Appendix C

Cost and Technical Evaluation of Priority Missions

BACKGROUND

Concerns have been voiced for some time about the accuracy of the mission cost estimates used in past decadal studies. A National Research Council (NRC) report published in 2006 concluded that “major missions in space and Earth science are being executed at costs well in excess of the costs estimated at the time when the missions were recommended in the National Research Council’s decadal surveys for their disciplines. Consequently, the orderly planning process that has served the space and Earth science communities well has been disrupted, and balance among large, medium, and small missions has been difficult to maintain.”1 In response to this concern, the same report recommended that “NASA should undertake independent, systematic, and comprehensive evaluations of the cost-to-complete of each of its space and Earth science missions that are under development, for the purpose of determining the adequacy of budget and schedule.”2

An extended discussion of cost estimates and of the technology readiness of candidate missions took place during a subsequent NRC workshop concerning lessons learned from past decadal surveys. Workshop participants found that cost and technology readiness evaluations that were conducted independently of NASA estimates would add value to the surveys. They also suggested that uniform cost-estimating methods should be used within a given survey to facilitate cost comparisons among initiatives.3

With this guidance in hand, NASA called for an independent evaluation of cost and technology readiness in the statement of task for the NRC assessment of the agency’s Beyond Einstein program.4 Finally, in an act codifying the decadal surveys, Congress mandated that the NRC “include independent estimates of the life cycle costs and technical readiness of missions assessed in the decadal survey wherever possible.”5 Therefore, the statements of task for the most recent astronomy decadal survey,6 for this study (see Appendix A), and for the heliophysics decadal survey currently in progress all call for independent cost and technical evaluations of recommended initiatives.

THE CHALLENGE OF COST, SCHEDULE, AND TECHNICAL ESTIMATES

The mission concepts used in decadal surveys are typically in preliminary stages of development. In NASA parlance these are “pre-Phase A concepts.” Experience shows that the cost of a space mission is usually not well understood until its preliminary design review (PDR) has been completed. Even then, unexpected growth of mass, cost, and schedule can occur during the later phases of design and development. Further challenging costing is the fact that some pre-Phase A concepts are more mature than others because more resources have been devoted to



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Appendix C Cost and Technical Evaluation of Priority Missions BACKGROUND Concerns have been voiced for some time about the accuracy of the mission cost estimates used in past decadal studies. A National Research Council (NRC) report published in 2006 concluded that “major missions in space and Earth science are being executed at costs well in excess of the costs estimated at the time when the missions were recommended in the National Research Council’s decadal surveys for their disciplines. Consequently, the orderly planning process that has served the space and Earth science communities well has been disrupted, and balance among large, medium, and small missions has been difficult to maintain.”1 In response to this concern, the same report recommended that “NASA should undertake independent, systematic, and comprehensive evaluations of the cost-to-complete of each of its space and Earth science missions that are under development, for the purpose of determining the adequacy of budget and schedule.”2 An extended discussion of cost estimates and of the technology readiness of candidate missions took place during a subsequent NRC workshop concerning lessons learned from past decadal surveys. Workshop participants found that cost and technology readiness evaluations that were conducted independently of NASA estimates would add value to the surveys. They also suggested that uniform cost-estimating methods should be used within a given survey to facilitate cost comparisons among initiatives.3 With this guidance in hand, NASA called for an independent evaluation of cost and technology readiness in the statement of task for the NRC assessment of the agency’s Beyond Einstein program. 4 Finally, in an act codifying the decadal surveys, Congress mandated that the NRC “include independent estimates of the life cycle costs and technical readiness of missions assessed in the decadal survey wherever possible.”5 Therefore, the statements of task for the most recent astronomy decadal survey,6 for this study (see Appendix A), and for the heliophysics decadal survey currently in progress all call for independent cost and technical evaluations of recommended initiatives. THE CHALLENGE OF COST, SCHEDULE, AND TECHNICAL ESTIMATES The mission concepts used in decadal surveys are typically in preliminary stages of development. In NASA parlance these are “pre-Phase A concepts.” Experience shows that the cost of a space mission is usually not well understood until its preliminary design review (PDR) has been completed. Even then, unexpected growth of mass, cost, and schedule can occur during the later phases of design and development. Further challenging costing is the fact that some pre-Phase A concepts are more mature than others because more resources have been devoted to 331

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332 VISION AND VOYAGES FOR PLANETARY SCIENCE their formulation. Accordingly, ensuring that a costing exercise is level and fair requires that the relative maturity of concepts be taken into account. Several different types of cost, schedule, and technical risk evaluations are used when discussing spacecraft missions. The best known are the so-called independent cost estimates (ICEs) and NASA’s technical, management, and cost (TMC) estimates. Less well known is the cost and technical evaluation (CATE) process. Each has its own strengths and weaknesses (Table C.1). ICEs are typically done late in the life cycle of a project after it has matured. ICEs often do not consider certain aspects of cost growth associated with design evolution in the earliest phases of a project. The objective of the CATE process is to perform a cost and technical risk analysis for a set of concepts that may have a broad range of maturity, and to ensure that the analysis is consistent, fair, and informed by historical data. Typically, a concept evaluated using the CATE process is early in its life cycle and therefore likely to undergo significant subsequent design changes. Historically, such changes have resulted in cost growth. Therefore, a robust process is required that fairly treats a concept of low maturity relative to one that has undergone several iterations and review. CATEs take into account several components of risk assessment (see Table C.1). Because the CATE is best suited to the comparative evaluation of a family of pre-Phase A concepts, it is the methodology used in this decadal survey. OVERVIEW OF THE CATE PROCESS The NRC engaged the services of the Aerospace Corporation to perform independent CATEs of mission concepts identified by the committee’s steering group during this study. Aerospace’s CATE team consisted of technical, cost, and schedule experts. The committee’s five panels identified a total of 26 missions (see the list in Appendix G) that could address key science questions within their respective purviews. To ensure that the mission concepts were sufficiently mature for subsequent evaluation by the CATE team, the committee commissioned technical studies at leading design centers, including the Jet Propulsion Laboratory, Goddard Space Flight Center, the Johns Hopkins University Applied Physics Laboratory, and Marshall Space Flight Center. The committee’s steering group selected concepts to be studied from among those recommended by the panels. One or more “science champions” drawn from the ranks of the panels were attached to each of the centers’ study teams to ensure that the concepts remained true to the scientific and measurement objectives of the originating panel. The design centers conducted two different types of studies: rapid mission architecture (RMA) studies and full mission studies. The RMA studies were conducted for immature but promising concepts for which a broad array of mission types could be evaluated in order to choose the one most promising approach. The resulting TABLE C.1 Similarities and Differences in Three Methodologies for Assessing the Technical, Cost, and Risk Characteristics of Spacecraft Missions Approach TMC ICE CATE Is approach used consistently to compare several concepts? Yes No Yes Concept cost is evaluated with respect to what? Cost cap Project budget Budget wedge Maturity of concept occurs when? Phase A-B Phase B-D Pre-Phase A Does the evaluation process include: Quantified schedule growth cost threat? No Typically Yes Quantified design growth cost threat? No No Yes Cost threat for increase in launch vehicle capability? No No Yes Independent estimates for non-U.S. contributions? No No Yes Reconciliation performed with project team? No Yes No Technical and cost risk rating (low, medium, high)? Yes No Yes NOTE: TMC, technical, management, and cost; ICE, independent cost estimate; CATE, cost and technical evaluation.

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333 APPENDIX C “point design” could then be subjected to a full mission study along with more mature concepts. Not all missions receiving RMA studies were selected by the steering group for full mission studies. Nor were all full mission studies selected for CATEs. Prior to concepts being submitted to the CATE contractor, significant evaluations of trade-offs were conducted, led by panel science champions, to initially determine the science value or science return for an initial cost estimate as determined by the relevant design center. It was understood that these numbers were rough orders of magnitude. In some cases, a down-selection was made between two planetary bodies (Uranus and Neptune as an example), and then more detailed work was performed prior to submission of the concept to the CATE contractor for evaluation. A key aspect of the CATE process is that there were multiple interactions between the committee and the CATE contractor. For at least four concepts, the CATE contractor was redirected to consider alternative solutions, as defined by the committee, that would lower cost and risk but maintain science return. This last step or itera- tion was considered confidential to the committee; it was deemed unnecessary for NASA to participate in these iterations in view of the experience of the committee members and the experience and knowledge of the CATE contractor. The committee believes that this iterative process ensured a tighter correspondence between science priorities and prioritized missions. The 13 most promising full mission studies were identified by the steering group and passed to the CATE team for detailed technical, cost, and schedule assessments. These “priority missions” are listed below in the section titled “CATE Results for Priority Missions.” When follow-up was required, the CATE team worked with the appropriate science champion to request additional information. The members of the CATE team worked interactively to deter- mine an initial assessment of technical risk and cost and schedule estimates for each of the 13 priority missions. (Two of these 13 missions have a two-part assessment: Mars Astrobiology Explorer-Cacher and Mars Astrobiology Explorer-Cacher Descope, and Uranus Orbiter and Probe with Solar-Electric Propulsion [SEP] and Uranus Orbiter and Probe with No SEP.) The CATE team strove, to the greatest extent possible, to be consistent across all concepts presented. In particular, recognizing that the design center that studied the mission might not be the one that ulti- mately implements it, the CATE process made no assumptions about what would be the implementing organization. Following an initial internal review within the Aerospace Corporation to ensure that the 13 assessments were mutually consistent, the results were presented to the committee. The committee provided feedback to the CATE team, which in turn, incorporated this feedback into revised technical, cost, and schedule risk assessments. The CATE team’s approach (Figure C.1) is based on the following principles: • Use multiple methods and databases relating to past space systems so that no one model or database biases the results. The CATE team used proprietary Aerospace Corporation models (e.g., the Small Satellite Cost Model) and space-industry standards (e.g., the NASA/Air Force Cost Model [NAFCOM]). • Use analogy-based estimating; tie costs and schedule estimates to NASA systems that have already been built and that thus have a known cost and schedule. • Use both system-level estimates as well as build-up-to-system-level estimates by appropriately summing subsystem data so as not to underestimate system cost and complexity. • Use cross-checking tools, such as Complexity Based Risk Assessment (CoBRA), to cross-check cost and schedule estimates for internal consistency and risk assessment. • In an integrated fashion, quantify the total threats to costs from schedule growth, the costs of maturing technology, and the threat of costs owing to mass growth resulting in the need for a larger, more costly launch vehicle. In summary, an analogy-based methodology ties the estimated costs of future systems to the known cost of systems that have been built. In other words, it provides an independent estimate of the cost and complexity of new concepts anchored with respect to previously built hardware. The use of multiple methods such as analogies and standard cost models ensures that no one model or database biases the estimate. The use of system-level estimates and arriving at total estimated costs by statistically summing the costs of all individual work breakdown structure elements ensures that elements are not omitted and that the system-level complexity is properly represented in the cost estimate.

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334 VISION AND VOYAGES FOR PLANETARY SCIENCE FIGURE C.1 Schematic illustration of the flow of the Aerospace Corporation’s cost and technical evaluation (CATE) process. The blocks in green indicate interaction by the CATE team with the committee. The assessments of technology, cost, and schedule are inextricably intertwined. However, it is easier to describe each element of the overall assessment (e.g., technical, schedule, and cost) separately, noting in each instance the linkages to the overall CATE assessment. Technical Assessment The evaluation of technical risk and maturity in the CATE process focuses on the identification of the technical risks most important to achieving the required mission performance and stated science objectives. The assessment is limited to top-level technical maturity and risk discussions. Deviations from the current state of the art as well as system complexity, operational complexity, and integration concerns associated with the use of heritage components are identified. Technical maturity and the need for specific technology development, including readiness levels of key technologies and hardware, are evaluated by the CATE technical subgroup. During the assessment of the technical risk areas and concept maturity, the technical subgroup interacted with the cost and schedule subgroups so that technical risks could be translated into schedule and cost risk. The CATE technical evaluation is limited to high-level technical risks that potentially impact schedule and cost. The CATE process places no cost cap on mission concepts, and hence risk as a function of cost is not considered. Concept maturity and technical risk are evaluated in terms of the ability of a concept to meet performance goals within proposed launch dates with adequate mass, power, and performance margins. CATEs also evaluate proposed mass and power contingencies with respect to technical maturity. If the CATE technical subgroup concludes that these contingencies are insufficient, the contingencies are increased on the basis of historical data on mass and power growth. In some cases, growth in mass and power requirements necessitate the use of larger launch vehicles to execute the scientific mission. The assessments of required mass and power

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335 APPENDIX C increases—and the potential needs for more capable launch vehicles—are provided to the CATE cost and schedule experts for incorporation in their estimates. Schedule Estimates To aid in the assessment of concept risk, independent schedule estimates are incorporated as part of the CATE cost estimate. This is especially true for the assessment of risk with respect to proposed mission development and execution timelines. Like the CATE assessment of cost risk, schedule risk is also derived from analogies in the historical NASA record. Historical data from past analogous NASA missions, properly adjusted, are used to gauge the realism of the proposed durations of the development phases. Similarly, the time to critical mission reviews (e.g., PDR and critical design review [CDR]) and the time required for integration and testing are evalu- ated for each mission concept and contrasted with appropriate historical experience. Statistical analysis is utilized to create a schedule probability “S curve”—that is, a curve of the probability that a development time will exceed some value as a function of that value. The overall schedule, as proposed, is then adjusted with the historical data in mind. The independent schedule estimates are not tied to specific launch windows because the start dates for the concepts can be adjusted and because launch dates can usually be met by additional application of resources (e.g., double-shifting). If the schedule estimate predicted a launch date between launch windows, the cost of additional resources is used in the independent cost estimate. However, for concepts at this early stage of formu- lation, adding to the schedule in order to accommodate a future available launch window is not warranted. Costs incurred because the original schedule cannot be met are then added to the total cost of the mission. The committee requested that the CATE team use the 70th percentile value in its schedule estimate—i.e., there is a 70 percent probability that the schedule will be shorter than indicated and a 30 percent probability that it will be longer. Cost Appraisal The primary goal of the CATE cost appraisal is to provide independent estimates (in fiscal year [FY] 2015 dollars) that can be used to prioritize various concepts within the context of the expected NASA budgetary con- straints for the coming decade (see Appendix E). The CATE team developed high-level cost estimates based on the information provided by the various mission study teams with a focus on treating all projects equally. To be consistent for all concepts, the CATE cost process allows an increase in cost resulting from increased contingency mass and power, increased schedule, increased required launch vehicle capability, and other cost threats depending on the concept maturity and specific risk assessment of a particular concept. All cost appraisals for the CATE process are probabilistic in nature and are based on the NASA historical record and documented project life-cycle growth studies. Traditional S curves of cost probability versus cost are provided for each concept, with both the design center’s estimate and the CATE estimate at the 70th percentile requested by the committee indicated. The focus of the CATE costing process is to estimate the cost of conceptual hardware—for example, instru- ments, spacecraft bus, landers—using multiple analogies and cost models based on historical data. A probabi- listic cost-risk analysis is employed to estimate appropriate cost reserves. Ensuring consistency across the range of concepts—from those that are immature to those that are significantly more mature—the cost estimates are updated and adjusted with information from the CATE team’s technical subgroup with respect to mass and power contingencies, and potentially required additional launch vehicle capability. Using independent schedule estimates, costs are adjusted using appropriate “burn rates” to properly reflect the impact of schedule changes. Finally, the results are integrated, cross-checked with other independent cost- and schedule-estimating capa- bilities, and verified for consistency before being presented to the committee (Figure C.2). Complexity-Based Risk Assessment Comparisons The cost and schedule estimates for the committee’s priority missions are compared to historical experience by plotting cost and schedule as a function of the estimated complexity of the mission—resulting in a CoBRA

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336 VISION AND VOYAGES FOR PLANETARY SCIENCE FIGURE C.2 Schematic illustration of the process of developing cost versus cumulative risk probability S curve for a notional mission. The terms MICM and NICM in the upper-left quadrant refer to NASA-developed instrument cost models. FIGURE C.3 Complexity Based Risk Assessment cost analysis superimposing the cost of a notional mission on historical data of cost versus complexity. A similar analysis can be performed plotting a schedule against complexity.

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337 APPENDIX C plot (Figure C.3). Such an analysis shows the locus of a notional mission compared to the historical experience of complexity versus cost for other missions. The expectation is that a proposed mission is on the road to success if the locus of the cost (and schedule) versus complexity point lies in the vicinity of the data for successful mis- sions in the past. CATE RESULTS FOR PRIORITY MISSIONS Results for the priority missions selected by the committee and analyzed using the Aerospace Corporation’s CATE methodology are presented in Boxes C.1 through C.15 (in approximate order of the target object’s distance from the Sun). The full text of the studies for each of the missions is provided on the CD included with this report. Acronyms used in Boxes C.1 through C.15 are defined in Appendix F. Images of the missions were obtained from the respective mission studies. The missions are as follows: • Venus Climate Mission (Box C.1); • Lunar Geophysical Network (Box C.2); • Mars Astrobiology Explorer-Cacher (Box C.3); • Mars Astrobiology Explorer-Cacher Descope (Box C.4); Mars Sample Return Lander and Mars Ascent Vehicle (Box C.5);7 • Mars Sample Return Orbiter and Earth Entry Vehicle (Box C.6);8 • • Io Observer (Box C.7); • Jupiter Europa Orbiter (Box C.8); • Trojan Tour and Rendezvous (Box C.9); • Saturn Probe (Box C.10); • Titan Saturn System Mission (Box C.11); • Enceladus Orbiter (Box C.12); • Uranus Orbiter with Solar-Electric Propulsion and Probe (Box C.13); • Uranus Orbiter and Probe (No Solar-Electric Propulsion) (Box C.14); and • Comet Surface Sample Return (Box C.15). These missions were chosen by the committee on the basis of their strong science return and their potential technical readiness.

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338 VISION AND VOYAGES FOR PLANETARY SCIENCE BOX C.1  Venus Climate Mission   Carrier Spacecraft and Entry Flight System  Key Challenges    • Multiple Element Communications Architecture  High Gain Antenna   1.7 m Diameter – Critical Mini‐Probe/Dropsonde science data are relayed  Aeroshell through Gondola/Balloon to Carrier to Earth.  Support Structure – Mini‐Probe must communicate with Balloon/Gondola  during inflation process.  Reaction Wheel (4X) – It is a challenge to predict Gondola/Balloon location for  Avionics Radiator Propulsion Tank (2.85 m2) Support Structure reacquisition.  • High‐Tempo Operations near Venus Orbit Insertion (VOI)  Closeout Panel – VOI is 2 hrs prior to Entry Flight System (EFS) entry.  Solar Array = 5.0 m2 – Mini‐Probe is jettisoned minutes after EFS entry.  • T ime Elapsed Since Heritage System Development  Carrier Spacecraft  Entry Flight System – Study uses Pioneer Venus and Galileo Probe as basis for  several estimates.  • Potential for Carrier Spacecraft Instrument Growth Science Objectives  Key Cost Element Comparison  • Examine the Venus atmosphere  3.0 – Improve understanding of the current state and  Cost Threats evolution of the strong CO2 greenhouse climate  $ 2 .4 B Reserves Es�m ated Cost ( FY 15 $B) • Improve modeling of climate and global change on  Launch Vehicle 2.0 Earth‐like planets  Phase E Costs and Educa�on $ 1 .6 B and Public Outreach • Key science issues addressed:  Pre-launch Ground – Characterize the CO2 greenhouse atmosphere of Venus  Flight System – Characterize the dynamics of Venus’s superrotating  1.0 Instruments atmosphere  Project Management/Systems – Constrain surface/atmosphere chemical exchange  Engineering/Mission Assurance Phase A – Determine origin of Venus’s atmosphere  0.0 – Understand implications for climate evolution of Earth Project CATE Key Parameters  Cost Risk Analysis S Curve  • Carrier Spacecraft  100 – V isible/Infrared Imager  90 Distribu�on Cumula�ve Probability (%) • Gondola/Balloon  80 CATE es�mate – Atmospheric Structure Investigation, Nephelometer   70 Design center es�mate – Neutral Mass Spectrometer  CATE without cost threats 60 – Tunable Laser Spectrometer  50 – Net Flux Radiometer  40 • Mini‐Probe (one) and Dropsondes (two)  30 – Atmospheric Structure Investigation (All)  20 – Net Flux Radiometer (All)  10 – Neutral Mass Spectrometer (Mini‐Probe only)  0 2 • 5 m  Gimbaled Solar Array on Carrier Spacecraft  1.0 1.5 2.0 2.5 3.0 • Launch Mass:  3,984 kg Es�mated Cost ( FY 15 $B)  

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339 APPENDIX C BOX C.2  Lunar Geophysical Network  Key Challenges  Lunar Lander Network⎯Four Landers    • DACS Propulsion    – Development needed for MON‐25/MMH combustion    stability    • Mass    – Low dry‐mass contingency for this development phase    – Impact to overall mass growth multiplied by propulsion    requirements   • Reliability    – Single‐string network reliability    • Mission Operations    – High‐tempo operations for multi‐lander cruise and  landing phase  Science Objectives  Key Cost Element Comparison  • Enhance knowledge of lunar interior    $1.6 Cost Threats • Key science issues addressed:  $1.4 $ 1 .3 B Reserves – Determining lateral variations in the structure and  composition of the lunar crust, upper mantle, lower  $1.2 Launch Vehicle E s tim a te d C o s t ( F Y 1 5 $ B ) mantle, and lunar core  Phase E Costs and Educa�on and $1.0 $ 0 .9 B Public Outreach – Determining distribution and origin of lunar seismic  Pre-launch Ground $0.8 activity  Flight System – Determining the lunar global heat flow budget to  $0.6 better constrain knowledge of lunar thermal evolution  Instruments $0.4 – Determining bulk lunar composition of radioactive  Project Management/Systems Engineering/Mission Assurance heat‐producing elements  $0.2 Phase A – Determining nature and origin of lunar crustal  $0.0 magnetic field  Project CATE Key Parameters  Cost Risk Analysis S Curve    100 • Payload    Distribu�on 90 – Seismometer  CATE es�mate 80 Cumula�ve Probability (%) – Heat Flow Experiment  Design center es�mate 70 CATE without cost threats – Electromagnetic Sounder  60 – Lunar Laser Ranging  50 – Guest Payload  40 30 – Education/Public Outreach Pancam   20 • Advanced Stirling Radioisotope Generator Surface Power  10 • Launch Mass: 3,572 kg (257 kg individual lander mass)  0 • Launch Date: 2016 (on Atlas V 511)  0.5 1.0 1.5 2.0 • Direct Lunar Near‐Side Landing  Es�mated Cost ( FY 15 $B)

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340 VISION AND VOYAGES FOR PLANETARY SCIENCE BOX C.3  Mars Astrobiology Explorer‐Cacher  Caching Mars Rover  Key Challenges    • Vehicle Capabilities Beyond Mars Science Laboratory    – Terrain‐relative descent navigation and precision  landing with pallet  – Aeroshell volume to accommodate rover, European  Space Agency’s ExoMars, and pallet  – Increased rover traverse speed over MSL and MER   • Sample Handling, Encapsulation, and Containerization  (SHEC)  – Lack of maturity in SHEC subsystem  – Effect of planetary protection and sample transfer  requirements  • Mass  – Insufficient mass growth contingency for this  development phase  – Low launch margin for this development phase  Science Objectives  Key Cost Element Comparison  • Perform in situ science on Mars samples to look for    $4.0 Cost Threats evidence of ancient life or prebiotic chemistry  $ 3 .5 B • Collect, document, and package samples for future  Reserves collection and return to Earth  $3.0 Launch Vehicle Es� mat ed Cost (FY 15 $B ) • Key science issues addressed:  Phase E Costs and Educa�on and Public $ 2 .2 B Outreach – Searching for extant life on Mars  Pre-launch Ground $2.0 – Searching for evidence of past life on Mars  Flight System – Understanding martian climate history  – Determining the ages of geologic terrains on Mars  Instruments $1.0 – Understanding surface‐atmosphere interactions on  Project Management/Systems Engineering/Mission Assurance Mars  Phase A – Understanding martian interior processes   $0.0 Project CATE Key Parameters  Cost Risk Analysis S Curve  • Model Payload with Sampling/Caching System     100 – Panoramic high resolution stereo imager (on mast)  Distribu�on 90   CATE es�mate – Near‐Infrared Point Spectrometer  80 Design center es�mate Cumula�ve Probability (%) – Microscopic Imager  70 CATE without cost threats – Alpha‐Particle X‐ray Spectrometer  60 50 – Dual Wavelength Raman/Fluorescence Instrument  40 – Sample Handling, Encapsulation, and Containerization  30 (arm, corer/abrader, organic blank, handling and  20 container system)  10 • 2 x 2.2 m Diameter Ultraflex Solar Arrays   0 • Launch Mass: 4,457 kg  1.0 2.0 3.0 4.0 5.0 • Launch Date: 2018 (on Atlas V 531)  Es�mated Cost ( FY 15 $B) • Orbit:  Type I Transfer Direct to Mars Surface  – 15° S to 25° N latitude 

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341 APPENDIX C BOX C.4  Mars Astrobiology Explorer‐Cacher Descope  Key Challenges  Caching Mars Rover  • Keeping Within Mars Science Laboratory (MSL) Design    Constraints     – Potential need for modifying MSL entry and descent  system to accommodate a single rover  • Sample Handling, Encapsulation, and Containerization  (SHEC)  – Lack of maturity in SHEC subsystem  – Effect of planetary protection and sample transfer  requirements  • Increased Rover Traverse Speed over Mars Science  Laboratory and Mars Exploration Rover    Science Objectives  Key Cost Element Comparison  $3.0 • Perform in situ science on Mars samples to look for  Cost Threats evidence of ancient life or prebiotic chemistry    $ 2 .4 B Reserves • Collect, document, and package samples for future  Launch Vehicle collection and return to Earth  Es� mat ed Cost (FY 15$B ) $2.0 Phase E Costs and Educa�on and Public MAX-C Descope • Key science issues addressed:  concept cost was Outreach not estimated by Pre-launch Ground – Searching for extant life on Mars  project. Full MAX-C concept was estimated by the – Searching for evidence of past life on Mars  Flight System project at $2.2 B $1.0 – Understanding martian climate history  Instruments – Determining the ages of geologic terrains on Mars  Project Management/Systems Engineering/Mission Assurance – Understanding surface‐atmosphere interactions on  Phase A Mars  $0.0 Project CATE – Understanding martian interior processes     Key Parameters: Descope Concept  Cost Risk Analysis S Curve  • MAX‐C Rover Identical to Original Proposed Concept    100 CATE es�mate (see Box C.3)  90 CATE without cost threats • Mission Identical, Except:   80 Distribu�on Cumula�ve Probability (%) – Launch Mass:  3,421 kg  70 – Launch Vehicle:  Atlas V 521  60 50 • Descope Assumptions:  40 – No ESA ExoMars rover  30 – No landing pallet  20 – Use of heritage MSL entry and descent systems  10   0 1.0 1.5 2.0 2.5 3.0 3.5 Es�mated Cost ( FY 15 $B)

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344 VISION AND VOYAGES FOR PLANETARY SCIENCE BOX C.7  Io Observer  Io Observer Spacecraft  Key Challenges    • Radiation    – Electronics vault design  – Radiation‐tolerant electronics and detectors   • System Power  – Negative power margin when accounting for power  growth contingency  – Likely to require three Advanced Stirling Radioisotope  Generators (ASRGs) instead of two     Science Objectives  Key Cost Element Comparison  • Determine internal structure of Io and mechanisms    $1.6 Cost Threats contributing to Io’s volcanism  $ 1 .4 B $1.4 Reserves • Key science issues addressed:  $1.2 Launch Vehicle – Modeling volcanic processes on Io  $ 1 .1 B Es� mat ed Cost (FY 15 $B ) – Determining the state of Io’s mantle  Phase E Costs and Educa�on and Public $1.0 Outreach – Modeling Io’s tidal heating mechanisms  Pre-launch Ground $0.8 – Modeling tectonic processes on Io  Flight System $0.6 – Understanding the interrelation between volcanic,  Instruments atmospheric, plasma torus, and magnetospheric mass‐  $0.4 Project Management/Systems Engineering/Mission Assurance and energy‐exchange processes  $0.2 Phase A – Determining whether Io’s core is generating a magnetic  $0.0 field  Project CATE – Characterizing Io’s surface composition  – Improving understanding of the Jupiter system  Key Parameters  Cost Risk Analysis S Curve  100 • Flight System Payload    Distribu�on 90 – Narrow Angle Imager  CATE es�mate 80 – Thermal Mapper  Design center es�mate Cumula�ve Probability (%) 70 CATE without cost threats – Ion and Neutral Mass Spectrometer  60 – Flux Gate Magnetometer  50 • Powered by Two ASRGs   40 • Launch Mass: 1,946 kg  30 • Launch Date: 2021 on Atlas V 401  20 • Orbit: 46‐degree Inclined Orbit at Jupiter with Multiple  10 Io Flybys  0   0.5 1.0 1.5 2.0 Es�mated Cost ( FY 15 $B)

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345 APPENDIX C BOX C.8  Jupiter Europa Orbiter  Flagship‐Class Europa Orbiter  Key Challenges    • Radiation  – Systems engineering for electronics vault repartitioning  – “Fail operational” fault management to handle  environment  • Mass  – Uncertainty in instrument and shielding mass  – Low launch margin for this development phase  – Overall sensitivity of system mass to changes  • Power  – System impacts of changing number and design of  radioisotope power system units  – Availability of plutonium‐238  • Instruments  – Uncertainties in design of model payload  Science Objectives  Key Cost Element Comparison  • Explore Europa to investigate its habitability    $5.0 $ 4 .7 B Cost Threats • Key science issues addressed:  Reserves – Characterizing the extent of the europan ocean and its  $4.0 relation to the deeper interior  Launch Vehicle $ 3 .4 B Es� mat ed Cost (FY 15 $B ) – Characterizing the ice shell and any subsurface water,  Phase E Costs and Educa�on and $3.0 Public Outreach including the nature of the surface‐ice‐ocean exchange  Pre-launch Ground – Determining global surface compositions and  Flight System $2.0 chemistry, especially related to habitability  Instruments – Understanding the formation of surface geology,  including sites of recent or current activity, and  $1.0 Project Management/Systems Engineering/Mission Assurance characterizing sites for future in situ exploration  Phase A – Understanding Europa in the context of the Jupiter  $0.0 system   Project CATE Key Parameters  Cost Risk Analysis S Curve  • Model Payload     100 – Ocean:  Laser Altimeter, Radio Science  90 Distribu�on CATE es�mate 80 – Ice:  Ice Penetrating Radar  Design center es�mate Cumula�ve Probability (%) 70 CATE without cost threats – Chemistry:  Vis‐IR Imaging Spectrometer, Ultraviolet  60 Spectrometer, and Ion and Neutral Mass Spectrometer  50 – Geology:  Thermal Instrument, Narrow Angle Imager,  40 Wide and Medium Angle Imager  30 – Particles and Fields:  Magnetometer, Particle and  20 Plasma Instrument  10 • F ive Multi‐Mission Radioisotope Thermoelectric  0 2.0 3.0 4.0 5.0 6.0 7.0 Generators   Es�mated Cost ( FY 15 $B) • Launch Mass: 4,745 kg  • Launch Date: 2020 (on Atlas V 551)  • Orbit: 100‐200 km Europa Orbit + Jovian Tour 

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346 VISION AND VOYAGES FOR PLANETARY SCIENCE BOX C.9  Trojan Tour and Rendezvous  Trojan Tour and Rendezvous Spacecraft  Key Challenges    • System Power  – No power growth contingencies currently allocated  – May limit downlink capability and science operations  • System Mass  – Low mass contingencies and launch margin for this  phase of development    Science Objectives  Key Cost Element Comparison  $1.6 • V isit, observe, and characterize multiple Trojan    Cost Threats asteroids  $1.4 Reserves $ 1 .3 B • Key science issues addressed:  $1.2 Launch Vehicle – Characterizing the bulk chemical composition of a  Es� mat ed Cost (FY 15 $B ) $ 1 .0 B Phase E Costs and Educa�on and Trojan asteroid surface   $1.0 Public Outreach – Observing the current geologic state of the surface and  Pre-launch Ground $0.8 inferring past evolution and the relative importance of  Flight System surface processes  $0.6 Instruments – Characterizing the bulk physical properties and interior  $0.4 Project Management/Systems structure of a Trojan asteroid  Engineering/Mission Assurance $0.2 – Searching for or constraining outgassing from  Phase A subsurface volatiles   $0.0   Project CATE Key Parameters  Cost Risk Analysis S Curve  100 • Payload     Distribu�on 90 –  Wide‐ and Narrow‐Angle Imagers  CATE es�mate 80 Design center es�mate – Infrared Mapping Spectrometer  Cumula�ve Probability (%) 70 CATE without cost threats – Thermal Imager  60 – Ultraviolet Spectrometer  50 – Gamma Ray Spectrometer  40 – Neutron Spectrometer  30 20 – Lidar  10 • Two Advanced Stirling Radioisotope Generators  0 • Launch Mass:  1,176 kg  0.5 1.0 1.5 2.0 • Launch Date:  2019 (on Atlas V 411)  Es�mated Cost ( FY 15 $B) • Orbit:  One Trojan Orbit (~50 to 100 km) + Multiple  Trojan Flybys 

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347 APPENDIX C BOX C.10  Saturn Probe  Saturn Atmospheric Entry Probe  Key Challenges  • Entry Probe    – T ime elapsed since mass spectrometer heritage mission  – High‐tempo operations after long hibernation period  – Reproduction of heritage thermal protection system  manufacturing process  • Payload Requirements Growth  – Concept study indicates that multiple probes are a  consideration though baseline design has a single probe  – Instrument suite is minimal and possible future design  iterations may consider enhanced payloads  Science Objectives  Key Cost Element Comparison  • Determine noble gas abundances and isotopic ratios of  $1.6   Cost Threats hydrogen, carbon, nitrogen, and oxygen in Saturn’s  $1.4 $ 1 .3 B Reserves atmosphere  $1.2 • Determine the atmospheric structure at the probe  Launch Vehicle $ 1 .1 B Es� mat ed Cost (FY 15 $B ) descent location  $1.0 Phase E Costs and Educa�on and • Key science issues addressed:  Public Outreach Pre-launch Ground $0.8 – Constraining models of solar system formation and the  origin and evolution of atmospheres  Flight System $0.6 – Providing a basis for comparative studies of the gas and  Instruments $0.4 ice giants  Project Management/Systems – Providing a link to extrasolar planetary systems  $0.2 Engineering/Mission Assurance Phase A $0.0 Project CATE Key Parameters  Cost Risk Analysis S Curve  100 • Entry Probe Payload    Distribu�on 90 – Mass Spectrometer  CATE es�mate 80 – Atmospheric Structure Instrument  Design center es�mate Cumula�ve Probability (%) 70 CATE without cost threats • Carrier‐Relay Spacecraft Bus  60 • Two Advanced Stirling Radioisotope Generators  50 • Launch Mass:  957 kg  40 • Launch Date:  2,027 (on Atlas V 401)  30 • Probe:  Direct Entry to Saturn, Carrier‐Relay:  Saturn  20 10 Flyby  0   0.5 1.0 1.5 2.0 Es�mated Cost ( FY 15 $B)

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348 VISION AND VOYAGES FOR PLANETARY SCIENCE BOX C.11  Titan Saturn System Mission  Titan Orbiter + In Situ Elements  Key Challenges    • In Situ European Space Agency‐Supplied Elements   – Uncertainty in accommodation, pending element  maturation  – Element operations and communications relay using  Orbiter  • Mass  – Uncertainty in instrument mass  – Low launch margin for this development phase  • Power   – Battery recharge time in Titan orbit  – Impact of switching to Multi‐Mission Radioisotope  Thermoelectric Generators (MMRTGs) from Advanced  Stirling Radioisotope Generators (ASRGs)  Science Objectives  Key Cost Element Comparison  $8.0 • Explore Titan as an Earth‐like system     Cost Threats $ 6 .7 B • Examine the organic chemistry of Titan’s atmosphere  $7.0 Reserves Project estimate • Explore Enceladus and Saturn’s magnetosphere for clues  shown includes $6.0 Launch Vehicle CATE estimate to Titan’s origin and evolution  of ESA elements Es� mat ed Cost (FY 15 $B ) ($1 B) Phase E Costs and Educa�on • Key science issues addressed:  $5.0 and Public Outreach $ 4 .5 B – Exploring organic‐rich environments  Pre-launch Ground $4.0 – Determining the origin and evolution of satellite  Flight System systems  $3.0 Instruments – Understanding dynamic planetary processes   $2.0 Project Management/Systems Engineering/Mission Assurance $1.0 Phase A $0.0 Project CATE Key Parameters  Cost Risk Analysis S Curve  • Model Payload     100 – High‐Resolution Imager and Spectrometer  Distribu�on 90 CATE es�mate – T itan Penetrating Radar and Altimeter  80 Design center es�mate Cumula�ve Probability (%) – Polymer Mass Spectrometer, Sub‐Millimeter  70 CATE without cost threats 60 Spectrometer, Thermal Infrared Spectrometer  50 – Magnetometer, Energetic Particle Spectrometer,  40 Langmuir Probe, Plasma Spectrometer  30 – Radio Science and Accelerometers  20 • In Situ Elements:  Balloon and Lake Lander  10 • Radioisotope Power Sources: 5 ASRGs + 1 MMRTG  0 • Launch Mass:  6,203 kg  4.0 5.0 6.0 7.0 8.0 9.0 • Launch Date:  2020 (on Atlas V 551) Gravity Assist SEP  Es�mated Cost ( FY 15 $B) • Orbit:  1500 km Titan Orbit + Saturn Tour Including  Enceladus Flybys 

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349 APPENDIX C BOX C.12  Enceladus Orbiter  Enceladus Orbiter Spacecraft  Key Challenges  • Planetary Protection    – Potential modifications to design required if planned  Enceladus impact disposal is not acceptable for  planetary protection  • Particle Impact Damage  – Potential for spacecraft damage from Saturn E‐ring or  Enceladus plume particle impact  – Primary concern: high‐gain‐antenna surface quality  • System Power  – Some potential for reduced science operations with  assumed Advanced Stirling Radioisotope Generators  (ASRG) degradation  Science Objectives  Key Cost Element Comparison  • Investigate the internal structure, geology, and    $2.0 $ 1 .9 B Cost Threats chemistry of Enceladus and plumes discovered by  Reserves $ 1 .6 B Cassini  $1.5 • Prepare for potential future landing  Launch Vehicle Es� mat ed Cost (FY 15 $B ) • Observe interactions between Enceladus and the Saturn  Phase E Costs and Educa�on and Public Outreach system and explore the surfaces and interiors of Saturn’s  Pre-launch Ground $1.0 moons  Flight System • Key science issues addressed:  Instruments – Investigating the nature of Enceladus’s cryovolcanic  $0.5 Project Management/Systems activity   Engineering/Mission Assurance – Providing improved measurements of plume gas and  Phase A $0.0 dust  Project CATE – Measuring tidal flexing, magnetic induction, static  gravity, topography, and heat flow   Key Parameters  Cost Risk Analysis S Curve  100 • Payload     Distribu�on 90 – Medium Angle Imager  CATE es�mate 80 Design center es�mate – Thermal Imaging Radiometer  Cumula�ve Probability (%) CATE without cost threats 70 – Mass Spectrometer  60 – Dust Analyzer  50 – Magnetometer  40 • Three ASRGs  30 • Launch Mass: 3,560 kg  20 10 • Launch Date: 2023 (on Atlas V 521)  0 • Orbit: Enceladus Orbit (100 km x 267 km, 62 deg  0.5 1.0 1.5 2.0 2.5 3.0 inclination) Plus Saturn Satellite Tour  Es�mated Cost ( FY 15 $B)  

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350 VISION AND VOYAGES FOR PLANETARY SCIENCE BOX C.13  Uranus Orbiter with Solar‐Electric Propulsion and Probe  Uranus Orbiter with Solar‐Electric Propulsion and  Key Challenges  Entry Probe  Pressurized Probe • Demanding Entry Probe Mission  Aeroshell – High‐tempo operations just prior to orbit insertion      – Probe mass spectrometer    – High probe deceleration environment at entry    • Long Life (15.4 years) for Orbiter  Solar Arrays (20 kW)   Orbiter Batteries – Ensuring reliability and performance of Advanced    Probe is mounted Stirling Radioisotope Generators (ASRGs)  underneath orbiter   • High Magnetic Cleanliness for Orbiter    SEP Stage – Demanding requirement to reduce spacecraft magnetic    noise to 0.1 nT background    NEXT Engines (2+1) • System Mass and Power  – Low‐mass and ‐power margins for this phase  – High mass multiplying factor from large propulsion  delta‐V requirements  Science Objectives  Key Cost Element Comparison  $4.0 • Investigate the interior structure, atmosphere, and    Cost Threats composition of Uranus  $ 3 .4 B Reserves • Observe the Uranus satellite and ring systems  $3.0 • Key science issues addressed:  Launch Vehicle Es� mat ed Cost (FY 15 $B ) – Determining atmospheric zonal winds and structure  Phase E Costs and Educa�on – Understanding Uranus’s magnetosphere and interior  and Public Outreach $ 1 .9 B Pre-launch Ground $2.0 dynamo  – Determining noble gas abundances and isotopic ratios  Flight System of H, C, N, and O within Uranus’s atmosphere  Instruments $1.0 – Determining the internal mass distribution of Uranus  Project Management/Systems – Determining horizontal distribution of atmospheric  Engineering/Mission Assurance Phase A thermal emission  $0.0 – Observing Uranus’s satellites  Project CATE Key Parameters  Cost Risk Analysis S Curve  • Orbiter Payload    100 – W ide‐ and Narrow‐Angle Imagers  Distribu�on 90 CATE es�mate – V isible/Near‐Infrared Mapping Spectrometer  80 Design center es�mate Cumula�ve Probability (%) 70 – Ultraviolet Imaging Spectrograph  CATE without cost threats 60 – Mid‐Infrared Thermal Detector  50 – Plasma Instruments (2), Magnetometer, Ultra‐stable  40 Oscillator  30 • Entry Probe Payload  20 – Mass Spectrometer  10 0 – Atmospheric Structure Instrument, Nephelometer   1.0 2.0 3.0 4.0 5.0 – Ultra‐stable Oscillator  Es�mated Cost ( FY 15 $B) • Three ASRGs  • Launch Mass:  4,129 kg  • Launch Date:  2020 (on Atlas V 531)  • Orbit: 1.3 Ru x 51.3 Ru, 97.7 deg Inclined Orbit +  Satellite Tour 

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351 APPENDIX C BOX C.14  Uranus Orbiter and Probe (No Solar‐Electric Propulsion)  Uranus Orbiter with Entry Probe  Key Challenges    HGA (2.5 m) • Demanding Entry Probe Mission  MGA   – High‐tempo operations just prior to orbit insertion    Pressurized Probe – Probe mass spectrometer  Aeroshell   – High probe deceleration environment at entry  Radiators   • Long Life for Orbiter  – Ensuring reliability and performance of Advanced  Stirling Radioisotope Generators  • System Power  Batteries – Low power margins for this phase  ACS Engines (12) • Sensitivity of Launch Opportunities to System Mass  ASRG (3) – More trajectory analyses recommended  Magnetometer Boom • High Magnetic Cleanliness for Orbiter  – Demanding requirement to reduce spacecraft magnetic  noise to 0.1 nT background  Science Objectives  Key Cost Element Comparison  $3.0 • Investigate the interior structure, atmosphere, and    Cost Threats $ 2 .7 B composition of Uranus  Reserves • Observe the Uranus satellite and ring systems  Launch Vehicle • Key science issues addressed:  Es� mat ed Cost (FY 15 $B ) $2.0 – Determining atmospheric zonal winds and structure  Phase E Costs and Educa�on and Public Outreach Uranus No SEP – Understanding Uranus’s magnetosphere and interior  Pre-launch Ground concept cost was not estimated by dynamo  project. Uranus Flight System concept with SEP – Determining noble gas abundances and isotopic ratios  was estimated by $1.0 Instruments the project at of H, C, N, and O within Uranus’s atmosphere  $1.9 B Project Management/Systems – Determining the internal mass distribution of Uranus  Engineering/Mission Assurance – Determining horizontal distribution of atmospheric  Phase A thermal emission  $0.0 – Observing Uranus’s satellites  Project CATE Key Parameters: Descope Concept  Cost Risk Analysis S Curve  100 • Uranus Orbiter and Entry Probe Identical to Original    CATE es�mate 90 Proposed Concept (see Box C.13)  CATE without cost threats 80 • Mission Identical, Except  Distribu�on Cumula�ve Probability (%0 70 –Launch Mass:  2,245 kg  60 –Launch Date:  2019 (on Atlas V 551)  50 • Descope Assumptions  –No Solar‐Electric Propulsion Stage  40 –Chemical propulsion trajectory with gravity assist flybys  30   20   10 0 1.0 1.5 2.0 2.5 3.0 3.5 4.0 Es�mated Cost ( FY 15 $B)

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352 VISION AND VOYAGES FOR PLANETARY SCIENCE BOX C.15  Comet Surface Sample Return  Comet Sample Return Orbiter  Key Challenges    • Sample Acquisition    – Need for Brush Wheel Sampler to be integrated into    system design    – Need for Spacecraft control during touch and go  sampling to be addressed  • Mission Design  – Access to surface characterized comets within current  schedule  – Trajectory constraints with 1+1 solar‐electric propulsion  system and Atlas V 521  • System Mass  – Low mass contingencies and launch margin for this  phase of development    Science Objectives  Key Cost Element Comparison  • Acquire and return to Earth for laboratory analysis a    $1.6 $ 1 .5 B Cost Threats macroscopic (≥500 cc) comet nucleus surface sample  $1.4 Reserves • Characterize the surface region sampled  • Preserve sample complex organics  $1.2 Launch Vehicle Es� mat ed Cost (FY 15 $B ) $ 1 .0 B • Key science issues addressed:  Phase E Costs and Educa�on and $1.0 – Determining the physical and chemical conditions in the  Public Outreach Pre-launch Ground $0.8 outer solar system during its formation  – Unraveling the history of the early solar system through  Flight System $0.6 age dating of cometary grains  Instruments – Elucidate the hypothesis that comets are the purveyors  $0.4 Project Management/Systems of water and organics throughout the solar system  Engineering/Mission Assurance $0.2 Phase A – Understanding the nature of giant‐planet cores  $0.0   Project CATE   Key Parameters  Cost Risk Analysis S Curve  • Payload   100   Distribu�on 90 – Brush‐Wheel Sample Acquisition System  CATE es�mate 80 – Sample Return Vehicle  Design center es�mate Cumula�ve Probability (%) 70 CATE without cost threats – Sample Monitoring: Sample Imagers, Temperature and  60 Pressure Sensors  50 – Site Characterization: Narrow Field Visible Imager, Wide  40 Field Visible Imager, Thermal Infrared Imager  30 • 17.4 kW (1 AU Beginning of Life) Ultraflex Power System  20 (6.3 m diameter)   10 • Launch Mass: 1,865 kg  0 0.5 1.0 1.5 2.0 • Launch Date: 2015 (on Atlas V 521)  Es�mated Cost ( FY 15 $B) • Orbit: 1 km Comet Orbit + Touch and Go Surface  Sampling Followed by Earth Return 

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353 APPENDIX C SUMMARY Linked technical, cost, and schedule estimates were developed for each of the priority mission concepts selected by the committee. The use of historical experience databases and evaluation of the technical risk, cost, and schedule histories of analogous space systems that had already flown plus the extensive interaction of technical, cost, and schedule experts with the proposing teams provide, in toto, a high degree of confidence that the resulting assessments are realistic and credible. The CATE process estimated mission costs that are considerably higher than the cost estimates provided by the design center study teams. The reason is that project-derived cost estimates are typically done using a bottom- up or so-called grass roots approach, and beyond standard contingencies they do not include probabilities of risk incurred by necessary redesigns, schedule slips, or launch vehicle growth. In other words, project estimates typically do not account for the “unpleasant surprises” that historically happen in nearly all space mission developments. CATEs include a probabilistic assessment of required reserves assuming that the concept achieves the mass and power as allocated or constrained by the respective stated project contingencies within the schedule as stated by the project. In addition to these reserves, additional cost threats are also included that quantify potential cost growth based on design maturity (mass and power growth) and schedule growth. Potential cost threats for larger required launch vehicle capability are also included. It is the combination of these reserves and cost threats that are often the main reason for the large differences between the CATE appraisal and the project estimate. Differences in the estimates for hardware costs (instruments and flight systems) can also be a contributing factor. As noted in several places in this report, the planetary program has been plagued for many years by use of cost estimates that, in retrospect, turn out to have been too optimistic. The result has been cost overruns that can be highly disruptive to the program. The CATE process, which uses history as its guide, has been designed and is used in this decadal survey to prevent this problem. NOTES AND REFERENCES 1 . National Research Council. 2006. An Assessment of Balance in NASA’s Science Programs. The National Academies Press, Washington, D.C., p. 32. 2 . National Research Council. 2006. An Assessment of Balance in NASA’s Science Programs. The National Academies Press, Washington, D.C., p. 33. 3 . National Research Council. 2007. Decadal Science Strategy Surveys: Report of a Workshop. The National Academies Press, Washington, D.C., pp. 21-30. 4 . National Research Council. 2007. NASA’s Beyond Einstein Program: An Architecture for Implementation. The National Academies Press, Washington, D.C., pp. 66-114. 5 . Congress of the United States. 2008. National Aeronautics and Space Administration Authorization Act of 2008. Public Law 110-422, Section 1104b, October 15. 6 . National Research Council. 2010. New Worlds, New Horizons in Astronomy and Astrophysics. The National Academies Press, Washington, D.C., Appendix C. 7 . As described in Chapter 9, the Mars Sample Return Lander mission is expected to be carried out jointly with the European Space Agency (ESA). Because the details of this collaboration have not been negotiated yet, however, the cost calculated for this mission does not include any ESA contribution. 8 . As described in Chapter 9, the Mars Sample Return Orbiter mission is expected to be carried out jointly with the European Space Agency (ESA). Because the details of this collaboration have not been negotiated yet, however, the cost calculated for this mission does not include any ESA contribution.

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