Preliminary Assessment of Thrust Augmentation of NEP Based Missions

Science Applications International Corporation (SAIC), with support from NASA Marshall Space Flight Center, has conducted a preliminary study to compare options for augmenting the thrust of a conventional nuclear electric propulsion (NEP) system. These options include a novel nuclear propulsion system concept known as Hybrid Indirect Nuclear Propulsion (HINP) and conventional chemical propulsion. The utility and technical feasibility of the HINP concept are assessed, and features and potential of this new in-space propulsion system concept are identified. As part of the study, SAIC developed top-level design tools to model the size and performance of an HINP system, as well as for several chemical propulsion options, including liquid and gelled propellants. A mission trade study was performed to compare a representative HINP system with chemical propulsion options for thrust augmentation of NEP systems for a mission to Saturn's moon Titan. Details pertaining to the approach, features, initial demonstration results for HINP model development, and the mission trade study are presented. Key technology and design issues associated with the HINP concept and future work recommendations are also identified

Al2O3-films on Ni3Al(111): a template for nanostructured cluster growth

In scanning tunnelling microscope images of thin Al2O3-films grown on Ni3Al(111) at 1000 K two super-lattices with periodicities of 2.6 and 4.5 nm, respectively, can be identified. These well-ordered nanostructures can be used as nucleation centres for metal particle growth. It can be shown that both nanostructures act as a template for the fabrication of ordered assemblies of metal clusters by mere physical vapour deposition. The degree of ordering of these nanostructures is largely dependent on the metal deposited. Here we report on the growth of Cu, Ag, Au, Mn, and V clusters on the Al2O3-films. The best results as far as ordering of the clusters is concerned was reached for V deposition at 550 K, which resulted in a nearly perfect hexagonal array of clusters with a spacing of 2.6 nm