Historical mass, power, schedule, and cost growth for NASA science instruments
In the early stages of NASA instrument development, science instruments are typically the most nascent part of any NASA mission development. As the building of spacecraft become less challenging for a mature industry, NASA's continual need to push the cutting edge of science requires the revolutionary and evolutionary development of instruments to meet science requirements. Instruments then face substantial issues that can result in significant increases in mass, power, cost, and schedule. Although previous studies have identified such issues, there are few industry standard reserve/contingency design and programmatic guidelines for instruments. This paper compares historical mass, power, cost, and schedule growth to industry reserve guidelines while offering potential recommendations to minimize instrument mass, power, cost, and schedule growth for future missions.
Space Chicken: A Historical Look at How the Critical Path Changes over a Mission's Development
The critical path in schedule analysis defines the series of tasks that have no schedule slack leading to the delivery of a system. The critical path for NASA science missions, which typically runs through a spacecraft subsystem or a scientific instrument, is dynamic and changes over the development lifetime of a project. Often the critical path at the start of preliminary design will be through a specific spacecraft subsystem while the final, delivered critical path item is often a scientific instrument that is delivered late. The research for this paper looks at the postulated critical path at different milestones, and the actual critical path item at final delivery, for a variety of NASA science missions to understand what elements are impacting the delivery schedule the most. Recommendations are made based on these quantitative results relative to what elements should potentially be considered more often in early development schedules to more robustly plan for development issues.
INSTRUMENT FIRST , SPACECRAFT SECOND : A NEW PARADIGM IN SPACE MISSION DEVELOPMENT
The development of NASA missions is difficult. Developing world class science instruments that constantly push the state of the art can present a series of developmental challenges that are difficult to both anticipate and overcome. For many NASA missions, the development of an instrument can become the primary key technological challenge for the success of a mission [1]. As such, the difficulty of developing an instrument can lead to delays in delivering the instrument to the spacecraft for system integration which, in turn, can lead to cost growth while the spacecraft, mission and ground system team waits for the instrument to be delivered. The subsequent “marching army” cost can be significant and is one of the primary causes of cost growth for NASA missions [2]. This paper addresses this issue by hypothesizing that developing the instrument first and bringing it to an acceptable level of maturity prior to procuring the spacecraft and initiating ground system development could provide an overall cost reduction or minimize cost growth for NASA missions. To test this theory, the cost and schedule of representative missions from the recent Earth Science Decadal Survey [3] were analyzed to determine if potential cost and schedule growth could be minimized by developing the instrument(s) prior to starting full mission development. The results of the study show that significant cost savings could potentially be achieved by applying the instrument first, spacecraft second (IFSS) mission development paradigm.