Overview of START Case Studies
START's methodology and tools have evolved in response to the needs expressed by NASA decision-makers over the years. These case studies illustrate application of the START methodology at various stages in its development. It is worth noting that, while all of these studies were for NASA, the techniques employed are applicable to a wide assortment of mission types both inside and outside of that agency.
The studies are grouped on the navigation bar in four categories:
- NASA agency-level studies
These studies cross the boundaries of NASA's individual directorates -- typically the Exploration Mission Systems and Science Mission directorates.
- Science Mission Directorate (SMD)
These include individual science-investigation missions to Mars and other worlds, space telescopes, and the prospect of selecting technological capabilities with a view toward their serving multiple science missions. All of these are typically robotic missions.
- Exploration Systems Mission Directorate (ESMD)
These studies involve aspects of potential future missions with human crews as well as robots. Most were undertaken for the Constellation program in effect from 2004 to 2010, but methodologies developed in these studies are very transferable to any of the other programs under consideration at NASA, such as crewed missions to asteroids and to the Martian moons.
- Aeronautics Research Mission Directorate (ARMD)
This section consists of a study of air-travel issues.
For each of these case studies, it is important to note that the outcome was not intended to be a definitive conclusion, but rather a basis for further investigation and discussion. Ultimately, the START process provides solid support for a decision-maker's judgment.
The studies are grouped below by the major issues they address:
Virtually all of our studies deal with managing complexity; the following two focus in particular on complexity-management techniques.
- Mission to Schrödinger Crater
Response surface analysis is used to interpolate the impact of varying constraints for a given mission (in this case, to a lunar crater). This technique drastically reduces the computing time needed to analyze a very large number of variations and produces a table that includes most of the trade space under consideration. The table serves as a tool that enables scientists and mission architects to answer the "inverse" question: For a given desired level of science (or any other objective), what are the sets of constraints that would be acceptable?
- Sensor for hazard detection and avoidance
This study introduces SAGE (Select Alternative by Graded Evaluation), a system for formulating a unitless numerical value for each attribute of a technology. This enables calculation with all the attributes to arrive at values with which to compare technologies competing for funding. SAGE serves as an analysis system for a broad range of design trade problems that have too many conflicting attributes to plot simply against each other.
Optimizing mission architectures
- Mission to Malapert Mountain
Here we determine which constraints are the most important drivers of results on hypothetical 7-day and 14-day lunar missions, covering more than 260 km round trip, from a presumed landing site at Shackleton crater to Malapert Mountain and back.
- Comparing architectures: Pressurized vs. unpressurized rovers
A hypothetical 14-day mission near the lunar south pole in which astronauts use robotic rovers for transportation and as assistants for certain tasks. Two mission architectures are compared: one with pressurized rovers and one with unpressurized rovers. Then we explore the impact on productivity of adding margins to the times required for various activities and augmenting the list of tasks to be performed. Finally, to test the robustness of the analysis, we identify the most important parameters, vary them within a range of uncertainty, and assess the impact on overall productivity.
- Titan surface and subsurface in situ system
We identify a mission design capable of performing useful science based on a payload mass that could realistically be landed on Titan's surface. We evaluate various launch, cruise, and capture alternatives, and complete orbital-insertion analysis with final mass breakdowns. Included is a way to eliminate the need for an orbiter -- at a great mass savings -- and instead provide direct-to-Earth communications from an aerial platform.
- Earth observatory at L2
A concept for a space-telescope mission to make a detailed study, from the L2 vantage point, of the constituents and dynamics of Earth's atmosphere over a span of 10 years. In addition to developing the advanced spectrometry science-and-engineering requirements and the overall architecture of the telescope and its operation, we design an optimal method of transport from Earth and deployment at L2, and develop preliminary designs for guidance, navigation, and control.
- Projected improvements in human and robot performance
To facilitate analysis of future collaborative human-robot missions, improvements in the performance of both humans and robots are projected. We compute the integrated net performance (performance minus resource demands) of humans, robots, and human-robot teams over future decades. While the specific results presented here apply to assembly of a large space telescope, our approach to projecting performance improvements is common to all applications.
- Human-robot system architectures
This study is based on a hypothetical future mission in which humans and robots explore the surface of Mars. We assume a set of goals for the mission, decompose the mission elements in terms of capability requirements, and overlay the projected performance of human and machine agents to determine a suitable task decomposition.
- Robotic precursor mission
Determining the relative value per investment dollar of two alternate Robotic Prospecting Precursor missions to the Moon, one of which would last 19 days and the other of which would run for nearly a year. This was the first START study to compare different mission architectures for the same goal, and to consider the entire life-cycle costs of the technology capabilities, rather than just their development costs to TRL 6.
- Capability prioritization for ETDP support of Constellation
Scheduling technology development so that it meets mission needs while fitting optimally into a multi-year budget schedule. In response to "what if" inquiries from the Technology Prioritization Panel (TPP), a set of focused portfolios is computed, each of which shows the impact of a different set of budget-parameter variations. The study demonstrates the flexibility implicit in the schedule and the advantages of using it appropriately. We find, for example, that delaying some of the TPP's top-priority development projects by one year would permit all of those projects to meet their deadlines while enabling other important technology capabilities to meet theirs.
- Return-on-investment analysis for JPL Chief Technologist
An effort to develop a systematic process that JPL's Chief Technologist could use to help him select a group of technologies for development, on the basis of the probability that they will lead to mission assignments from NASA. The study produces not only optimal portfolios of technology investments, but also an optimal schedule for funding each technology. It determines the sensitivity of the results to variation in the input values, identifies optimal portfolios that contain a required element (K-best sets), distinguishes technologies that enable multiple missions, and includes relative mission value when calculating a technology's value.
Ranking missions competing for funding
- Estimating Uncertainty in Above-Ground Biomass Derived from Remote-Sensing Data
An approach to integrating the uncertainties associated with measurements and modeling regressions used in estimating above-ground biomass to help the climate-change community better assess the amount of carbon stored in forests.
- Quantitative Assessment of Expected Space Mission Return
A first attempt to address the problem of how to quantitatively assess the value of the various missions competing for NASA funding, as a tool to help decision-makers make funding decisions and to assist in future mission design.
Ranking technologies competing for funding
- START Lite: A decision-making aid for SBIR ranking
A semi-quantitative analog to the START process, which ranks prospective technologies according to a well-defined and agreed-upon set of attributes targeted to upcoming missions. The objective in this study is to increase the likelihood that technologies selected for funding by Small Business Innovation Research (SBIR) would actually be employed by NASA missions.
- Structured Approach to Strategic Decision Making for NASA's Technology Development
A "democratic" approach to technology selection based on relative performance gain over state of the art. This agency-level study demonstrates that quantitative data collection can be conducted across a broad range of missions, and analytical decision-making based on the construction of optimal portfolios is feasible for complex systems such as NASA's technology-development program. The process has the advantages of being objective, traceable, quantitative, and repeatable.
- A Multi-Mission, Multi-Program Technology Resource-Allocation Approach for NASA
We demonstrate a system for determining, in an auditable fashion, optimal portfolios for advanced space technology development across a wide spectrum of missions and technologies. Our system can accept new missions and technologies easily, and can produce a prototyped example rapidly. (Phase 1 of this pilot study progressed from a dead start to a conclusion in only four months.) As part of this study, we show that risk-management software can be included in the analysis like any other technology.
- Hierarchical Database and Tools for Relating Technologies to Mission Requirements for the New Millennium Program
Development of a hierarchical data base and a tool for using it (called "XCALIBR" for XML Capability Analysis LIBRary), to help NMP identify the technologies best suited for testing in space. This system would be useful for decision-makers across a broad range of programs and missions.
- Selecting technologies for multiple Mars missions
A study that addresses selection of technology capabilities to develop on the basis of the missions they would enable at three possible levels of funding.
- Lander vs. Rover
Compares the impact of investments in precision landing vs. long-range roving technologies on a hypothetical mission to Mars. We show how to develop an optimal investment strategy that minimizes mission risk, given a fixed total technology-investment budget.
The study demonstrates a system for evaluating and comparing groups of advanced autonomy-software technologies, most of which are currently at the R&D stage (TRL 2 or 3), in terms of the impact they would have on science return in each of two missions on the Martian surface.
- Predicting the cost of new technologies
A process for estimating the cost of new technology that includes uncertainty, an independent peer review of the estimate, and the interrelationships of science returns. It also helps to determine where to set cutoff points for technology budgets.
- Europa lander study
We evaluate candidate technologies according to their risk, R&D costs, and probable science return, and use a decision-tree methodology to rank them.
- Tools for improving technology-investment strategies (as illustrated by large space telescopes)
The process outlined here conducts a systematic flow-down analysis of scientific investigation goals and measurements for a mission class, of the corresponding mission and system concepts, and of the enabling technologies needed to achieve the desired investigations.
- Assessment of capability-development portfolio for the NASA Aeronautics Program
Illustrates a "mission-enabling" approach to investment decisions, in which sets of technologies are selected to enable particular missions. In such an approach, no technologies for a particular mission are funded unless they can all be funded, since the mission would fail unless all were developed.
- Human-robot polar mission
Demonstrates that START's software tool can help NASA rapidly analyze multiple alternate budget scenarios. As an example task, we determine which among several budget scenarios over a multi-year time span would enable development of nine specified missions, and which capability areas would constitute optimal portfolios under those budget scenarios, given the specified constraints. Predicted performance is given in a range that includes lower limit, most likely level, and higher limit, and partial funding of enhancing capabilities is allowed.
Other automation tools
- Landing-site selection for Mars exploration rovers
An automated system to help decision-makers make well-informed choices in a much shorter amount of time -- and possibly with a wider range of options to consider -- than has been done without such a system.
- Automation tool for rapid design of space systems
Using the manipulator arm of the MER rover as a design subject, we demonstrate a systematic methodology for an analytical framework that provides a highly comprehensive automated exploration of the system tradeoff space, and enables designers to focus their efforts in the regions most likely to yield the best, most cost-effective design solutions. This illustrates the advantages of combining the number-crunching power of a good algorithm with the experience, intuition, and judgment of a good human engineer, and holds the promise of making the design process much more efficient at a great savings in cost and time.
Human-robot task management
- Task scheduling
Analysis of a hypothetical 60-day lunar mission that includes two astronauts and a teleoperated rover, with the objective of minimizing EVA time. Tasks are allocated and a timeline is computed.
- Autonomous inspection of spacecraft
Quantifies the benefit of robotic vs. human inspection of a spacecraft exterior while in flight.