Interplanetary Trajectory Optimization with Powerlimited Propulsion Systems

A trajectory-optimization process is described in which the optimum thrust equations are derived using the calculus of variations. The magnitude of the thrust is constrained within an upper and a lower bound, but the thrust direction is arbitrary. This formulation allows both the constant-thrust program and the variable-thrust program to be considered. For the constant-thrust program, certain propulsion-system parameters are optimized for maximum final vehicle mass. This theory has been used to study interplanetary missions to Venus and Mars using a power-limited propulsion system. Both one-way and round trip rendezvous trajectories are considered. The analysis employs a two-body inverse-square force-field model of three dimensions. An iterative routine used to solve the two-point boundary-value problem is described in the Appendix

Space radiation dose analysis for solar flare of August 1989

Potential dose and dose rate levels to astronauts in deep space are predicted for the solar flare event which occurred during the week of August 13, 1989. The Geostationary Operational Environmental Satellite (GOES-7) monitored the temporal development and energy characteristics of the protons emitted during this event. From these data, differential fluence as a function of energy was obtained in order to analyze the flare using the Langley baryon transport code, BRYNTRN, which describes the interactions of incident protons in matter. Dose equivalent estimates for the skin, ocular lens, and vital organs for 0.5 to 20 g/sq cm of aluminum shielding were predicted. For relatively light shielding (less than 2 g/sq cm), the skin and ocular lens 30-day exposure limits are exceeded within several hours of flare onset. The vital organ (5 cm depth) dose equivalent is exceeded only for the thinnest shield (0.5 g/sq cm). Dose rates (rem/hr) for the skin, ocular lens, and vital organs are also computed

Single-nucleotide polymorphisms: analysis by mass spectrometry

Matrix-assisted laser desorption-ionization (MALDI) mass spectrometry has evolved as a powerful method for analyzing nucleic acids. Here we provide protocols for genotyping single-nucleotide polymorphisms (SNPs) by MALDI based on PCR and primer extension to generate allele-specific products. Furthermore, we present three different approaches for sample preparation of primer-extension products before MALDI analysis and discuss their potential areas of application. The first approach, the 'GOOD' assay, is a purification-free procedure that uses DNA-modification chemistry, including alkylation of phosphorothioate linkages in the extension primers. The other two approaches use either solid-phase extraction or microarray purification for the purification of primer-extension products. Depending on the reaction steps of the various approaches, the protocols take about 6–8 hours

The Problem of Declining Enrollment in the Elementary Schools of Fall River County

During recent years, enrollments in most South Dakota elementary schools have declined at a very rapid rate. The prevailing type of rural school district organization in most counties has proved rather ineffective in coping with dwindling enrollments and with the consequent high costs per pupil. It is the purpose of this pamphlet to assist educators, school board members and other Fall River County leaders, by analyzing the nature of the problem and by presenting suggestions for its solution; as they have grown out of the experiences of other South Dakota communities. This study was made possible through the cooperation of the State and Federal Work Projects Administration and the South Dakota Agricultural Experiment Station. The project is officially designated as W. P.A. Project No. 265-1-74-57. The authors gratefully acknowledge the cooperation of Genevieve Frawley, the Fall River County Superintendent of Schools, from whose office most of the data used in this study was secured; and of high school superintendents who supplied lists of their tuition students

The Problem of Declining Enrollment in the Elementary Schools of Deuel County

During recent years, enrollments in most South Dakota elementary schools have declined at a very rapid rate. The prevailing type of rural school district organization in most counties has proved rather ineffective in coping with dwindling enrollments and with the consequent high costs per pupil. It is the purpose of this pamphlet to assist educators, school board members and other Deuel county leaders by analyzing the nature of the problem and by presenting suggestions for its solution as they have grown out of the experiences of other South Dakota communities. This study was made possible through the cooperation of the State and Federal Work Projects Administration and the South Dakota Agricultural Experiment Station. The Project is officially designated as W. P.A. Project No. 665-74-3-143. The authors gratefully acknowledge the cooperation of Miss Julia Dokken, the Deuel County Superintendent of Schools, from whose office most of the data used in this study was secured; and of high school superintendents who supplied lists of their tuition students

The Problem of Declining Enrollment in the Elementary Schools of Corson County

This study was made possible through the cooperation of the State and Federal Work Projects Administration and the South Dakota Agricultural Experiment Station. The project is officially designated as W. P.A. Project No. 265-1-74-57. The authors gratefully acknowledge the cooperation of Miss Margaret Gillis, the Corson County Superintendent of Schools, from whose office most of the data used in this study were secured; and of high school superintendents who supplied lists of their tuition students

The Declining Enrollment Problem in the Elementary Schools of Hamlin County

During recent years, enrollments in most South Dakota elementary schools have declined & at very rapid rate. The prevailing type of rural school district organization in most counties has proved rather ineffective in coping with dwindling enrollments and with the consequent high costs per pupil. It is the purpose of this pamphlet to assist educators, school board members and other Yankton County leaders, by analyzing the nature of the problem and by presenting suggestions for its solution as they have grown out of the experiences of other South Dakota communities. This study was made possible through the cooperation of the State and Federal Work Projects Administration and the South Dakota Agricultural Experiment Station. The project is officially designated as W. P.A. Project No. 665-74-3-143. The authors gratefully acknowledge the cooperation of Mrs. Doris Boadwine, the Hamlin County Superintendent of Schools, from whose office most of the data used in this study was secured; and of high school superintendents who supplied lists of their tuition students

The Problem of Declining Enrollment in the Elementary Schools of Ziebach County

During recent years, enrollments in most South Dakota elementary schools have declined e.t a very rapid rate. The prevailing type of rural school district organization in most counties has proved rather ineffective in coping with dwindling enrollments and with the consequent high costs per pupil. It is the purpose of this pamphlet to assist educators, school board members and other Ziebach County leaders, by analyzing the nature of the problem and by presenting suggestions for its solution; as they have grown out of the experiences of other South Dakota communities. This study was made possible through the cooperation of the State and Federal Work Projects Administration and the South Dakota Agricultural Experiment Station. The project is officially designated as W. P.A. Project No. 265-1-74-57. The authors gratefully acknowledge the cooperation of Lewis R. Schetnan, the Ziebach County Superintendent of Schools, from whose office most of the data used in this study was secured; and of high school superintendents who supplied lists of their tuition students

The Problem of Declining Enrollment in the Elementary Schools of Codington County

During recent years, enrollments in most South Dakota elementary schools have declined & at very rapid rate. The prevailing type of rural school district organization in most counties has proved rather ineffective in coping with dwindling enrollments and with the consequent high costs per pupil. It is the purpose of this pamphlet to assist educators, school board members and other Codington County leaders, by analyzing the nature of the problem and by presenting suggestions for its solution as they have grown out of the experiences of other South Dakota communities. This study was made possible through -the cooperation of the State and Federal work Projects Administration and the South Dakota Agricultural Experiment Station. The project is officially designated as W. P. A. Project No. 665-74-3-143. The authors gratefully acknowledge the cooperation of Miss Agnes Kieley, the Codington County Superintendent of Schools, from whose office most of the data used in this study was secured; and of high school superintendents who supplied lists of their tuition students