Signature Redacted

JUL 2NS 94 JUlL 2 1945') PROPAGATION OF ELECTROMAGNETIC PULSES IN THE IONOSPHERE by Pauline Morrow Austin B.A., Wilson College 1938 M.A., Smith College 1939 SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIRElI&ETS FCR THE DEGRETh OF DOCTOR OF PHILOSOPHY at the MASSACHUSETTS INSTITUTE O TECHNOLOGY 1942 Signature Redacted Signature of Author ............. ........ Department of Physics, October 7, 1942 Signature Redacted Certified by: ... b71 Thsis Iiperyisor Signature Redacted Chairman!, Department Committee on Graduate Students MANAGEMENT GUIDELINES FOR THE EVALUATION AND SELECTION OF THE WELDING TECHNOLOGIES FOR USE IN OUTER SPACE by Ravikumar Ramiah Nagabushanam Submitted to the department of OCEAN ENGINEERING in partial fulfillment of the requirements for the degree of Master of Science in Ocean Systems Management ABSTRACT Future construction of space structures and inter planetary vehicles will be carried out in space. Also due to the increased service life of the space structures there is an increased need of repair and maintenance work to be carried out in space. NASA has plans for using welding for this purposes. By using welding reliable repair, maintenance and construction of space, structures can be achieved. However, at present research on space welding is at its infancy and not many experiments have been conducted so far. This is mainly due to the resource constraint faced by NASA. This thesis explains the need for using proper evaluation and selection methods for choosing R&D projects. It also examines the drawbacks involved in using conventional financial techniques and suggests the use of option valuation techniques and decision tree analysis to overcome those drawbacks. In order to overcome the resource constraints the need for developing alternate strategies has been discussed. The benefits of developing space technologies and the opportunities for developing commercial products and processes have been analyzed. The main focus of this thesis is the financial and strategic issues involved in the decision making process for R&D. Thesis Supervisor: Koichi Masubuchi Title: Professor of Ocean Engineering and Material Science 2 ACKNOWLEDGEMENTS I wish to express my deepest gratitude to Professor Koichi Masubuchi, who advised and guided me during my stay at MIT as a professor and a friend. He made the necessary financial aid available and always provided a clear view of the big picture. I am forever indebted to his cheerful and kind support. I would like to thank Professor Henry S. Marcus, my thesis reader. His help was always enthusiastic and direct, and was available despite his busy schedule. I would like to thank my great friend and guru Dr. Vasudevan for everything he has done for me. I would like to thank Sushi, Kulasekar uncle, Ram, Mani anni, Anand, Gheetha and Ashok for their immense faith and confidence in me. I would like to thank M.E. Devarajan uncle and family for their kindness and love. My deepest thanks to my parents and wife, Jaya, who have made many sacrifices and have always encouraged me. Saluations to the Great Lord Anjeneya. 3 DEDICATION DEDICATED TO THE IMMENSE LOVE AND AFFECTION OF MY FATHER NAGABUSHANAM AND MOTHER RANGANAYAKI KUMARASAMY AND TO THE WONDERFUL MEENA, ASHWIN, SUNDER, DHIVYA AND SEENU 4 TABLE OF CONTENTS 1 Thesis Overview...................................................................................... 9 2 Background............................................................................................... 16 2.1 History of Space Research.................................................... 17 2.2 Space Policy............................................................................... 23 2.3 Space Program s Under Development................................. 25 2.3.1 Space Station Program ............................................ 25 2.3.2 Other Space Programs............................................... 31 3 Introduction.................................................................................................. 34 3.1 Fabrication, Maintenance and Repair of Space Structures................................................................................... 35 3.2 Advantages of Using Welding................................................... 37 3.3 Requirements of the Welding Technologies......................... 41 3.4 Welding Methods Considered for Space Welding............... 46 3.4.1 Strengths and Limitations of these Welding Technologies........................................................................ 52 3.4.2 Present Status of Space Welding................................ 58 5 3.5 Resource Constraints Faced by NASA........................................ 63 4 Managing R & D ................................................................................................. 65 4.1 Risky Nature of the R&D Projects.............................................. 69 4.2 R&D Expenditures Vs Capital Investment Expenditures ... 71 4.3 Need for Proper Evaluation and Selection Methods.............. 73 4.3.1 Analysis of Alternatives................................................. 74 4.4 R&D in the Public Sector.............................................................. 78 5 Evaluation Techniques.................................................................................. 81 5.1 Conventional Financial analysis........................... 84 5.1.1 Limitations ....................................... 86 5.2 Alternate Methods of Evaluation....................... 90 5.2.1 Option Pricing Valuation................................................ 90 5.2.2 Decision Tree analysis.................................................... 95 6 Strategic Planning ............................................... 102 6.1 Benefits of Strategic Planning................................................ 103 6.2 Strategies............... ................................... ...................................... 107 6.2.1 International Co-operations........................................ 107 6.2.2 Commercialisation of the Space................................... 110 6 6.2.3 University Research.......................................................... 116 7 Benefits of Developing Space Technologies........................................... 118 7.1 Opportunities for Developing Commercial Products and Processes ......................................................................................... 126 8 Sum m ary..............................................................................................................134 9 Reference and Bibliography......................................................................... 140 LIST OF FIGURES AND TABLES fig(1): International partners contribution to Space Station [34].... 27 fig(2): Artist's conception of US and Soviet's Space Station [28]...... 28 fig(3): Future Activities in space [28]........................................................ 30 fig(4): Astronauts explore the Moon using a variety of Lunar vehicles [42]........................................................................................................ 32 fig(5): Comparison of welded and riveted structural joints [7]......... 38 fig(6): Welding selection considerations [14]......................................... 48 fig(7): Survey of space welding publications [24]................................ 60 fig(8): Projected benefit and cost stream for projects [32]................ 85 fig(9): Value of a call expiration [33].......................................................... 92 7 fig(10): Basic diagram of a decision analysis [30]................................. 96 fig(11): Simple decision tree for product development [30]............. 99 Table(l): Characteristic of the space environment [14]....................... 43 Table(2): Welding processes and related issues of concern for space applications [14]................................................................................................... 49 Table(3): Investments, options and R&D options [36].......................... 93 8 chapter 1 THESIS OVERVIEW 9 chapter 1 THESIS OVERVIEW NASA has plans for an aggressive space exploration program in the next 30 years, which includes a manned space station, lunar base and mission to Mars. The manufacture and assembly of efficient orbital stations and operating platforms directly in space are also planned. These projects require advanced technologies for construction of vehicles and structures that can withstand high gravitational forces, long term exposure to radiation and bombardment by space debris and micrometeorites. In case of repair and maintainance of space structures, in order to achieve a high reliability and ease of repair for a structure that is expected to last 20 or more years, joining by welding is considered by the NASA's space structures designers. The _1se of welding to assemble large complex structures has many advantages. It will be more economical to launch only structural components, saving the final joining of these sub- structures until they are in the orbit. By performing the final construction in space, structure does not have to be designed to withstand the high stresses which could occur during launch. Moreover, welding does not increase the weight of the structure, offers greater flexibility in the selection of joint designs, and yields gas tight coupling of components. 10 In order to successfully perform welding in space, considerable knowledge is required to select the proper welding processes. Therefore, more studies and experiments

Load more