^[1]

J.F. Kennedy, “Special Message to the Congress on Urgent National Needs.” Speech delivered in person before a joint session of Congress, May 25, 1961.

^[2]See I.D. Ertel, M.L. Morse, J.K. Bays, C.G. Brooks, and R.W. Newkirk, The Apollo Spacecraft: A Chronology, Vol IV, NASA SP-4009 (Washington, DC: NASA, 1978) or R.C. Seamans Jr., Aiming at Targets: The Autobiography of Robert C. Seamans Jr. (University Press of the Pacific, 2004).

^[3]T. Hill, “Decision Point,” The Space Review, November 2004.

^[4]J.R. Hansen, Spaceflight Revolution: NASA Langley Research Center from Sputnik to Apollo, NASA SP-4308 (Washington, DC: NASA, 1995).

^[5]W. von Braun, F.L. Whipple, and W. Ley, Conquest of the Moon (Viking Press, 1953).

^[6]J.C. Houbolt, “Problems and Potentialities of Space Rendezvous,” Space Flight and Re-Entry ­Trajectories. International Symposium Organized by the International Academy of Astronautics of the IAF Louveciennes, June 19–21, 1961, Proceedings, 1961, pp. 406–429.

^[7]W.J. Larson and J.R. Wertz, eds., Space Mission Analysis and Design (Microcosm, 1999).

^[8]V.A. Chobotov, ed., Orbital Mechanics (AIAA, 2002).

^[9]J.C. Houbolt, Manned Lunar-landing through Use of Lunar-Orbit Rendezvous, NASA TM-74736, (Washington, DC: NASA, 1961).

^[10]J.R. Hansen, Enchanted Rendezvous, Monographs in Aerospace History Series 4 (Washington, DC: NASA, 1999).

^[11]C. Murray and C.B. Cox, Apollo (South Mountain Books, 2004).

^[12]J.N. Wilford, “Russians Finally Admit They Lost Race to Moon,” New York Times, December 1989.

^[13]Hoffman, R. R., “Decision Making: Human-Centered Computing,” IEEE Intelligent Systems, vol. 20, 2005, pp. 76–83.

^[14]“Decision,” American Heritage Dictionary of the English Language, 2004.

^[15]S.O. Hansson, Decision Theory: A Brief Introduction (KTH Stockholm, 1994).

^[16]H.A. Simon, The New Science of Management Decision. The Ford Distinguished Lectures, Vol. 3, (New York: Harper & Brothers, 1960).

^[17]E. Turban and J.E. Aronson, Decision Support Systems and Intelligent Systems (Prentice Hall, 2000).

^[18]C. Barnhart, F. Lu, and R. Shenoi, R., “Integrated Airline Schedule Planning,” Operations Research in the Airline Industry, Vol. 9, Springer US (1998), pp. 384–403.

^[19]C. Alexander, A Pattern Language: Towns, Buildings, Construction (Oxford University Press, 1977).

^[20]D. Power, Decision Support Systems: Concepts and Resources for Managers (Greenwood Publishing Group, 2002), pp. 1–251; R.H. Bonczek, C.W. Holsapple, and A.B. Whinston Foundations of Decision Support Systems (Academic Press, 1981); and E. Turban, J.E. Aronson, and T.-P. Liang, Decision Support Systems and Intelligent Systems (Upper Saddle River, NJ: Prentice Hall, 2005).

^[21]J. Banks, J.S. Carson II, B.L. Nelson, and D.M. Nicol, Discrete-Event System Simulation (Prentice Hall, 2009), pp. 1–640 and B.P. Zeigler, H. Praehofer, and T.G. Kim, Theory of Modeling and Simulation (Academic Press, 2000), pp. 1–510.

^[22]F. Zwicky, Discovery, Invention, Research through the Morphological Approach (Macmillan, 1969).

^[23]G. Pahl and W. Beitz, Engineering Design: A Systematic Approach (Springer, 1995), pp. 1–580; D.M. Buede, The Engineering Design of Systems: Models and ­Methods (Wiley, 2009), pp. 1–536; and C. Dickerson and D.N. Mavris, Architecture and Principles of Systems Engineering (Auerbach Publications, 2009) pp. 1–496. See also T. Ritchey, “Problem Structuring Using Computer-aided Morphological Analysis,” Journal of the Operational Research Society 57 (2006): 792–801.

^[24]D.V. Steward, “The Design Structure System: A Method for Managing the Design of Complex ­Systems,” IEEE Transactions on Engineering Management 28 (1981): 71–74.

^[25]S.D. Eppinger and T.R. Browning, Design Structure Matrix Methods and Applications cambridge. MA: The MIT Press, 2012), pp. 1–352.

^[26]Multi-attribute utility theory was developed by economists Keeney and Raifa in the seventies. See: R.L. Keeney and H. Raiffa, Decisions with Multiple Objectives: Preferences and Value Trade-Offs (New York: Wiley, 1976), p. 592. Since then, it has been widely applied in systems engineering. See also: A.M. Ross, D.E. Hastings, J.M. Warmkessel, and N.P. Diller, “Multi-Attribute Tradespace Exploration as Front End for Effective Space System Design,” Journal of Spacecraft and Rockets 41, no. 1 (2004): 20–28.

^[27]An example of the application of this algorithm can be found in C.W. Kirkwood, “An Algebraic Approach to Formulating and Solving Large Models for Sequential Decisions under Uncertainty,” Management Science 39, no. 7 (1993): 900–913.

^[28]Alternative tools for dealing with ambiguity include again fuzzy sets, or simple interval analysis. See, for example, J. Fortin, D. Dubois, and H. Fargier, “Gradual Numbers and Their Application to Fuzzy Interval Analysis,” IEEE Transactions on Fuzzy Systems 16, no. 2 (2008): 388–402. An application of interval analysis to system architecture appears in D. Selva and E. Crawley, “VASSAR: Value Assessment of System Architectures Using Rules,” in Aerospace Conference, 2013 at Big Sky.

^[29]Note that categorical variables are often implemented as integer variables in optimization problems, but that does not make them discrete variables. One cannot define a gradient-like concept in categorical variables unless some meaningful distance metric is defined within the discrete set of abstractions, which is often not trivial.

^[30]The foundational paper on multi-attribute utility theory is R.L. Keeney and H. Raiffa, Decisions with Multiple Objectives: Preferences and Value Trade-Offs (New York: Wiley, 1976), p. 592, and an example of a recent application to system architecture can be found in A.M. Ross, D.E. Hastings, J.M. Warmkessel, and N.P. Diller, “Multi-Attribute Tradespace Exploration as Front End for Effective Space System Design,” Journal of Spacecraft and Rockets 41, no. 1 (2004): 20–28. Concerning fuzzy sets, the foundational paper is L.A. Zadeh, “Fuzzy Sets,” Information and Control 8, no. 3 (1965): 338–353. An application to conceptual design can be found in J. Wang, “Ranking Engineering Design Concepts Using a Fuzzy Outranking Preference Model,” Fuzzy Sets and Systems 119, no. 1 (2001): 161–170.

^[31]See, for example, Koo’s development of the Object Process Network meta-language for systems architecture, focusing on the simulating layer: B.H.Y. Koo, W.L. Simmons, and E.F. Crawley, “Algebra of Systems: A Metalanguage for Model Synthesis and Evaluation,” IEEE Transactions on Systems, Man, and Cybernetics–Part A: Systems and Humans 39, no. 3 (2009): 501–513. Simmons’s Architecture Decision Graph is a related tool that focuses on the structuring layer: W.L. Simmons, “A Framework for Decision Support in Systems Architecting” (PhD dissertation, Massachusetts Institute of Technology). Selva’s VASSAR methodology is a third example, focusing on the structuring and simulating layers: D. Selva and E. Crawley, “VASSAR: Value Assessment of System Architectures using Rules,” in Aerospace Conference, 2013 at Big Sky.