Architecting Space Communication Networks - System Architecture

122 Pages·2014·2.55 MB·English

Architecting Space Communication Networks
by
Marc Sanchez Net
Submitted to the Department of Aeronautics and Astronautics
in partial fulfillment of the requirements for the degree of
Master of Science in Aeronautics and Astronautics
at the
MASSACHUSETTS INSTITUTE OF TECHNOLOGY
June 2014
(cid:13)c Massachusetts Institute of Technology 2014. All rights reserved.
Author ..............................................................
Department of Aeronautics and Astronautics
May 22, 2014
Certified by..........................................................
Prof. Edward F. Crawley
Professor of Aeronautics and Astronautics and Engineering Systems
Thesis Supervisor
Accepted by.........................................................
Prof. Paulo C. Lozano
Associate Professor of Aeronautics and Astronautics
Chair, Graduate Program Committee
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Architecting Space Communication Networks
by
Marc Sanchez Net
Submitted to the Department of Aeronautics and Astronautics
on May 22, 2014, in partial fulfillment of the
requirements for the degree of
Master of Science in Aeronautics and Astronautics
Abstract
Reliable communication and navigation services are critical to robotic and human
space missions. NASA currently provides them through three independent and un-
coordinated network that consist of both Earth-based and space-based assets, all
managed under the Space Navigation and Communication Program. Nevertheless,
the ever increasing mission requirements and funding limitations motivates the need
of revising the current network architectures in order to identify areas of potential
performance and cost efficiency improvements.
The main objective of this thesis is to present a tool that helps decision-makers
during the process of architecting a space communication network by (1) systemat-
ically enumerating and exploring the space of alternative network architectures, (2)
identifying those with better performance and lower cost, and (3) providing trace-
ability between the outputs of the tool and the architecting decisions. The tool is
tailored to the high level design of near Earth space communication networks that
support robotic and human activities in the Earth vicinity through a set of relay com-
munication satellites and their supporting ground stations. The decisions available to
the network architect (both technical and contractual) are presented and along with
their couplings.
The tool is validated by comparing it to NASA’s Space Network. The current
operations of the system are analyzed and used as the baseline case for the validation
process. Results demonstrate that the both performance model and spacecraft design
algorithm are accurate to less than 10%, while the cost module produces estimates
with a 15% error.
Finally, the utility of the tool is demonstrated through three case studies on the
evolution of the Space Network. In particular, the impact of new radio-frequency and
optical technology to increase the system capacity is analyzed based on the predicted
demand for the 2020-2030 decade. Similarly, the savings of flying relay transponders
in commercial satellites as hosted payloads are quantified and benchmarked with
respect to NASA’s current approach of procuring and operating the entire network.
Lastly, the tool is used to compare the current Space Network bent-pipe architecture
with a constellation of satellites that takes advantage of inter-satellite links to provide
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full coverage of low Earth orbits with only one ground station.
Thesis Supervisor: Prof. Edward F. Crawley
Title: Professor of Aeronautics and Astronautics and Engineering Systems
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Acknowledgments
This thesis is the result of two amazing year of collaborative work in the System
Architecture Lab. I want to first thank Dani, Bruce and Ed for all their support and
valuable insights. Neither the work that I have done, nor the passion I have put into
it would have been possible without your guidance, help and encouragement. I have
really enjoyed every moment that we have shared, be it at MIT or somewhere else in
our numerous trips.
I also want to acknowledge all my other friends in the lab - Peter, Morgan, In˜igo,
Alessandro, Francisco, Alexander and John -, in 409 - Patricia, Paul, Narek, Sreeja,
Sydney, and Ioana - and around campus - Ana, Hector, Alexandra, Roberto, Fer-
nando, Ada, Carlos. You are a fundamental part of what it means for me to be
at MIT and Boston, and I can hardly imagine going through these past two years
without you. For those of you who are leaving us, all the best of luck in your future
endeavors, you will be very much missed!
Thanks to Jim Schier, Bernie Seery, Antonios Seas, Greg Heckler and David
Milliner. It has been a pleasure to work side by side with you as part of the SCaN
program.
Romina, you have been the best source of support and affection that I could have
everwishedfor. Theselasteightmonthshavebeenamixofgreatmoments, incredible
experiences and unforgettable memories.
Finally, I would like to thank my family and in particular my mother. You have
always encouraged me to be ambitious, curious and hardworking, and this has been
key to the success of this thesis and all previous accomplishments I might have had.
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Contents
1 Introduction 13
1.1 Background and motivation . . . . . . . . . . . . . . . . . . . . . . . 13
1.1.1 History of NASA’s space communication networks . . . . . . . 13
1.1.2 Motivation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
1.2 System Architecture . . . . . . . . . . . . . . . . . . . . . . . . . . . 16
1.2.1 Tools for System Architecture . . . . . . . . . . . . . . . . . . 18
1.3 Generic problem statement . . . . . . . . . . . . . . . . . . . . . . . . 19
1.4 Architecting space communication networks . . . . . . . . . . . . . . 20
1.4.1 Network simulators . . . . . . . . . . . . . . . . . . . . . . . . 21
1.4.2 Point designs . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
1.4.3 Architecture studies . . . . . . . . . . . . . . . . . . . . . . . 23
1.4.4 Tradespace exploration . . . . . . . . . . . . . . . . . . . . . . 24
1.5 Specific problem statement . . . . . . . . . . . . . . . . . . . . . . . . 25
1.6 Thesis overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
2 The Space Network Architecting Tool 27
2.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27
2.2 Decisions to architect a space communication network . . . . . . . . . 27
2.2.1 Network topology . . . . . . . . . . . . . . . . . . . . . . . . . 29
2.2.2 Business model . . . . . . . . . . . . . . . . . . . . . . . . . . 30
2.2.3 Network technology . . . . . . . . . . . . . . . . . . . . . . . . 32
2.3 SNAT architectural decisions . . . . . . . . . . . . . . . . . . . . . . . 33
2.4 Model overview . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 35
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2.5 Model description . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 37
2.5.1 The VASSAR framework . . . . . . . . . . . . . . . . . . . . . 38
2.5.2 Space and ground segment design . . . . . . . . . . . . . . . . 39
2.5.3 Network evaluator . . . . . . . . . . . . . . . . . . . . . . . . 47
2.5.4 Cost estimation . . . . . . . . . . . . . . . . . . . . . . . . . . 59
2.5.5 Search engine . . . . . . . . . . . . . . . . . . . . . . . . . . . 65
3 Validation of SNAT 67
3.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67
3.2 Validation strategy for the performance model . . . . . . . . . . . . . 68
3.3 Validation of the performance model . . . . . . . . . . . . . . . . . . 68
3.3.1 Dataset description . . . . . . . . . . . . . . . . . . . . . . . . 68
3.3.2 Definition of network metrics . . . . . . . . . . . . . . . . . . 70
3.3.3 Analysis of TDRSS operational data . . . . . . . . . . . . . . 72
3.3.4 Validation of the scheduling algorithm . . . . . . . . . . . . . 81
3.4 Validation of the spacecraft design algorithm . . . . . . . . . . . . . . 84
3.5 Validation of the cost model . . . . . . . . . . . . . . . . . . . . . . . 85
3.6 Tradespace validation . . . . . . . . . . . . . . . . . . . . . . . . . . . 86
4 Evolving NASA’s Space Network 89
4.1 Introduction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 89
4.2 Network customer characterization . . . . . . . . . . . . . . . . . . . 89
4.3 Case study 1: Valuation of new technology and hosted payloads . . . 92
4.3.1 Tradespace definition . . . . . . . . . . . . . . . . . . . . . . . 92
4.3.2 Results: Infusion of new RF and optical technology . . . . . . 95
4.3.3 Results: Procurement vs. hosted payloads . . . . . . . . . . . 98
4.4 Case study 2: Valuation of inter-satellite links . . . . . . . . . . . . . 101
4.4.1 Tradespace definition . . . . . . . . . . . . . . . . . . . . . . . 101
4.4.2 Results . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 103
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5 Conclusions 109
5.1 Thesis summary . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 109
5.2 Main contributions . . . . . . . . . . . . . . . . . . . . . . . . . . . . 111
5.2.1 Methodological and modeling contributions . . . . . . . . . . . 111
5.2.2 Findings from the case studies . . . . . . . . . . . . . . . . . . 112
5.3 Future work . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 114
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