Human-Robot Polar Mission
A demonstration that START's new integrated software tool can help NASA rapidly analyze multiple alternate budget scenarios.
This study features the following innovations:
- It is the first study to be conducted with START's new multipurpose software tool.
- Predicted performance is given in a range that includes lower limit, most likely level, and higher limit.
- Partial funding of enhancing capabilities is allowed.
Our primary objective for this first phase of the study was to demonstrate that START's new integrated software tool can help NASA rapidly analyze multiple alternate budget scenarios. As an example task, we determined which among several budget scenarios would enable development of all 9 missions listed on the top page, and which capability areas would constitute optimal portfolios under those budget scenarios, given the specified constraints.
In this phase of our study, we simply assumed that the robotic precursor mission will have been accomplished before the first new human mission is launched. (We have since conducted an analysis of the robotic mission, and that is described on the Robotic Prospecting Precursor page.)
Collecting the data
|Lunar South Pole
(Click on enlarge for further information)
In consultation with various experts, we identified constraints including budgets, Congressionally mandated tasks and capabilities not subject to competition, and relative value of the missions and of the capability areas.
We formulated a capability-requirements database from the 3 human-robot prospecting and 3 human-robot ISRU mission scenarios at the lunar south pole and determined whether each requirement would contribute to science or resource exploitation or both.
We used Technology Project Data Sheets compiled by Langley Research Center (LaRC) and priorities set forth by the Exploration Technology Development Program (ETDP), and supplemented the data set with our own data where the existing information did not have adequate fidelity or relevance to our needs.
We assumed that, based on neutron-spectrometer readings, the robotic precursor mission will have found 3 promising places to look for water within a 1-km circle in Shackleton crater. To avoid the need for lunar vehicles, we based this diameter on how far the Apollo astronauts were able to walk on the Moon. We also made a number of other assumptions to define and constrain the tasks to be accomplished on the lunar surface.
We listed all of the activities to be done by astronauts and by robots, and translated each functionality into quantitative capability requirements. For example, placing an instrument into a borehole might imply a requirement for a measurable level of dexterity or precision. Selecting a sample for return to Earth might mean a chemical analysis to a particular degree of accuracy. All pertinent words had to be translated into numbers.
We derived each capability's enabling or enhancing status from a table provided by ETDP. "Enabling" capabilities are those which are required for a given mission. "Enhancing" capabilities are those which promise to benefit a mission but are not required.
The data was inserted into our Excel-based data sheets and fed into the START optimization tool.
Note that in the crewed mission scenarios under consideration here, humans are working inside the dark crater so they will be on hand to make repairs in situations that might stymie robots, and possibly to make discoveries difficult to do remotely. However, we fully recognize that the ultra-low temperature and darkness of these permanently shadowed areas are extremely hazardous, and that development of space suits capable of protecting astronauts there is a major critical area not yet undertaken. The temperature in the dark crater is estimated to be as low as 40 K (-233 °C or -388 °F), while current space suits are designed to operate only down to 100 K. This study did not have access to budgets for suit development, so this was not included in our analyses, but it must be included in future rounds. If an appropriate suit is not to be developed, then alternate mission scenarios must be considered that do not require astronauts to enter the crater.
At the time of this study, the 2007 budget was initially expected to be $369 million and to decline sharply in following years before rising again (see the black curve in the graph below). Thus, a development task that is affordable in the first year might get choked off in the less affluent later years, given the constraints that development must be performed in contiguous years and that every capability development that is funded must be completed. (That is, during those contiguous years, enabling capabilities must be fully funded and enhancing capabilities must be funded to their assigned percentage, to permit staffs to retain some stability.)
Our temporal analysis is designed to recommend the optimal scheduling of development which would make the most productive use of the expected budgets without exceeding them.
In our initial recommendation, only $300 million is to be spent in 2007, even though the available budget (black line) is $369 million. The remaining funds can't be used (under the current flat-spending-profile constraint for each capability) because there would be insufficient budget the following year to continue any additional tasks. We adopted a requirement to complete capability development in contiguous years because of the staffing problems associated with skipping years and then resuming development.
As the study progressed, our sponsor anticipated a possible reduction of the first year's budget and asked us to determine the impact of reducing the 2007 budget to $188 million. We showed that this amount would not enable the missions to be conducted, since the budget would be insufficient to fund all the enabling capabilities under the same set of constraints. However, the missions could be enabled by lengthening the schedule by one year or by dropping the requirement that funding for each capability must be apportioned equally among all of its development years (although dropping this requirement could adversely affect staff stability).
The START tool makes it easy to perform "what if" analyses. In this case, reducing the 2007 budget to $188 million leaves insufficient funds to develop the capabilities required to enable the mission.
When that analysis was conducted, the capabilities needed for non-polar ISRU were considered enhancing rather than enabling, since the primary focus was on the polar missions. However, subsequent thinking was that in order to be sure that non-polar ISRU would be available as a backup mission, its enabling capabilities should be designated enabling and included in an analysis to determine the minimum 2007 budget that would allow the mission set to proceed. We therefore performed an additional analysis which determined that a budget of $263 million in 2007 is the least amount for that year that would enable all of the desired missions. As a bonus, we determined that there is enough anticipated budget in later years to permit some funding of enhancing capabilities as well.
In another "what if" analysis, a 2007 budget of $263 million is shown to be sufficient to fund not only all enabling capabilities, but also some enhancing capabilities.
Our sponsor also asked us to consider the possibility of having the budget for each year (not just 2007) cut in half. We determined that this would disable the missions unless the schedule was extended by 2 years and we were permitted to vary the amounts allocated to each technology task from year to year.
In each "what if" analysis, the START tool completed its run within a few minutes. We took some additional time to analyze the implications of those runs, and we returned answers and presentations to the sponsor the following working day.
For more information, contact Charles Weisbin at Charles.R.Weisbin@jpl.nasa.gov