posted August 23, 2012
NASA identified a need to evaluate budgets and schedules probabilistically rather than deterministically. The desired outcome was to treat the future as a trade space of possible outcomes, each with a probability, as opposed to a single track that NASA will follow to achieve its objectives.
Aerospace created a SCT to evaluate the agency budget. SCT was developed to provide insight into the behavior of large portfolios and strategic issues associated with replans and execution of the specified content. This new tool is sensitive to “what if” analyses and evaluates the probabilities of achieving certain outcomes from a budget and schedule perspective. The SCT is a single visual representation over time of the contributions of all factors (layers of sand) that contribute to cost (or schedule) changes. There are a variety of factors that might initiate a need to replan the portfolio, including budget cuts, new mission content, new administration direction, different reserves strategies, and cost and schedule overruns. The use of the SCT led to the identification of a $4B shortfall in the NASA Constellation out-year budget that ultimately resulted in a rebaselining of the development and flight schedule. The impact of such a shortfall would have been the delay of approximately three years to the Human Lunar Return date. SCT was also used in an affordability trade for a future joint NASA/European Space Agency Mars Sample Return (MSR) architecture. Due to funding constraints, it was recognized that the MSR architecture must be implemented as a three-mission architecture, instead of a two-mission architecture, in order to collect a sample from the surface of Mars and return it to Earth.
The Independent Assessment Program Office within the NASA Programs Division led the SCT development and support efforts, with technical implementation performed by the Space Architecture Department and NASA Programs Division. The capability is now being applied to develop program-level budgets and schedules for the Science Mission Directorate. Since its development, NASA has requested that Aerospace use the SCT to support multiple programs.