion systems were continued. Other subjects discussed during October 4 included trends incombustion research resulting from space exploration, and the exploration of the solar system by radar and radio astronomy.The scheduled contributors to the latter sessions included T. N. Nazarova, K. I. Gringauz and Vladimir A. Kotelnikov of theUSSR, Dr John Thomson from Jodrell Bank, T. R. Kaiser of Sheffield University and Zdenek Kopal of Manchester University. At a luncheon meeting of the National Capital Section of theAmerican Rocket Society on the same day, the Secretary General of the International Telecommunications Union, Mr Gerald C.Gross, spoke on the subject of the ITU and space communications. [To be concluded] These photographs show the degree of definition achieved with the 70mm camera carried by the unmanned Mercury capsule (MA-4) which made a single orbit on September 13. During its IO9min flight the capsule passed over Morocco (left) and central Africa (right, showing Lake Rudolph in the centre of the picture). MA-4 achieved an apogee of 158 miles, and these pictures were taken at an altitude of about 100 miles
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