Solar activity catalogue. Volume I - Catalogue of solar activity during 1954 - 1956

Catalog of solar activity during 1954-195

Optimal Finite Thrust Guidance Methods for Constrained Satellite Proximity Operations Inspection Maneuvers

Algorithms are developed to find optimal guidance for an inspector satellite operating nearby a resident space object (RSO). For a non-maneuvering RSO, methods are first developed for a satellite subject to maximum slew rates to conduct an initial inspection of an RSO, where the control variables include the throttle level and direction of the thrust. Second, methods are developed to optimally maneuver a satellite with on/off thrusters into a natural motion circumnavigation or teardrop trajectory, subject to lighting and collision constraints. It is shown that for on/off thrusters, a control sequence can be parameterized to a relatively small amount of control variables and the relative states can be analytically propagated as a function of those control variables. For a maneuvering RSO, differential games are formulated and solved for an inspector satellite to achieve multiple inspection goals, such as aligning with the Sun vector or matching the RSO\u27s energy. The developed algorithms lead to fuel and time savings which can increase the mission life and capabilities of inspector satellites and thus improve space situational awareness for the U.S. Air Force

Continuous hydroponic wheat production using a recirculating system

Continuous crop production, where plants of various ages are growing simultaneously in a single recirculating nutrient solution, is a possible alternative to batch production in a Controlled Ecological Life Support System. A study was conducted at John F. Kennedy Space Center where 8 trays (0.24 sq m per tray) of Triticum aestivum L. Yecora Rojo were grown simultaneously in a growth chamber at 23 C, 65 percent relative humidity, 1000 ppm CO2, continuous light, with a continuous flow, thin film nutrient delivery system. The same modified Hoagland nutrient solution was recirculated through the plant trays from an 80 L reservoir throughout the study. It was maintained by periodic addition of water and nutrients based on chemical analyses of the solution. The study was conducted for 216 days, during which 24 trays of wheat were consecutively planted (one every 9 days), 16 of which were grown to maturity and harvested. The remaining 8 trays were harvested on day 216. Grain yields averaged 520 g m(exp -2), and had an average edible biomass of 32 percent. Consecutive yields were unaffected by nutrient solution age. It was concluded that continual wheat production will work in this system over an extended period of time. Certain micronutrient deficiencies and toxicities posed problems and must be addressed in future continuous production systems

Theoretical Studies of Sodium Metal Clusters.

Theoretical methods were used to study small sodium metal clusters. The goal was to find a simple way to model the electronic structure in these clusters that can be used to study large sodium clusters. Monte Carlo studies using Feynman\u27s path integral formulation of quantum mechanics with Bose-Einstein statistics were used to study sodium metal clusters whose valence electrons with opposite spins were paired as bosons. Next, non-atom-based Gaussian s orbitals were used in a Hartree-Fock Monte Carlo procedure. Based on these results, standard quantum chemistry programs were used to test the utility of using non-atom-based basis sets made up of both s and p Gaussian functions to represent the valence electron density in sodium clusters. The Hartree-Fock Monte Carlo procedure was then modified to include Gaussian p functions in addition to the Gaussian s functions. Neutral and cationic clusters with three to six and eight atoms were studied to determine the geometries of the most stable isomers, the correlated energies, and the ionization potentials. Geometries were compared with published geometries and the ionization potentials were compared with experimental and theoretical ionization potentials. The small, non-atom-based basis set was found to be successful in modeling the electronic structure of small sodium metal clusters, and it is applicable to large sodium clusters and other metal systems