Space Chicken: A Historical Look at How the Critical Path Changes over a Missions 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

Strategic change in the market for domestic electricity in the UK

This paper examines developments in the market for domestic electricity supply in the UK since September 1998 when the market was thrown over to competition using a variety of sources including firm interviews and a consumer questionnaire. We find that there was a substantial amount of entry, but that there has since been significant consolidation. There is still a substantial gap between the prices set by a firm in its incumbent area and prices obtainable from entrants to the market. There is no evidence that the market is near to Bertrand in operation

TIRS-2 and Future Thermal Instrument Band Study and Stray Light Study

Landsat thermal instruments have been a significant source of data for thermal remote sensing applications, and future Landsat missions will continue this tradition. This work was designed to help inform the requirements for several parameters of future Landsat thermal instruments, and assess the impact that these parameters can have on the retrieved Land Surface Temperature (LST). Two main studies were conducted in this research. The first will investigate the impact that uncertainty in the spectral response of the bands will have on the LST product using the Split Window Algorithm. The main parameters that will be tested are the center and width of he bands. The second study will investigate the impact of stray light on LST, including different magnitudes of stray light and different combinations of in-field and out-of-field targets. The results of the band study showed that shifting of the bands seems to be have a larger impact on the LST than widening of the bands. Small shifts of only +/- 50 nm can cause errors of over 1 K in the LST. This study also showed that atmospheres with more water vapor content will have more effected than those with lower water vapor. The stray light study showed that using the stray light coefficients from TIRS-2 will not have a significant impact, when compared to the residual errors associated with the Split Window Algorithm

Explanation of Change Cost and Schedule Growth Study Interim Status Briefing

This slide presentation reviews the study to understand the changes in cost and schedule growth for NASA projects. A second goal was to determine the percentage of growth that was outside the control of the project. The study examined project documentation, conducted interviews with key project personnel, and allocated growth events to an Explanation of Change (EoC) tree to quantify the reasons for growth in the scheduled time. This briefing reviews the results of the study of the first 20 missions

Exploring star formation in high-z galaxies using atomic and molecular emission lines

The conditions under which stars are formed and the reasons for triggering and quenching of starburst events in high-z galaxies, are still not well understood. Studying the interstellar medium (ISM) and the morphology of high-z galaxies are therefore key points in order to understand galaxy evolution. The cosmic star formation rate density peaks between 1<z<3. This period in the history of the Universe is therefore crucial to investigate in order to know more about the star-formation triggering and quenching mechanisms. Phenomena such as major mergers and galactic nuclear activity are believed to be mechanisms dominating the star formation activity at this period of time. It is therefore necessary to study galaxy populations which show signs of major merger events and active galactic nuclei (AGN). This thesis presents three studies of the ISM in high-z galaxies and their morphologies by: Exploring the physical conditions of the ISM in a sample of dusty star-forming galaxies (DSFGs) using the relative observed line strength of ionised carbon ([CII]) and carbon monoxide (CO). We find that the line ratios can best be described by a medium of [CII] and CO emitting gas with a higher [CII] than CO excitation temperature, high CO optical depth tau(CO)>>1, and low to moderate [CII] optical depth tau(CII)<1. Combining millimetre/sub-millimetre and optical data cubes for the high-z radio galaxy (HzRG) MRC0943-242, has revealed a much more complicated morphology than seen in the individual data sets. The millimetre/sub-millimetre observations data have allowed us to spatially separate of the AGN and starburst dominated components, which ~65 kpc apart. The optical data reveal structures of emitting and absorbing gas at multiple wavelengths. A deep high resolution millimetre/sub-millimetre study of the HzRG MRC1138-262, shows emission from water (\water) and an unusually large amount of neutral atomic carbon ([CI]) relative to highly excited CO compared to lensed DSFGs. The detection of water (H2O) emission, which is not associated with the 246GHz continuum emission, suggests excitation by shocks.The uncommon line ratio between [CI]2-1 and CO(7-6) might be due special conditions of the ISM in MRC1138-262 dominated by cosmic rays or differential lensing in other DSFGs thereby not representing the intrinsic ratio. These three studies of the physical conditions of the ISM and morphology of high-z galaxies at z>2, pave the road for future investigations of the star-forming ISM in high-z galaxies, by illustrating the importance of multi-wavelength, fine structure- and molecular line studies