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.
Instrument schedule delays: Potential impact on mission development cost for recent NASA projects
NASA space-borne instruments, while trying to pursue world class science, have had a history of developmental delays. These development delays can lead to cost growth for the overall mission, as shown in recent studies of NASA missions and a larger historical data set. An analysis was conducted to assess if a new mission development process, labeled instrument first, spacecraft second (IFSS), could provide reduced cost and schedule growth in future missions by minimizing the impact of instrument development issues on mission development. A cost and schedule analysis was conducted for representative Tier 2 and Tier 3 Earth Science Decadal Survey missions to quantify the benefits. The results indicate that the savings resulting from such an approach is on the order of $2.5B, making more funding available for future missions, while providing a less volatile and more manageable mission portfolio.
An analytical approach to the design of electrodes in high-power, fast-transverse-flow CO2 lasers
Abstract Usually, the design of the electrodes of fast-transverse-flow CO 2 lasers relies more on experimental data than on theoretical analysis. Traditional systems sustain a stable, high-power discharge but the current distribution generates a peaked, non-uniform small-signal-gain pattern. We present a theoretical model suitable for the design of electrodes that achieves a quasi uniform gain distribution. The analysis, based on a two-temperature model and the gas-transport equations, computes the electron density that supports a flat gain pattern. Combining the desired electron density with the electron-balance equations, the model determines the required electric field. The results were used to design a new set of electrodes for a home-made fast transverse flow CO 2 laser. A stable, large volume discharge ( 4 × 8 × 90 cm 3 ) with very good uniformity was obtained. The resulting gain distribution was registered in a bi-dimensional map. The peak gain rose from 1.2 m - 1 , attained with the old electrode set, to 1.6 m - 1 with the new one and the gain showed a homogeneous profile.