Exploration Architecture – RFI White Paper Response
MIT Space Systems Architecture Group 20 May, 2004
The Massachusetts Institute of Technology Department of Aeronautics and Astronautics has for much of the past year been carrying out research for NASA’s Space Architect Office, aimed at applying modern techniques of systems architecting to the problem of developing a new space transportation system to support the Space Exploration Vision. During the spring of 2004, the Graduate Space Systems Design course was devoted to this endeavor. The class, composed of 19 students from the Aero/Astro, Mechanical and Electrical Engineering Departments and the Engineering Systems Division, produced a substantial report on this subject, entitled, “Paradigm Shift in Design for NASA’s New Exploration Initiative”.
This report addressed in considerable detail many “Focus Areas” mentioned in the Request for Information recently issued by NASA’s Office of Exploration Systems (Code T). We feel that the report, containing over 250 pages, is too long to constitute an appropriate direct response to the RFI. However, believing that the work done by the class has significant value in the search for an appropriate architecture in which to frame the design of individual exploration hardware elements, we have taken several steps to make the results accessible.
First, we are submitting as a formal white paper the 25-page executive summary of the document. The first part of this summary deals with the two elements we feel are the most significant contributions to the overall conception of the problem: an examination of the nature of sustainability and a recasting of the exploration paradigm as the creation and transmission of new knowledge. We believe that using sustainability and knowledge creation/transmission as evaluation criteria gives us powerful tools to compare the effectiveness of alternative architectures. The second part of the summary presents details of a baseline systems architecture which we developed to evaluate individual architectural elements and search for commonality among in-space, lunar and Mars missions. The interplay of an architectural system with its component parts is an iterative process, but in the confines of a single semester we only had time to go through a single iteration. Therefore the actual descriptions of the hardware are less significant at this point than the explanations of the design processes and tools which we used for the analysis, which are described in the last part of the summary.
In addition to submitting the executive summary, we have posted the entire report on the web (http://web.mit.edu/spacearchitects/1689report.htm). We have developed a table showing the correlation of various parts of the report with the focus areas and sub-areas listed in the RFI, so that anyone interesting in looking more closely at this work can easily navigate the document to find areas of specific interest. The table is included as part of this white paper.
In closing this cover letter, we want to emphasize the importance of designing all the hardware elements of the new space exploration system in the context of a sustainable, overreaching architecture, always taking into account how the system will support the ability to generate and transmit new knowledge as exploration proceeds. We believe that continued research into space systems architecture must accompany the development of new hardware if the space exploration vision is to be realized.
Correlation Table for Full Report
Focus Area / Subtopic / Description / LinkDesign Principles, Objectives and Guidelines / Sustainability / Sustainability described, along with types. Extensibility described, operators explained as method for describing system evolution over time. Antarctic exploration as an example of sustainability. Design process presented for sustainable systems. / Chapter 2: Intro to Sustainability
Effectiveness / The key to an effective exploration system is the identification and fulfillment of the system’s primary purpose, knowledge delivery. Knowledge delivery is discussed in terms of types, carriers and drivers. Data from the Apollo program is presented. / Chapter 3: Knowledge Delivery
Crosscutting Design Drivers and Architecture Elements / Mission Model/Utilization Assumptions / A potential mission strategy is staged deployment. Short duration Moon missions lead to intermediate and longer-stay missions with increasingly ambitious objectives. A similar strategy is proposed for Mars. A manned Phobos mission could serve to decouple long duration spaceflight technology from Martian landing. / Chapter 4: Baseline Mission Designs
Commonality:
In-Space and Lunar Surface
Mars and Lunar Missions / Commonality has been addressed through separation of the in-space transport function from launch and landing. Initial Moon, Mars and LEO requirements were understood and then compared across missions. / Direct Discussion:
Chapter 5: Commonality
Supporting information:
Chapter 4: Baseline Mission Designs
Section 6.4: Trades
Payloads / A brief discussion of the benefits of separation of human and cargo transport is provided. Pre-positioning of cargo using low thrust/high ISP propulsion will be a key strategy, leading to mass reduction. / Section 4.4: Transport
Additional information:
Section 6.4: Trades
CEV and Other System Concept Options and Variations / Important considerations for CEV architecture include entry-descent-landing (EDL) and interfacing with lunar propulsion stages. The trade space includes capsules, blunt bodies and lifting bodies. Provides high-level inputs into CEV studies. / Section 6.4: Trades
Additional Information in the Appendix:
Section 9.1.1:CEVModel
Program Management, Acquisition, and Interfaces / Requirements Formulation and Evolution / There are two important points to be made regarding requirements definition:
1. Requirements must come from knowledge delivery, not mass transport requirements alone. 2. Flexibility must explicitly be accommodated in order to track changing needs. / Chapter 3: Knowledge Delivery
Public Outreach and Engagement / Public outreach cannot be an afterthought, but must be considered as the main mechanism that delivers value to the public. We distinguish between news and knowledge. / Chapter 3: Knowledge Delivery
Contact Information:
All investigators are members of MIT’s Department of Aeronautics and Astronautics and Engineering Systems Division.
Address: MIT; 77 Massachusetts Avenue; Cambridge, MA 02139
Principal Investigator:
Professor Edward F. Crawley 33-413; 617-253-7510;
Co-Investigators:
Professor Oliver L. de Weck 33-410; 617-253-0255;
Professor Jeffrey A. Hoffman 37-227; 617-452-2353;
Professor Dava J. Newman 37-307; 617-258-8799;
16.89/ESD.352 Graduate Space Systems Design Class:
Sophie Adenot, Julie Arnold, Ryan Boas, David Broniatowski, Sandro Catanzaro, Jessica Edmonds, Alexa Figgess, Rikin Ghandi, Chris Hynes, Dan Kwon, Andrew Long, José Lopez-Urdiales, Devon Manz, Bill Nadir, Geoffrey Reber, Matt Richards, Matt Silver, Ben Solish, Christine Taylor
Paradigm Shift in Design for NASA’s New
Space Exploration Vision
16.89 Space Systems Engineering Final Report
Massachusetts Institute of Technology, May 12, 2004
Executive Summary
Table of Contents
Introduction 6
Sustainability 6
Knowledge 8
Proposed Design Process 11
Application of the Design Process 13
Lunar Mission Baselines 15
Mars Mission Baselines 17
Form/Function Mapping and Commonality 19
Analysis 21
Integrated Baseline 23
Strategy Development Tools – Scenario Planning 26
Conclusions 30
Appendix: Table of Acronyms 31
Introduction
On January 14, 2004, President George W. Bush presented the nation with a bold new space exploration initiative. NASA has been given the task of developing the program, which will take humans back to the Moon by 2020, to Mars, and beyond. The directive raises two important questions for space systems design: First, given the extended life cycle of the project, how can one architect a space exploration system to accomplish the directive in a sustainable fashion? Second, what measures should be used to evaluate the performance and effectiveness of a sustainable exploration system? The following report, based on the work of the 2004 MIT spring graduate course in Space Systems Design, addresses these questions. It presents a method for taking sustainability into account during the conceptual design of a space system, and uses it to design a preliminary exploration system architecture. In answering the second question, the report argues that the primary purpose of an exploration system is the delivery of knowledge to the stakeholders. Effectiveness and performance are thus intimately related with the acquisition, synthesis and delivery of knowledge both in space and on the Earth.
Sustainability
What is a sustainable exploration program? To “sustain” means literally: to maintain in existence, to provide for, to support from below. At the programmatic level, an exploration system will be maintained in existence so long as it is funded, and it will be funded provided it meets the needs of key stakeholders, members of Congress, the Administration, and ultimately the American people. Realistically, however, system designers must recognize that these needs themselves will change. A multi-year, multi-billion dollar program in the US Government must expect to face a great deal of uncertainty with respect to objectives, budget allocations, and technical performance.
In order for an exploration system to be sustainable, then, it must be able to operate in an environment of considerable uncertainty throughout its life cycle. Traditional engineering definitions of sustainability are often limited to the physical and technical realms, defining sustainability in terms of physical operation over a long period of time. Space systems, however, are subject to influences from several realms, including policy decisions, budgetary uncertainty, organizational changes and the more traditional technical and supply chain issues that are incorporated into most engineering definitions of sustainability. It is important to recognize that threats to the sustained operation of a space system may not only come from these realms, but from the interactions between them. For example, a policy decision change may mandate a technical change that is responsible for the system’s ultimate failure to survive. Thus, different forms of sustainability may interact with one another and form a cyclic relationship between the policy, organizational, technical and operational realms.
Designing for sustainability thus implies identifying various sources of uncertainty, and managing them through up-front system attributes. Various terms have been used to describe such system attributes, including: flexibility, robustness, and extensibility.
While a large complex system must react to changing environments in order to be sustainable, technological aspects of systems can themselves impact the environment. Once in development and operation, a multi-billion-dollar system will mediate political interests, organizational decisions, and technical alternatives, creating potential sources of stability and positive feedback loops, as well as sources of uncertainty. Early decisions that create high switching costs or large infrastructure sites, can “lock-in” architectural configurations and influence the objectives and development path of later systems. A sustainable design will be one in which, to the greatest extent possible, the dynamics behind political, technical, and financial sources of stability support, rather than hinder, system development and operations.
There are two different sustainability design concepts that may be used to increase the length of a system’s lifecycle. At one extreme is robustness. A robust system is one that is designed to be able to withstand changes in its environment with minimal redesign. Unfortunately, this method is limited when designing for extreme uncertainties, since one may never know what factors it may be required to be robust to. At the other extreme lies flexibility. This design methodology encourages changes within a system so that it may adapt and evolve to meet the constraints imposed by the different environments in which it will operate. One element of flexibility that is particularly relevant to the creation of a long-term space exploration infrastructure is extensibility. Extensibility is the capability of a system to evolve or adapt through time such that it is better able to meet the needs of the key stakeholders. Unlike a point design, which is optimal for one point in time only, an extensible system is created such that it is able to change and evolve in the face of future environmental uncertainty. Often, creating an extensible system will require some additional up-front cost so as to reduce expected cost over the system’s life cycle. An extensible space exploration system is one that will continue to deliver knowledge to the stakeholders, even in the face of unfavorable policy, organizational and budgetary changes, while also successfully incorporating most of the benefits of changes in these and breakthroughs in the technical realm. Extensible systems are therefore sustainable by their very nature, because of their ability to evolve through time, thus increasing the chances that such systems will not become useless or prohibitively expensive to operate.
Examples of space systems architectures that are not sustainable include the Apollo program, which was not able to successfully scale down operations following budget cuts in 1972, and the Space Transportation System’s Space Shuttle, which is both costly and difficult to upgrade and refurbish due to its inflexibility in the face of new technologies. Neither of these systems were designed with extensibility in mind; a design decision that led to the Apollo program’s eventual demise. On the other hand, an example of a sustainable program may be found in the Antarctic exploration program, even though it was never designed with sustainability explicitly in mind.
The successful evolution of Antarctic exploration may be attributed to the fortuitous interplay of many factors, which converged to begin the Modern Age of Antarctic exploration in 1928. Previous to this time period, the Heroic Age of Antarctic exploration occurred, in which most exploration was limited to the coastal areas of the continent and was severely limited by inclement weather patterns and the numerous ice floes and pack ice, which limited naval access to interesting sites. Although the invention of steel-hulled ships and icebreakers helped somewhat, exploration was still very limited. The Modern Age of Antarctic exploration began upon the widespread use of the airplane and the radio, both inventions that had been extant for about 25 years prior to the commencement of the Modern Age. Another major enabler for Antarctic exploration was the political support from numerous countries, many of which wanted to use the new capabilities delivered by the airplane and the radio to stake a claim to Antarctic territory before other countries could. Thus, the true commencement of the Modern Age may be attributed to interplay between technological, political and geo-political factors. With recent events, including the President’s speech on January 14th, 2004, the recent discovery of the previous existence of Martian water, and the commencement of China’s new human space flight program, the political, organizational, scientific and technological environments are now ripe for a paradigm shift in the approach to sustainable space exploration. This paradigm shift comes in the form of recognition that the primary purpose of exploration is knowledge return.