Impact of instrument schedule growth on mission cost and schedule growth for recent NASA missions
This study explores instrument schedule delays and their impacts on mission development schedule and cost growth for recent NASA missions. This study examines 86 instruments across 32 NASA missions. First, the relationship between instrument schedule growth and mission development cost growth is examined. It is found that instrument development delays have a prominent role in contributing to mission development schedule and cost growth. Second, instrument developments are analyzed in order to explore specific trends related to schedule growth and to determine potential contributing factors. Instrument schedule growth is examined as a function of mass, power, instrument type, and spacecraft destination. The results are then used to establish schedule rules-of-thumb that can be used for planning purposes by project and program managers in charge of future NASA development efforts.
Explanation of change (EoC) study: Considerations and implementation challenges
This paper discusses the implementation of considerations resulting from a study investigating the cost change experienced by historical NASA science missions. The study investigated historical milestone and monthly status report documentation followed by interviews with key project personnel. The reasons for cost change were binned as being external to NASA, external to the project and internal to the project relative to the project's planning and execution. Based on the results of the binning process and the synthesis of project meetings and interviews, nine considerations were made with the objective to decrease the potential for cost change in future missions. Although no one “magic bullet” consideration was discovered, the considerations taken as a whole should help reduce cost and schedule change in future NASA missions.
Chemical-Looping Combustion of Biomass in a 10 kWth Reactor with Iron Oxide As an Oxygen Carrier
Chemical-looping combustion of biomass was carried out in a 10 kWth reactor with iron oxide as an oxygen carrier. A total 30 h of test was achieved with the same batch of iron oxide oxygen carrier. The effect of the fuel reactor temperature on gas composition of the fuel reactor and the air reactor, the proportion of biomass carbon reacting in the fuel reactor, and the conversion of biomass carbon to CO2 in the fuel reactor was experimentally investigated. The results showed that the CO production from biomass gasification with CO2 was more temperature dependent than the CO oxidation with iron oxide in the fuel reactor, and an increase in the fuel reactor temperature produced a higher increase for the CO production from biomass gasification than for the oxidation of CO by iron oxide. Although the conversion of biomass carbon to CO2 in the fuel reactor decreased with the increase of the fuel reactor temperature, there was a substantial increase in the proportion of biomass carbon reacting in the fuel react...