Architecting a Family of Space Tugs Based on Orbital Transfer Mission Scenarios
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Architecting a Family of Space Tugs based on Orbital Transfer Mission Scenarios by Kalina K. Galabova B.S. in Mechanical Engineering/Aeronautical Systems (2001) United States Military Academy Submitted to the Department of Aeronautics and Astronautics Engineering in Partial Fulfillment for the Degree of Master of Science in Aeronautics and Astronautics at the MASSACHUSETTS INS-TifffT Massachusetts Institute of Technology OF TECHNOLOGY February 2004 JiL 0 1 2004 LIBRARIES @ 2004 Massachusetts Institute of Technology All Rights Reserved AERO Signature of Author......................... ----------- ............. .. Department of Aeronautics and Astronautics A Certified by............................ .. .. .. .. .. .. .. .. .. .. .......... .. .. .. .. .. .. .. .. .. .. .. .. Olivier de Weck Assistant Professor of Aeronautics and Astronautics and of Engineering Systems Thesis Supervisor Accepted by........................ ................ Edward M. Greitzer H.N. Slater Professor of Aeronautics and Astronautics Chair, Committee on Graduate Students -4*wmftli6 - -- . 1 7, -- --- Room 14-0551 77 Massachusetts Avenue Cambridge, MA 02139 Ph: 617.253.2800 MITLbries Email: [email protected] Document Services http://libraries.mit.eduldocs DISCLAIMER OF QUALITY Due to the condition of the original material, there are unavoidable flaws in this reproduction. We have made every effort possible to provide you with the best copy available. If you are dissatisfied with this product and find it unusable, please contact Document Services as soon as possible. Thank you. The images contained in this document are of the best quality available. 2 Architecting a Family of Space Tugs based on Orbital Transfer Mission Scenarios by Kalina K. Galabova Submitted to the Department of Aeronautics and Astronautics on January 16, 2004 in Partial Fulfillment of the Requirements for the Degree of Master of Science in Aeronautics and Astronautics Abstract The consequences of satellite misplacement or collision with space debris reach far beyond the realm of money. The vast number of people affected by the loss of just one spacecraft indicates the vulnerability of our society to spacecraft failure. Thus, one of the biggest problems that satellite makers face today is the lack of a margin of error of any type. This thesis analyzes the business case for employing a special type of on-orbit servicer referred to as a space tug as an alternative to redundancy and replacement option. The main objective of a space tug is to prevent satellites from prematurely ending their missions. It was found to be more realistic to design a tug (or tugs) that service groups of satellites with similar orbital and physical characteristics, rather than to design a "monster" vehicle expected to traverse the huge distances between LEO and GEO and deal with satellites of all types and sizes. Thus, the approach of this work was based on the exploration of the entire satellite population currently in orbit around Earth and on the identification of potential target groups of satellites, along with mission scenarios for servicing each of these groups. Eight mission scenarios were identified as most necessary. Two of them-GEO communications satellite retirement and satellite rescue-were presented as case studies to illustrate the modeling approach suggested by this thesis. The ultimate objective of the research was to create a family of modular, economically feasible space tugs that used a common platform and shared various components, which would allow to provide relatively inexpensive and responsive on- demand tugging services. It was found that the optimal space tug for GEO retirement missions should be initially parked in the GEO belt and be controlled via supervision. This space tug should have a 300-kg low capability grappling mechanism and utilize storable bipropellant (Isp = 325 sec). The maximum number of satellites the tug could visit was calculated to be 20. The minimum fee for the service was estimated to be $20.48M, and the uncertainty of cost estimations should not exceed $7.5M for the nominal case. The optimal tug for satellite rescue missions was an ion electric spacecraft parked on Earth and controlled via supervision. It was not designed as reusable, and various types of grappling mechanisms or any number of fuel tanks could be attached to it, depending on mission requirements. Both architectures could use a common bus and share the same type of grappling devices. Thesis Supervisor: Olivier de Weck Title: Assistant Professor of Aeronautics and Astronautics and Engineering Systems 3 4 Acknowledgements For me, working on this thesis was an opportunity to be creative and bring together the skills I have acquired in my two and a half years at MIT, but most of all to make a real professional contribution. However, I would have not been able to accomplish this without the continuous support of my advisor, Prof. Olivier de Weck, and the rest of the team working on on-orbit servicing. This work would not be possible if not for the interest and support provided by our sponsor, Dr. Gordon Roesler, from DARPA (TTO). My gratitude also goes to Prof. Daniel Hastings and Dr. Hugh McManus for their expertise and advice throughout the completion of this thesis. Michelle McVey from Adroit Systems Inc. has also been extremely helpful in providing useful information regarding the current state of the satellite industry. I would like to express my appreciation to my friends and teammates Roshanak Nolchiani, Carole Joppin, Gergana Bounova, and Todd Schuman, who monitored and critiqued my work at a number of presentations and group meetings. I have also immensely enjoyed being a part of the "33-409 family," and I would like to thank my officemates for making each day interesting. I feel extremely lucky to have received the opportunity to be part of the MIT Space Systems Laboratory and to be surrounded by such intelligent, motivated, and entertaining people. Last but not least, I and am grateful for the support of Dimitar Zlatev, who read and edited every page of this thesis and cheered and encouraged me throughout. 5 6 TABLE OF CONTENTS 1 Introduction............................................................................................................. 17 1.1 Definitions and Acronyms ............................................................................ 18 1.2 M otivation for Space Tug M issions............................................................... 20 1.2.1 Need for an Alternative Option............................................................. 20 1.2.2 Mission Scenarios ................................................................................. 22 1.3 Value of This Research...................................... 24 1.3.1 A Different Approach ............................................................................ 25 1.3.2 Business Case Analysis.......................................................................... 25 1.4 Thesis Outline ............................................................................................... 26 1.5 Chapter Summ ary .......................................................................................... 26 2 Literature Review ................................................................................................. 27 2.1 On-orbit Servicing .......................................................................................... 28 2.1.1 Servicing of M anned Spacecraft/Station .............................................. 28 2.1.2 Servicing of Satellites by Humans........................................................ 30 2.1.3 Servicing of Satellites by Unmanned Spacecraft.................................. 32 2.1.3.1 Early Space Tug Concepts................................................................. 32 2.1.3.2 Recent Proposals............................................................................... 37 2.1.3.3 Research at M IT................................................................................. 45 2.2 Summ ary of Previous W ork Shortcomings ................................................... 48 2.3 Recommendations for Improvement............................................................. 51 2.4 Chapter Summ ary .......................................................................................... 53 3 New Architecting Approach............................................................................... 55 3.1 Description of the Proposed Approach .......................................................... 55 3.2 Database and Target Clusters........................................................................ 57 3.3 Orbital M ission Scenarios............................................................................. 61 3.3.1 Satellite Rescuing.................................................................................. 61 3.3.2 Crowding and Collision Risks .............................................................. 62 7 3.3.3 Satellite Lifetime and Retirement ............................................................. 67 3.3.4 National Security and Military Advantage ............................................... 68 3.3.5 Economic Profit from Satellites Reconfiguration..................................... 69 3.3.5.1 Demand Uncertainty for LEO Constellations....................................... 69 3.3.5.2 New Markets or Market Shift (Non-Constellation Satellites).............. 70 3.3.6 On-orbit Assembly of Massive Structures...............................................